CJ5 1975 prestolite question...

Timgr that is the ticket.. I would feel more comfortable with this route .....thanks for the help guys

BTW this CJ5 was one of those purchased by GSA for government use...sold surplus and used as a beach / surf fishing vehicle, then put in a storage unit for several years... a friend of mine bought it, had it for a few months and sold it to me...Will post some pics of it when it stops raining here in DE....
coolest part is the Meyers top and a heater errr well it does put out some heat.. I took the box out...cleaned out the mouse nest...that opened things up a little...


anyway thanks guys...
John

 

I still vote bad cap and or rotor.

 

Tim what is mounted on your fender in the BG? My guess is ignition module..

 

Yes, 4-pin GM HEI module. The heat sink is something I took from some discarded equipment.

 

Yep, just dealt with this exact situation on my buddy's 75 CJ with a 304 yesterday. No spark - it was the module box, which BTW, was only 10 months old! He freaked out because he tuned it up (plugs, cap, rotor, ignition wires and a fuel filter then got one drive to the store and quit running on the way home. So he got a tow home, then a tow to the shop so I could look at it yesterday.

Had to dial in the carb for him also to eliminate the popping noises in the dual exhaust (mix was too lean and choke fast idle was way off).

 

Cool Tim. My module is mounted close to the same spot. I too used a large heat sink. I ruined one by mounting it over the center of the engine on the firewall.. I carry a spare just in case.

FWIW anyone wanting an ignition module for the Prestolite I have 2 new ones I'll give away

 

Soooo....I still have fire from the coil ...out of the coil wire when grounded...I pulled the #2 plug and no fir from the spark plug to ground....The cap has continuity from the coil top to the carbon contact inside...the rotor looks good, can see where there is contact with the coil button..

So it is defintely not the trigger wheel or the sensor??? those are the only two things in the distro that I have not checked...they look okay but have not idea how to bench test them...
so it looks like a reman 74 distro..... unless u guys know of anything else to check???

thanks for the help..

John

 

need to see if there is fire out of the dist at the cap test with a wire known to be good odd it wont pass through the cap...the rotor turns whilst cranking ?

 

The pickup coil does have a resistance spec of 1.2 to 2.4 ohms on the Prestolites. My buddy's was measuring 2.2. Never could get a scope signal out of my buddy's until the module was replaced. The vacuum advance pulls the pick-up coil to change the timing. Always move the wires as well as the vacuum advance when checking the resistance and make sure the reading you get stays at a steady reading.

 

Thanks commo...will check the resistance..module has been replaced

Sterlclan the rotor is spinning while cranking

 

Ok, you have spark from the coil wire to the cylinder head when you crank it? And you have taken a spark plug out, laid it on the cylinder head when connected to the plug wire and distributor, with the coil wire in place, and get no spark?

You should also get a spark from the coil wire three times for every time the engine spins.

Try putting the plug wire directly into the center coil terminal of the distributor and see if you have spark. If you do, then there is a problem with the phasing of the rotor wrt the distributor cap. Again, you should get spark from the coil wire six times as often as you do from a single plug wire. The plug wire will only fire once for every two revolutions of the crank.

Look at the picture of your open distributor above. The coil fires every time the pickup (white post sticking up) goes between the two arms on the wheel (the reluctor wheel). With the crank at roughly 10 degrees BTDC, the wheel should cover the post. The rotor should also be pointing right at one of the posts on the distributor cap. If it is not, the distributor is out of phase with the engine. This can happen if you jump time at the timing chain, or if the reluctor wheel somehow gets turned wrt the distributor shaft, or if the distributor gets turned away from in-time a lot. If the rotor is half-way between two of the posts on the cap when the coil fires, you will have spark at the coil but it won't get past the "distribution" of the spark by the distributor, because the distance from the coil to the nearest post is too large.

How new are your ignition wires? What does the spark from the coil look like - it should be blue-white, make a distinct snap in the air, and jump at least a 1/4" gap.

 

Timgr,

Thanks for that info, I will check it out tonight..yes there is spark from the coil wire to head when cranking it. It is a bright blue snapping spark...distance??? maybe not 1/4 inch maybe half that....no spark from plug to head while cranking...all the plugs look good for gap andd burn....wires have continuity



wires were replaced by the PO about a year ago as was the cap and rotor....
the first time this happened, I had the loss of power drifted to the road side...popped the cap and found the rotor cracked ...replaced rotor no joy. replaced the coil and it ran great for three days

then again a gentle loss of power and died...I have never had a vehicle jump time, but would think if it did while driving it would be rather violent?? or at least a lot of back firing???

will check the alignment of the timing vs reluctor wheel tonight..

thanks for the heads up ....

JZ

 

with timing checked tdc at #1 on the comression stroke... I rotated the engine to 10deg BTDC...that is the 10 deg mark on the tming cover right??? I hope so cause that is what I did and this is what the trigger looked like it was just before the pick up..

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then I backed up the distro, by loosening the lock bolt on the distro and backed it off to where the trigger and pickup were aligned... correct ?? or no?

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but still no spark at the #1 plug against the head...battery was draining so will have to charge it up
pick up was at 1.8 solid for the resistance check

 

second pic is the wrong pic wouldn't let me delete it here is the correct "after" pic... with the trigger in alignment, and the rotor was pointed to #1 wire post

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rebuilt 74 distro came in the mail today...going to swap the distro tonight....I pregapped the points at .020...or is the gap closer to .017?....no dwell meter...


Had the fuel pump go out in the 2A this week...been a good week for jeep maintenance...2A is back up and running with a pump from NAPA, no bowl or filter...but has a good pump now...

 

Thanks guys for the help...dropped in distro...no fire at points.... closed the gap to .016 cleaned em...and she fired right up..adjusted timing after a warm up and sweeeeeet...