Vehicle will start up and run fine for no more than twenty minutes

Tiny
EWC177
  • MEMBER
  • 1995 FORD RANGER
  • 4.0L
  • V6
  • 2WD
  • 190,000 MILES
Vehicle will start up and run fine for anywhere up to 20 minutes. Replaced fuel pump and filter. Fuel relay and pressure sensor. I'm only getting 28 psi at the fuel rail test port. I have also replaced lots of other parts and tested the inertia switch and run wires straight to the fuel pump, but still having problems. Please make suggestions of what I need to do.
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Saturday, April 25th, 2020 AT 10:11 AM

113 Replies

Tiny
KASEKENNY1
  • EXPERT
I see you replaced the pump but you have a return fuel system which means the regulator will route "excess" pressure or fuel back to the tank. We need to check the return system for issues including restrictions. However, I suspect the regulator may be allowing too much fuel or pressure back to the tank which causes your low pressure. The reason is, your running pressure should be a minimum of 30 PSI so it is not that far out but with a new pump you would expect it to be higher so that means one of three things. First it is a weak pump. Second, you have a restriction in the supply line, or there is a "leak" in the system allowing pressure to bleed off to the tank.

Let me know if you have questions and we can go from there. Thanks
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Saturday, April 25th, 2020 AT 11:56 AM
Tiny
94 TRANSAM
  • EXPERT
Fuel pressure should be 35-45 psi. I would suggest replacing the regulator.

OE instructions below.

Let me know if this helps.

Rich
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Saturday, April 25th, 2020 AT 11:58 AM
Tiny
ASEMASTER6371
  • EXPERT
Good afternoon,

If you only have 28 pounds, it is a fuel pump issue.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

I attached the spec for you.

What brand pump did you use?

Roy
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Saturday, April 25th, 2020 AT 12:10 PM
Tiny
EWC177
  • MEMBER
The new fuel pump was made by car quest. Don't know what brand the new pressure regulator is and the running pressure is 28 psi, no higher. It wont keep a constant idle. I have to check the rpm with the obd 2 that I bought because truck wasn't made with a rpm meter and which lines on the fuel pump is the return line? Thanks in advance.
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Saturday, April 25th, 2020 AT 6:02 PM
Tiny
ASEMASTER6371
  • EXPERT
The large line goes to the fuel rail and the smaller line is the return line form the rail.

When it shuts off, does it start right back up?

https://www.2carpros.com/articles/stall-at-idle

Roy

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Saturday, April 25th, 2020 AT 6:08 PM
Tiny
EWC177
  • MEMBER
Yes, will usually run for a few minutes then instantly shuts off and cranks back up and run few minutes and shuts off again. Wish could talk on phone. I'm a bad typer.
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Saturday, April 25th, 2020 AT 6:30 PM
Tiny
EWC177
  • MEMBER
When I first got it I was told it had a bad EGR valve. Replaced that. IAC valve, MAF, fuel pump, filter, pressure switch. Checked inertia switch. Checked for vacuum leaks with starter fluid. Alternator, battery. Bought pressure tester. Checked all fuses and relays. And bought a obd2.
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Saturday, April 25th, 2020 AT 6:34 PM
Tiny
EWC177
  • MEMBER
No check engine light on.
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Saturday, April 25th, 2020 AT 6:36 PM
Tiny
EWC177
  • MEMBER
Also cleaned the throttle body and the mass air flow area and filter and put on a new throttle position sensor.
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Saturday, April 25th, 2020 AT 6:39 PM
Tiny
EWC177
  • MEMBER
Can I test the pressure straight from the pump?
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Sunday, April 26th, 2020 AT 7:12 AM
Tiny
ASEMASTER6371
  • EXPERT
You can but it will read the same as at the rail.

I think your new pump is either wrong or bad.

Roy
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Sunday, April 26th, 2020 AT 7:31 AM
Tiny
EWC177
  • MEMBER
Okay, thanks Roy. I'm going to clean the return line first and if that does not help. Off with the pump. Thanks
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Sunday, April 26th, 2020 AT 10:02 AM
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Always glad to help.

Keep me updated.

Roy
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Sunday, April 26th, 2020 AT 10:05 AM
Tiny
EWC177
  • MEMBER
Took it back for another pump and now pressure is lower.
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Sunday, April 26th, 2020 AT 12:57 PM
Tiny
EWC177
  • MEMBER
That's idling pressure.
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Sunday, April 26th, 2020 AT 12:58 PM
Tiny
ASEMASTER6371
  • EXPERT
Yep, you need a pump.

Replace it and ask either for an AC delco or delphi pump.

Roy
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Sunday, April 26th, 2020 AT 1:10 PM
Tiny
EWC177
  • MEMBER
This is the second new one I put on. First was a Carquest. This one is a Airtex. How long should line hold pressure? Mine loses pressure within seconds of it shutting off.
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Sunday, April 26th, 2020 AT 1:24 PM
Tiny
ASEMASTER6371
  • EXPERT
It should only drop about 3-5 pounds.

There is a check valve in the pump that keeps residual pressure. If that is not holding, it will bleed down.

When you drop the tank. Look inside for any debris or dirt in the tank.

Roy
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Sunday, April 26th, 2020 AT 1:33 PM
Tiny
EWC177
  • MEMBER
I have the bed off of my truck and the inside of the tank is clean.
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Sunday, April 26th, 2020 AT 1:43 PM
Tiny
ASEMASTER6371
  • EXPERT
Okay, check the pressure when you install the pump.

Roy
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Sunday, April 26th, 2020 AT 1:51 PM

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