Fox W.

Minor issues after engine work

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It's quite a nice gauge.  In any case, it holds about 40psi with the pump-prime connected, and about 37psi with the engine running, but all the pressure quickly drains right out to the tank (I believe) when the pump is off.  The pressure increases a few psi with the regulators vacuum line disconnected, so I believe the FPR is working fine.   It still feels hard to believe this was just a coincidence after I did all that work, but I suppose it may just be.. especially since the hard starting issue didn't happen the first few times I used it after..  but it did happen after I replaced the fuel filter. (which is not leaking.)    So I guess next I need to drop the fuel tank.  I wish it were possible to get a whole new assembly because I figure I'll have some rust on the lines. 

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Was there any gas in the regulator vacuum line ? Your pressures sound low and the quick drop off says there is a leak somewhere. If hard starting and stumbles a bit that could indicate a leaky injector.

 

Another reader suggested a sender assembly  from eBay.

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I got the same email and I don't know if that one would work as I never had to deal with a fuel pump/sender issue. Maybe Barney could chime in and let us know...

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No gas was in the vacuum line for the regulator.     If it's a leaky injector, where would it leak from? The bottom in to the plenum?  These injectors were totally perfect before removal, and were removed all together (I never removed them from the fuel rail) gently. They are new as of 2012, so that would be another new coincidence. I thought we established  a bad pulsator dampener or  a fuel-pump check valve was most likely based on my symptoms?    It does hard start, but that's because there is no prime-pressure, I wouldn't say it really stumbles at all, just starts as if there isn't enough fuel for the first 3 seconds of cranking and then starts suddenly and normally.  I will try to keep the fuel rail connected to the lines at the same time as all 6 injectors are out of the plenum, and I can then run the pump and inspect for leaks.

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I was away on a trip for the whole Summer, back now.    Upon returning I have so far pulled the rail/injectors while still all connected up and run the pump to find none of the injectors leak at all.   I then dropped the tank, replaced the dampener thing along with the fuel pump,  connected it all back up, same thing.   So now I'm really needing help..  The only thing I had done related to fuel before this started was replace the filter.   The regulator is now the only original thing, but it passed the tests (changes pressure based on vacuum, and no fuel leaks out of the vacuum line, even when the pump is running)   Do our fuel filters have a check valve??   I'm really confused what's next.   My old pump seemed to properly be only 1-way when I tested it, so its own check valve seemed fine.

Edited by Fox W. (see edit history)

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Using the proper fittings, I would connect the gauge directly to the pressure line coming from the pump eliminating the regulator and fuel rail as the source of the problem. IF the pump pressure still drains down quickly - fuel leaking at the rubber seal/connector between the Pulsator and the pump is likely the problem.

 

fuel_pump_dis-assembly-3.jpg

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I have a slightly used fuel pressure regulator for my 88 that I will send you for postage only.  I replaced it as I had a leak at the connection to the return fuel line.  I then found out that I had chewed up the threads on the fuel line. The regulator came from NAPA.

PM me with your address and I will send it to you.

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No worries, I already picked up a new one last night for $18, it should arrive in a couple days.   I guess the only other thing to do is submerge the pickup assembly fully in water and do 20psi in to the outlet and look for bubbles, as per the shop manual.

 

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I disconnected the return line from the regulator and put a cup under the regulator output and ran the pump.  Fuel shot out instantly and when I stopped the pump it kept draining out.  Is this abnormal?  I would think that it would not let the fuel drain out unless it was ~>40psi.  

Edited by Fox W. (see edit history)

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I haven't tested a regulator in that way with fuel but I have applied air pressure and it did not leak air until near the set point in the low 40#'s. It will be interesting to see if replacing the regulator helps. I am experiencing similar issues, nothing from the injectors, no fuel in vacuum line, replaced regulator and problem persists. I don't really want to drop the tank but looking like it. Oh yeah, fuel pressure is normal and responds normally to vacuum, but extended cranking at irregular intervals.

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The regulator seems to have two functions really.  Without it, the return flow is wide open.. So its function isn't just to vary the pressure based on its vacuum with the diaphragm, it also is supposed to prevent fuel flow back entirely when it's below 40psi.    The thing is, the new one I put on did mostly fix the problem.  But it's still not quite in spec I don't think.. though it is good enough.  I hear it open at 40psi, but then it fairly quickly tends to still bleed down to 30psi, and from there very slowly bleeds down to 5psi, but still much faster than I hear some people say.. Some say their rail holds 40psi for a day or more.  *shrug*   I -thoroughly- tested the input line (output from pump) and it is not flowing back with that path, not even slightly.

 

  I submerged my assembly in water,  and blew 20psi in to the out, and zero bubbles or pressure loss.   I also put a block-off bolt in to the regulators' output for the return line,  just entirely block that off, I ran the pump for half a second to charge the rail to 40psi and there was zero loss.  Therefore all my loss is through the return, through the regulator.    In any case the car starts, runs and drives great now, so I'm happy.  BUT, my damn fuel sending unit doesn't work right now, it reads I have an 1/8th when I have a full tank. gerrrrr. Maybe from the water test, I don't know, but it's unhappy now.   I dread dropping the tank all over again, what a pain in the #*@.  

 

My unit has two short lines, and the vapor is a long steel line.  On the other side there are rubber lines that mate to these.   Delphi HP10010 seems to be the closest new replacement match I can find.  It's vapor line is short but you can just use rubber for that anyway.

Anyone know if that unit will fit right with our lines?

Edited by Fox W. (see edit history)

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