I recently started to notice a few things happening with my 1990 Cherokee.

1. It is hard to start when its warm. Takes a while like 10 seconds for it to crank to start. Starts very good when cold.

2. After idling for a while it is slow to rev up. Today i was waiting for wife to get out of an appointment for about 10 minutes idling. The truck was idling nice and steady. When we took off it felt like the car had no power and was choking a little bit. After a few seconds it stopped and the truck took off.

3. I noticed that recently when i am driving around in town or on a hwy the truck has much less power under 3k rpm. So i can be going, lets say, 30mph and if i stomp on the gas the truck is slow to respond and even if it downshifts it feel like something is holding it back and as soon as it hits 3k rpm it almost feels like it gets a kick in the butt and it takes off.

I replaced the fuel filter and fuel pressure regulator.

Could this be that my fuel pump is about to give up on me?

Thanks.

 

just a thought maybe you getting to much fuel at low rpms

 

check fuel pressure, but could very well be the cat clogging up also. When it acts up like this take a peak under your jeep (disclaimer: Make sure you are stopped and in a safe place, do NOT open your door while driving to look under your jeep) And see if the cat is glowing, thats a sure sign of it being clogged

 

have you notice this while turning? what level is the fuel when this seems to happen? Im asking cuz yes the fuel pump can indeed act up during these conditions--if so-hook up a gauge to test while driving(just lay it on windshield) and if so you'll be able to see pressure drop--if not, state and we'll go from there.

 

a suggestion drop your tank and look at your fuel screen if its black you should change it and change your fuel filter too then it should be fine but in case change your pump to hope that helps

 

Thanks for the tips guys. Couple things. Just replaced the exhaust. Its brand new from the head to the tail pipe. Pacesetter header( egr is capped on both sides), magnaflow OE direct swap cat and borla exhaust.

I did replace fuel filter not too long ago. like 3 weeks ago i think. I am not sure if its different when the tank is full or low. I keep the fuel level at about half most of the time.

 

Couple more observations today. When i turn the truck off and restart it right away it starts immediately, cranks about 2-3 times and fires up, even when warm. I did a test, waited about 3 min and it took a little longer to start, after about 5 min it took about 7 cranks to start, after 20 min it took like 10-15 cranks to start. If i drive it right away after I start it its got way more power than after about 5 min of driving. After about 5 min it really looses power. In second gear if I go halfway on the throttle it almost feels like somebody is holding the truck back and as soon as. It hits like 3k rpm it jumps but thats about the area where it shifts to the next gear. So its hard to tell. The starting issue is for sure fuel related, I am thinking a check valve in the pump is bad. But not sure how to explain the lack of power. oh and it does feel like the truck has less power under 3k with the tank full of gas.

 

Im just throwing it out there but if you can continue to drive the vehicle with no other problems other than sitting at idle and having temporary stutters. I would say heat soak.. Imagine as your driving there constant air flow through the engine bay, when stopped all that heat just rises and heats up anything above it, in this case its your fuel rail and injectors that are being soaked with heat, which in turn evaporates the fuel inside. it would take around 20 min. for the heated fuel in the rail to cycle out with normal temp fuel..

Now i may be wrong, im thinking off of common sense and with what problems heat can cause with our motors. So if im mistaken don't mind me.

 

Yeah good guess but i dont think it's the case. why would i pretty much feel a kick in the but as soon as the car hits 3k rpm? And even when i am cruising on the highway if i push half way on the throttle the truck barely moves, its go no torque at all. And if i push further it downshifts and starts to accelerate.

Its got to be either timing issue or fuel. But i am leaning towards fuel.

 

Yea timing doesnt seem to be the issue, you would have more issues. Im not to familiar with the renix engine, if you have, im going by year. Did any of this ever happen before you replaced filter and exhaust??

 

Its Renix.
Yeah i really doubt its timing. I did have to take the distributor apart to replace the stator. But if i put it together wrong i assume the truck would just not start or run like total crap.

I am not even sure when this started really. It just kind of came from no where. I was having issue with stuttering at light throttle and the stator fixed it. It seems like this lack of power started slowly and got worse and worse.

Before i did the exhaust the truck had a huge hole in the intake/exhaust gas and clogged 20 year old cat and rotten catback. So it had barely any power.

I just filled the tank up all the way and added 20oz of Chevron fuel cleaner. I only driven about 40 miles. It actually feel like i lost power after i put that stuff in. So maybe it dislodged some crap in the tank or fuel lines?


The only think i don't understand is why the lack of power under 3k rpm and then its fine after that.

BTW, does anyone make an intake for Renix Jeeps? I see a ton of simple setups on ebay for H.O motors but nothing for Renix.

 

So any ideas? Anyone experienced similar issues?

 

Sorry for the long link but check this out... Since i dont know much of renix it may give you an idea what else to look for

http://webcache.googleusercontent.co...&ct=clnk&gl=us

 

Great Thank you Jeepsrt. I am going to check my FP later today and see how it is.

 

O2 sensor??? Bad injector?? Fuel pressure??