Ford F-150 - 1997-2003 :: 2002 - Stumbles - Hesitates During Acceleration - Fuel Pump?
May 19, 2010
My 02 F150 4.6 has 84K miles on it, and started stumbling/hesitating during accellartion about three weeks ago. Before this problem started (about 2,000 miles ago), I installed a new fuel filter and air filter. Since I noticed the problem, I installed new plugs. The problem didn't go away, so today I checked the fuel pressure. At idle the pressure is 32psi with the vacuum line left on the fuel pressure regulator (30-45 is normal as per Chilton's), and 42 with the vacuum line off (40-50 is normal as per Chilton's). I also had someone else rev the engine so I could observe, and found that the fuel pressure went as low as 28 when the engine speed was quickly increased. The standing fuel line pressure is 30 (30 is normal as per Chilton's) Does this sound like a fuel pump problem, or is there something else that I'm missing.
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2001-F150 5.4 Eng. bucking/stumble. I think my problem is slightly different than what I am reading about. Here is what I get (125k miles):
* Engine only bucks/stumbles intermittently and not at idle or at harder acceleration (this bucking is really harsh and makes the truck feel like a learner trying to drive a manual transmission and it is jumping down the street). The engine stumble is not a regular timing such as a cylinder going out and staying out for a period of time. It is quite a random pattern to the jumping
* Originally thought it was humidity related, but now I realize it happens in any climate
* No stumble in neutral at any rpm... only at a stop if I put it in a power brake load.
* When the stumble shows up, it seems like the throttle is around 10-25% (my best guess)
* Sometimes goes days without issue, but sometimes every ride and virtually every acceleration.
* Normally no stumbling at highway speeds, unless going up a hill.
* Every time it stumbles, it can be eliminated by either backing off on the accelerator some, or hitting the accelerator harder.
* No engine codes or CEL has ever come on
* Fuel mileage appears to be the same before and after the trouble started
Here is what I have done to try to correct it:
-> Fuel related (bad gas)... tried to run the tank as close to empty and fill it with fuel from different stations... when this didn't work, I have added HEET to it to dry up any water in tank.
-> Fuel delivery... replaced the fuel filter... seemed to work for one day, but then the gremlins came back.
-> Fuel delivery... ran multiple injector cleaners through tanks of gas.
-> Intake... replaced the filter.
-> Electrical... I don't believe this is related, but my battery died... parts store tested the system and stated the alternator was bad... replaced it, and took the old one to the parts store for bench testing and it was 100% OK... even thought the old showed OK, I left in the new one as a precaution. Only other item was a set of plug changes around 30k miles ago... I think I put in the super duper Bosch plugs with a lifetime warranty.
Current thinking and items I don't understand:
A) The bucking is so severe, it appears to be a random harsh loss of either fuel or ignition. A component that has failed electrically should give me a fault code with this level of severity. No trouble codes or indicators to electrically sense this disturbance...
B) For the fuel path, the most likely item is bad gas and I emptied my tank by running it as close to empty as possible and then used different gas and HEET to eliminate water. THIS MIGHT STILL BE THE CAUSE???
C) Another one for the fuel path is an intermittent fuel pump electrical connection or a weak pump from a pressure point. But if this is the cause, then why does it dissappear upon harder acceleration?
D) One last fuel thought is injectors... perhaps one or more have a range of delivery that they don't work properly... but this doesn't make much sense as at idle and harder accels are fine
E) From an ignition standpoint, perhaps I have failing COP's. I have not just gone out an replaced them due to my limited budget and the difficulty I read about changing them. Again, if one of these is failing in an either open or short condition, the computer should set a code for a misfire for the related cylinders. I get nothing. Hence my hesitation in making this change so far.
One thing i don't understand from the various posts is that the cops can fail under loading. what makes this happen as electrically, i don't think they can detect a load or not? it is hard for me to also understand why my truck would allow me to back off on the throttle or hit it harder and the issue disappears.
