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81 Wont Start

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Old Feb 21, 2019 | 12:31 AM
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Default 81 Wont Start

I bought an 81 automatic last week. Took it for smog and they had to re install the distributor reset timing and fix a vacuum leak and it passed. I was driving it around and it was getting a random miss and small backfire. Next day it didn't start but seemed like it was firing on a few cylinders. As time went on it stopped firing at all. Charged battery and it turns over well.
I have the shop manual and the coil passes the test but I tried a Blue Streak DR 31 and no change. It passes the ohm test for the pickup coil. I dont have a HEI module tester so tried a Master Pro 2=7024 HEI module and no change. Its getting spark and gas. The distributor does not have the vacuum module Tried both coils and made sure the groundwire was making a good connection. Thinking about going back to all original coil and module with the better groundwire connection. Thanks
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Old Feb 21, 2019 | 09:05 AM
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Good luck with it, and welcome to the forum.
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Old Feb 21, 2019 | 10:10 AM
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Does your 81 still have the ECM controlling the engine. Your statement about no Vacuum advance on the distributor leads me to believe that it does. If the distributor is computer controlled it will have a four pin connector on the drivers side. The carb should also be computer controlled. It will have two connectors, one on the top front and one on the front side. If they are both there -- are you getting check engine lights.

You can read the codes without a reader on the 81 by shorting two pins on the connector under the ashtray. look on the net to find out how to read the codes or I can send you instruction. Are there any codes? From experience you should understand what codes it is throwing before you start troubleshooting

Last edited by wajulia; Feb 21, 2019 at 10:14 AM.
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Old Feb 21, 2019 | 09:51 PM
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Thanks for the reply. It did not have a check engine light on when it was running. It turns on when the key is first on then it turns off after starting. I did compression checks on cylinder 1 and 2 today with a cold engine they were both 120. There is gas in the oil from all the cranking and it may be leaking so i will change it and get the carb rebuilt before I go on. The car was stored since 1988 so i was planning to rebuild it anyway.
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Old Feb 22, 2019 | 02:13 PM
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My guess is that the carb needs rebuilding after sitting that long. Might as well change the fuel filter while you are at it.
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Old Feb 26, 2019 | 05:24 PM
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While the carb was in rebuild I pulled the plugs and did a compression check. Plugs were covered in carbon and most likely fouled out. Compression was 120 on all cylinders cold after the gas wash. Changed the oil to get the gas out and installed new plugs and it started with the rebuilt carb and ran smooth. I think its still carboned up and will need to be driven around to blow it out. Coolant was leaking around a small crack in the radiator at the cap so will need to replace it before I go on.
A couple of questions in the pic below there is a connection in the middle of the round vacuum device and I cant find a wire for it. Is it a braided ground wire to the block?
Correct me if I am wrong are there two temp sensors one next to the thermostat housing and one near the #8 spark plug. Anyone know which one is the sender for the gauge. The gauge is not moving from 100 degrees. Thanks

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Old Feb 27, 2019 | 01:05 PM
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the round vacuum device is the controller for the cruise control. if you are looking at the tab in the middle of the diaphram, there should be a rod that goes to the accelerator linkage on your carb not a wire. If the rod is not there (and I don't see it in that picture) -- I bet the cruise control doesn't work

Two observations from that picture. 81 had an aluminum intake that was not painted (at least not on mine) and there are blue drips on the oil cap. Someone was in there -- maybe just painting stuff. Dont know it to be a problem, just an observation.

Also -- all those green wires -- definitely not stock, I would check to see what that is all about.

And from memory -- I believe the temp sensor is in the drivers side of the intake manifold in the front of the engine near the thermostat housing. The sensor near plug 8 is the oil temp sensor.

Last edited by wajulia; Feb 28, 2019 at 11:23 AM.
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Old Feb 27, 2019 | 04:42 PM
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The temp gauge sensor is in the head on the drivers side.

The oil temp sensor is just above the oil filter.

