Phaeton :: Surging Of Engine / Momentary Loss Of Power At Normal Highway Operating Speeds


Jan 24, 2014

The primary electric fuel pump in the fuel tank of my 2004 W12 failed last month, shortly after I had set out on a cross-Canada trip from Vancouver Island to Toronto. The whole process of diagnosing and identifying the cause of the problem, mitigating it so that I could continue the trip, and finally replacing the fuel pump was kind of complex, so, here's the write-up.

The problem presented itself as a surging of the engine - a momentary loss of power - at normal highway operating speeds. The onset was progressive, but it didn't take very long - only about 60 miles of driving - from the first little cough of the engine until total failure of the pump. The first indication was failure of the car to maintain speed (while on cruise control) when climbing hills. That progressed to failure to maintain speed on flat surfaces, and finally led to the car coasting to a stop, engine stalled, at the side of the road.

I soon learned that if I floored the accelerator pedal and held it against the floor, the car would cough and burp for a few seconds, then take off like a rocket. So, for the next 40 miles, I coaxed the car into the next city by flooring it, accelerating to about 80 MPH, then coasting until the speed dropped to 20 MPH, and flooring it once again and accelerating to 80 MPH. Fortunately, I was on a remote road with few other cars, and no police.

I checked the fuses for the two fuel pumps - fuses 34 and 35 in panel C (above the left battery), and they were both OK.

The next day, I visited a VW dealer in the Canadian Rocky Mountains, and together with the parts manager and one of the technicians, we looked at the Self-Study Guides (SSGs) for the Phaeton, and looked at wiring diagrams. Eventually, we came to a tentative conclusion that the primary electric fuel pump in the fuel tank had failed. The SSGs stated that the primary electric fuel pump (the pump on the right side of the car) operates all the time, and the secondary electric fuel pump (the pump on the left side of the car) only operates during starting and during 'periods of high demand'. That made sense to us - the car started fine, and worked OK when the accelerator pedal was held to the floor (high demand). It just didn't work worth a darn at any other time... the engine would stall, or, the car would not accelerate at all.

Here are two illustrations taken from the SSGs that describe how the fuel delivery system works. The first image is taken from the 'Phaeton Overview' SSG, which applies to all vehicles. The second image is taken from the W12 engine SSG. I kind of suspect that all the Phaetons operate in the same way, regardless of engine, because the fuel tank in all the Phaetons has the same shape - two lower lobes, which means two pumps are required.

Descriptions from the SSGs

I think that there may be an error in the description above. My experience suggests that the right hand pump (identified as G6, above) is the primary pump, and the left hand pump (identified as G23) is the one that switches on during starting and periods of high demand. Note also how the identification of G6 and G23 in the illustration above is reversed from what is shown in the illustration below. I believe that the text and illustration below is correct, and the text and illustration above is incorrect.

The 'effects of failure' in the description above would, I believe, make sense if it was the left-hand pump that failed. In my case, the right hand pump failed, and the effects of failure that I experienced were as I set them out in the beginning paragraphs of this post - quite different from the 'effects of failure' of the left hand pump that are described in the SSG above.

After coming to the tentative diagnosis that the primary electric fuel pump (the right hand pump) had failed, we checked the parts stock status in North America. There was one pump in stock, but it was in the United States, and being that it was a Thursday, the pump could not be delivered before the following Tuesday. I didn't want to spend that much time waiting for it, so, we started thinking about other possible solutions.

If we could somehow get the secondary electric fuel pump - the pump on the left side of the car that only operated during starting and heavy demand - to operate, that just might put me back on the road again. So, I removed the plastic cover from the small relay that operates the secondary pump, and wrapped a rubber band around the relay, thus keeping the relay in the closed position. A short test drive proved that this solution worked just fine, the car once again operated normally. The only "problem" was that the last 25% of the fuel in the tank would be unusable, because that fuel would be left behind in the right-hand lobe of the tank - the lobe with the defective primary fuel pump.

Electric Fuel Pump Relays

Here is an illustration from the Phaeton wiring diagrams identifying the various relays above the left battery.

Here you can see the two relays for the electric fuel pumps. They are identical part numbers.

Here you can see the relay for the secondary electric fuel pump, with a rubber band wrapped around it to keep it continually closed.

