Topic: YJ starts hard

[casco]

My yj started to start hard in the morning about a month ago. Now it starts hard aftet sitting for more than 20 minutes. Thinking it may be the fuel filter which i replaced today, i put a fuel gauge on the fuel rail and its right at 31 psi running and when i remove the vacum line it goes up to 39 psi just like thr book says. How ever when i shut  it off and let it set for a half hour and rechecked it it was at 10 psi. I cant find ant leaks ant were is there a  check valve which could be bad causeing the pressure to relieve its self. And help would be greatly appreciated. Thanks

[sharpxmen]

10 psi after 1/2 an hour is not ideal but it's actually pretty good. Once you put the contact on the pressure would build up again and by what you're saying would stay there for some time so fuel pressure is not your problem.

I'd look for a spark related problem or maybe even take a compression test and see what that says as well.

[Bounty Hunter]

Try leaving the key in the run position for a few seconds before cranking.  If it fires instantly, fuel pressure bleeding off is your problem.

[casco]

Turning the key on the pressure go fro 10 to 18 psi still wint start with out excessive cranking. If i turn the key on and off 3 or 4 time the pressure goes up to 31 psi it starys right up. So wgat cause the pressure to bleed off.   Thanks

[sharpxmen]

Turning the key on the pressure go fro 10 to 18 psi still wint start with out excessive cranking. If i turn the key on and off 3 or 4 time the pressure goes up to 31 psi it starys right up. So wgat cause the pressure to bleed off.   Thanks

most likely causes in this order
FPR
internal o-ring of the  FPR
fuel Pump check valve
external o-ring of the FPR (but that would leak out and you would actually smell gas and probably see it as well).

[Jason280]

I'm having a similar issue with my '95 YJ 2.5L.  It takes a couple of seconds of turning before it finally cranks, and it seems as though it is losing fuel pressure while sitting.