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I've got a misfire problem with my Focus. It started about a month ago and did not trip a code until last week. It stumbles on acceleration between 2,000 and 4,000 rpms. It is only a slight stumble and although noticeable, it does not impede driveability much. Last week I was able to get it to finally trip an OBD code. P302 - Cylinder 2 misfire. I changed the plugs and wires with no effect. I thought I had it narrowed down to the coil or injector until my wife noticed a new wrinkle.
Under normal driving conditions the misfire is annoying, but my wife found that if she turns on the A/C, it is undriveable and will not accelerate past 30 mph without some patience and a neck brace for the bucking. My first thought was the A/C compressor was freezing up. I turned off the A/C and left the blower on and it would not stop missing. I turn off the blower and it smooths right out to the annoyance I described first.
Right now I drive the car without A/C and blower whenever I accelerate. If I'm going a steady speed, all is well and I can run the blower and A/C.
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The car takes off from a stop as it should. However, it shifts hard from 2nd to 3rd gear and that's when it stumbles and doesn't want to accelerate. It'll go if you press pedal at least halfway down. It runs great other than that. It only has 60k.
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I've got a 1997 4x4 xlt with a recently rebuilt engine less than 2000 miles on it I just replaced the fuel filter fuel pump and the relay and what's wrong some times the fuel pump will turn on sometimes it won't don't know what to do now. It turns over just not getting fuel I'm know the pump isn't getting power since I can't hear it kick on...
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I have a 2000 F150 with @175K miles. Replaced the clutch about a year ago, replaced the front calipers a few weeks ago, due to the right front locking up on my way home from work. Since then, when I try to start, it blows the fuel pump fuse. (#10)...
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I've got a strange problem on my '01 F-150 4.6L 4X4. When the outside temperature gets below 40-45 degrees the fuel pump won't always run when trying to start the truck. You can cycle the key switch on/off 8-10 times and the fuel pump will run. The engine will then start and run fine. You probably have to use this procedure 80% of the time. It started this last winter. I replaced the fuel pump relay in the power distribution box under the hood but that did not work. When the outside temp warms up the problem goes away.
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My van stumbles & hesitates when I am gradually accelerating up a hill. It does not happen if I accelerate quickly or on level ground. It only happens going up hills slowly. It can be very violent.
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How do you test the fuel pump regulator, the truck wont start. I tested the schrader valve and it does have pressure but didn't seem like much. (need a gauge) I replaced fuel pump a few years ago so was wondering about the regulator. Is there a test procedure?
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Drove for 25 miles. Park, try to restart to park truck at other place. Truck start but very rough. Did drive for 20 yards and truck stop. Try to restart no way. I think I do not hear fuel pump when I turn key and gas pedal fill completely empty, no any force to move it. Should I assume fuel pump or should check some sensors first? I have P0420 for a few weeks, not source of this problem. Drove truck before with P0420 for years. No other code. Do we have PATS in keys? My truck is f250 99 LD. My pickup have PATS. How to check it?
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My brothers 2001 is having an issue with the fuel pump. It has a random no fuel pump basically the fuel pump does not come in, he turns the ignition off then back on and you can then hear the fuel pump turn on and the truck starts and runs normally. I'm not looking forward to dropping the tank to replace the sending unit so I was thinking maybe the relay is the issue? I'd eater do that than a sending unit job...
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New to this site, my problem is on my 2003 4.6L fuel pump not working.My problem is that I am not getting voltage to contacts on pcm and fuel pump relays.
Getting volts to #30 fuse 30amps ok, voltage to pcm diode ok. Voltage on #30 on both relays(pcm & fuel) but I am loosing voltage across coils contacts #85 & #86, these makes hot #30 & #87 to make pump work. Inertia sw ok, Don't know if PCM is bad, ck fuse #2 ok 5 amps.
