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Discussion Starter · #1 ·
Hey yall.
I have questions and need help. I have just put a rebuilt 258, 4.2L in my 87 jeep wrangle. I am having a hard time to get it to start. I had it running but it often takes me some time to get it start.

One problem that I have noticed is that when I am cranking the engine, I get no spark in the plugs. But when I quit cranking it, the spark catches and the engine starts running. Sometimes it makes for quit a back fire. I have already replaced the exaust manifold gasket a few times.

Also, I would like to get rid of all of the emmisions stuff. There is a mess of vacuum lines going everywhere. It is a giant headache that I am constantly battling. I know that the carb and the distributor work on a vacuum loop of some sort. I guess I would have to do some swaps, or a few modifications to make these work properly.

Thanks in advance for the help.

Talk to you later, I have some buckmasters to watch.
 

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If an 87 can be considered an 'old' jeep. /ubbthreads/images/graemlins/wink.gif

You've got 2 separate problems.

1) Could be an ignition switch, could be the way it's wired, could be could be could be.... You're not getting power on 'crank' just on 'run'. But I guess you knew that. /ubbthreads/images/graemlins/grin.gif I guess you know that the reason it's backfiring is because you're dumping in gas without spark while it's cranking too. /ubbthreads/images/graemlins/grin.gif

2) The carburetor/emissions systems on the 87-90 YJs isn't great, and there's a lot written about it. Depending on the emissions laws in your state, you have various options. Do a search on the following items, both here and internet-wide and you should find more than enough info to keep you reading for a while.

MC2100 carburetor.
Weber 32/36 carburetor.
Weber 38 carb swap
GM HEI distributor swap
TFI Team Rush Upgrade
Pulse Air System
Nutter Bypass
Howell Fuel Injection
4.3 GM TBI
MOPAR Fuel Injection Upgrade
4.0 swap
GM 4.3 swap
etc.
etc.

Pick your poison -- you'll get lots of opinions. My choice has been a weber 32/36, with a GM HEI, and no pulse air system at all, keep the cat, run an EGR (because I do have to pass emissions). If I had the resources at the time, for the money I'd probably have tried an MC2100 with the GM HEI first.

Good luck
Pete
 

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Discussion Starter · #3 ·
Man,

I did some reading on the MC2100 swap. It seems to be the thing to do.

I have not shecked the GM HEI option yet.

Thank you so much for spending the time to type all of that out. It is vary valuable information. I'll definitly have more questions for you as as I collect all the other parts.

Thanks,

Chuck
 

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Be very carefull how you hook up the MC2100 and be careful of what you take off the system. We still have a visual check of the engine in NC...If you get an inspector that wants to be pissy he could slap you with non-original equipment. The best thing to do would be to do the MC2100 and the Nutter Bypass. But, instead of pulling out the old computer and all the vac hoses, leave them in place. Just block off all the non used vacuume hoses and splice into the harness for what you still need to use. Use the original air cleaner so it will hide the carb...Most inspectors won't go digging to far if it looks right at first glance.
 
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Have you checked the timing while you crank it? You could be off one tooth.

And I would not pull the vacuum hoses. One thing you can be sure of, the emissions laws will get tougher....in many states, you can't sell a vehicle unless it has all of it's original emissions equipment....and it has to be in working order.

Truth is, disconnecting the hoses will NOT make it run better. The MC carb might help....but it you get all of the stuff working right, it will run very good.
 
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