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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: rockable on June 04, 2011, 02:29:57 pm
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My '86 Truck w/ 305 and all smog equipment has been running great and was doing so until a minute ago. All of a sudden, while going through a drive through, the engine started to idle rough and then die. It will crank back up but as soon as I release the ignition key, it dies.
It's like a ballast resistor is burnt out or something. There is no ballast resistor on this truck, is there?
Thanks for your help.
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Start with the simple stuff, make sure it's getting fuel. Might be as simple as a clogged fuel filter. If it's getting fuel then, check the cap and rotor, next guess would be an ignition module, especially if it's hot outside heat tends to knock those out, but normally it will not try to start at all with a bad module. Just start with the small stuff and eliminate them one by one.
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Sounds like its choking on fumes. Try putting gas in your tank and into your intake.
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It's full of gas.
What do you mean by ignition module? The coil in the cap?
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The ignition module is in the distributor has wires that plug into each end. I'll see if I can find a pic. Are you still down?
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Yes. It WAS hot today. The truck has been running fine and pulling hard at WOT, so I don't really think it's a fuel issue. 25 year old electronics are more likely the culprit. Since I didn't have anyone with me, I couldn't test for spark but it starts instantly and then dies. It's like when it switches over from "start" to "run", it dies.
So this module is in the distributor. I know I replaced the plugs, cap and rotor less that 6k miles ago. Someone suggested to me that the green wire from the solenoid to the distributor is pretty commonly known to go "open" on these engines. Anyone know about that?
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I have never had that issue with one of these trucks, but an easy way to check it would be to get a length of wire and run it from the pos post on the battery to the dist, be sure and unplug the orig one. The truck should start up. If it doesn't I'm guessing fuel supply or ign module. Have you tried squirting gas to it to see if yu can keep it running?
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Best way to rule out the distributor is either swap it or test it. If youre going to take it out, i recommend pulling the cap off, and take a picture of the rotor and which way it is pointing. When you put it back in, just match everything up to your picture and your timing should stay the same. But, the correct and safest way is to bring number 1 piston to tdc conpression and set your distributor in with the rotor pointing at the number 1 cylinder. This is the easiest way to reinstall your distributor(in my opinion) http://forum.73-87chevytrucks.com/smforum/index.php?topic=20821.0 (http://forum.73-87chevytrucks.com/smforum/index.php?topic=20821.0). If you pull your distributor you should be able to take it down to a parts store and have each component tested. Good luck!
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Check your battery cable connections at the battery. I've had several cars do what you said your is or just totally die in the middle of driving because of corrosion.
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did you ever check the fuel to see if its the problem. your tank can be full but a clogged filter will do this also. it will let enough fuel in to fill the bowls but thats it, then once you start it the filter wont allow enough fuel in and kill the engine. once it dies how soon before it can restart i.e. multiple turns or till it cools down
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After loading up my jack, jackstands and half the tools I own, I drove back to the scene of the crime this morning to check it all out. I had nothing to work with yesterday and it was hot as blazes. I got in the truck and it started right up and I drove it home without a single hiccup. Now, I know whatever is wrong is going to happen again. So, I've got to figure it out. At least I can do it in my shop and not in some hot parking lot.
The truck had been running fine down the highway and it was idling when it shut off. I've had no indications of a fuel supply problem. In fact, I was just thinking about how great it was running yesterday morning.
I'm going to remove the distributor cap and inspect everything under it for cracks. Also, I'm going to check the fuel filter. I guess the one that goes into the inlet of the carb is the only one. Correct? If I'd had to guess now, I'd say vapor lock is a likely culprit but there is no restriction on the inlet side of the fuel pump that I can see. I hate troubleshooting intermittent problems. You never know when you've got it fixed............for sure.
Thanks, Guys.
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since it started back up and gave you no fuss then i would say more electrical problem. to me its had to say since it would initially fire up then once you stopped the starter it would cut off
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I think the fuel filter would be a good place to start, some sediment could have clogged it up, then backed off after it set.
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next time it happens, try your best to check for spark...it will either point to or eliminate ignition module and or pick up coil in distributor. Running at WOT for a while put a lot of heat under da hood and i had a bad pick up coil once and it wouldn't work when truck was hot. cool it down, worked fine. I replaced the whole distributor. If you are getting spark, i'd go with the last post of rwhit57.
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This has Electronic Spark Control written all over it.
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Fuel filter was as clean as it was when I put it in two years ago. I replaced the cap, rotor, ignition control module and the original coil. Time will tell if it is truly fixed. It's running fine for now. :)
Thanks, Guys!
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good luck man..
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I agree with it possibly could be the ESC. Was your module the 5 pin?
In this there's a way to get disconnect the ESC in your current distributor:
http://www.73-87.com/7387garage/drivetrain/escrepl.htm
You may want to print those instructions out with the picture and take some tools with you for awhile to try that trick.
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I agree with it possibly could be the ESC. Was your module the 5 pin?
Nope. 3 Pin. I put a new one in it yesterday. Time will tell.
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This has Electronic Spark Control written all over it.
I agree. After 3 or 4 weeks, I've had no further problems. I replaced both the coil and the ESC but I'm betting it was the ESC. It didn't have any of that conductive grease smeared on the bottom of it, so it probably burned up.