Aside from the loss of use of the last 25% of the fuel in the fuel tank, the car worked just fine with the secondary electric fuel pump running all the time. There were no problems noted even under heavy acceleration. It was, however, necessary to physically remove the rubber-banded relay from its position in the relay panel whenever the car was shut down for more than half a hour. The power to this relay comes from Terminal 30 (battery direct) - it is not switched on and off with the ignition as Terminal 15 power is. This meant that if the rubber-banded relay was left in position overnight, the left hand battery would totally discharge, because the fuel pump would operate continuously all night. I discovered this the morning after the first night...

So, for the next 8 days, I drove across Canada, removing the relay each night and replacing it each morning. I didn't bother to remove it when I stopped for meals or fuel. The rest of the 3,000 mile trip was uneventful - except once, when I let the fuel tank run down a bit too close to the 1/4 full mark, and the car began surging again because the left hand lobe of the fuel tank (with the functional secondary pump) had emptied out. That was a close call, but I managed to get to a gas station and refuel.

After arriving in Toronto, I called the parts staff at my home VW dealer and ordered a new primary electric fuel pump. I discovered that the left and right hand pumps are slightly different (the various hoses coming out of the pumps are different), and I also discovered that a pump costs about $400. The parts staff suggested I order two seals (one for each side of the tank), because I would have to remove both the right and left fuel tank covers to change the right pump. The seals were not expensive.

Here are two pictures that illustrate where the pumps sit in each lobe of the fuel tank. Note the fuel filler port on the left side of the pictures (as we know, it is on the right side of the car) for orientation.

Phaeton Fuel Tank, showing pumps

Fuel Pump Access Panels

Below is a picture that shows where the access panels to the two fuel pumps are. It's easy to get to these access panels, just remove the carpeted panel from the floor of the trunk.

Here's a close-up of the right side (primary) electric fuel pump access panel.

The instructions (from the VW Repair Manual, or the ELSA / ErWin system) for replacing the fuel pump are quite well written. The repair manual suggests that the fuel tank be drained before replacing a pump. I didn't want to drain the tank, so, I ran the fuel level down as low as I dared (remembering that 1/4 full is effectively 'empty' with a failed primary pump). That proved to be adequate.

There are a heck of a lot of steps involved in disconnecting all the hoses and loosening the various components before the pump can be removed. I strongly suggest that anyone attempting this task have a printed set of instructions before starting disassembly.

The fuel pump has quite a few hoses and connections on it, but fortunately, each connector is unique in design, thus it is not possible to hook things up the wrong way when installing the new pump. It is possible to 'lose' a hose inside the tank... for this reason, I attached a small piece of string to each hose I disconnected from the pump.

The process goes more or less like this:

1) Remove the two 404 relays, to ensure no power is sent to either fuel pump.

2) Lift the rubber cover, and remove the electrical connections from both pumps (left and right).

3) Using a special tool, lift up the three fasteners that hold the cap over top of the access panel (these are NOT threaded fasteners!)

Here is a side view of the three fasteners that hold the plastic cap in place - they are friction fit, not threaded.

4) Now you have a clear view of the access panel. It will probably be dusty and rusty, and should be vacuumed clean before proceeding, to prevent crap from falling into the fuel tank when the cap is removed. The rust is due to condensation forming on the cold metal part whenever the car is filled with cold fuel from an underground storage tank.

5) A special VW tool is used to remove the locking ring from the access panel.

6) After removing the locking ring, I buffed it up with a wire brush to remove surface corrosion.

7) The plastic access cap can now be lifted. There are two electrical connectors on each fuel pump, but three possible fittings on the plastic cap. Fortunately, the three fittings are keyed differently.

8) This is what you see inside the tank after removing the plastic cap.

9) After following all the detailed instructions for disconnecting and stowing hoses, disconnecting the fuel measurement probe from the pump housing, etc., it is possible to lift the pump out. It will be full of fuel.

10) The old and new pumps, side by side. I was very surprised at the amount of crap that was trapped in the filter screen at the bottom of the pump. The car only has 60,000 miles on it, and I have always used premium fuel in it.

11) I was also a bit surprised at the discolouration of the pump components. Below you can see the old and new pumps side by side.

