[2000' SOHC] Third fuel pump is broken

[slisman]

Hi guys,
I have "small" problem with my 2000 SOHC EX, which is returning few months after installing each new fuel pump. I have had problems with rough idle - car was stalling few seconds (5-15 seconds) after idling, sometimes there were misfires too. After this short time, car started working smoothly, no problems with acceleration etc. I have a returnless fuel system. All in all, after following repairs, I have replaced fuel pump...three times:
1. New OEM IAC.
2. New spark plugs and spark wires (autolite / motorcraft).
3. New in tank pressure regulator.
4. TPS sensor and throttle regulation.
5. New fuel filter.
6. New intake manifold gaskets (that was main suspect of stalling).
7. Vacuum checked (vacuuometer shows healthy/proper vacuum).
8. New in-tank fuel pressure regulator (unknown origin, bought by previous owner, can be cheap replacement part).
9. Voltage on fuel pump is constant and has proper value.
10. PCM reset and learning "new values" after each fuel pump replacement

During above replacement/repairs/regulations - I have had to replace a fuel pump three times. Since last replacement (done after new spark plugs and wires) everything has been running smoothly...but last weeks it got worse. Stalling and choking (especially on cold idle after night) became alarming. What it weird - if I turn off shortly after idle, and then idle again - everything runs almost smoothly.

Fuel pressure checked on schrader valve is 1,5 bar (21 psi) with turned key off and 2,2 bar (31 psi) on neutral after idle. Far to low values. Long term fuel trims at idle speed (1,5k rpm) are about 30%, at 2,5k rpm are nearly 0%. Short fuel trims at 1,5k rpm are about 5-10%, at 2,5k rmp rise to 20-30%.

I have no idea what to do - is it time to install fourth fuel pump? Have you any ideas what can cause continuous problems with fuel pump? May it be FPR's fault? Today I will also replace PCV valve. It can be related with stalling but I don't think that it could lower fuel pressure.

Everybody on our Polish forum is out of ideas and I am afraid of installing new fuel pump if it will become broken in few weeks. I will be grateful for every help

 

[Turdle]

Which brand of fuel pump are you using? Aftermarkets and low cost fuel pumps are unreliable in my opinion.
You also need to make sure you are getting the correct unit, as the earlier 1998 and down use a return fuel system which operates at lower pressure.

The unknown fuel pressure regulator is suspect

loose connections at the fuel pump relay socket might cause intermittent fuel pump operation. You might also disconnect and reseat the 2 large wire bundle connectors on the firewall and above the heater blower ( pcm)


Also, there is a fuel pressure damper on the fuel rail. I doubt this is your problem though.


I have moved this thread to the stock 1995-2001 explorer sub forum for better views.

 

[david4451]

Your fuel pressure should be 65 to 70 psi. If you have the correct pump, the in tank pressure regulator could be your problem. Also carefully check rubber lines inside tank for splits, they can be difficult to spot.

 

[slisman]

Thanks.

Unit is correct for sure (all of them). Used fuel system is returnless, operating pressure is correct as well. My first choice was Autobest fuel pump from rockauto, but bearing in mind number of brands -> it doesn't matter in my case.

I will start with replacing fuel pressure regulator then. I hope I will get reliable part in Poland or maybe is it possible to mount part from other car? Explorer is not so popular here in Poland

Additional, I observed that after 8 hours of work - there is no pressure in fuel system. Schrader valve does not throw any fuel when mounting manometer gauge. Is it proper behaviour or should it be any pressure there?

 

[slisman]

Thanks for your help.
I've just returned from garage...and...I'm 98% sure that fuel pressure regulator will solve my problem.

I plugged old one into fuel tank (OEM Motorcraft) and then tried idling...and nothing, engine was only cranking with no idle. And there was no pressure in fuel system on schrader valve. So again I've mounted replacement part (FPR) and again there was fuel pressure as described above (2,2 bar (31 psi)).

