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Old 08-21-2006, 09:13 AM
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motor swap problem.

hello people. realy need help.please. i got.a 1988 k1500 chev truck.

with older motor.and no efi.

i have a carb.idont know what year motor 82-85.

it has benn to the shop severl times.

efi wires stiil hang off fire wall.

does have a hei.dist.

motor does not start all the time.

put new dist. new coil pack. ingition mode.

still onley starts after it sits for hours.

are thre any relays that can cause this because of motor swap. with no efi. thanks in advance.

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Last edited by docvette; 08-21-2006 at 04:46 PM. Reason: Ease of read...
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Old 08-21-2006, 04:57 PM
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Doc here,

I take it in the swap you abandoned the Computer, Correct?

If you are not using a Computer nd you have a STOCK GM HEI, newer than 1980, you need The EST signal to the HEI. (To get it to run, or run better than an Idle)

Are you sure it's fire and not fuel?

Two tests to first try..

Put a bunch of start fluid down the carb throat and start it..CAREFULLY over-spray it as it starts to bog down, (run dry) and see if you can get a minute or so steady run time..If you can It's probably not fire..It may be fuel pump, filters, BAD GAS, blocked tank pickup.

If you can't , run a jumper wire from the battery to the HEI Battery terminal, and Crank it , see if it will start and run..If it will , you need to troubleshoot the Ignition primary circuit..

Is the swapped engine Pre ~1980?

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Old 08-21-2006, 08:08 PM
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wnt to speed shop today to buy point dist. to trouble shoot better.guy talked me out of it said hei is better.said maby vapor lock its no vapor locked.i have power going to dist but nothing coming out.but control mod has been changed.it still has computer hooked to truck.but that what would onley cut power to dist.rite.its geting power in.nothing out driveing me crazy.
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Old 08-21-2006, 08:48 PM
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Doc here,

Sounds to me like the Magnetic pickup inside the HEI is dead..(The sensor that replaces the points, the Ring with wires shown under the Vac Advance above..this is a pre ~80 dizzy, but the pickup is the same idea..)



If you have 12 volts going in on BOTH CRANK and RUN but no spark out..

Don't rule out the module either..It is not uncommon to get 2 or 3 dead right out of the box..Have it tested (free at auto zone) Be sure you use the heat-sink grease when ever you pull or replace a module or it WILL burn up..Have it tested several times in a row to heat it up good before you put it back.

The Computer should only control EST, (Electronic Spark timing) Advance/retard..The power to the HEI (Batt) terminal should be constant AND 12 volts or higher whenever it's running or "On"..

This isn't a TBI (looks like a carb..with 2 injectors on top) Is it?

And is this an pre computer engine in a Computer Body trying to interface with the body? No spark may not be your only problem..according to the 88 K1500 EC Schematic..

Doc


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Old 08-22-2006, 07:16 PM
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First of all I like to say thank you for the help. Talk to previous owner. If I'm understanding things right this will be the third control modular. Owners said he bought one distributor thought it was bad second one did the same. That's 2 modulars went to garage once it wouldn't start so they change the modular and started. What would you do . This motor don't seem to like it. I am thinking of going to a dual point set up works great for me in the old days. And then I should be able to **** can computer or do I still need computer for transmission. I already have under the dashboard gagas for oil and temperature. And so on. I would love to **** can that computer. Your advice would be greatly appreciated thanks. Please keep in mind I already have a 4 barrel eldeBrock carburetor and intake manifold. So I don't see much use for that computer. My cars and trucks ran fine without them. Back in the day.

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Old 08-22-2006, 07:38 PM
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Doc here,

If it is eating modules that bad..

Inspect the Distributer for Arc over internally, Be sure ALL the plug wires are good and fire strong..you may have a high tension Arc backing up the module killing it. Be sure all wires are not chafed inside the distributer.

Next, I would take the Car and have the alternator checked, a bad rectifier Diode (Raw alternator AC) Can damage a module, as well as high Voltages.

Can't comment on your Computer..the stock diagram shows many modules and sensors..and you say it been hacked and grafted by the previous owner..so I have no idea what remains and what does not..

I'd say, if Emissions are not an issue, and you don't want computer control..get a pre~1980 HEI , and remove the system..(there fuel issues on that schematic..like fuel temp??..pressure..ECT..) so some creativity must be used ..

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Old 08-23-2006, 03:34 PM
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Went to AutoZone today as you suggested. Climbed under my hood and pulled out my modular checked over and over everything was all right and tested six times. He told me his neighbor had the same problem. I have an older distributor it is a large one with coil on top He said I needed the newer distributor he won't guarantee it but he thinks that is my problem. What do you think maybe I'm having a little conflict sending different signals. Because of an older distributor and a new computer sending newer signals.
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