fuel pump issue
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fuel pump issue
Truck is a 2001 f350, V10, 4x4. Having intermittent starting issues, checked all the relays including the ones located behind the dash near the radio. Can't find anything wrong on that part. Issue may be temp related, seems to act up when it's cold out, less than 40 F, but that may have nothing to do with it. One thing that seems to effect the issue is the igntion switch/key, sometimes turn the key and you can hear pump kick on and prime, may work several times in a row, pull key out, re insert, turn it and pump won't kick on, giggle key, turn on/off a few times and pump starts kicking on like it's supposed to. I guess question is, is there something in the ign switch that could cause my problem, it sure seems like it.?
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From: Southern Cal
Your fuel pump only works in the start position, and then the run position but only when the engine has fired.
There is a fuel pump relay that actuates the fuel pump and the ecu needs to determine the engine is operating in a split second to keep the fuel pump operating. A safety factor.
You might first check the relay, then the fuel filter to ensure no obstruction, and then finally the fuel pump.
Not sure how many miles but if these guys are driven with 1/4 tank or lower regularly, I'd expect 125-150k miles before failure.
There is a fuel pump relay that actuates the fuel pump and the ecu needs to determine the engine is operating in a split second to keep the fuel pump operating. A safety factor.
You might first check the relay, then the fuel filter to ensure no obstruction, and then finally the fuel pump.
Not sure how many miles but if these guys are driven with 1/4 tank or lower regularly, I'd expect 125-150k miles before failure.
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it's really acting like the switch is involved in the problem. I checked the relays, they bench test fine. I'm doubting it's a pump problem, when I turn the key I can hear if the pump kicks on/primes, if it primes it starts and runs fine, if I don't hear the initial prime it will crank but not start, turn the key off, giggle the key, try again and it will work almost every time. Sometimes it will prime, sometimes it won't, the ignition key/switch seems to be a contributing factor.
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From: Mt. Shasta California
Yes, it helps with diagnosing but when people leave it out, well...............
I never could figure out why they won't post it.
I never could figure out why they won't post it.
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From: Southern Cal
it's really acting like the switch is involved in the problem. I checked the relays, they bench test fine. I'm doubting it's a pump problem, when I turn the key I can hear if the pump kicks on/primes, if it primes it starts and runs fine, if I don't hear the initial prime it will crank but not start, turn the key off, giggle the key, try again and it will work almost every time. Sometimes it will prime, sometimes it won't, the ignition key/switch seems to be a contributing factor.
I don't believe the ignition switch is the culprit.
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ok, here is what I've found. From a wiring diagram I traced the fuel pump circuit to the inertia switch behind the pass kick panel. The diagram shows a pink/black stripe wire leaving the inertia switch going directly to the pump. I tapped into the p/b wire with a 12v test light. Every and I mean every time I turned on the ign switch, the light would light up for a short time and then go out. I assume the short time on was indicating the short time the pump should run to prime the system. Even though the light came on every time, I did NOT hear the pump prime every time, sometimes it did, sometimes it didn't. when I would hear the pump prime I went ahead and started the engine and the light stays on til I turn the truck off. This is telling me the pump is faulty, correct? I'm having a hard time understanding why the pump will kick on at one time and then not the next, I thought it would either work or it wouldn't? Tomorrow I'm going to try tapping into the pink wire back where it goes into the tank to see if I get the same results. Also, does anyone know where the "ground wire" connection is located for this fuel pump circuit?
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From: Southern Cal
The light stays on because the fuel relay recognizes engine spark and continues to operate until turned off. If you are getting an intermittent working pump, chances are that's the issue.
Fuel pumps operate with an electric motor attached. The brushes on these motors do start to create an intermittent contact with age. When cold, they tend to work but once warmed with internal friction, the brushes can fail and the pump stops working.
Not too uncommon to get this symptom and leave you sitting on the side of the road.
Alternators will do the same thing. You start up and the dash gauge looks like all is working properly. Once you get going, the alternator brushes again fail and once the battery is drained, there you go again, sitting.
You can carefully over ride you system with a portable battery and two contact wires to ensure it's working without the relay. Once connected, you can test your pressure at the fuel rail too.
Fuel pumps operate with an electric motor attached. The brushes on these motors do start to create an intermittent contact with age. When cold, they tend to work but once warmed with internal friction, the brushes can fail and the pump stops working.
Not too uncommon to get this symptom and leave you sitting on the side of the road.
Alternators will do the same thing. You start up and the dash gauge looks like all is working properly. Once you get going, the alternator brushes again fail and once the battery is drained, there you go again, sitting.
You can carefully over ride you system with a portable battery and two contact wires to ensure it's working without the relay. Once connected, you can test your pressure at the fuel rail too.
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When cold, they tend to work but once warmed with internal friction, the brushes can fail and the pump stops working.
You can carefully over ride you system with a portable battery and two contact wires to ensure it's working without the relay. Once connected, you can test your pressure at the fuel rail too.
You can carefully over ride you system with a portable battery and two contact wires to ensure it's working without the relay. Once connected, you can test your pressure at the fuel rail too.
Mine has done the opposite, acted up in the spring, worked fine once the weather warmed up, and recently started acting up as the temps have dropped into the 30's.......go figure.
I plan to try and and just isolate and power the pink wire back to the pump tomorrow and see if it will run every time power is applied.
to top it off, the tank is FULL, which will make it even more fun to remove.
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From: Southern Cal
Putting an in line pressure gauge in place is the simplest way to identify pump pressure. Do that before dropping the tank. Way too much effort.
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