I thnik that new FPR will help. And I have some conclusions. Previous owner must have bought FPE for Ford Explorer Sohc with return system -> lower fuel pressure is stable.

Thanks again, I will inform you about progress

 

[daisyrocky]

I did it once with a Bosch from Advance Auto. Also cut out a door under the seat for it just in case I need to change it out. Been 3 years and never used the handy door yet.

 

[slisman]

I have such door/revision hole under the seat.
Without it I wouldn't diagnose it and replace so many times

 

[slisman]

Bad news - new FPR mounted but fuel pressure still is about 2 bar. Too low.

Any further idea? Maybe should I replace fuel pump again?

 

[slisman]

Small thred update:
1) PCV valve replaced. Engine is now working smoothly.
2) But first idle is still connected with stalling. It is like I turn ignition, idle, car is stalling so I turn it off, then a turn ignition on again, idle and it runs smoothly with only intermittent stalling for 30 secs, then it works smoothly. I don't get it. Should I reset PCM after replacing FPR?
3) Fuel pressure is still to low.

Regards

 

[Macgiobuin]

You may have a slow leak in the rubber hoses that enter and leave the fuel pressure regulator housing, that plastic thing with the entry port, exit port, and relief port that uses a big U clip to hold in the pressure regulator. When you first start up your car, the fuel pump activates for 2 seconds, hopefully to get the whole system up to pressure, 65 psi. But because there is a leak in a hose or the plastic housing itself, the system doesn't get up to full pressure. So try this: Without activating the starter, turn the key to 'ON' for 3 seconds. Turn off for 1/2 second. Try to start car now. It should fire right up, because it has not had enough time to lose all the fuel in the pressure line yet. I have seen both instances: invisible cracks in the regulator housing, and pressure holes in the hoses that attach to the regulator housing. Also you must be sure that the 2 O rings on the regulator are in place and not broken or sliced.

 

[slisman]

Thanks for advice. But my observations are as follows:
-turning on Key many times (3 or 4) for 3 seconds doesn't make idling better.
-idle is good - revs goes up, but then engine starts to idle and choke.
-I checked it at shrader valve - fuel presser is constant and does not fall after few seconds.
-When revs are higher - engine runs smoothly. When revs goes to idle speed - it stalls (only after startup, first 30 seconds)

So two questions:
1) Maybe it is leak in hoses. I will today check this hoses from pump to regulator. I will also check fuel filler neck - should it causes such problems when leaking?
2) Could have faulty FPR broken three fuel pumps? I finally replaced this FPR and maybe should I try replacing fuel pump again?

Somthing like here -> Low fuel pressure on start/ intermittent starting

 

[Macgiobuin]

'When revs goes to idle speed - it stalls (only after startup, first 30 seconds)'
That sounds like a vacuum leak to me. Even though you have a new IAC, it may be sticking. Here's how I fix that. I get a beer can and cut off the top. Clean it out, place the IAC in it and then fill it with sea foam. Let it sit over night. The sea foam will dissolve any gum that causes the plunger to stick.

 

[slisman]

I have done measurements with vacuuometer and vacuum is fine I think (I've plugged vacuuometer in intake manifold and it is perfectly healthy).

I would rather focus on fuel pressure - it is still 2,2 bar (31 psi) at idle speed instead of 60 psi.
It is no problem to install new pump (I've purchased it yesterday)...but I have no idea what is going on with fuel system that another fuel pump is broken. It will be fourth pump replacement. Maybe should I detect real cause of this malfunction, not only replace fuel pump? But I have no idea

 

[slisman]

I have done measurements with vacuuometer and vacuum is fine I think (I've plugged vacuuometer in intake manifold and it is perfectly healthy).

