runner6 Posted September 29, 2009 Share Posted September 29, 2009 We are long-time owners of a 1991 XJ that we restored for our son. My son and I found a 1987 MJ this weekend. 97,000 original miles, 4WD, 4.0L, 5-speed short bed. Lot of cosmetic work, but engine is solid and body is straight. Picked it up for $500. The engine is hard to crank. Turns and turns and turns before catching. The previous owner told us this problem started after he installed a new fuel pump at the gas tank. He said the gasket or o-ring did not seal correctly, and it is pulling air. He said that it is an easy fix - there is a bracket that spins around to release the fuel pump, and then the gasket is simply replaced. Does anyone have experience with this? I searched on the forum, but could not find anything specific. Thanks in advance for any info. My son and I are excited about restoring another Jeep! Link to comment Share on other sites More sharing options...
Pete M Posted September 30, 2009 Share Posted September 30, 2009 tech questions should really go in the Tech forum so more people will see them. :thumbsup: The Projects forum is more for telling us about your truck as you work on it and we ask you questions about it. :cheers: Link to comment Share on other sites More sharing options...
dfreeman616 Posted October 1, 2009 Share Posted October 1, 2009 i haven't had that problem, but if he's right about a bad pump gasket seal, it is about that easy. where are you located? Link to comment Share on other sites More sharing options...
runner6 Posted October 3, 2009 Author Share Posted October 3, 2009 Thanks for the info. Located in NC. We've had the MJ a week now, and we've had a little time to spend with it. What we have found is that it is almost impossible to crank - runs the battery down and we have to jump it before it will finally fire up. Once it is running, you can restart it with no problem. I've had it sit as long as two hours and it still starts up fairly well. However, if it is left overnight, it is again almost impossible to crank. In addition, most if not all of the fuel injectors are leaking a little. Could the fuel injectors be the problem? Could they be allowing the fuel rail to lose fuel pressure, and everything has to prime after sitting for a long time? I've checked the spark plugs, and they are clean and gapped correctly. I'm thinking if it were the CPS, it would continue to be difficult to crank after we get it started the first time. As always, thanks for any ideas. Link to comment Share on other sites More sharing options...
juan Posted October 4, 2009 Share Posted October 4, 2009 How about checking the fuel pressure at the fuel rail with a fuel gauge... you will be able to tell if your problem is fuel related. Link to comment Share on other sites More sharing options...
tugalo Posted October 4, 2009 Share Posted October 4, 2009 Changing the fuel pump or the gasket can be a pain....just did it on my brothers MJ. you have to drop the gas tank to do it. If you decide to change either one, I recommend disconnecting the drive shaft from the differential to give you additional room for tank removal. I don't think the gasket/oring is your problem...it looks to me as if it is just there to prevent gas from leaking out of the tank...I don't see it as a pressure seal. First thing I would recommend is to remove and thoroughly clean allthe ground wires in the engine bay, and then add an additional heavy ground from the battery to the front clip. Link to comment Share on other sites More sharing options...
tugalo Posted October 4, 2009 Share Posted October 4, 2009 One other thing, before you start replacing parts or getting involved in labor intensive troubleshooting, go here: http://www.naxja.org/forum/forumdisplay.php?f=44 and do some additional searching. XJ's and MJ's are identical when it comes to diagnosing problems. Where in NC are you located? Link to comment Share on other sites More sharing options...
daltonmcgill7 Posted October 4, 2009 Share Posted October 4, 2009 Thanks for the info. Located in NC. We've had the MJ a week now, and we've had a little time to spend with it. What we have found is that it is almost impossible to crank - runs the battery down and we have to jump it before it will finally fire up. Once it is running, you can restart it with no problem. I've had it sit as long as two hours and it still starts up fairly well. However, if it is left overnight, it is again almost impossible to crank. In addition, most if not all of the fuel injectors are leaking a little. Could the fuel injectors be the problem? Could they be allowing the fuel rail to lose fuel pressure, and everything has to prime after sitting for a long time? I've checked the spark plugs, and they are clean and gapped correctly. I'm thinking if it were the CPS, it would continue to be difficult to crank after we get it started the first time. As always, thanks for any ideas. i think its the injectors because that was the same thing mine was doing after it sat for 5 years try tapping the injectors with a screw driver while its running to try and free them up but don't do it to hard or u mite break them also unplug them then plug them back up that also freed mine up 2 Link to comment Share on other sites More sharing options...
Eagle Posted October 4, 2009 Share Posted October 4, 2009 Changing the fuel pump or the gasket can be a pain....just did it on my brothers MJ. you have to drop the gas tank to do it. No you don't. Drop the drive shaft, and the access to the fuel pump is wide open. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now