Testing fuel system / replacing fuel pressure regulator

[phychotron]

To answer my own question for anyone else who might have the same problem:

Yes, it was the fuel pump. It hummed for a second or two when I jumped the connector, I pulled the jumper and fired right up after that.

I wanted to note though that I should have tested for power at the pumps 2 prong plug just above the drive shaft before i dropped the tank. If it wasnt the pump it would have been all in vain.


Tank looked fine. A mechanic I talked to said if the outside looks fine the inside is usually fine...but there are some tank restore systems that work. I just replaced the rotting hoses amd clamps. he suggested brake cleaner thru the hard lines but that would have been teedious.



Ospho suggested their product would have worked fine though...

[Ian R.]

Hi all!

I have been trying to track done an issue with my van. Nothing serious, but it is more of an annoyance. Basically it takes a few cranks and taps to gas peddle to get the van started while it is cold. But it starts up perfect once the engine is warm. The second issue ( maybe unrelated) is I can’t get the idle to be below 1000rpm. I have changed out the TPS (had to make a throttle body gasket from a universal gasket as they are no longer available, but that is a different story) with no luck. I have also tried to adjust the idle with the idle screw. But the idle seems to revert back to where was prior to adjusting the idle screw after a few minutes of driving.

So my theory is that the fuel pressure regulator is not functioning properly. Maybe letting to much fuel in with increased pressure creating a higher rpm idle. Secondly, when the engine is off the pressure then leaks in the line creating the starting issue.

A question I have for those that have changed a fuel pressure regulator is, have you replaced the two brass gaskets highlighted in the attached image? I have purchased them along with a new union bolt (the one currently on the van is slightly stripped and I am afraid it will not be able to be reused), but the existence of the brass hackers are not described in the repair manual when replacing the fuel pressure regulator.

Thank you for your shared experience in advance!

if interested in part numbers

Union bolt part number: 90401-08004
Brass gasket part number: 90430-08011

attached is the parts diagram and image of the replacement parts I have

Ian

[Ian R.]

Sorry part of previous post

[Jan-Willem]

Hi Ian, I am sure you already have checked it, but a longer start, when cold, and a high idle, are both also symptoms of a bad battery. If the voltage when cranking drops too low, it is harder to start. Then the alternator makes then engine idle up, to charge the battery.

[Ian R.]

Thank you for the tip! I’ll check the battery before I replace the FPR.

[MarkH]

... it takes a few cranks and taps to gas peddle to get the van started while it is cold. But it starts up perfect once the engine is warm. The second issue ( maybe unrelated) is I can’t get the idle to be below 1000rpm. ...

I would check the fuel pressure with a gauge to rule out fuel pressure issues before replacing components that might not be the issue. Your symptoms sound like a vacuum leak to me. It's a quick check make sure all the vacuum hoses are attached and not cracked or degraded. A vacuum leak could also be caused by leaking intake manifold gaskets, leaking rubber grommets around the nuts holding down the valve cover, valve cover gasket, oil dipstick seal, pcv valve grommet, etc. I've never tried it, but many people use a flammable spray like carb cleaner/throttle body cleaner. You spray around those components when the engine is running at idle. If the idle speed changes when you are spraying at a particular component, it's because the spray was sucked into the component meaning it is leaking. I'd be semi-afraid of causing a fireball using this technique, but it seems to be pretty common and most people claim to have survived.

[Metalghost]

Looks like this might be the right place for my issue. I have similar issues to another user where the 86 Van starts but dies immediately. I measured my pressure for the PR and it is a little high. 42 for a range that is spaced 33-38psi.

1) is 4psi over enough to cause trouble. I saw an earlier answer was the van can compensate some with the O2 sensor. But not sure when is too much. 50psi was deemed not working from the authors post.

2) I’m in process of changing all vacuum lines off the throttle body. I read that vacuum leaks can cause idle problems of start/running problems. I check spark and saw spark in all 4 but thinking of going through the distributor for timing and rotor/cap condition next.

3) Could a bad mass air flow sensor be throwing off the mix after it turns over?

Open to any help. Trying my best to be smart and diagnose over throwing new parts at the problem.

[timsrv]

Having a little too much fuel pressure will not cause your problem. I have full gauge sets in my vans (including fuel pressure) and my 86 van had high pressure like that for years before I replaced the FPR. You are correct about the system compensating. The ECU adjusts injector fire times based on info it gets from the o2 sensor, so if there were too much fuel pressure it would be compensated for. So even though the FPR is not within it's specified range, it's not the cause of your issue.

There are other threads that should be able to help you diagnose. Search for "coil" "igniter" (maybe some results in "ignitor") and "Electronic Control Unit" Having some extra parts around is a good thing, so if you can find any of these things cheap in a salvage yard or maybe eBay, they can save lots of troubleshooting time and heartache. Good luck! Tim

[MarkH]

Looks like this might be the right place for my issue. I have similar issues to another user where the 86 Van starts but dies immediately. I measured my pressure for the PR and it is a little high. 42 for a range that is spaced 33-38psi.

1) is 4psi over enough to cause trouble. I saw an earlier answer was the van can compensate some with the O2 sensor. But not sure when is too much. 50psi was deemed not working from the authors post.

3) Could a bad mass air flow sensor be throwing off the mix after it turns over?

I think if the signal from the O2 sensor goes out of range (too high or too low), it should generate a fault code. Same with the MAF sensor. Assuming your check engine light isn't burnt out, are you getting any codes? There is a connector in the engine bay to jumper to check this.

[MarkH]

Also, there is that flapper-type valve in the air intake that makes a switch to run the fuel pump. If that switch is faulty or the valve is not opening properly, the fuel pump will shut down. When you tested the fuel pressure was it with the fuel pump test connector jumpered?

[Metalghost]

Wow. This is good info.

Yep I jumpered the pump to test it. Also I don't see any fault codes on the engine light. That does work as I see the bulb on when I turn on the car. I saw how to get into that code reading. I can check again but didn't see any errors popping up. But if there is a way to check the O2 and MAF sensor I will do that.

I'm replacing all vacuum tubing and the big Tbody/cleaner hose to make sure I don't have a leak. After "air" is all sorted I'll try poking around the spark side more. Already check there is a spark but can dive into the distributor/ignitor/wire.

Open to anything else or redirects to articles. Been through the search for ignitors and coils already.

[Ian R.]

Closing out my question about the part numbers. Yes these fit the FPR (the ones originally on the van were washers without the tabs).

This is a tedious task. I recommend unbolting the heater hoses nearby, wrapping a rope or shop towel around them, and pull them out of the way (tie them off when retracted). I was able to sneak a 3/8 drive socket on the shortest extension to remove the union bolt.

Also use a Phillips head on the two FBR mounting bolts to get the started. It took a few tries to have them threaded properly. Once they are threaded use a socket and long extension to get them snug and followup with a torque wrench 5.9 Nm for the two mounting bolts and 20Nm for the union bolt.