i have HAD IT with this truck!! still randomly dies...

[yellow400ex05]

Alright I made a thread a week or so ago about my truck randomly dying on me, so i lowered the floats on my new 780CFM quick fuel carb to the proper level, new plugs, new wires, new ignition switch, took out a kill switch under the dash and just eliminated it thinking the switch was bad. IT RAN GREAT for 3-4 hours tonight, perfectly FINE! then all of a sudden it started dying on me at random times a couple miles from home, it would start right back up, every time, and run for a few minutes and die while driving, I'd pull over and fire it back up, it did this about 4 times.

this last time it died, I pulled over started it up, drove 100 yards and it died again, and now it just cranks and cranks, I'm getting fuel to the carb. there's fuel in the line. it has a new clear fuel filter and its CLEAN as a whistle!

WHAT IN THE HECK is causing this thing to die? I've eliminated any misfires, and fuel issues, its got a MECHANICAL pump so if it were bad it would've ran terribly.

one thing I've read is that it could be the Ignition Control module??

any idea on how hard it is to replace? and where it is located. i have HEI ignition as well. its a late 60's 417 block but I'd assumed the ICM would be the same location as a SBC?

I'm about ready to just let the damn truck sit and ROT

[willett]

Keep a spare plug in the glove box. When it dies pull a lead and check for spark with your extra plug!

Check beside the cap for your ign module

[naphtali5725]

does it have a plugged up catalytic converter ?
mine acted like that, and it was the cat...

[Tx Firefighter]

I'd bet you're losing spark. The ignition module is very likely in that situation. All it takes is a nutdriver to change it. Ten minute job tops.

[geezer#99]

The module is easy to change.
Here's a link with some good pics.
http://www.popularhotrodding.com/tec.../photo_06.html

[84chevyguyid]

How about a loose ground or power wire to the ignition circuit? Maybe a dying fusible link? It does sound like your spark is going away rather than being fuel related

[MylilBowTie]

Don't forget the thermal paste for the new module. I'd recommend acdelco for the replacement most parts stores can test the module to see if it's failed. Sometimes it will show a false pass because the tester can not get the module hot enough.

[Tx Firefighter]

When I'm dealing with an intermittent no-run situation, I carry one of these in the truck with me. You can get them on the tool aisle of the auto parts store.



When it dies, quickly pop the hood and jerk a plug wire and hook up the tester. Then crank the engine and see if its got spark.

About 80% of the time a no spark condition on an HEI is caused by a bad module. Like the fellow above said, get a good one. Don't buy the generic parts store cheapie. When you remove the old module, clean the little shelf where it mounts to the distributor thoroughly to remove old dried on grease. Then install the new module with the supplied grease.

[blazer2007]

Is your gas tank venting properly,I had a small moon tank and it would die when is was full of gas until I put a bigger vent on it,just a thought

[Greenlee]

Originally Posted by blazer2007

Is your gas tank venting properly,I had a small moon tank and it would die when is was full of gas until I put a bigger vent on it,just a thought

This happened to me. Truck would die at random times, but would always start right back up. I had replaced all of the metal fuel lines and still had a rubber cap on the vent line. I hooked up the vent line to the charcoal canister tank and it stopped dying.

[Boog]

Ah so familiar. I had the same happen to 85 blazer i had. I put up with it for a year or so until i found the problem. There was a broke wire in that 4wire group from the module where it runs through the side of the dist housing. The wire insulation was fine but the wire was broken inside. I moved the harness then it started. To be sure i moved the harness back and sure enough it would not start. I robbed a harness from an extra dist and took care of that. Those wires get brittle with age.

[Low Elco]

Also, check your Main power lead going into the HEI. Work hardened and broke the copper inside the sheathing. Looked fine, acted like an on off switch.Drove me nuts and damn near got me killed in my '86 Camino. Would just randomly turn itself on and off. Stick your test light probe in the end of the lead with the power on, wriggle the hell out of it and see if the light flickers. Also, the pickup coil can do weird things too. In my experience, the module is an all or nothing type thing, but ya never know. Check all your HEI wiring right at the plugs, using the light and wiggle method. Good luck!

[hatzie]

Back in the dark ages My dad had a G20 van that did this for 8 months and finally just outright died. It drove me nuts.
Turned out that the spark was intermittently arcing through a thin point in the rotor and it finally burned a big enough hole to keep the spark from going where it belonged all the time.

[yellow400ex05]

well i replaced the ICM and it seems to be running fine now, the metal backing plate actually separated from the plastic, from heat and age I'd asssume. and there was a small burn mark on the side that the metal part was supposed to be attached to.

[krazy_texan]

sounds like an ignition module to me my suburban did this to me about a month ago and it finally just quit all together changed the module and it fired right up first turn of the key and been running since

[INSIDIOUS '86]

I just went through this on a brand new HEI from msd

Put in a new a/c delco coil and all was fine.