The thermo switch on the pass side head is for the aux fan.

The sensor up front near the stat is for the ECM.

The oil pressure sensor is at the rear drivers side atop the China wall.
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Old Feb 27, 2019 | 04:43 PM
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The braided ground wire is for the ignition shield you are missing.
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Old Feb 27, 2019 | 08:14 PM
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Thanks for the reply. The cruise control is not a priority but I need to trace down and remove that green wire.
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Old Feb 27, 2019 | 08:18 PM
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Originally Posted by Dan _R
Thanks for the reply. The cruise control is not a priority but I need to trace down and remove that green wire.
Where in So Cal are you?
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Old Feb 27, 2019 | 08:33 PM
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Thanks Big2Bird when I turn the key on the check engine and battery lights come on. Is there an oil light above the battery light? I have the shop manual it shows an oil light but it doesn't show where. Is there an owners manual online. Where is the jack and tire iron?
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Old Feb 27, 2019 | 08:36 PM
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I'm in canoga park kind of far from Anaheim
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Old Feb 27, 2019 | 08:53 PM
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Originally Posted by Dan _R
I have the shop manual it shows an oil light but it doesn't show where. Is there an owners manual online. Where is the jack and tire iron?
The jack is in rear compartment passenger side.

Owners manual do a google. Fbay and Venders have them.
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Old Mar 2, 2019 | 01:46 PM
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Put the rebuilt carb on with new radiator, temp gauge sensor and stat and it started up and ran pretty smooth and the temp gauge worked. Coolant was coming out from around the radiator cap and noticed some coming from in between the pass side 1st two cylinders. Some from the head bolts and some from between head and block. At first I thought this sux but I'm retired and can pull the heads and hopefully get away with minor head work and a head gasket.

I took pics and labeled all the wires and hoses and pulled them out of the way and got the AC Air Pump and Alternator and brackets off.

This is my 1st Vette and it looks like it should be pretty easy to get the heads off.

This car was used in a recent butterfinger commercial with a space alien, I got it from the stunt guy and he degreased the engine and cleaned it up before I saw it. It had not been registered since 1988 and he had the original 1981 title so I knew it was going to be a project. Odometer says 58k but who knows what happened over 30+ years. In the commercial they used a plastic fence and movie dirt. The front jump put a small crack in the fiberglass by the headlight but other than that it seems ok.

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Old Mar 4, 2019 | 08:34 PM
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I can't believe this thread is stalled out. I would have thought for sure that jump would have smoked that frame. Like when the Duke boys jumped that dirt Hill in the first episode (opening credits).
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Old Mar 4, 2019 | 08:36 PM
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Did the stunt guy actually slide that parallel parking job in??
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Old Mar 5, 2019 | 01:57 PM
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The stunt guy told me that the rear jump with the fence was not really a jump but they used some CGI to make it look like it. They put a new cat back exhaust system on and new shocks. He showed me the ramps they used for the front jump and said something about a standard jump and that they put a shield and other protection underneath. They only had one car and different stunts so they couldn't do a frame bending destroyer. They must have different levels of jump. He gave me 2 extra tires and wheels and they put on a new e-brake for the parking slide.

Got the heads to the machine shop yesterday. The VIN on the engine is matching. I showed the guy some pics of the engine and he said its been rebuilt based on markings on the pistons.
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Old Mar 5, 2019 | 01:59 PM
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Originally Posted by Dan _R
This is my 1st Vette and it looks like it should be pretty easy to get the heads off.
Don't ever say anything is going to be easy. The Vette Gods will be angered and strike thee down. And it will be 5 times harder than you ever imagined. Just sayin'...be cautiously optimistic, but don't ever assume easy. -Compressions 1:11
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Old Mar 5, 2019 | 06:00 PM
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You are right htown81 the head was cracked and there were 8 bad exhaust valves. The #4 cylinder has a pit in it so the block is going to have to come out and be rebuilt.
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