1975 Cj5 Problems

Need some help here. Purchased a 1975 CJ5 from a kid that started this project a few months ago. According to him he rebuilt the engine from using an 84 inline 6. He had a new lift kit still in the box, shock, drums, brake hardware etc. Needless to say I couldn't pass up this deal at $1500. Since then we got it together, I've put a new distributor, water pump, thermotstat, radiator, hoses, plugs, Carter YF carb, battery, starter, master cylinder, brake lines, proportioning valve, and probably a few other things I can't think of. My dilemma is this, It runs great at idle, timing is dead and can rev it up with no issues. Once it gets warm it shuts down and won't restart. Once its cool I can start it again and go through the same issues. Choke is working fine, new fuel pump and lines, pulled the tank and its clean, pickup is clean and appears to be a new sending unit. I'm at a loss and wondering if anybody has any ideas on what I may be missing. No vacuum leaks either. Fire away...

 

What kind of ignition system are you using? The factory Prestolite ignition is known for the symptoms you describe.

When it won't run, pull the coil wire and see if you have spark.

 

I did replace the ignition module when I first got the jeep, just went and checked spark, very intermittent.

 

I should add that the distributor and ignition are for an 84 as well.

 

I'm still betting on ignition. Gas and spark are the two things that will cause a failure like this, and I presume you see gas in the carburetor. Intermittent spark is not good, but it does not conform to how you described the problem. The aftermarket Duraspark modules do not have a very good reputation, so a module failure is possible even if the module is fairly new. It could be simple like a failing ignition switch. Since you can make it fail, I would suggest that you get it warm so it won't run and trace everything from the switch to the coil.

 

Hey Tim, thanks for the responses. I found that the connector was loose and fixed that, was still doing the same thing and still had spark. Been chasing this issue for a couple of weeks. For whatever reason, dropped the tank again and happen to look at the fuel line from the sending unit to the hard line. The PO used a fuel vent line instead of a fuel line. My problem has been $6 worth of hose, replaced the hose and the problem went away, I'm guessing that when the hose was collapsing on it self as it was trying to draw more fuel. Been driving it for the last hour with no issues.

 

Good to hear.. My least favorite Jeep job. Dropping the fuel tank..

 

When you purchase someone else's project you never know what your going to get.

 

I think you did fine for that price.

 

the real test will come with repeated driving. has the problem really gone away, or is it temporarily absent? hope that it was as simple as the collapsing hose, but that doesn't really fit the symptoms, ie, didn't run well/at all when warm.

i long ago replaced my BID prestolite ignition with a buick/chevy 250 distributor HEI unit. eliminated the idle and running issues that plagued me for years, and i kept trying to attribute to the fuel delivery, vacuum leaks, and other things. turns out it was the crappy original ignition/distributor system.

 

Believe me when I say I have toiled with this for the last two weeks, looking at everything from ignition to fuel delivery, this thing was beating me up. I have a 70 with the oddfire and never had this many issues. I am still waiting for this issue to arise again, but as for now, it is running like a new rebuilt engine should. I put over 75 miles on it today with no issues and is still purring. I couldn't even get it 5 or 6 houses down the street before it would shut down and not start. This purchase was for my teenage son, I'll be driving it for the next bit to make sure that all of the gremlins are gone for now. I will say he is excited about it and can't wait to have it as his daily driver. Lets hope it was only a hose issue at this point...

 

As others have said 90% of carburetor problems are found in the distributor.

 

You got a great set of slot wheels!

 

You should have seen them when we got it. My son spent two days polishing them by hand and they turned out nice.