92 Explorer XLT 4.0 OHV 4x4

[blacktail4x5]

Hello all. My first post in this forum but have read and learned alot form here for a long time. I will try to keep this as short as possible d;/)

Rig runs great. After short runs and barley warm if it is turned off it wont start. After sitting for 1/2 to 1 hour it ussually fires right up. Temp gauge also was not moving up at all. Checked the fuel pressure without cranking and it is 40 psi. Runs at 32 psi at idle but only let it run a very short time as the gauge was leaking. Will get teflon tape tomorrow and get a good solid reading.
I put a new thermostsat in tonight and I think the rig ran at normal temp for the first time since I bought it several months ago. While I was burping it I was running the rpms up to 1500. As I held it there I noticed that the rpms jump 150 to 200 rpms. In other words I hold it at 1500 and it will bounce down to 1300 and back up to 1500. It will do that over and over and the same when running up to 2000 rpms. Is this a sign of a fuel pump going out. I thought it could be the ETC valve getting warm and causing the vapor lock problem but when I found that the rig never warmed up right I changed the stat. Trying to not pull the fuel pump but may have to. It runs great at first start and more for me but my duaghter gets stuck often. Last time took several hours to start agian but when it did it fired right up and ran good all the way home about ten miles. We know have good heat in the rig and I will get my fuel injection tester sealed good tomorrow for a good reading but I think I got one already just not a reading running it up to 2000 rpms and see if it still bounces then. Any ideas will be greatly appreciated. I was leaning torwards ETC sensor first but with the flucuation in rpms is making me tthink fuel pump. Any Ideas??? d;/)

 

[MrShorty]

The results to date of fuel pressure tests don't indicate a problem with the fuel pump. Get a good seal for the gauge and then test it and see if the pressures ever drop off below the results you've got so far.

My first thought with a hard warm start is a leak FPR. Pull the vacuum line to the FPR and see if there's gas in that vacuum line (gas =bad FPR). Does the fuel pump run when it won't start?

 

[blacktail4x5]

I will check it out this evening. No the fuel pump does not engage when it will not start. After it cools down it works fine except for the last time. I took several hours but then it has worked fine ever since. It only seems to happen to my daughter. It works fine for me even when it is warm. I will check the FPR and Pressure check this evening. Thanks

 

[MrShorty]

No the fuel pump does not engage when it will not start.

I have heard of cases where the relays have trouble closing when they are hot. If the fuel pump isn't coming on when it won't start, that's probably where I would go next: checking the relay.

 

[Wrench]

Are you sure your daughter has her foot off the throttle pedal during the start cycle?

 

[blacktail4x5]

OK. Got the pressure guage leak stopped and here is what I have. 42 psi before start and 32 while running. It maintians 32 psi no matter what the rpms are unless I punch the gas. when I rev it up quick the psi bumps up to 35 real quick and right back down to 32. I turned it off and it stayed at 32 psi for 3 or 4 minutes while I found the FPR and got a wrench to fit it. PSI never dropped at all until I depressurized the system to check the FPR. I took a pic becuase I am resonably sure this is the FPR but I am not positive. I thought it would be a rubber hose but it has a metal weave on the hose. It does have gas in it. You can see the glare off it in the pic. The hose had a bit in it but the neck of the FPR was half full I would say. Is this the FPR? You can see the pressure gauge to the left to give you a better idea of where I am taking a pic of. Well....maybe you can see it when I figure out how to post a pic Well, it is the only thing on the rail and it is right in front of the test valve.


Wrench: I have had her try it several different ways but mostly with foot off the gas. She apparently has been successful in getting it started a couple times after 5 minutes or so and it ran real ruff for a couple seconds and then cleared right up. I guess this has been an issue for awhile that I didnt know about. Children!

 

[MrShorty]

Got the pressure guage leak stopped and here is what I have. 42 psi before start and 32 while running.

Fuel pressure testing seems normal. But then, it started while you were testing it, so one would expect the fuel pressure to test normal. Have you had a chance to test the fuel pressure when it won't start? With an intermittent problem like this, it is often important to do your testing when the problem is present.

I thought it would be a rubber hose but it has a metal weave on the hose. It does have gas in it. You can see the glare off it in the pic. The hose had a bit in it but the neck of the FPR was half full I would say

Those metal hoses are for the fuel. The supply line attaches to the fuel rail towards the rear of the rail, the return line attaches to the FPR at the front of the rail. There should be gas in both of those lines. The line to check for gas is the small vacuum line attached to the body of the FPR and runs towards the back of the engine along the intake.

 

[blacktail4x5]

Well we have been driving the rig more and more since I put a new thermostat in and have not had a problem yet. I hope it fixed the problem and am not going to complian. If it happens again I will run a fuel pressure check on it when it will not start and let you know. I think it may have been the problem as she was starting to have the problem atleast every other day for a couple weeks and it hasnt acted up once since. Seems strange if that was it though. God is Good!!! And this forum rocks also d;/) I learn more in an evening here then in two weeks in manuals and under the hood. Time saved here equals $ right!! Thanks a ton!!Will post if and when it acts up again.