12) It is necessary to get access to the opposite side (in this case, the left side) fuel pump, because hoses from each pump travel horizontally across the tank and connect to the other pump.

13) Here you can see a new hose from the right side pump connecting into a T fitting above the left side pump. It is easy to thread this hose across the top of the inside of the tank.

14) As mentioned earlier, there are three possible fittings on the base of each plastic cap, but only two connectors within the fuel tank. Everything is keyed, thus improper assembly is not possible.

Once the new pump has been installed, the hoses connected, and the fuel measuring probe reset into the side of the new pump, re-assembly of everything is quite straightforward. I replaced the rubber ring around the access panel opening on each side of the tank, and I also buffed up the locking rings using a wire brush (to remove corrosion) on each side.

It was not a pleasant job - your hands get covered in fuel, and there are some hazards associated with working on an open fuel tank with vapour escaping, but it is not a particularly difficult job. It is time-consuming, though.

View 24 Replies

Advertisement

Ford 7.3L Power Stroke (1999-2003) :: Intermittent Engine Light / Momentary Surge At Highway Speeds

I have a 1999 F350 200,000 miles. Now getting an intermittent engine light. Still runs well, although once or twice I felt a momentary surge at highway speeds. The light is on intermittently about 1/2 time. I read the codes and the following codes, as in the thread title, came up:

P0280 - ICP circuit out of range - low
P0113 - intake air temp sensor circuit - high input
P0470 - Exhaust back pressure sensor circuit malfunction
P0478 - Exhaust pressure control valve - high input

What would make these all code at the same time? Would these not make a noticeable problem driving? And how do I resolve these?

View 2 Replies

Ford 6.0L Power Stroke Diesel :: Subtle Engine Sound Changes While Driving At Highway Speeds - Surging

I've been noticing some weird, very subtle engine sound changes while driving at highway speeds lately. Something almost like surging, but not. I don't know how to describe it. I might try to make an audio recording next time I take it out so I can explain it.

Anyway, I don't know why but ICP popped into my head. Maybe, for some reason, the engine was varying ICP causing the surging sounds.

So I hooked up AE and did a test. I've attached a screen shot.

With my idle speed actuated as high as it will go, and ICP actuated as high as it can go, I can only get a pressure of about 1450 PSI. I always thought ICP should go higher than that. I seem to recall reading somewhere around 3600 PSI.

So am I misinformed, am I reading the data wrong or do I have a problem? How high should Injector Control Pressure go? I missed it in the screen shot, but ICP is actuated to 100%.

View 14 Replies

Santa Fe (CM - 2007-12) :: 2009 - Loss Of Power When Engine Is Under Load At Highway Speeds

We have had had our Santa Fe for a year, done 38000 km and love it. The car will start up and drive around town fine but as soon as the engine is under load at highway speeds or driving up a hill it loses all power.

In Automatic when this happens the gear will drop back to third. You can switch it over to manual mode and slowly accelerate back up to around 80-90km/hour with your foot flat to the floor but the rpm don't get above around 2000 to 3000.

If you stop and turn the engine off for a minute or so, when you start again everything will appear to back to normal but after another minute or two the problem will be back. The engine malfunction light comes on and sometime it's flashing but at other times it's constant.

The car's been in at our local Hyundai dealer for a week but at this stage they still can't quite figure out the exact cause of the problem. The code they pulled out suggested it was the exhaust particulate filter (apparently quite an expensive part) so they replaced that but it didn't fix it. They've also replaced the fuel filter and some temperature sensors that are part of the particulate filter apparently but still no joy.

View 9 Replies

Ford Aerostar :: Engine Is Revving / Surging Then Falls Back At Highway Speeds

1995 3.0L 6 Cylinder Aero, aka the Green Goblin.

I've recently noticed that when I'm running between 50-65MPH the GG can't seem to decide whether it wants to stay in D or OD, I think. It's hard to tell whether or not the transmission is shifting or if it's just the engine revving. I don't have a tachometer but it's almost like the engine is revving /surges and then falls back, sometimes repeatedly. Could this be due to a vac line leak?

History- GG has 167K on it. I recently changed the oil, plugs, wires, distributor and air filter. Cleaned the MAF. Due to a failed AC compressor and low funds, had it removed and a bypass pulley installed. Needs a new pipe & muffler which is on the agenda.

