1991 fj80 crank but no start.. Will start the next morning ...?!?!??!??

[Markoloma]

Ok so I just picked up a 1991 fj80. 180k. I drive about 150 miles a day on it. Ran two full tanks, stop and go. Turned it off and on with no issue.. Was taking a trip and pull over at the rest area.. Won't start! Cranks and gives spark but no start.. Towed it home. Did research.. Started checking the problems.. Everything is working perfectly.. But won't start.. Got tired..went to bed. Next morning it fired right up with no hesitation..that's cool

Drive it for about another 300 miles no issue.. Park and a store.. Same thing. This time I changed my spark plugs thinking maybe I flooded them.. Nope. So I just went home and came back the next morning and behold. It fired right up.

Heard about an intake boot leak so I put on a new one.. Old one was cracked.. Ok cool.

Drive another 200 miles.. No problem. Stop and go and starts every time. Even took it to the mountain and flawless..

Went to the post office this morning... WONT START AGAIN!!!!!!! This time I can't get picked up. Anyone have any idea what is going on with it???

 

[SUMMIT CRUISERS]

Here's the flow chart provided by Mr. Jon Held: http://www.sdsysdesign.com/tlc/images/Strife/3FE EFI Diag.pdf

If I was guessing I'm thinking EFI relay is getting hot. Follow the flow chart above and you should figure it out.

 

[Markoloma]

If I was guessing I'm thinking EFI relay is getting hot. Follow the flow chart above and you should figure it out.[/QUOTE]




I thought so too and I've read that page.. Thing is, my relay works perfectly fine..I even took is apart and watched it work.. Lol

 

[SUMMIT CRUISERS]

When it doesn't start you mentioned it gives spark. Sounds like fuel then. Start with changing the filter, the in tank sock and see what happens. If you can hook up a fuel pressure gauge to the fuel rail where the CSI gets its supply, you can test there.

Here's a thread I did when I had a similar problem: https://forum.ih8mud.com/threads/intermittent-starting-problem-solved.801912/

 

[Motleyone]

X3 on the EFI relay. Had it happen to me on several occasions when really hot. I keep a few in the glove box.

 

[Markoloma]

X3 on the EFI relay. Had it happen to me on several occasions when really hot. I keep a few in the glove box.

I'll have to look into the fuel filter. Well aren't the symptoms of the relay the "no check engine light= no start" ?

My check engine light goes on every time. And the relay always clicks.

 

[Motleyone]

I never had a check engine light and did not see that in your post. It sure sounds like the EFI relay. They are not that expensive. It would be a fast way to eliminate it the next time it gets hot toss one in. You will need pliers or a glove as mine were crazy hot and could not be touched.

 

[jonheld]

If the CE light comes on when the key is in the ON position, then the efi relay is good. If you're getting spark then the efi relay is good and the rest of the system is functioning properly.
Let's move away from the efi relay. Possibly the FPR is failing. It is known to cause difficult hot engine starts and will eventually damage the check valve in the fuel pump.

 

[Markoloma]

If the CE light comes on when the key is in the ON position, then the efi relay is good. If you're getting spark then the efi relay is good and the rest of the system is functioning properly.
Let's move away from the efi relay. Possibly the FPR is failing. It is known to cause difficult hot engine starts and will eventually damage the check valve in the fuel pump.

Hmm... What's the FPR

 

[robertk61]

Fuel Pressure Regulator

 

[sdbrassfield]

I am having same issue. Starts fine when cold. Drives fine. Turn it off after warm or hot, whether it has idling for 3 min or drove an hour, will not start. Cranks fine. I have confirmed spark and fuel. Driving me crazy. Am going to look into fpr and damper. Mine is a 92.

 

[WarWagon]

Fuel pump

 

[jonheld]

Fuel pump

Not likely. The OP stated that he could go on 300 mile trips without issue. The problem is on a re-start when hot.

 

[Aggiesdm]

FPR is fuel pressure regulator

 

[Markoloma]

Interesting. Yes because when it starts up it runs flawlessly. I can drive it all day long no issue. Every now and then rpms go low in reverse...? Not sure if this will help or not to clarify.. But say for example if I try crawling up a hill. With center diff locked. I have to make sure my AC is on. Because if I don't it will stall out on me.
I'm afraid to take it too high up in the mountain because I don't want to have it randomly not start.. I bought it mainly for camping. And been driving it just to make sure it's all good. Would love to fix this issue.

 

[TX Cruiser]

Go get a new EFI relay.

 

[Offroads4x4]

You can always try jumping the fuel pump relay to see if that helps as well couldn't you. Jump wire at the diagnostic plug?

 

[Markoloma]

You can always try jumping the fuel pump relay to see if that helps as well couldn't you. Jump wire at the diagnostic plug?

How would I jump it?

 

[SUMMIT CRUISERS]

Locate the Diagnostic box on the passenger firewall. Insert a jumper wire in the FP and the B+. Turn the ignition key on and fuel pump should run.

Have you changed your FPR and your Fuel damper? My bet it is one of those. Mine was the damper that was causing a similar no start problem.

 

[jonheld]

Interesting. Yes because when it starts up it runs flawlessly. I can drive it all day long no issue. Every now and then rpms go low in reverse...? Not sure if this will help or not to clarify.. But say for example if I try crawling up a hill. With center diff locked. I have to make sure my AC is on. Because if I don't it will stall out on me.
I'm afraid to take it too high up in the mountain because I don't want to have it randomly not start.. I bought it mainly for camping. And been driving it just to make sure it's all good. Would love to fix this issue.

Inspect the intake hose for cracks or splits.