Stuck at 30psi

[kmorgan23]

Do you have some new, cool ones I haven't heard yet?

 

[Uncle Gump]

You must be missing something simple.

When you said rebuild the engine... is it all fresh?

 

[alwaysFlOoReD]

If you pinch off the vacuum line to the fuel pressure regulator , does the fuel pressur go to 80psi or so?

 

[Uncle Gump]

What plugs did you screw in it? Proper gap?

Have you pulled them to read them? I would think if it was a low fuel pressure issue... the plugs would look near white.

 

[kmorgan23]

What plugs did you screw in it? Proper gap?

Have you pulled them to read them? I would think if it was a low fuel pressure issue... the plugs would look near white.

I'm out and about for the evening. I'll give that all a test tomorrow, gaps should be accurate but I'll double check. But yes, everything is fresh, new cam too. Basically the block, wiring, and belt components are original. Most everything else has been replaced. This was given to me for nothing, and I don't have a car payment, that's why I've had no issue just replacing everything. It was in gnarly shape and been a fun rebuild... And now I'm frustrated haha

 

[Cees Klumper]

I would think none of the engine, ignition stuff would influence the fuel pressure - should that not be a relatively simple issue, of (1) fuel in tank (2) pumps moving it to the fuel rail via (3) the pressure regulator?
Given pressure regulator and pumps are likely to be good, the other suspects then become the tank and the lines/filter. Could there be obstruction in the lines and/or filter?
I suppose the other possibility would be a leak somewhere 'downstream', meaning after the regulator, in the fuel rail or one or more leaking injectors. But injectors were checked/swapped, so maybe somehwere in the fuel rail a leak?

 

[lil_Blue_Ford]

Well that’s a tough one, although I’ve seen pumps and regulators fail it sounds like you’ve tried to cover that possibility. The one that irritated me the most was I put a new high pressure tank pump in mom’s Explorer. Delphi I believe it was. Couple weeks later it was running like poo again. Can’t possibly be the pump but I’ll check pressure and sure enough it was low. Replaced the pump again, went with a different brand because I needed it NOW and sure as can be, the new Delphi pump was junk. Oh, and BTW, the pumps are NOT fun to change in the 02 Explorers.

 

[fastpakr]

Since it doesn't hold pressure after shutdown, we can temporarily ignore any non-fuel problem and focus on fixing this one.

Fuel pressure has to be bleeding off somewhere (seems obvious, but stating it mostly as I step through it in my head). So the question is how to narrow that down. The obvious culprits would be an external leak (which ought to be pretty obvious with a good visual search), the fuel pressure regulator, and the check valves in the fuel pumps.

If you pressurize the fuel system with key on and then immediately disconnect the return line from the FPR, do you continue to see fuel leaking from the FPR?
Is there a spot in the fuel system where the lines could be clamped after each pump? From memory it's almost entirely hard lines, but if there's anywhere that you -can- clamp, that ought to eliminate fuel coming back through the supply side. If the act of clamping stops the pressure bleedoff, then that would seem to indicate a bad check valve on the upstream pump.

 

[kmorgan23]

Since it doesn't hold pressure after shutdown, we can temporarily ignore any non-fuel problem and focus on fixing this one.

Fuel pressure has to be bleeding off somewhere (seems obvious, but stating it mostly as I step through it in my head). So the question is how to narrow that down. The obvious culprits would be an external leak (which ought to be pretty obvious with a good visual search), the fuel pressure regulator, and the check valves in the fuel pumps.

If you pressurize the fuel system with key on and then immediately disconnect the return line from the FPR, do you continue to see fuel leaking from the FPR?
Is there a spot in the fuel system where the lines could be clamped after each pump? From memory it's almost entirely hard lines, but if there's anywhere that you -can- clamp, that ought to eliminate fuel coming back through the supply side. If the act of clamping stops the pressure bleedoff, then that would seem to indicate a bad check valve on the upstream pump.

So I think the depressurized system was a fluke or one off.. I replaced ALL the lines with nylon 5/16" yesterday. Before doing that, I bled the system again, and lo and behold there was pressure. I replaced the pump with another brand pump I had, same with the regulator, and there was no change. Haven't had a chance to check the plugs yet, and I'm going to recheck timing too. I think it's safe to eliminate the fuel system since I confirmed neither pumps nor regulator, and all lines have been updated and replaced along with new motorcraft filter . Unless someone has other thoughts/suggestions!

 

[kmorgan23]

I would think none of the engine, ignition stuff would influence the fuel pressure - should that not be a relatively simple issue, of (1) fuel in tank (2) pumps moving it to the fuel rail via (3) the pressure regulator?
Given pressure regulator and pumps are likely to be good, the other suspects then become the tank and the lines/filter. Could there be obstruction in the lines and/or filter?
I suppose the other possibility would be a leak somewhere 'downstream', meaning after the regulator, in the fuel rail or one or more leaking injectors. But injectors were checked/swapped, so maybe somehwere in the fuel rail a leak?

I replaced ALL lines yesterday with new 5/16" nylon while digging in there. Filter was replaced with new motorcraft too. No leaks and everything is appropriately tight.

 

[JerryC]

Have you checked the voltage and ground at the HP pump?
Maybe run jumper wires to the HP pump from battery while running and check pressure?

 

[Uncle Gump]

Hmmm... voltage drop on the fuel pump circuit. Worth consideration... easy enough to check.

 

[kmorgan23]

Have you checked the voltage and ground at the HP pump?
Maybe run jumper wires to the HP pump from battery while running and check pressure?

I'll give this a try today. Any chance you know correct voltage reading?

 

[kmorgan23]

Hmmm... voltage drop on the fuel pump circuit. Worth consideration... easy enough to check.

Also.. fun, frustrating update. I'm in the process of moving 40 mi north of current location. Yesterday was the inaugural trip in the B2. Flooring it the whole way, could barely make 55-60mph on straight aways. A couple times as I would shift to neutral to coast, the engine would stall out. Was able to restart while coasting, but happened twice there and once heading home.

 

[sgtsandman]

If the voltage and the grounds check out, it might be an amperage issue. Think of volts as “pressure” to the line and amperage as the amount of “flow”. If the wires can’t provide the right amount of flow, the pump isn’t going to turn enough to provide enough fuel pressure.

The amp rating on the fuse would tell you how many amps should be at the pump.

A poor connection or a damaged wire can cause an amperage issue.