View 14 Replies

Santa FE SM (2001-06) :: 2004 - Momentary Loss Of Power / Engine Management Light Came On

I have a problem with my 2004 Santa Fe, 2l diesel. Will try to keep this short!

When driving it suddenly 'heaves' (not sure how else to describe it), then it cuts out. I wait about a minute and then it restarts.

At first there was no 'heave' but there would be a momentary loss of power (I thought it was the clutch). Then it progressed to the 'heave' and then cut out, this happened now and then. Very quickly it started to do it every time I drove it. My neighbor mechanic blew down the fuel line, said the fuel pump in tank sounded ok, seemed to do it more when below quarter of tank.

So I kept tank topped up, it seemed ok, then on one 11 mile journey it did it 3 times, the last time the engine management light came on, crawled it home, after which it would not start at all. The computer said it was either fuel rail or coolant sensor. Neighbor replaced coolant sensor, it started ok. Tried it next day - 6 miles and it heaved and cut out again. This time no light coming on.

I've read about cam sensor, crank shaft sensor, fuel pump at back of engine...

View 5 Replies

Ford F-150 (2004-2008) :: Momentary Moan / Growl And Bog Down At Town And Highway Speeds

5.4L... My truck has a momentary moan / growl / bog down issue. It happens at town and highway speeds and usually when I have cruise on OR when I lightly apply the gas peddle. It moans for a few seconds and seems to bog down then comes out of it and carry's on its way. You can hear it plainly while driving even with radio on. I have a regular muffler on the truck but when this happens, it makes it sound like I have a catback on it.

Things i have done...

- New air filter
- New oil/filter
- New fuel filter
- Ran techron injector cleaner through tank of gas

View 6 Replies

Ford 7.3L Power Stroke (1999-2003) :: Surging Noise While Driving At Highway Speeds

I have a 45 min drive to work every day, all highway. Lately on the way home in the afternoon I have been experiencing a surging noise that seems to just happen while I'm doing hwy speeds. It sounds to me like the fan is tuning on and off. Is that possible? It comes on for a few min. And then off again. I have new icp ipr cps. New oil and filter and fuel filter.

Also I'm still having a battery light on and off issue while I'm driving. Is possible the two issues are connected. I plane on doing extensive search for a bad wire this weekend. Batteries and alternator have checked out and are fairly new.

View 5 Replies

Golf IV / Jetta IV :: 2002 VW 2.0 - Loss Of Power While Driving At Normal Highway Speed

Ok, so I was driving normal highway speeds and all of a sudden, I realize a major drop in power. I pull over and restart it and it changes nothing. Now when I floor it, it takes 20-30 seconds to get to 90K.

I checked the air filter... Nothing. Used a code reader... Nothing. Then I decided to pressure test the cylinders... Nothing, except now the check engine light is on.

The Ol Dub is still drivable, but it is extremely slow and rough at idle. I am thinking it might be a MAF or fuel filter.

View 5 Replies

Nissan - 300zx :: Engine Surge At Highway Speeds For Several Seconds Then Drops Back Down To Normal

my 1990 Nissan 300zx with 136,000 miles often surges at highway speeds for several seconds then drops back down to normal. the surge is usually 1000 rpm. does not happen if not in overdrive, and will not happen unless having been driving for 15 minutes or so. also seems to occur more on hot days (80 degree +) than on cool days. mechanic has looked at this several times but not yet able to determine why.

View 2 Replies

Phaeton :: Sudden Loss Of Power When Driving At Around 140KM/H On Highway

I've been driving my V10 for 3 years now without a problem. The other day, while I was on the Highway in Italy driving at around 140KM/H, I suddenly had a loss of power. I could continue to drive the car, but I had no more tork... I stopped at the next gas station, turn the engine off, turned it on again, and the car drove normally again as before. About 200KM later the same happened again...

I went to check with the dealer - he hooked up the car to the computer - and told me that they had to change both turbos... What I find weird is that when I turn the car off and on again it works again. If the turbos would be defective, they wouldn't work again just by turning the car on and off. I think that it is more a problem with the turbo controller and if that's the case why change both turbo.

