My jeep can sit all night and it has a rough time starting and sometimes it won't start on the first try. But as soon as I try it again it starts right up. And after its ran for a while an is warmed up it starts fine. There's no check engine light on so idk what it could be. Anyone have any ideas?

 

'No start' as in no cranking? Or cranking but not firing?

 

Cranking but not starting, then you stop and give it a second then it'll start

 

i have this problem on my 2000. do you have the heat sink problem? i do, and i assume it has something to do with that problem. i have just come to live with it, its a minor inconvenience, but i know that it will always start.

my thoughts on the heat sink, is that when the fuel vaporizes in the fuel rail, it cools off and from the fuel "shrinking" it causes air in the line. when you brank it up, its spitting out air for a second, so it doesnt watn to run. if you turn the key on, let the fuel pump prime for about 3 seconds, then start it. it starts much better then. the solution is putting high temp insulation between the exhaust and intake manifold.

if this is not a heat soak issue, then none if this is helpful.

 

Sounds like a fuel delivery issue. To check your fuel pump and fuel pressure regulator, you need a pressure gage. Hook up this pressure gage to the fuel rail for your fuel injectors. Turn the key on, not crank, just on, and keep an eye on this gage. I don't know the specific numbers, but the fuel pump should build up pressure to a certain amount (around 30-35 psi, I think). Turn the key off and keep an eye on this gage for about five minutes, see how long it takes to bleed off this pressure. You should not have a fast drop, fast drop means either a bad fuel pressure regulator, or a leak. Inadequate fuel pressure on the first place means either a bad fuel pump, or a leak. Before doing any of this, it's not a terrible idea to do a look around ( or sniff around) for fuel leaks. It's not a bad idea to look at your fuel filter, it may need a changing, a slow pressure build may be indicated from this. Sorry it's so lengthy, but getting a pressure gage is not hard, I think AutoZone may lend one, they're cheap to buy, as far as tools are concerned. Good luck!

 

Fuel vaporization would cause a hard pressure build, or no fuel delivery at all (pump fighting an air bubble, basically).

 

I checked my fuel pressure with an older type R12 AC test gauge,

fit on the XJ fuel rail very good. I believe the pressure should

be about 49PSI.

 

Like I said, I want sure on the specifics (time of psi drop and psi value), best to look it up!

 

right...and as it cranks, the injectors open and close, effectively purging the air...after you shut it down, and try again, the fuel pump sends fuel, and it cranks right up.

am i missing something?

 

Yeah, I once was a car mechanic, it's been a while since I worked on cars. I work on helicopters now, but the principals are still the same.. vapor lock came to mind when you mentioned air in the rail.

 

Sorry, I'm new, but I have a starting problem as well in my 4.0 98 jeep Cherokee sport, as soon as I start it up and drive it it goes but then accelorating my rpms go up then I hold the gas to just about keep that speed then the rpm guage goes down slowly without me letting up on the gas ( doesn't sound like switching gears) and it does this thing were it stays one speed clicks, knocks, or sounds like popping and then jumps up speed, and I have replace my distributor car and rotator for the inside of it, and no luck, could it be a throttle position sensor, or bad gas

 

I have the same issue, I just turn it to the on position a few times and it generally fires right up.