Ford 7.3L Power Stroke (1999-2003) :: Fuel Pump Runs Only When Low Beam Lights On?
Jul 2, 2016
Went to start my truck (2003, 7.3 F250) one evening and I found the headlights on. No keys in the ignition and the truck hadn't been driven for 2 days. There was a strong smell of plastic and or electrical components burning in the cab. The truck started without a problem. I shut it off and the lights remained on. Cycling the MFS and light switch would not turn the lights off. I had to disconnect the batteries and leave it till time allowed for trouble shooting.
I've had it in my shop for three months now and this is what I've found so far.
-Source of the burn smell is coming from the fuse panel. More specific it's coming from a bulkhead that plugs into the panel. One pin connected to a White wire with 2 purple traces. I've traced this wire to one of 2 small relay packs in the engine compartment next to the driver side fender. I've replaced the relay this white/purple wire connects to as a precaution. This did not remedy my trouble.
-The local ford dealer told me this relay was for the A/C clutch. I located a 10amp fuse in position 10 and removed it. The headlights finally turned off.
-I started the truck and the A/C compressor clutch still engaged and ran. Smoke began to pour from the fuse panel once again. I killed the truck and head lights remained off. All done with the fuse in position 10 removed.
Here's where it gets weird!
-With the key/engine off and I turn the headlight switch on and MFS to low beam the fuel pump is running. Change the MFS to high beams and the fuel pump turns off.
I've looked over the wiring harness and there are no noticeable problems indicating multiple wires being shorted. How are all these issues related?
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This applies to a 2001 F-350 with 73,000 miles on the engine. Engine oil level is good, batteries charged, HPOP reservoir is full and passes Cody test with flying colors. Fuel pump runs for 20 seconds at key on. Start takes about 6 seconds. If I shut the key off and restart immediately it starts in under 2 seconds but if I wait about 30 seconds it's a 6 second start. Here is an AE that I ran on it, it has me stumped. FWIW it seems to start quicker when AE is hooked up. ?? An odd whir type of noise comes out from somewhere under the hood when I first turn the key on and when I clear the codes with AE.
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01 7.3. Cranks, won't start. Tank was at 1/4 but is full now. The lift pump runs, I can feel and hear that the motor is spinning when I cycle the key. I removed the fuel filter and cycled the key and get no fuel into the bowl. It looks like the lines are stainless from the pump to the tank so I doubt it is sucking air. I pressurized the tank with a shop vac and I get fuel coming into the filter housing. Am I missing something obvious? I have never seen an electric pump that would run and not pump fuel. I removed the suction line at the pump and don't feel any suction there.
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Just joined today, I have a 2003 550 7.3. New HPOP, 3 new injectors, new seals on others, new fuel pressure regulator, new fuel pump, sending unit mod to eliminate filters. 733 HPOP pressure, 65 fuel pressure at idle. Truck runs out of fuel pressure after its warmed up and driven about 20 miles. Haven't checked voltage at pump while driving. I had taken it to a seasoned tech of 20 years and he had replaced HPOP and 2 injectors and it does start better but problem is still there.
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The relay for the fuel pump keeps going bad. Is this a sign my fuel pump is going ? I just replaced my 2nd relay ( lasted about 1 week ) 1st lasted 16 years. Or is there another issue to look at ?
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Every time I hit a hill, loaded or empty, or get on the truck on level ground after about 15 seconds it acts like it's running out of fuel. The pump starts getting noisy like it has air in it, but it'll straighten out eventually. If you don't let off the fuel it'll eventually stall out. No check engine light, no codes. Truck has a ts chip but it does it on all settings. New fuel filter, changed oil with hot shots secret, new air filter, hutch mod done. I'm at a loss for what to do. Good fuel pressure also.
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2003 F-350 - 7.3. With the key in the on position there is zero voltage to the fuel pump. Fuel pump fuse is good. I traced the red with black tracer wire from the pump up through the firewall and to the safety inertia switch. The switch has continuity so it's OK. Then from the safety switch I traced the green with yellow tracer wire to a fuse block plug connector. Then I checked continuity from that connector out to the #40 fuel pump fuse and it's open.
So I then i checked from the fuel pump fuse to all the back connections on the back of the fuse block and there was no continuity to any of them. So I removed the back cover off the fuse block to expose any issues. I found two board mounted relays. Now, from the fuse I get continuity to one of the relay connections. So did Ford hide the fuel pump relay and make it non replaceable? Also if this is the pump relay then what circuit energizes it? I need to make sure before I replace the fuse block.