View 12 Replies

Passat (B5) :: V6 Tiptronic - Momentary Loss Of Power

2001.5 V6 Tiptronic ... A few times in the last couple of months I've felt what I think is a quick lapse in power, like 1 sec. or less. I say "think" because sometimes a bump in the road, traction related, or some other perceived issue can feel strange, especially when cruising along on a smooth cruise-controlled drive.

Each time this has occurred I've been in cruise control, freeway driving, relatively low speeds (65 MPH) . No other signs of anything wrong, chimes, flickering lights, vibration, nothing.

I can't be sure this time around but it seems in the past it's been on the same stretch of freeway, perhaps the same spot. In other words perhaps just a subtle anomaly in the road ...

View 6 Replies

Jetta - Volkswagen :: 2011 TDI - Momentary Loss Of Power

I have had the car sense it was brand new and sense I have had it I have had this problem. I mostly notice a problem soon after starting the engine up and come to a stop, but is not limited to that all the times. When I come to a stop the car will feel like it is struggling to maintain an idle as I sit at the light or stop sign and it will actually shake the car a bit. I have noticed when it does do this the fan is on and it might be related to having the alternator trying to keep up with power draw.

I have noticed a loss of power when I am driving down the road it will cut out for maybe a half a second and come back. Usually doesn't happen more than once in one trip. I have brought it to the dealership multiple times to try and see if the can hunt down a problem but it keeps coming back with a clean bill of health. So my question is it something that is normal with diesel engines or is it something that I should take a further look at.

And while on the topic of diesel engines, my uncle a mechanic for diesel engines suggested that I spray a small amount of propane into the air intake to burn up sludge to keep the engine relatively clean. Need to get second opinion of that idea before I try it?

View 4 Replies

Santa Fe (CM - 2007-12) :: 2009 - Momentary Power Loss While Driving

The car started rough idling and a few weeks ago while driving "lost power" momentarily. I went to take a look at it and even just idling it will randomly drop 1000 rpm, or when the gas is one in P it does the same thing. also the dash lights dim at the same time.

I pulled these codes (below). I cleared the codes and tried to replicate with no luck. The car had been sitting in a parking lot outside for a few days and it has been -15C. I asked if it seemed to only happen when it was warm (the week before it was +10C) and they said yes. It has been another week (still cold) and the codes have not returned.

Quick google of these codes suggests maybe a throttle position sensor and/or loose battery connection.

View 8 Replies

Ford - Mustang :: Sudden Momentary Loss Of Power When Accelerating

It did this funny thing about 4-5 times over a span of about 24 hrs before dying and then won't start. It was like hitting the limit on a speed governed car.....sudden momentary loss of power..and it seemed to be when accelerating if that matters. The thing I'm sure of at this point is that the fuel pump is not coming on when the key is turned, I know that sound well, but also checked it at the external connector with a test light for thoroughness. I also found a blown fuse under the hood which coincided with a little smokey smell inside the car when the fuse was replaced and blew again.

There is no spark as well. My Haynes book says that the PCM is behind the passenger kick panel but I only see the eecv and it doesn't smell burnt. The IFS is good. There is power at the coil packs. Fuel pump relay fuse is good. Is it more likely the ccrm since it contains the fuel pump relay and PCM relay or could it still be the eecv? It feels like one part failed but is causing more than one "problem", no power to fuel pump and no spark.

View 19 Replies

Golf IV R32 :: Hard Acceleration In 3rd Gear / Momentary Loss In Power

Having problems where sometimes the car won't go into gear, other times it's fine? The problem started after some hard acceleration in 3rd, there was what felt like a momentary loss in power. I dipped the clutch as I thought a boost pipe had popped off, all was fine (still seeing boost when revved). After this it got progressively harder to get gears, finally resulting in not being able to get into gear at all.

I found I could get it into 1st with the engine off and could go up gears normally, but couldn't change down without stopping and turning the engine off. The clutch is working fine, the biting point is normal. The problem seams to come and go randomly, it will work fine for a while and then start playing up again. When working the gearbox feels normal, there is no grinding or wining noises. I can move between gears normally and do clutch less gear changes.

There is now a vibration which can be felt at 1000rpm when stationary. It feels like it coming from the engine/gearbox and seems like something is out of balance as it shakes the whole car. The car is on 91k, supercharged running 470hp & 370lb/ft (at flywheel) and is fitted with a Spec stage 3+ clutch and solid flywheel.