Thanks for the help, guys.
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Well, it happened again. Now, I'm darn sure it isn't an electronic problem or a fuel filter problem. It happens after the truck sits idling for a while on a hot day. It just stumbles and cuts off. Today, I raised the hood and let things cool off for a few minutes and was able to get it going. Once I got on the road, no problem.
It's seems like vapor lock but there are no restrictions that I can tell in the fuel system. (I do have the twin tank setup.) I'm thinking this junky ethanol diluted gasoline is the main problem.
Anyone else had this problem? I don't have any fuel delivery issues that I can tell at WOT, so I don't suspect the fuel pump.
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Just to clarify, what exactly did you replace regarding the ESC? I think that our terminology may be off here.
Having the same issues again now still points to ESC, and unless you have completely removed the system and replaced your distributor with a non-ESC distributor (or repinned it like in the link TexasRed posted), I would expect that it will have intermittent issues in the future as well. Were you able to check for spark like SgtDel suggested?
The electronic spark control systems on these trucks are notorious for working fine and then suddenly leaving you stranded on the side of the road, and then when you go back to get the truck it fires right up and works fine for a month until it does it again. Even if this is not the cause in your case, I would still remove the ESC controller and everything associated with it and install a new non-ESC HEI distributor. They are cheap nowadays, and even if the ESC is not your problem now, bet that it will be later on down the road.
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did you replace the pick-up coil?
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I replaced the three pronged ESC control module located in the distributor and the ignition coil, rotor and cap. What else is there?
Yesterday, after I raised the hood for about 10 minutes, I got it cranked and drove it home without a hitch. It never completely went dead. It stalled out when I attempted to pull away after having sit idling for 5 or 10 minutes. Then it would crank but die a few seconds later. Finally, I raised the hood and let it cool down for just a few minutes. It cranked and remain cranked, so I got on the road and got the air and fuel flowing.
What is the easiest way to troubleshoot this? I've been driving it without problems since June. ???
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the pick-up coil is under the icm. im guessing about it being a problem but it sound like the only thing you havnt done. when mine went bad i lost everything wouldnt start up for nothing
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What else is there?
There is a computer box in the cab that goes bad. With the right distributor you can bypass the ESC. The power wire to your distributor is piggybacked with the ESC so if the computer acts up it will cut power and you will lose spark.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=17443.0
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What else is there?
There is a computer box in the cab that goes bad. With the right distributor you can bypass the ESC. The power wire to your distributor is piggybacked with the ESC so if the computer acts up it will cut power and you will lose spark.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=17443.0
friggin' computers.
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What else is there?
There is a computer box in the cab that goes bad. With the right distributor you can bypass the ESC. The power wire to your distributor is piggybacked with the ESC so if the computer acts up it will cut power and you will lose spark.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=17443.0
I'm not buying this one. The AC was on, so the computer box in the cab was as cool as I was. I still say it's some sort of vapor lock or fuel problem but I don't know how to troubleshoot it.
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My guess is the fuel pump. The rubber diaphragm in there gets warm and gets weak, when it cools, becomes stiffer. I had a car that done the exact same thing as you are saying, and it was the pump. As long as I was on the road keeping air moving it was fine, but let me sit for awhile and let a little extra heat build, and I was sitting for a while till it cooled down.
Final Answer: FUEL PUMP....
Good luck with it...
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you have a couple options. one is to replace everything that you havnt yet or wait till next time it does this then test for spark.you can do this by taking a jumper cable and ground one end somewhere then remove a plug and wire put the cable on the threads of the plug and put it somewhere you can see and crank the engine. If you got spark then it’s a fuel problem. if no spark make sure you’re getting power to the red wire on the cap with a volt meter if no power it could be the ignition switch in the column. if thats getting power your problem should be under the cap. And since you replaced the the coil and icm or as your calling it the ecm. Next is the pick-up coil. You have to pull the distributor out to take this off, then at the bottom of the shaft there is a pin that holds the gear on you pop that out then slide the shaft out. And replace the pick-up coil
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Stop over thinking it. This is about as simple as they get. What else is there? As already mentioned the pick up coil and ignition control module. The ESC module is for emissions spark control.
Back to basics:
Got spark?
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I'd have to assume so, since it would re-fire every time I tried. It just wouldn't continue to run. I could rev it up but it would not keep running. It would just die like it ran out of fuel.
I had a spare spark plug in my glove compartment for checking spark but since it had bee 3 mos, I forgot about it. I'm willing to bet that I would have had spark.
VZ, does the fuel pump theory make sense to you? Or is the fuel perhaps percolating in the carb?
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dont bet on anything yet spark would be the first thing to check then go from there.
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my guess, is electrical. also just because the computer module is in the cab doesnt mean the A/C is helping it stay cool.
the only thing i could think of relating to fuel is a problem i had one time after changing the rubber line that went from my brand new fuel sending unit to the hard metal fuel lines. even though the rubber line was rated for fuel the ethanol garbage octane i was using made the rubber super soft and weak, when my brand new fuel pump would get goin', the line collapsed under the pressure.
if i let the car rest a while it would start and drive like normal.