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I have a 1998 Ford F150 with 4.2.. Started off a intermittent problem of not starting acct no fuel. Now will not start at all. Checked all fuses and relays.. Am not getting voltage at fuel pump. Changed ECM thinking that was the problem.. Have checked all multi wire connectors for corrosion and tightness. Am at a lost what to try next.
Also, not sure if its related or not. The turn signals and hazard flashers do not work. When I turn on the hazard flashers, nothing happens. If I leave the flashers switch on, the turn signal work. Checked all fuses and relays and they appear good.
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I own a 2003 Ford Ranger 4x4 Automatic with the 4.0l V6. I bought the truck a little over two years ago with 150k miles. The Engine had alway had a slightly rough idle and I never really noticed until a friend pointed it out at around 170k. Every time the pump engages after a short warm up period there is a distinct stumble in the engine, although it never stalls or trips a check engine light. I have replaced the spark plugs with four prong pre gapped Bosch platinum plugs and new plug wires as well. I have installed an Optima red top battery that tests at 1100cca and have tested the voltage draw when the AC engages and it only drops .2 volts from 14.48v to 14.24v. I thoroughly cleaned the MAF sensor and before changing plugs I ran a can of non chlorinated brake cleaner through the throttle body to clean out carbon deposits and dirty throttle body. The engine still stumbles. Yesterday at 182k I disconnected the low pressure switch on the AC pump and boom, smooth low idle with no stumble. What could be wrong with the AC pump that could cause this stumble in the engine?
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Ok so I have a 2002 f-150 4.2. I was replacing the PCV elbow that always crack and I figured while I'm down here, I might as well replace the PCV valve as well. I have the PCV valve that has 3 connections, 1 to the crankcase and then 2 "vacuum" type connections connected to the water pump and is full of coolant of course. What am I missing here, I though sometimes these things were connected to a vacuum line, is this some kind of heater for the PCV?
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Ok I have recently bought a 1998 Ford F-150 V6 4.2L 2WD and when the guy sold it to me the check engine light was on and he told me that randomly when you turn the key to the on position you will not hear the fuel pump buzzing sound and he knew it wouldn't start, he said you would have to turn the key from the on and off position many times until you hear this sound and then the truck will start and run fine.
First off I got the codes read and there were three of them P0171, P0174, and P1537 some things to note are that the drivers air bag looks like it had deployed, the cover is loose and when I pulled it back the air bag looks duct taped up inside there that would cause the air bag light to continuously flash while driving. I noticed the battery leads were corroded so I replaced the battery and put new battery clamps on both wires, after that the problem did not happen for a week and I though it was over but it happened again.
Next is that the truck has the PATS system and it did not come with a remote which I have also read that the PATS system can cause the fuel pump not to turn on but not sure if this would cause it to not start randomly because sometimes it starts right up. When I started to look at the simple things to fix I noticed it did not have an air filter in the housing. so I thought the MAF sensor could be dirty so I cleaned it with the special cleaner, I put sea foam into the intake via a vacuum hose and also have put a fuel system cleaner in a full tank and have driven most of the gas out. After putting in an air filter, cleaning the MAF sensor, and sea foaming the intake, it seems to run a bit better but I am still having the random fuel pump issue.
I have checked the fuses and the and the fuel pump and ECM relays both are fine. Today I put new exhaust on it because it had some bad exhaust leaks and the truck did not start again, so the guy trying to put my exhaust on, hit the fuel tank with a hammer and it didn't work then hit it again and it finally worked. Im not sure if the hitting it did it or if it just randomly turned on like always from turning the key on and off. The new exhaust has made a huge difference in driving it feels and sounds much better.
Also to note is that when I am stopped at stop lights it will idle at about 1500 and then it drops down to 500 and back up and back down again and it does this at most stop lights, and it is not an abrupt drop it just slowly idles down and back up again. Again once the truck is started it runs perfectly fine with no issues, and there are no specific times when it has the problem it seems to be randomly. I know that many people will tell me to change the fuel pump out and I am already prepared for this but if there is any easy things I haven't thought of yet...