View 10 Replies

Lexus SC430 :: 2002 - Intermittent Hesitation Or Stumble / Momentary Power Loss

When I take off from a start it will intermittently stumble or hesitate, seems to be around 1500 rpm. have also noted it at higher speed while cruising. its more like a momentary power cut than a miss fire.

So far I have done the following

new fuel filters
clean MAF
new PCV valve
new spark plugs
check all hoses and plugs etc
injector clean
checked techstream for codes. there is one for a heated O2 sensor but dont think thats it.

2002. SC430

View 3 Replies

Intrepid :: Won't Start Up When Engine Is At Normal Operating Temperature

Sometimes, when the engine is at normal operating temperature, it won't start up when I turn it off. For example, let's say on my way home I stop off in a supermarket to pick up some stuff. I'll come back out 20 minutes or so later, only to find out my car isn't starting. I'll turn the key and the engine will crank, shake and then immediately die on me [I'm under the impression the engine isn't even starting at this point because tapping the gas does nothing]. Again, this is a problem that is only happening sometimes. I can do the same routine tomorrow and it'll start up flawlessly.

1) This is only an intermittent problem. The problem doesn't seem to be occurring more frequently, but when it does happen, the engine is harder to start. For example, the first time this happened to me, I got it started after one or two tries. After my latest episode, it took me 11 tries to get it running!

2) After the engine does finally start, the engine will run really rough and shake a lot until I tap the gas a few times (which is leading me to believe this is some sort of fuel related problem [sometimes, the engine will start on one try, but will run rough until I tap the gas a few times]).

3) When the car is cold, it starts up flawlessly every time without fail.

4) The car runs mint! No hesitation or otherwise stalling, etc.

What I've done so far to try to remedy the problem:

1) Changed spark plugs

2) Fuel line cleaning/flush

View 7 Replies

Camry :: XLE V6 - Tapping Noise When Engine Is Not At Normal Operating Temperature

I have a 2003 Corolla with 178K miles and a 2007 Camry V6 XLE with 30k miles. Both make a tapping sound when the engine is not at normal operating temperature (when the engine is still cold during the morning). I've changed the oil regularly on the Corolla with 5W-30 oil every 5k miles. I'll be making my first oil change on the Camry in about a 1 week.

The tapping noise goes away once the engine gets warm. Is the tapping noise normal? I don't hear this noise from our Honda Odyssey, which uses 5W-20). Can using a different weight oil work?

View 3 Replies

SC/SL/SW :: 98 SL2 1.9 DOHC Idles Really High At Startup Until Engine Gets To Normal Operating Temperature

Idles really high at startup until the engine gets to normal operating temperature and falls back to normal. Takes 10-15 minutes. I recently de-greased the engine and think I may have fouled a sensor...though the check engine light is NOT on. I'm afraid if I keep this the way it is it will cause damage to the engine.

View 2 Replies

Nissan - Altima :: 1997 GXE Stalling When Engine Warmed Up To Normal Operating Temp

I've got a 1997 Nissan Altima (automatic, GXE). Recently it has started stalling. Usually this happens when the engine has warmed up to normal operating temperature (though last night it happened when the engine had just started).

Usually when it stalls it will start right back up, but sometimes it takes a few minutes. Sometimes it will start back up and die right away, other times it will turn over and over but not start. After a few minutes it will start back up. Sometimes it will stall momentarily and then restart right away, but not usually.

The rest of the time the car runs smooth as ever, no surging, no stalling, no erratic idling, no sputtering or anything. Usually the check engine light will come on after a stall, but I get a "no code" code when I check.

This started about two weeks ago, it did it once on a Saturday and then didn't do it again until Wednesday. Since then it has happened at least once a day, and yesterday it happened a lot while I was driving home, but not at all when I headed to work. Today it was fine for about 15 minutes and then started doing it a lot, but the last 3 or 4 miles it was fine again.

What may be the problem? I'm going to check the MAF and throttle position sensors, though I would assume if they were malfunctioning I'd either have more symptoms or I'd be getting a code.

View 10 Replies





Copyrights 2005-15 www.bigresource.org, All rights reserved