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I have a 2003 F250 and dont have power at fuel pump, or fuse #30. I put power directly to fuel pump and it worked and truck fired right up.
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There was no power getting to the fuel pump on my 2002 Ford F250 73 diesel traced it back to the inertia switch no power in or out but I'm getting power at the fuel pump relay put the code scanner to the PCM and no communication....
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So the other day my 20amp maxi fuse for my fuel pump decided to blow, put a new one in & everything has been going good since. Is it just a fluke or is this an indication my pump is going out? I inspected wires off the pump & connections for corrosion & that's good, fuel filter is also new about 2 months ago & I always run #1 diesel with a little additive in the winter.
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I was wondering if it is possible, due to budget, to perform the electric fuel pump conversion in steps. By that I mean could I remove the mechanical pump and install the electric pump on the frame, but retain the stock filter housing and regulator? I would use high pressure hose and run from the stock pump supply line on top of the engine to the fuel bowl inlet and then use high pressure to run to a three way fitting, and a bit more hose to join the fitting to the stock lines running to the head. later as budget allow I will replace the filter assembly and regulator and then the lines to the heads.
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I was driving my truck then all sudden truck started losing power then slowly died. I restarted it, it was a lil shacky then died again. Iunscrewed the fuel filter and looked in the housing and there was lil fuel in bowl i turned the key to on position and bowl did not fill with fuel looked as if it were shooting some bubbles up(air) could it be outta of fuel???
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Where the fuel pump is located on a 2000 F-350 7.3L Diesel? Also, how complex is replacing this?
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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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My 16 year old F250 4X4 diesel has developed a problem with no backup lights working, and the vacuum pump is not getting power. The fuse (#28) checks out OK, and I'm told to check for a broken wire on or near the backup switch. I don't know where to locate the backup switch. I have the huge Ford Service manuals, but they are written with the perspective that you should already know where the switches are. Where to find the switch?
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I am installing a fuel pressure gauge into my 02 7.3 I went to the thread the sensor into the plug hole on the fuel filter housing and it wasn't threaded, turns out the sensor thread is slightly smaller and a different thread ... The directions say to install it into the filter housing or the lift pump ... So I'm assuming I have to go the lift pump direction of installing it but where the lift pump is or how to install the sensor into it while not throwing a code or causin problems ... A step by step and even pictures.
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Stuck 398 miles from home. Car kept losing power, running out of fuel (even though I had a quarter tank). Stopped and filled it, but could only barely get to next exit. Step on gas- no go. Let off gas, car catch back up and run. Wife noticed definite new sound in back. Took her many miles and comments before it finally sunk in and I remembered the same groaning noise from a fuel pump going out on a cabrio. So, fuel pump bad.
Am preparing to go out and jump terminals, as per bentley manual. That should tell if it is transfer pump or fuel pump. My main concern now is are the pumps under the rear seat or in the trunk?
By the way, I made it to a motel (lucky enough one that accepts pets!)
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I am going along and the power just goes away. Sometimes it is a 50% loss other times it is an 80% loss. I hooked up my scanner and found an IPR code. I replaced the IPR and connector, nothing changed.
As the scanner info shows the Duty Cycle and Pressure track about identically until something goes wonky. When I loose about 50% power the pressure will not get above about 1500 psi but the duty cycle will run up to 60%. Other times when I have a bout an 80% loss the pressure and duty cycle both track low, no more than 1200psi and about 20%.
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My truck runs very rough and lacks power when cold, even during the Texas summer. Once it warms-up, everything is fine. It's almost like turning on a light switch. If it's plugged in for a couple/few hours, it's smooth as soon as it starts. I'm assuming it likes the oil once it reaches a specific temperature. What my problem is?
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Been fighting a coolant issue on '02 F250 4x4 with 7.3. Truck runs hot when under load (ie towing, or ac running on a hot day going down the road). Will sit and idle all day with ac on high and 100 outside. I hear my fan at cold start as normal but that's the only time I hear it. Still has original water pump, fan clutch and radiator. I know all three could stand to be replaced with 340,000 on it. But can't afford to do it all at once.
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Changed CPS,EBPV sensor and tube,replaced IPR&fuel pressure regulator,batteries 100%,HPOP full,oil level full,fuel in bowl and lift pump runs(have not tested pressure but has good flow).After replacing IPR truck started quickly and idled for 15 minutes,decided to try a test drive ,truck stalled after reversing 10 ft as I shifted into first gear.Now no start!!Losing my mind.
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