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1999 4.6L won't start after sitting a month. Ran fine before, now won't start. Cranks fine. Cannot hear fuel pump turn on when key is turned. Fuel pump fuse is good.
Fuel pump relay clicks a few times when key is turned. Is this normal? I am hoping it is the relay and not the pump. What should I check next? The wires at the pump? What should they read?
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I have a 2002 f-150 4.6 that sometimes has a miss upon acceleration but not all the time.the truck is a 4.6 with a manual trans.has no engine codes and scanner never show a misfires but sometimes it does , have replaced all spark plugs and coil boots twice.
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I just got delivered a 7.3L from down south. Batteries were dead so replaced both. Fuel was a couple notches above red line (much closer to red line than 1/4 tank) so I added about 7-8 gallons.
It will crank forever and ever...Won't start.
With starter fluid it starts but not strong enough to pump the pedal and rev it up to keep it idling.
I know s-fluid is bad but if I continuously spray with key turned forward it will run but as soon as I let go of key it shuts off.
20 degree weather and it was delivered to a parking lot so I cannot plug it in.
Was told to check filter cap, turn key, and see if it fills bowl with fuel....if not then it is fuel pump. Someone else mentioned that it could be bad crank position sensor? Does this sound like fuel pump?
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I just checked my computer I have a couple codes
P0453 evap emission system pressure sensor/ switch high
P0232 fuel pump secondary circuit high
C1303 right front isolation clamping circuit..
P0305 cylinder 5 misfire.
I changed the fuel pump 2 days ago and the coil on cyl 5.
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2002 F-150 4.2L. About a year ago, it threw the P0171 and 0174 codes up. After replacing all the simple stuff, I bit the bullet and replaced the lower intake gasket as well as the upper intake gaskets. Buttoned it all up, reset the codes and we were back in business. No issues, truck ran good. About 6-8 months later, the check engine light came back on, I check it and it was that pesky set of codes again, 0171 and 0174.
It still ran fine, but the codes were there, so I just drove it for a while (it's a company truck that doesn't get driven that much).
A couple of weeks ago while driving it, it acted very sluggish. You could mash the accelerator and it would just very slowly run up the speed. It never hesitated or missed, it just got very very sluggish. Checked the codes, no additional codes.
Then it began to stumble when you mashed the gas.
I put new plugs (old one's looked great, other than a huge gap), new wires, new coil pack and started it. Pushed the gas pedal, it just dies.
I look for obvious vacuum leaks and replace a couple of elbows for the PCV and it seems to run a little better. Enough so that I can drive it, but still not running right.
I ordered all the intake gaskets and new isolator bolts and spend Saturday pulling that apart. I didn't do the lower intake because the upper intake gaskets looked so good, I just don't believe this is a intake gasket problem. None the less, I installed the new gaskets on the plenum and upper intake, new isolator bolts, replaced a couple pieces of vacuum hose that looked cracked, started it back up, it ran as smooth as silk.
Convinced I had it fixed, I went for a test drive. Idling, it is as smooth as you could ask for. Pull up to a stop sign, wait, step on the gas and it chokes. Just stumbles and you can hear it almost backfiring and pushing air back through the system.
I've put new PCV, new EGR, new vacuum lines in several places, new upper intake gaskets, new plenum gaskets, new isolator bolts, and even new o-rings on the injectors, and I'm still getting the 0171 and 0174 codes.
With the diagnostics on, I can see voltage varying on all O2 sensors, so I assume they are working (none of them are reading 0 volts). It doesn't throw any other code up, other than the 0171 and 0174.
At this point I feel like I'm replaced every single thing ever mentioned in any 0171 and 0174 thread on the internet. Where to go next? 1 more point, if you very slowly push the gas, it runs fine, but any pressure on it, it bogs down and just stumbles.
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