I would rather focus on fuel pressure - it is still 2,2 bar (31 psi) at idle speed instead of 60 psi.
It is no problem to install new pump (I've purchased it yesterday)...but I have no idea what is going on with fuel system that another fuel pump is broken. It will be fourth pump replacement. Maybe should I detect real cause of this malfunction, not only replace fuel pump? But I have no idea

By the way, is it possible that if fuel filler neck (to tank) is leaking it causes low fuel pressure?

 

[Macgiobuin]

I would eliminate voltage as problem first. Run pair of jump wires from the battery to the red and black wire terminals on the fuel pump pigtail. Check pressure then. If 65, then you have a voltage problem. Trace the ground first, then the positive thru the momentum collision safety switch then thru the fuse block and the relays.

 

[slisman]

Guys, problem solved, but I think that temporarily. I've replaced fuel pump and idling is brilliant now, voltage is good.

But another strange things - my 2000' SOHC should definitely have returnless fuel system.

But I have this fuel pump assembly with two lines (see photo enclosed). Maybe I have this system with return? But second blue line looks like vacuum, not fuel hose. How can I check it - there should fuel pressure regulator on fuel rail?

 

[slisman]

Five first idles - smoothly and perfect, fuel trims ideal (-2% / 2% - both long and short term).

But then, long term fuel trims started to become to be higer -7% / 7% .
I am scared that it is new fuel pump's end... instant.

First I have to diagnose this fuel system - have somebody seen such system? I 've thought that it should be only one pipe from assembly in returnless system. But I have additional one - maybe vacuum?

 

[Macgiobuin]

The little vacuum looking line measures the air pressure differential between the fuel tank and the outside air. When you leave your fuel cap off, this sensor detects that the pressure between the two is 0. There is not a fuel pressure regulator on your rail; what you have is a pressure damper; it keeps the pressure from bouncing while the fuel injectors activate. Your fuel pressure regulator is in the tank.

 

[CDW6212R]

Guys, problem solved, but I think that temporarily. I've replaced fuel pump and idling is brilliant now, voltage is good.

But another strange things - my 2000' SOHC should definitely have returnless fuel system.

But I have this fuel pump assembly with two lines (see photo enclosed). Maybe I have this system with return? But second blue line looks like vacuum, not fuel hose. How can I check it - there should fuel pressure regulator on fuel rail?

View attachment 153069

That picture is scary, there should not be any fuel line with a hose clamp holding it together. The proper 65psi is too high for a hose clamp to handle safely.

I have no clue what that blue line is for, and all 1999 up Fords have only one fuel line going to the tank/pump. You need to figure out what that assembly is, who did it and why. I would not run the engine with that hose clamp there, and trace the blue line to try to figure out what someone else has done.

It sounds like someone has changed the fuel system, and likely the FPR to a low pressure system, besides the blue hose. Mixing fuel systems and the computer, is not wise. The PCM is likely a 99+ and requires 65psi, the 32psi level is proper for 98 and older Fords, which also have a FPR on the rail, and with a vacuum line going to that. Did they run a vacuum source back into the tank, and put the FPR there also? Very weird, but the hose clamp is the big problem, get that off of there quickly. The proper repair for high pressure lines is OEM parts, or high pressure hose and proper high pressure connections. Good luck,

 

[slisman]

Thanks for another bunch of advices.

I hate previous owner's DIY solutions.

1) Hose is new (special for fuel systems up to 10 bar, so high pressure is not a problem). But clamp was here when I bouht Ford. I thought it ok, because it is tightened before pipe "bold" and hose should not get off the pipe.

2) The pressure after new pump install is still 31 psi, but engine runs and idles smoothly. Maybe it is really coverted into low pressure?

3) Intank FPR is from returnless fuel system (65psi)...but fuel pressure is lower. I think I should look for FPR on fuel rail. But which part of fuel system make pressure so low...

4) I will trace this blue vacuum line. It goes with fuel line, but I don't know destination.

5) Is it possible to check PCM version?

Only one word is proper for that situation - "WHY?" .
Hope it will not be hard to get back to OEM fuel system.