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Help with a starting/running issue!

Discussion in 'Stock 1995 - 2001 Explorers' started by jakegator, December 31, 2016.

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  1. jakegator

    jakegator Active Member

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    Hello, I just finished replacing my heads and manifolds with headers. Got it all back together went to start it and it started right up. Wouldnt idle but thats nothing new (Probably bad IAC). Normally it will idle after a minute or so of holding the gas to about 1K rms. It did eventually idle and I let it run for about 5-10 minutes. I turned it off and went to turn it back on and it wouldnt turn on. All the lights still work and the starter is working. No check engine lights. I looked around on here and saw some people talking about the fuel pump relay acting up so i switched it up, but no change. I let it sit for a about a half hour or so and went to start it again and it fired right up perfectly. Let it idle for a bit, turned it off, turned it back on and nothing. Let it sit again and it starts fine. And repeat.

    I double checked the plugs and they are correct,all vacuum lines are where they should be and appear to be in good condition. I have done this exact job on the same engine on my 92 explorer a few years ago and am very confident the heads/LIM /injectors were all put back correctly. The engine is a 4l OHV on a 98 explorer.

    My thought is that it could be the fuel pressure regulator? I did spray the inside of it with carb cleaner so maybe that force broke the diaphram? The engine has 240,000 miles on as does all of the parts.

    Does anyone have any suggestions on how to fix this issue? I do not have a pressure tester that fits the test port...
     
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  3. jakegator

    jakegator Active Member

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    Just an update. I finally got someone to come crank it so i can check a few things. There is spark during the no starts as well as 35ish psi of fuel pressure. When it eventually runs the fuel pressure is 31 psi and when its turned off it stays at 40 psi for as long as my patience allows... about 20 minutes. If i start it and let it idle with out turning it off until it gets to operating temps and turn it off it will turn back on with no issues. I did use a stethoscope to try and listen to the injectors turning on and i believe they are opening.

    I just put new ignition wires and a coil pack on. The original coil pack was out of spec but uniformly on all coils. The fuel pressure regulator should be here tomorrow so hopefully that corrects the issues.

    Any thoughts?
     
  4. drdoom

    drdoom Well-Known Member

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    Might be a bad fuel pump.
     
  5. jakegator

    jakegator Active Member

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    I replaced it and the fuel filter about 3 months ago. It shouldnt have good bad that fast. but possible
     
  6. drdoom

    drdoom Well-Known Member

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    OK it's good that you replaced that. Is 35psi in spec for a '98?, I can't remember what model year it changed...
     
  7. jakegator

    jakegator Active Member

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    Yea at idle its suppose to be between 30 and 45. So i guess its a bit low. It doesnt say what its suppose to be while cranking but it reads 40 while cranking.
     
  8. Turdle

    Turdle Freelance Stuntman Staff Member Moderator Elite Explorer

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    35 psi at idle is good. For an accurate assesment of the FPR, you remove the vacuum line and check pressure. I bet it jumps to 40 psi with vacuum line removed and plugged.

    Blipping the throttle wide open quickly should also result in a jump of the gauge. Does it? There could be a flow volume issue even with good fuel pressure. Usually if the pressure jumps with the demand of the throttle blip though, the flow is ok.
     
  9. jakegator

    jakegator Active Member

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    Turdle - I just went out to check my numbers. It idles at 31 psi. If i rev it it jumps to 38 psi then falls back down to 28 then immediately corrects to 31 psi. That was with leaving the throttle open. Same thing happens if i open and close it quickly but. With the vacuum line disconnected and plugged it sits at 40 psi.

    Should the pressure stay high while the throttle is open?
     
  10. Turdle

    Turdle Freelance Stuntman Staff Member Moderator Elite Explorer

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    It sounds like the regulator is working, but the drop to 28 i do not like. I would try a fuel pump sock and fuel filter. If it was me, I would try to get a fuel pump motor and sock, since you have to remove the sock from the old motor. The old plastic might not like this.


    pumps made by Carter, Walbro,Bosch, or Holley are what I would shop for on ebay.
     
  11. jakegator

    jakegator Active Member

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    OK it does have a new fuel pump and sock as well as filter (less than 3 months). I need to replace a brake line behind the tank so i guess its not that bad to do again since i have to remove the tank anyway.
     
  12. jakegator

    jakegator Active Member

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    Just wanted to wrap up this thread. I had to cut the egr tube in three pieces to get it off of the stock manifolds and onto the new headers. When i welded it back together the angle where off since I couldnt do it in the car. To make it meat up the intake I cut the tube between the egr valve and the intake and connected the two with a supposed high temp vacuum hose. It was either not a high temp or a vacuum hose and was collapsing under those condition not allowing anything through when it was suppose to and also creating a vacuum leak. I replaced the hose with a more expensive one and now it runs great. The hose is just a bad aid until I can find a new egr tube but it seems they are not as common as other parts.

    Thank you all for your help!
     
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