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86 blazer ignition/fueling problems

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baldredhead

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i posted this in the 73-91 specific forum, i'm hoping i get more views here, sorry if this frowned upon....

pasted from old post:
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I acquired an 86 k5 blazer about a month ago and it ran, though i only got to drive it about 15 miles before parking it for a month. It has been thoroughly desmogged and kluged in innumerable ways. I tried at least starting it a few times in the mean time, though only managed to find time to drive around the block. No problems, i think.

Yesterday i decided it was about time to bring it the rest of the way home, a whopping 6 miles. It made it about 3 blocks before refusing to start. During the three blocks it would run ok till i had to stop, then cut out and immediately restart. this trick it did twice. It was at one of these stops that it didn’t come back.

i replaced the distributor cap, rotor, coil, plugs and wires. I presume the timing is good enough as it did run not too long ago. I forgot to reconnect the plugs in the dizzy for a minute or two of cranking, and it almost caught when i did reconnect them. It didn’t stay running so i tried grounding a spare plug attached to a wire to the intake manifold and it didn’t spark at all.

The carb is a holley 650 double pumper that is probably doing too much pumping. When i removed the old spark plugs they were dark sooty black.

another oddity: if i get it to start and run, removing the negative lead from the battery smooths out the idle and the revs seem to pick up a little (no tach, so not sure)

So, my theory is that for whatever reason i wasn't getting consistent spark and now somethign has completely failed. I’m not sure where to start, i’m not a good electrical person, and any help is much appreciated.

thanks
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yesterday, 7/10, the ignition module was replaced and still no luck. any help is appreciated.

i have a carb rebuild kit on the way, as well as some smaller main jets. i don't think it's the main problem though.
 
removing the neg is removing a load- possible that is ok- doa resistance check. carb prob or vacume maybe? im no tmuch help sorry but been looking at this thread with no one helping u for the last few days :(
 
I had an 86 k5 as well and mine had a similar prob with cutting out when I stopped and it was a big vacuum lead i had, i'd say check your vacuum lines thoroughly
 
To clarify, what is it doing now?

Start or no start, or at least very hard start?

If it doesn't start, are you getting spark?
 
i tried it againg last night, in hopes that the gm goowrench gnomes had been working on tthe truck without my knowledge and .... i think it fired on 2 or 3 cylinders then quit.

no start
no spark
 
coil? mine has always been weird just before it died. i know it was replaced. wires would be next guess. resistance check em :confused:
 
just put in a new coil, i suppose it could be a bad new one though. is there a way to bench test a coil? i'd like to avoid throwing money at it.
 
it should have very low resistance corect? high resistance = open circuit = broken wire in there somewhere?
 
no tto low =short it should say in a haynes or chilton for good numebr- im at work sorry or i would look it up. i tested mine bout 3 mo ago and i remeber it was in there
 
goto autozone.com they have online service manuals, they list what the resistance is supposed to be. You can check the pickup coil as well. You can check the module too, but it requires a machine, you have to take it off and take it to a large chain auto store that has a module tester.

Also, Have you checked the voltage to the dist? Years ago, I bought this '73 k5 from kid for a couple hundred bucks, he said it was running then it wasn't. Kinda of ran, but not real nice and wouldn't stay running for more than a couple seconds. I just wanted some other parts from it, didn't care about the engine, but I decided since it *was* running only a few weeks earlier to take my tool kit and see if I could get it running with some simple checks, would be better than flat towing it with a strap 60 miles. (which I all I had available).
Anyhow, 5 minutes into poking around I take my meter and notice power wire going to the distributor only had 4-5 volts. Battery had 12v. Excellent, took a piece of wire, connected it directly from the battery to the dist., turned the key and magic, that kid was pissed. Ran like a champ. drove her home 60mi no prob (well, except for that transmission not wanting to shift to 3rd and smoking).
Anyhow, easy check...
 
i did check the distributor for power with the ignition switch on, but not knowing what it's supposed to be i moved on. i'll check out autozone.com at work tomorrow to see what it's supposed to be :D
 
so just to be sure.... one of the 3 wires that plugs into the distributor should have +12 volts regardless of the position of the ignition switch? i.e. this is an constant, unswitched hot wire?
 
The large pink or red wire to the HEI should have 12v,but ONLY when the key is "on"..... :crazy:
 
sweeeeeeet

i know that pink wire. it had closer to zero than 12 volts. way closer to zero, like .5 or something. i need to talk to someone about geting that 25 hour inserted in the day now.....
 
found that 25th hour....

so

evidence so far:
1) one of the symptoms all along has been that after fiddling with the plugs on the dizzy it would almost start, then just crank

2) i found no power anywhere when the coil cover was off, checking the leads coming off the coil.

3) my buddy, after reading this thread sends me a message "hey dummy, i got 12v the other day when i came over"

4) remembering that said buddy had pulled the pink plug while checking for voltage

5) gut feeling all along that this was an electrical problem. mostly because i hate electrical systems and they hate me.

solution:

one (1) zip tie from the giant costco tip tie container i've been slowly going through for the last 10 years, strategically installed to force the pink wire all the way into the socket



vroooooooooommmmmm!


thanks for the help guys. :doah:

-bryan
 
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