CJ5 1975 prestolite question...

Hi guys...
new to the forum but not older flatfender (46 2A) jeeps or MX....
I have a 75 CJ5 that died otw to work the other day...dropped in a coil and it ran fine for a few days...then it died again...
It has power to the coil from the ign switch...has power at the coil from the ign module...and with the green (-) wire disconnected from the coil...I have flashing light which from internet searches this is good..and tells me all is fine up to the coil...the coil is throwing spark against the head ...yeah I know I pulled the coil wire...grounded it and cranked it just to check for spark and it is getting fire to the distibutor...

what can go bad in the distibutor??? there is a new cap and rotor...the black plastic cover/ring under the rotor (water proofing) is cracked a tad but not much...all else looks good..
ugh

and the coil is new, as is the ign module..any help beside an upgrade...????
Fuel is good not an issue there...
John

 

did you check at the plugs? if it fires at the coil wire i would look at the cap and rotor next. chase the spark, you know its at the dist,eliminate things one at a time...ive seen the carbon button under the coil wire in the cap crumble on some cheap caps.

 

There is a trigger wheel and a pickup sensor under the black dust cover.
Might take a look there before throwing parts at it.

 

My 8 year old neighbor helper ( key turner) had to go have dinner and get his bath before bed...so didn't get a chance to check the plugs for spark..I did put a new cap and rotor on it when I first had the trouble ...the original rotor was cracked so not seating on the shaft properly......

thanks for the help..

 

how to check the trigger wheel and pick up sensor...???they appear to be in good condition...nothing broken...could be the sensor shorted??? it looks to be wired to the white vacuum advance

 

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my memory is not that great...
the pick up sensor wants to be tight as mounted
the trigger wheel will sometimes hit the sensor and damage it
if the sensor is loose or the distributor shaft bushings are worn
plastic that old is brittle, so be careful trying to move anything around
there is probably a factory resistance value test for the sensor, I don't recall

 

JP, you say your memory may be faulty but you can still spell well. I talked to a teacher friend yesterday, they don't teach the younguns to write in cursive anymore. Some people type in here and all I can say is WTF are you saying? Sorry, I used one of their phrases.

 

I say ignition module. In my 75 I carried a spare as it was not reliable.. I have 2 spares sittin here, that I will never use. Replaced the Crapolite with a new ignition system. If ya want em they are yours

 

Thanks Zila..I put in a new module.. I have fire from the coil into the distributor....

 

I would not spend a lot of money on the Prestolite BDI (breakerless discharge) ignition. They were troublesome even when new. Jeep dropped the system after two years and changed to the Duraspark system from Ford/Motorcraft. I would cut my losses.

So you have hot blue-white spark at the coil wire and not at the plugs? I would certainly pull a plug and lay it on the engine connected to the wire and see if I got spark.

This suggests coil wire or no rotor or broken rotor. If the coil fires, there's nothing electronic beyond that. All the electronics does is turn the coil on and off. From there on, the circuit is all passive.

The discussion of this in the TSM is quite plain and thorough IMO - http://oljeep.com/gw/76_tsm/Section3.pdf - starting at page 41 ...

 

My '75 came with Prestolite - now it's Duraspark with "stealth" HEI module.



My '77 is still running the Prestolite stuff, but I have a Chevy 250 HEI distributor standing by.

 

Ok thanks for that...since there is spark from the coil wire that should be good.. I did replace the rotor and cap...with auto zone junk so they might be defective... I will check them again

and I will check for spark at plug tonight...

 

Does not pop at all? Completely dead?

If it pops and barks, maybe you jumped time.

 

No pop or backfire...just total loss of power...fuel is good...just no spark...had this on my 2A going to the beach...that was easy... coil wire came out of distro cap...I reseated it and was fine...

this was the same.... total loss of power drifted to stop...I thought about it jumping time, but again no fire, no bark no popping...just cranks around

what is involved in duraspark swap? Is there a kit to purchase...Generally I stay away from picking and piecing parts together

 

One other thing.....
From the factory, there was a two connector rubber plug for the wire harness to plug in at the distributor.
There was a factory recall to cut that plug out and just solder the wires together.
Long shot, but it was a verifiable problem.

 

There's a lot of info out there on the ignition swap. Try a google search.


Here's a link to get ya started.

http://www.jeepforum.com/forum/f8/prestolite-duraspark-conversion-hei-3121969/index2.html

http://forums.off-road.com/jeep-short-wheelbase/4720-jeep-258-i-6-ignition-upgrade.html

 

No kit.

With anything but the aftermarket HEI, you will need to mix and match the parts you need. There are lots of possibilities. AFAIK there is no one article that presents all the possibilities in one place.

 

I think I would be more inclined to go backwards with a points/condenser unit...it is not a daily driver...a weekend, have fun vehicle...like the 2A...

 

Simple. Buy a reman distributor for a '74 CJ5 and replace the Prestolite distributor. You'll need a rotor and cap. You can reuse your plug wires. Remove the module. I would remove the harness part to the module and from the module to the distributor. Keep the existing red wire from the ignition to the coil (+), send the green coil (-) to the points distributor. You will need to add a ballast resistor in series with the red wire to the coil, or use a coil with an internal resistor.