Fuel pressure

Tiny
WILKOM
  • MEMBER
  • 2000 FORD RANGER
  • 4.0L
  • V6
  • 4WD
  • MANUAL
  • 141,000 MILES
I have had a new fuel pump installed. The system is a non return system with the fuel pressure regulator in the fuel tank. The truck does not start immediately after being shut off for a few minutes. It starts and runs but the gas mileage has dropped by over twenty percent. Cannot seem to get rail fuel pressure over 50 psi. Specs indicate I need 56 PSI minimum. Does the fuel pressure damper have anything to do with this?

Prior to replacing the fuel pump (required due to pump failure) the engine ran fine with consistent 15 to 17 mpg depending on type of driving. Have been trying everything I can think of or google. Any ideas?
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Monday, August 8th, 2016 AT 6:03 AM

40 Replies

Tiny
WRENCHTECH
  • EXPERT
I am finding a lot of conflicting information on this vehicle but the one consistent thing I find is the fuel pressure spec of 30-65 PSI. That is an unusually wide range and normally associated with pulse modulated driver systems but I am not showing that on this vehicle. The data bases are showing this as being a return type system with the regulator on the fuel rail.
Could this be a non-US vehicle or something like that?
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Monday, August 8th, 2016 AT 6:40 AM
Tiny
WILKOM
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The tag in the door frame indicates US manufacture which is consistent with theVIN number starting with one. In my research, I found references to it being a non return system. I believe this is correct as there are three connections to the fuel filter. Two at the back which connect to the pump. I believe these are the supply line and re circulation. Then the one going to the fuel rail. The new pump is an Airtex model E2270S. The shop manual I have gives the fuel pump pressure spec as 64 +/- 8 PSI.
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Monday, August 8th, 2016 AT 7:19 AM
Tiny
WRENCHTECH
  • EXPERT
There is a good example of conflict. The factory shop manual that I have (Alldata) states the pressure spec is 30-65 as I stated before. I checked Mitchell and it agrees with you. I can't find any consistent information on this particular truck.
If you have a filter with three lines on it, that generally means it is acting as a regulator. You might try changing that.
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Monday, August 8th, 2016 AT 8:19 AM
Tiny
WILKOM
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I have changed it as well suspecting it was part of the problem. I use the Ford workshop manual I picked up on E-bay about seven years ago.
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Monday, August 8th, 2016 AT 9:20 AM
Tiny
WRENCHTECH
  • EXPERT
I have access to the Ford service site and it pretty much confirms everything you said about the system.

The first thing I would do is confirm there is no voltage drop or ground problem in the wiring to the pump. Beyond that, you have to be looking at an issue with the pump, either defective or wrong application or a problem with the regulator.
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Monday, August 8th, 2016 AT 9:48 AM
Tiny
WILKOM
  • MEMBER
I was told the voltage was checked. I will have to check it myself to be sure. Believe it or not, this is the second new pump installed. Due to the problem, I had the first replaced with a second. Problem remained. I picked up the idea somewhere that the pump controls pressure by varying the speed or somehow pulsing the pump. I am wondering where the signal comes from and how to check this. Have you ever run into anything like this? Am I misunderstanding something?
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Monday, August 8th, 2016 AT 10:02 AM
Tiny
WILKOM
  • MEMBER
Just wanted to add that I am appreciating your input regarding my dilemma. I have been working on this problem for about four to five weeks and have checked and changed anything I could find might be the problem. Thanks again for taking the interest.
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Monday, August 8th, 2016 AT 10:11 AM
Tiny
WRENCHTECH
  • EXPERT
No, you are describing Pulse Width Modulation which your truck is not equipped with. That requires a Fuel Pump Driver Module which you do not have.
Checking voltage and voltage drop are two different thing. A voltage drop test reads loss in the circuit.
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Monday, August 8th, 2016 AT 10:18 AM
Tiny
WILKOM
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Just wondering will running the vehicle as it is (rich fuel mix) damage the catalytic converter? Or any other components?
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Monday, August 8th, 2016 AT 1:19 PM
Tiny
WRENCHTECH
  • EXPERT
Yes, rich mixture will damage the catalytic converter, but how do you know you have a rich mixture?
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Monday, August 8th, 2016 AT 1:21 PM
Tiny
WILKOM
  • MEMBER
Thought I answered but seems I screwed up. I'm thinking rich mixture due to reduced MPG My understanding is that the injectors make up for the low pressure by opening longer resulting in poor atomization of fuel and incomplete combustion.
Since I don't have black smoke coming out of exhaust or smell fuel, this doesn't seem right does it?
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Tuesday, August 9th, 2016 AT 5:25 AM
Tiny
WRENCHTECH
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No, you can't assume anything like that. Lean fuel mixture would lead to lean misfire and poor mileage also. If your 0/2s aren't setting rich codes, it would be wrong to assume that.
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Tuesday, August 9th, 2016 AT 5:34 AM
Tiny
WILKOM
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Since I don't want to drop the tank again to check the power at the pump, I decided to check the pump pressure capability with a gauge. With everything set normally, I was getting the 50 PSI as Before. To eliminate the return valve as the culprit, I closed off the return valve from the fuel filter, Pressure immediately increased to 80 PSI. This is telling me that the problem is with the return valve. As mentioned previously this is a second new pump with the same results. Do you see anything I might be missing?
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Wednesday, August 10th, 2016 AT 8:39 AM
Tiny
WRENCHTECH
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No, you seem to be correct about it being the regulator. Kinda unusual though.
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Wednesday, August 10th, 2016 AT 8:47 AM
Tiny
WILKOM
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Thanks I appreciate you staying with me on this. I agree it seems unusual and it was the reason I didn't do this simple test sooner.
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Wednesday, August 10th, 2016 AT 9:09 AM
Tiny
WRENCHTECH
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Are you sure you can trust the gauge?
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Wednesday, August 10th, 2016 AT 9:11 AM
Tiny
WILKOM
  • MEMBER
I think so. The pressure was checked by the people who installed the pump and they said it was 50 PSI They didn't close the return line. I got 45 to 50 in that situation. When I closed the return off it jumped to 80 psi which is the range of the stated pump spec. SO the gauge might be off, but it shows the pressure increase when closing the return.
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Wednesday, August 10th, 2016 AT 9:19 AM
Tiny
WRENCHTECH
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Yes, it shows the increase but if that gauge was off by as little as 10PSI, that test would translate to no problem at all. That's all I'm saying. If you trust the gauge, then fine, replace the regulator.
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Wednesday, August 10th, 2016 AT 9:26 AM
Tiny
WILKOM
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You have a good point. Since the regulator is in the tank, I'll have someone else check the pressures again before tearing into it.
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Wednesday, August 10th, 2016 AT 9:32 AM
Tiny
WRENCHTECH
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If the regulator is in the tank, how were you able to close off the return?
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Wednesday, August 10th, 2016 AT 9:42 AM

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