I just put the 3rd fuel pump on my ’97 F-150 w V6 (4.2L) that has 111K miles.
Similarly to less than 2 years ago, it was running fine until I stopped, then when trying to start it again, the engine would sputter briefly but not start. After banging several times on the tank with a rubber mallet to no avail and doing a series of other tests, it was concluded that it needed a new fuel pump ($587 by the dealer since I was 400 miles into an 800 mile trip with no tools).
Today, when I got home, I tested the old pump by putting 12 volts across the terminals and it ran just fine. 2 pumps failing, one in fewer than 20K miles/2 years is unusual, so it got me thinking…
There seemed to be higher than expected pressure needed to get the return tube to flow. The rubber piece on the end of the return tube is sticky and after pinching it together it was hard to get air to flow through it initially until the sticky seal broke free.
As a theory, I am thinking that the problem is not the pump that is failing but instead the rubber end on the return pipe is deteriorating (ethanol?) causing it to block the return gas, in turn creating pressure which causes the computer to think there is enough gas so it fails to tell the pump to run. Not being intricately involved in the recent troubleshooting, I am not sure what the electrical test results looked like at the fuel pump connector.
If it happens again, before dropping the tank and removing the pump, I would like to try disconnecting the return line, putting it into a container and seeing if the truck starts.
Or maybe if I get a wild hair, I’ll try disconnecting the return line and blocking it to see if the truck sputters, but fails to start.
If anyone has a similar problem and thinks to try either of these troubleshooting approaches, I’d love to hear the results. It may save us all some coin. While it would still require dropping the tank and removing the pump, we probably can eliminate the rubber piece (it seems to be doing very little) and avoid a repeat performance.
Matt Ashenden
’97 F-150 w V6, 4.2L and 2WD manual tranny – 111K miles
Im not that familiar with this situation,but I would think about where the pumps came from.In alot of instances,a pump will work with no load on it.Once the pressure has built up.it can crap outThere are alot of aftermarket parts(pumps included) that are poorly manufactured,and cheaply made.My opinion here is to indeed check the hoses,and replace what looks worn.Typically you cant go wrong using an original FORD part.While it will most assuredly be more expensive,youll have the knowledge that is in fact the OEM part.Personally I buy all my "non emergency" parts from one of our sponsors www.rockauto.com I have had one instance in 10 years that a part I bought from them was defective.They corrected the problem immediately.
I bet you have blockage somewhere, causing the pump to work to hard, or its not shutting off when it has built up enough pressure.
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99' F-150 Super Cab Step Side
5.4l/4R70W (previously a 4.6l romeo)
CAI,Flowmaster 50 series dual exhaust,Gryphon Tuner with custom tunes (300 bhp est)
900LB AAL, cranked front Torsion Bars =(2in lift)Lariat LE Seats, Alpine cd player/6x9 speakers
2003 Fx4 Rims, 255/75/17 BFG MT KM
I bet you have blockage somewhere, causing the pump to work to hard, or its not shutting off when it has built up enough pressure.
I respectfully disagree. These would only be relevant if the pump had indeed stopped working. That was not the case. The engine stopped running - the old pump tested fine.
Quote:
Originally Posted by n5926g
Im not that familiar with this situation,but I would think about where the pumps came from.In alot of instances,a pump will work with no load on it. Once the pressure has built up.it can crap out
True, but in this case I am skeptical that this was the problem because we took several troubleshooting steps that would have reduced the pressure, which would have given the pump a chance to come back to life.
Also, it seems that if pressure caused it to fail then the same pressure would have allowed the truck to at least start for a bit.
Thank you for the lead on the parts provider. Pump #2 was probably not OEM. The current pump is OEM, though.
are you changing the fuel filter when you installed the pumps
Yes. This truck is on its 4th fuel filter in 111K miles.
Ironically, this time I asked that they not change the filter because it had been swapped a month ago, but they did it anyways. I was willing to take that risk to save $49 (their charge - I'm unemployeed at this time).
Generally, fuel filters do not need that frequent of changes, what with better refining, fiberglass tanks at stations, etc. Based on all of my other vehciles, where I have never changed a fuel filter, this vehcile has received way more. I doubt this contributed to the problem. Your input is appreciated, though.
Matt Ashenden
’97 F-150 w V6, 4.2L and 2WD manual tranny – 111K miles
A senior member on another forum stated that, contrary to my assumptions, the fuel pump is supposed to stay on all of the time, not switching on/off electrically at all. The fuel pressure sensor keeps the pressure at the right level and returns the excess gas to the tank. Again, the claim is that the pump is not supposed to cycle on/off.
Not meaning to be distrusting, but this truck is new to me and therefore I am new to these forums. I would like another source to confirm this.
Anybody agree or disagree? This is a '97 F-150 V6-4.2.
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