Hey guys, Im not new here, I couldn't log in with my other user name. anyways here is my problem

1989 cherokee limited 81k miles

was driving and running great up until the other day. it started to sputter and wouldnt go over more then like 45-50mph. it idled but crappy that day but after sitting a few days it wont start up without cranking it for a while and if or once it does start it stays running for a few seconds and stalls on its own unless i rev it up to keep it running

I limped it home and tried a few things. first i cleaned the throttle body, replaced the fuel filter and air filter and threw some lucas in the tank.

it would start and then stall. I can keep it running by free revving it. but if i let off then it stalls. I thought it was my fuel pump but im getting fuel from there. I think (without testing) maybe the regulator is ok. however after priming the truck there is hardly any fuel in the rail. I put a screw driver in the test port to see if fuel would pump out. just mostly air/pressure.

I ordered a new tps sensor thinking that was the problem and i havent received it yet to actually test if that is or isnt the problem. But to me it seems more fuel related.

I havent done really anything else to the truck since i got in January. the guy I bought it from said he did a tune up not too long ago. I havent changed anything except for parts that failed on me.. Really at a lost at this point. its not my daily driver so im not totally worried about fixing it but its going on like a week and a half now. i just wanna fix it.

if anyone has any info or could lead me into a better direction let me know..

thanks in advance

 

It sounds like a fuel pressure issue. If you're getting air out of your fuel line, it must be getting in somewhere. If the pickup for the fuel pump is submerged it shouldn't be drawing air.

 

alright yeah the tps did nothing...fail

and im starting to this its def fuel related. i pulled the fuel line going into the fuel filter and it sprayed fuel out no problem.

my guess is maybe the regulator?...from my past experience that rail should be filled with fuel..at least i thought so.

tomorrow im going to rent a fuel pressure kit and see where thats at and then look into the regulator some more.

Thanks for the help and if anyone else has any info please let me know

 

I would definitely check your fuel pump first. i just replaced mine on my 89 yesterday!

 

ok you did ....

 

From what you describe (little pressure in the fuel rail), this most definitely is a fuel delivery issue. #1 suspect is the fuel pump.

By design, when the key is turned to the ON position (not start), the fuel pump should come on and run for approximately 2 seconds. Does yours do this??

For an 89, you need approximately 31 psi for the vehicle to start. You can verify what you have with a gauge if you like, but it is likely negligible.

If you aren't in that 31 psi range, the engine won't start.

 

i pulled the fuel line going into the fuel filter off and turned the key over..fuel came out.

i also cranked it while the line was off and fuel came pouring out.

my guess then would be maybe the regulator isnt working. right now im going to autozone and renting their fuel pressure tester with a gauge to see where its at. if my pressure is low could the pump be the problem even though its still pumping?

 

Check how much psi its putting out

 

just by using the schrader valve there on the rail to test?

i have a question though, if my pump is actually pumping fuel but not enough pressure then it could be causing my hard starting due to lack of pressure and the fact that it stalls after revving it.??

and is there any specific way to test it? just put a gauge on the valve?

 

Thought you were going to rent a gauge. Pretty easy to get a reading. Hook up the correct fitting and it goes on the schrader valve (looks like a bike tire valve) on the fuel rail under the hood.

Get some readings and post em up. Gotta have data. Anything less is guesswork.

 

hey guys, figured i would give an update.

I bought a new fuel pump due to low pressure. But before i pulled the pump out i listened for the old one to prime. it sounded good, but i heard fuel draining back to the tank. I pulled the return line off and primed it out. nothing came out.

my problem turned out to be the feed line coming off the fuel pump going to pump assembly itself was only half way on. so thats why my pressure was so low and making the truck run so bad.

So i put the hose back on, and bought a new lock ring for the tank and fired the truck up, no problem runs good as before.

however this lock ring is being a huge pita to get back on, any tricks or tips?

 

When I did mine last week, I fought with mine forever too haha. And I never got it on 100%. Only like 3/4 or the way turned it. But its good enough for who its for! Haha

 

You need 3 hands..... One for the hammer one for the brass punch and one to hold the ring tight to the tank. I did mine with a no no method I do not condone. I bypassed the punch and struck the ring lightly with the hammer while holding the ring VERY firmly in position. When I barely got it started I used the punch to sorta force the other "ears" into there spots in the tank. Once all the ears were started it was easy does it till I had it clocked in. I did this at10pm in a field with a maglite resting against arm pointing at the tank. Talk about a PITA!

 

Sounds like typical fuel pump chores haha

 

My brother and i just got through dealing with that ring on his '90. If you put a new gasket with the ring check it against the old one. His new one was a little bigger than the old one making it impossible to assemble without it sticking out the side and thus leaking. Also try using something to lubricate the gasket so the ring can slide easier.