weird problem 76 cj 304 prestolite ignition

Well my 76 cj with a 304 and prestolite ignition is acting strange. I couldnt get it run the other day, saw I had no spark at the wire on the distrib. from the coil. So today I replaced the coil. Now I got it to start and run for a few minutes at idle but it would die as soon as I would try to rev it up. Then wher I go to try and start it, it cranks real slow like the timing is advanced alot. I let it sit for a few. then tried it again and it would crank fast run for a sec or two then die as soon as I try to give it gas. Then try to crank again but cranks real slow like the timing is way advanced.
Any ideas ?
Does the ignition module control the advance on the dizzy or am I looking at a bad dizzy ? I know I should change out the prestolite stuff but I really do not understand the conversion.
Please help.
thanks

 

In all the years that I have been an auto tech I have never worked on a prestolite ignition system but the HEI and Duraspark ignitions would act like that when they had a bad pickup coil. On a HEI you would usually find that one of the wires going to the pickup coil was broken inside the insulation and when the vac advance would start to move the pickup coil the wire would go open.

 

The slow starter motor cranking has me flummoxed. Makes me wonder if you may have an issue with intermittently reduced voltage (i.e. something going south in your battery). Electronic ignitions behave badly with low voltage so the symptoms may be consistent. Let's say one of your battery's cells are shorted sometimes. You'd now have a 10.5V battery. Starter would turn slower, ignition may not have sufficient voltage to function (either a cold yellow spark or no spark at all).

If you have a known good battery maybe try that.

Chilly

 

Like I mentioned, it will crank fast one minute, the the next it will crank slow like someone advanced the heck out of the timing, and at the end of the crank when I let go of the key, I get like a puff of smoke out of the carb. And when it did start and run, it only would do it for a few minutes at idle and it would die, or if I tried to throttle the gas it would die.

The jeep has been running decent up till now just kinda putting around to move it from the tent i have it in to the outside. It started this last weekend where it wouldnt start. the plugs were getting wet so fuel was fine. but no spark coming out of the coil to the distrib. So I installed a new coil yesterday. I started it up and it ran for about 5 minutes at idle. tried to give it gas, then all the above started.

 

I read in another post, in another forum, that a bad module can fail by triggering continuously, or maybe more often than 4 per revolution. If true, this could lead to the appearance of lots of advance.

Pardon me as I repeat my previous advice - make sure all your grounds and connections are good. Unplug the module plug and the reluctor coil plug and clean them. I'd put a little dielectric grease on the plugs. One common fix is to cut out the connector between the reluctor coil and the module and solder the wires together. I think the TSM has some advice about testing the reluctor coil with a multimeter - I'd expect to see continuity, and there may be a resistance spec.

Maybe someone has a good, used module that you can borrow for testing. If not, you're going to have to suck it up and buy a new module. The Airtex module is about $40 at Rockauto. Or put that $40 toward a distributor swap.

 

Have you read the TSM? Go here http://oljeep.com/gw/76_tsm/Section3.pdf and read the entire section on the ignition system.

You won't have the special tester, but you can do some of the tests with a multimeter.

 

Ok ,
what is the reluctor coil ?

I have the module which does look like its seen better days, plus the module has a tar like substance coming out the bottom. it has one plug coming out of it that goes to the wiring harness of the jeep. then one black wire coming out of it and going to a plug which then goes to ground.
Is it possible my prestolite distrib could be the problem ? or I guess if the module is bad , it would effect the distributor . gosh , soo overwhelming this ignition stuff.



I am seriously thinking of doing the hei swap, but kinda unsure about how to do it. I thought of team rush, but still do not understand it either.

 

Thanks, I will read it.

 

Jeep calls it a "sensor" - it's the pickup coil in the distributor. It senses the wheel as it goes by. Look under the distributor cap, and read the TSM.

A very bad sign. Indicates that the module is getting abnormally hot.

Yes. You really can't consider the module and the distributor separately.

The Team Rush (aka TFI) upgrade is for the Duraspark distributor. Not relevant unless you install the Motorcraft Duraspark distributor.

Points - through 1974.
Prestolite - 1975-77.
Motorcraft Duraspark - from 1978 on.

The HEI is a GM distributor that is an aftermarket replacement. It was never used in Jeeps.

 

I know, I was reading about the swap, Dr. Dantell wrote up in the tech section.

Now If I go with the team rush set up , I would be replacing my control module with a different one. and I would have to buy a durospark distrib, along with an adaptor to extend it ?

But if I go the route of just using a hei distrib, it has the coil in it and also the module in it, so its a one wire hook up and of course I would take my gear off the prestolite distrib. and mount it on the hei
correct ?

 

Now reading the tsm , i can maybe understand that how the sensor in the distributor and the ecu, work together it could be messing up and advancing my dwell angle causing it to crank slow as of the timing it too far advanced. And then when I leave it sit for a few minutes it gives time for the ecu to cool off and when I try to start it again, it cranks fast and starts and runs for a few minutes and then dies cause the ecu got hot again ?
whatcha think ?

 

That's what I did. But I had the points distributor. The HEI came with its own gear, but I've heard anecdotal horror stories about using the that gear. ( I think I addressed that in the write-up)

My Cheapo HEI has been on my jeep for about 2 years now and I've been extremely happy with it. Cold winter starts are so improved its amazing. The throttle respons seems to be a little more crisp and the jeep is more resistant to stalling from flooding. (this is likely more attributable to fuel system mods I've made, but I feel the HEI helped also) I would do it again in a minute.

 

The TeamRush/TFI is an upgrade to the Duraspark system. It mixes Ford parts with Jeep parts. You can use all Jeep parts, if you like, but you won't be doing the TeamRush/TFI upgrade.

Correct about the HEI. The gear should fit.

I prefer the Duraspark stuff, but if you are struggling with understanding the issues, the HEI will be much simpler.

 

Possible.

Goo coming out of the module is bad.

Keep reading - the manual describes how to test the 'sensor' in the distributor. If the sensor tests ok, that points to the module. But they could both be bad.

 

So am I correct to say that I can pull the gear off the old prestolite and install on the hei ? Isnt that what you wrote you did ?
thanks

 

Well I guess I will do some testing this evening. I know where to buy the ecu but who sells the little sensor ?

or should I just scratch buying new ecu and sensor if they are bad and just get the stuff for a hei swap. hhmm

 

That is what I did. I was just saying that my 72 had the points distrbutor and not the Prestolite.

 

ok , cool.

I sent you a pm .
thanks

 

Yes, that's a problem. Somebody still makes them, since you can buy reman Prestolite distributors. Buying a complete distributor is an option.

 

well I decided last night just to get a new module and distributor. I got both pcs thru advance auto. I replaced the module and she started. Still kinda slow starting after she gets warmed up, might be need some timing adjustment. So I will install the new distributor tomorrow. I think I will leave it stock till I get a bunch of other stuff done, then switch to Hei upgrade. Thank you all for your help and info.