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Fuel pressure problem…

Mr. Alligator

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1997 Ford Explorer SOHC. Return fuel system problem. I have been battling this for a few years, and replaced four or five fuel pumps in about four years. One of the fuel pumps had a bad check valve, allowing fuel to drain immediately back into the fuel tank. In the past, fuel pump replacement has always resolved the issue. a fuel pump access panel has helped greatly…

Here is the presenting problem: truck ran great yesterday, but today truck will not start. This may be good, as the issue is NOT currently intermittent.

No external fuel leaks, and no smell of fuel (until I get fuel sprayed all over me during attempts to test/repair).

Fuel tank is 3/4 full.

CHECKED FUEL PRESSURE AT RAIL: ZERO

As usual, I replaced the fuel pump… this time with new Walbro pump. Truck still does NOT start, and still has no fuel pressure at rail

I could hear the fuel pump run when I turn the ignition key to “on”. This should not be a wiring issue, as fuel pump engages immediately when the key is turned. Thus, inertia cut off switch should not be an issue. Only possible issue here would be if any electrical issue could command the system to dump all fuel back in the tank.

I disconnected fuel line above tank, and fuel shot out of the line. The new fuel pump is surely working fine.

Checked fuel filter, which was changed in past 20,000 miles. Fuel filter was oriented properly AND fuel tank is very clean. Disconnected filter and turned key… fuel shot everywhere. This does not look like a fuel filter issue.

A more telling test: had someone turn the key, while I monitored shraeder valve. Had gush of fuel for about two seconds, then system IMMEDIATELY returned to zero fuel pressure.

My current guess is fuel pressure regulator. I disconnected the vacuum line and nothing changed. Still no start and no fuel pressure. I have never changed fuel pressure regulator, and have no knowledge of this unit. Does this sound like valid part to replace? Do I need to remove intake manifold to get replace the fuel pressure regulator?

EDIT: fuel injectors are original with almost 600,000 miles. Could fuel injector(s) bleed off fuel pressure almost instantly?

Can anyone give me any great advice?

Great Forum has allowed me to keep this truck running.

Thank you all!
 



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Lee's Automotive

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99 Explorer XLT 4.0 SOHC
1997 Ford Explorer SOHC. Return fuel system problem. I have been battling this for a few years, and replaced four or five fuel pumps in about four years. One of the fuel pumps had a bad check valve, allowing fuel to drain immediately back into the fuel tank. In the past, fuel pump replacement has always resolved the issue. a fuel pump access panel has helped greatly…

Here is the presenting problem: truck ran great yesterday, but today truck will not start. This may be good, as the issue is NOT currently intermittent.

No external fuel leaks, and no smell of fuel (until I get fuel sprayed all over me during attempts to test/repair).

Fuel tank is 3/4 full.

CHECKED FUEL PRESSURE AT RAIL: ZERO

As usual, I replaced the fuel pump… this time with new Walbro pump. Truck still does NOT start, and still has no fuel pressure at rail

I could hear the fuel pump run when I turn the ignition key to “on”. This should not be a wiring issue, as fuel pump engages immediately when the key is turned. Thus, inertia cut off switch should not be an issue. Only possible issue here would be if any electrical issue could command the system to dump all fuel back in the tank.

I disconnected fuel line above tank, and fuel shot out of the line. The new fuel pump is surely working fine.

Checked fuel filter, which was changed in past 20,000 miles. Fuel filter was oriented properly AND fuel tank is very clean. Disconnected filter and turned key… fuel shot everywhere. This does not look like a fuel filter issue.

A more telling test: had someone turn the key, while I monitored shraeder valve. Had gush of fuel for about two seconds, then system IMMEDIATELY returned to zero fuel pressure.

My current guess is fuel pressure regulator. I disconnected the vacuum line and nothing changed. Still no start and no fuel pressure. I have never changed fuel pressure regulator, and have no knowledge of this unit. Does this sound like valid part to replace? Do I need to remove intake manifold to get replace the fuel pressure regulator?

EDIT: fuel injectors are original with almost 600,000 miles. Could fuel injector(s) bleed off fuel pressure almost instantly?

Can anyone give me any great advice?

Great Forum has allowed me to keep this truck running.

Thank you all!
I'm thinking either a stuck open injector or bad fuel pressure regulator
 






Lee's Automotive

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But that doesn't explain why there's no pressure when the regulator is disconnected from vacuum
 












C420sailor

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Vacuum simply adjusts FPR to compensate for MAP, I believe. Removing the line isn’t a fix all.

