Hello all. I recently purchased a 91 Cherokee with the 4.0 HO engine. It is an auto (unfortunately) and 4wd works great.

A problem has suddenly appeared. I brought it up to our garage to clean the inside out some and after that when i tried to start it, the engine would crank but would not fire. Now it fired up fine all the times before it. Even after sitting for 5 days in mostly sub zero degrees weather it fired up. I was finally able to get it to fire after keeping the throttle at full while cranking.

I was wondering what would cause this? It runs fine with no stuttering or misfires. I have not changed anything yet as i do not have any parts yet. I checked the fuse box under the hood and those are all good. I am getting spark as well.

Also the previous owner did not drive the jeep too much but when i purchased it i put $20 of gas into it so the gas should be good.

Anyone have some ideas for me to check?
Thank you in advance for any help.

 

From what I've picked up on here from others, check your fuel pressure

 

Ok. Do you think it could be crud built up on injectors or something? From old gas?

 

Did you clean the inside of the engine bay with a hose?

 

No why?

 

when you let off the throttle.. did the jeep stay at idle or die?

 

Apperantly our Jeeps don't really agree with water. I think the reason he asked was if you did, might've damaged something electrical. Building on that premise, any mud or water puddle splashing recently?

As for the injectors, it seems very possible they could become clogged from old gas sitting in them, although I'd think the new gas flowing through would've cleaned them out, but I could be wrong. In any case, upgrading them anyway would be a good investment. I swapped Dodge Neon 784's into my '93 down there and got quite a bit better gas mileage and acceleration. Plus it idles smoother!

Oh, and this

 

Nope it has only been driven around a bit in the snow as it doesn't have plates for it yet. And it stays at idle fine when i let off the gas.
(because there is no muffler on it, if i drop off the gas fast in park it sounds great )

 

i wonder.. remove the throttle body and clean it... clean the hell out of it.. remove the IAC from the throttle body and clean all up in there and the IAC itself...

when I removed mine.. i stripped the TPS.. the MAP.. and the IAC from it.. i even removed the butterfly valve.. ( i do not recommend this unless you know what you are doing)

I soaked it really good and got it to shine... put all the sensors back on.. ran like a dream..

this would be a good time to replace your sensors with good aftermarket sensors.. like mopar.. if you felt the need to!

 

Didn't think of cleaning the TB....Good suggestion! Might have to do that myself....

 

nothing wrong with a good cleaning..

it costs you relatively nothing.. and can only help!

 

That is taking the whole intake off right? Should i replace the intake gasket then too?

 

NO NO NO!!! lol

the throttle body bolts on top of the intake manifold.. you dont have to remove the manifold

there is a gasket at the base... but when i removed mine.. the gasket stayed intact.. so i just bolted her back on... you can replace that gasket if you want to... I should have but i was trying to get her to run right during the middle of the night when the stores were closed

here is a random google image for clarification



edit: your intake will not look EXACTLY like this because this is a 99+
the concept is still the same

 

No, just the throttle body. If you're not sure what that is, it's the part your air tube coming off the airbox goes to. Four bolts on each corner (at least on mine) and it's off. Gotta unplug sensors and unclip the cables, but it's really easy to take off. Get a new gasket while you're at it.

EDIT: Whoops, little later there....Lol Jack's got it right for ya!

 

My bad i was getting it confused there. Lol.

And sometimes i think i am good with cars. :P