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Old 08-17-2004, 03:49 AM
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86 chevy won't start

Hello all, I'm at a loss. I have a 2wd '86 1/2 ton chevy truck with a 305. Poor 'ol truck has seen it's better days but has done a good job getting my girl to work. Yesterday, she pulled into the parking lot and it died and wouldn't start. I changed cap, rotor, coil, checked control module, and the coil again just to be sure and still nothing. Engine turns over good but I'm not getting any fire (I'm pretty sure - pulled #2 plug wire off of cap and touched the post, nothing.) Rotor is turning and I have good power going to the distributor with the key on, so now I'm out of ideas. How can I tell if it jumped time? (hope it's not that.) Not sure where to go from here. I really don't want to have to let someone else fix it, bad for the ego. Thanks for any help getting this chevy back on its feet.

Robby

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Old 08-17-2004, 04:34 AM
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There is an ignition control module(Black with plug ins on both sides) located in the distributor under the rotor that has a bad habit of just going out , just like you described.
If you remove it, take it to a parts house (One of the big ones with testing equipment) and they can tell you if it's working or not.
Were that module working and you were holding the spark plug wire to the plug post with the engine turning over, you should have gotten a BIG jolt. I would suspect this to be your problem since you know you are getting power to the distributor but no power outward.
As to the timing issue, unless the chain jumped more than three or four teeth(Highly unlikely) it should still start, but would run really bad and have no power. You would also most likley hear the chain slapping the timing cover when you turn the engine over.
Good luck, hope this helps.
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Old 08-17-2004, 08:20 AM
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Don't forget to check the mag pickup while you are fooling with the module. As cheap as the module are($12) I would replace it rather than trust the wax part's men and there machines.
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Old 08-17-2004, 01:39 PM
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Thanks Mark, that sounds like the control module that I had checked, they checked it 3 times and said that it was good, is it suppose to heat up like that? sure got pretty hot. I hope your right about the timing chain. Hey John, what is the mag pickup your talking about? I'm going to pull it home tonight so I can get down and dirty. Appreciate the list of ideas Restore60s, I did replace the metal ground strip for the coil and haven't thought about a bad rotor out of the box. I'll get back to you on what else I narrow down. Thanks again for the replies, keep 'em coming, 'cause she's still not running.
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Old 08-17-2004, 03:29 PM
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Also make sure that the rotor is turning while cranking. If the chain is super loose and it took off all the cam gear teeth, the engine will crank fine, but the cam and dist won't be turning, thusly no spark.

I"ve got a '77 chevy 1/2 ton with 335,000 miles with the orig module. Second coil and second mag pickup.

My '86 3/4 chevy has the 4 pin module like my '77. Your 1/2 ton '86 may have the 5 pin module if you do in fact have the "electronic spark control". Spark module is about $250 at Chevy if you can find one. There was one on eBay last week for $10 NIB. Almost bought it till I remembered mine has the 4 pin module.

Mark
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Old 08-17-2004, 04:13 PM
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Mag pickup

[color=yellow]Doc Here

look at the photo, It shows the location of That mag pick up ...I'd look there first, those fail a lot!

If that module is getting hot, be-sure you cleaned off the old silicone grease, and put ample new grease back, they do run hot, but if the overheat, they will fail.

If that dosen't Get you going, Check your coil, It may have died , Since you say you have 12 volts to it (Batt Term)

Check your fuse box for a fuse that says ECM and if you have one is it good? You might want to just check the INJ and computer fuses while you in there.

If it cranks pretty much normally, and evenly I wouldn't worry about the Chain...Besides, unless it totally broke, it wouldn't kill the spark...and it would crank very erratic.. (because the valves aren't opening) akin to an over~advance situation.

Oh and one more thing, when you did the coil leads and grounds, make sure you didn't short the ground to one of the leads , cuz as I remember, you have to cross very close to the leads and the wires are tight inside the cap.

OOPS! Forgot the photo, will add on another reply...sorry!

Hope it helps!

Doc
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Old 08-17-2004, 04:41 PM
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Photo Sorry about that!

[color=yellow]Doc Here

Here is the photo!

Doc
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Old 08-17-2004, 06:06 PM
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Check the mag pick up by diconnecting the two wires that go from the module to the pick and measuring the voltage induced while cranking the engine. If the dist. is out of vehicle then just spin by hand and see if a voltage is being induced by the pick up. it will read just shy of 1 full volt so a digital multimeter will be needed. If no voltage is shown then change dist.
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Old 08-18-2004, 12:05 AM
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Also the module may check out Okay but under load it fails. If what my cousin who works at my local NAPA tells me is true.

But like was mentioned even with a bad chain you should still eventually get a spark cause the rotor will still be spinning.
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Old 08-18-2004, 06:44 PM
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Yep, I would still be looking at the module. My friend has a 92 suburban that just started running like garbage one day, and he had the module tested and it checked okay, so I went and pulled it again and took it to my parts store, and we ran the test on it 20+ times before it began failing. Replaced the module, and all is good now.
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Old 08-18-2004, 11:02 PM
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The testing machines put it under a "load" which is why it gets hot. However I always make sure to test it 12 or so times to get it nice and hot as many times they will work fine the first couple times but once they heat they will begin to fail.
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Old 08-18-2004, 11:40 PM
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module

[color=yellow]Doc Here

Or, just swap it with a known good one from another car, and see if neither one or both run...

Doc
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Old 08-19-2004, 01:00 AM
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you might also want to try the capacitor (item #6 in doc's pic) this will also kill your ignition. i'd just replace it, it is pretty cheap ($8 CAD). if it is blown, i'd replace the pick-up as well, as that is what usually fries the capacitor.
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Old 08-19-2004, 02:22 AM
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YOU GUYS FREAK'IN ROCK!!! Yee Haw, I don't have to be a taxi anymore and I still have my dignity. You called it John (you are the man,) the mag pickup was the ticket. If it wouldn't have been for ya'll, I would've probably have pulled the rest of my hair out. Boy the excitement, when she started right up on the first try, WOW! I love it, heck she starts better now than ever. My hats off to this board and to everyone that posted and helped me out. The amount of resources a board like this has is invaluable. I use to frequent a board on Aqualink (great board for fishys) when I was setting up my 100Gal reef but I never could find a board that was this active for autos. I feel like I just bought a new carb and manifold. A million thanks to everyone and I hope one day I will be able to help someone else keep their sanity.

Robby

BTW - great pic Doc, really helped
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Old 08-19-2004, 09:28 AM
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Glade to help.

I've only ever seen the mag pick up go bad three times in my entire life. Those three times have been within the last month.


Hmmm, strange
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