That fuel is going somewhere..if you’re getting flow but not developing pressure, my guess is either wide open injectors or FPR is stuck full open.
 






Lee's Automotive

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Vacuum simply adjusts FPR to compensate for MAP, I believe. Removing the line isn’t a fix all.

That fuel is going somewhere..if you’re getting flow but not developing pressure, my guess is either wide open injectors or FPR is stuck full open.
Yep the fpr is in the tank so i would check that
 






Mr. Alligator

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The fuel gushes out of the return fuel line. I see that when I disconnect the fuel return line at the fuel tank.

I would not think the injectors could bleed off so much fuel pressure almost instantly.

All of the help is appreciated.
 






Lee's Automotive

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The fuel gushes out of the return fuel line. I see that when I disconnect the fuel return line at the fuel tank.

I would not think the injectors could bleed off so much fuel pressure almost instantly.

All of the help is appreciated.
Could be a collapsed stainless line on the rail
 












Mr. Alligator

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Could be a collapsed stainless line on the rail

Good thought. But then fuel would not be able return to the tank, would it? And this has been intermittent, on/off problem for some time. It runs great, then hard starts. Then runs great. Now, it does not run.
 












imp

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Could be a collapsed stainless line on the rail
Consider that a closed, pressurized volume of fuel, like a fuel line, where the source of pressure (pump) is not running, will only bleed away a small quantity of fuel because liquid is incompressible, so remaining pressure would drop quickly to zero with only small amount of fuel leaking away, wherever it's going.
 






Turdle

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If the injectors are leaking that badly hydrolock is possible. Might want to remove spark plugs, look for a spray of fuel while someone cranks engine over.

Heck, the plugs might even show a clue
 






Lee's Automotive

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If the injectors are leaking that badly hydrolock is possible. Might want to remove spark plugs, look for a spray of fuel while someone cranks engine over.

Heck, the plugs might even show a clue
Yep very easy to damage the engine or hydrolock it
 






J_C

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If you have injector(s) leaking that bad, after a few attempts you should be smelling fuel out the exhaust pipe. Edit: At the same time, I suppose even with momentary, tiny amount of fuel pressure, you could still smell fuel since it's not being burnt starting.

With no fuel smell, I suspect the regulator which is on the end of the fuel rail, and hasn't been available for several years, unless maybe you get lucky and find new old stock on ebay or something.

I accumulated some info on it, for if/when the day comes that mine fails.

----------------------------------------------------------------------------------------------------------------------
Main Ford part # 97JF-9C968-AB

Alternate Part # that "seems" like it "might" be correct is:
F77Z9J338AD

Additional markings on the part itself
270 KPa 960308
0 280 160

At one point I saw a topic where someone used (adapted?) a 1998 Volvo V70/850/S70/C70 pressure regulator part # PR409, Bosch 0-280-160-554-INT might be the same. It was rated for 4PSI higher pressure but supposedly works, but doesn't have the hose built on like the Ford PR does.

Back when hunted for the motorcraft part, I kept seeing listings for the OHV version instead. The 97JF-9C968-AB 4.0L SOHC version should look like this:

2014-01-11_203713_104_1430.jpg
 






Lee's Automotive

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J_C

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^ I don't know if it would work or not. It isn't the same part # and has the nipple off the side. Don't know the pressure either.

I found a listing for the 2nd part # I posted previously, but two things.

1) They want $580

2) Conflicting info, listed applications 1997-2000 when SOHC pressure regulator did not stay the same part over this year span, changed on '99 and up to a returnless damper. The page reads SOHC but to only go to 2000 makes it look like the OHV version since that engine stopped being offered after 2000 model year.


I think I might have found one (not 100% sure about the hose), used though:


Looks like the Bosch/Denso part #s for it are 0-280-160-555

Here's someone who reported success with a GP Sorensen 800-521, which like the Volvo part #s, has to have the Ford hose cut off the original and reused:

 






Lee's Automotive

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^ I don't know if it would work or not. It isn't the same part # and has the nipple off the side. Don't know the pressure either.
Just noticed that but that's the part number that's very strange
 



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J_C

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^ Where do you see either of those ebay part #s as compatible? They are not the same as the part #s I posted previously. I could be wrong about the part #s I posted but all info I got from topics where people had already done the research.
 






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