- Location
- Hartsville, South Carolina
Just a thought but it might be blowing the spark out.... did you test the plugs or use a spark tester? Did you do a wet test?
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"84 Cherokee won't fire
- Thread starter Krapola
- Start date
Krapola
NAXJA Forum User
- Location
- Fairfield, Ca
Ghost said:
Plugs have been tested...All six spark when energized....Wet test? Not familiar with the term...Please explain....
- Location
- Hartsville, South Carolina
Krapola said:
Compresion wet test.... sorry should have been more specific. I know you pposted your compresion and it looked good but i had a 84 4 popper that would not run on the #1. Everything was fine like you say never could figure out what was wrong. Ended up dropping a 94 MPI 2.5 in its place and cannot keep the jeep together! The mighty 4 popper has a tendacy to break shiat when the skinny pedal is in play!
Grizzley
NAXJA Forum User
- Location
- North Central Mass.
Krapola said:
OK, that's just wrong. The only reason I can think of that you have positive pressure in the manifold is the cam and crank aren't timed and intakes are open on compression stroke, maybe only the start of it, but enough to cause an updraft.
Krapola said:
You didn't piss me off, just flash backs to my 84 and the hassle i had with that thing. Just a question that i don't think has been asked. I went through and reread from the beginning and I noticed that you said the timing is within 2*. Don't get upset, but how do you know?
Krapola
NAXJA Forum User
- Location
- Fairfield, Ca
Grizzley said:
I utilized a Timing light.....
Krapola
NAXJA Forum User
- Location
- Fairfield, Ca
Ghost said:
Yep, got yer point...Maybe I should toss the V6 2.8 for the 3.4 eh?
Grizzley
NAXJA Forum User
- Location
- North Central Mass.
Krapola said:
You'd be a lot happier with the power to weight ratio. Been done a lot here. Probably why we realy don't have definitive/quick fix answers for you cause they usually get tossed and replaced. Here's a link that may help.
http://forums.s-series.org/viewtopic.php?t=52
They deal with these engines all the time and may have an answer for you.
BigDadys94xj
NAXJA Forum User
- Location
- Naples, New York
Another thought to throw in here. How can you check for proper timing when the engine isnt running? Yes you can find out if you have spark through the wires with a timing light and you will get some sort of timing reading while cranking the engine but you can not check for proper ignition timing just by cranking the engine over. if it is backfiriing through the carb when cranking you have a SERIOUS timing issue! If this is to complicated for your current mechanical skills then take it to a tech who knows what he/she is doing. I would also bet if you talked to a trained Jeep tech (or even a GM tech that has been around long enough to have worked on a few 2.8's) I am sure that they could point you in the right direction . Without a doubt in my mind it is a timing issue and nothing else! Either the distrubutor and wires are out of time or your cam is out of time. I have worked on a bunch of 2.8's and they have been known to strech the timing chain to the point where the cam may jump a tooth or 2 . Just enough to really screw things up. Another thing to try is to take everthing back apart that you installed and start over from the beginning and see if maybe you missed something (I know you think it cant be but it does happen). Good Luck!
Krapola
NAXJA Forum User
- Location
- Fairfield, Ca
BigDadys94xj said:
I'll agree with you that I cannot set proper timing without it running but it can be checked for #1 fire....I also agree whole heartedly that this problem is Electrical....Tonight I will confirm indexing of the Distributor...Since I have not done anything to change the Distributor allignment, It is basically my last item before the Engine gets pulled and completely re-done properly....I guess this is the screwing I get for taking something off someone elses hands even after I was told it was re-built...Re-built wrong is my guess....
wish
NAXJA Forum User
- Location
- Austin, MN
My experience has never found an engine that was advertised as rebuilt to actually be so. Apparently "rebuilt" means a lot of different things to different people.
You know, the cam thing popped into my head too (2.8's are notorious for this as someone else mentioned), but I really have trouble believing you'd be getting good compression (or any) if the cam was out of time.
I also don't know how the spark could be getting blown out, especially at a .035" gap (this is what over-boosted engines typically run to prevent blow out), unless you had a REALLY weak coil, even then your timing light should pick up on it not firing and it should at least try to start.
Hope you get er figgered out ... I'll be interested to hear what the fix was.
You know, the cam thing popped into my head too (2.8's are notorious for this as someone else mentioned), but I really have trouble believing you'd be getting good compression (or any) if the cam was out of time.
I also don't know how the spark could be getting blown out, especially at a .035" gap (this is what over-boosted engines typically run to prevent blow out), unless you had a REALLY weak coil, even then your timing light should pick up on it not firing and it should at least try to start.
Hope you get er figgered out ... I'll be interested to hear what the fix was.
