I have an 89 S10 4.3L that will fuel but will not spark..The engine had weak compression and 160k on it so I swaped it out for a new one. After installing the new motor I tried to start but luck..I changed the coil and computer but still no spark. I checked for power and a pulsating ground and I have both. Before I change out the module is there anything else I should check??

Have you gone all over the engine bay to make sure you didn't miss any connections during the swap...did you get the computer from the same vehicle that you got the "new" engine from...I'll check my books for more info and post later..

Did you use the same disributor and ignition module?

I have gone over the engine bay for connections and have found one wire hanging off the firewall..I could not find anything to plug into it. The Distributor and module are the same from the old motor.

Oh and..the service # on the computer is the same

Hello,

Maybe the Ignition Igniter, Happened to me before,

Using the samer dist.ignition module may be your problem. TRy switching out the ignition module for a new one and see if that helps.

I just changed out the hole distributor, cap and rotor button..No Spark..rechecked connections, and checked fuses. also checked the fusible links on the alltonator..There are two wires going to the coil: white and pink: the pink has power with the key on but the white has no ground.I held the test light on the + side of the battery and the white while someone else turned the motor over and nothing happend..The computer flashes a code 12 which means the computer is working..SOS...HELP

Are you getting any Oil Pressure?, sometimes on the 4.3 if the computer doesn't see oil pressure it will kill the spark.

Mr.Rob

Good Luck..

I have to ask, is the distributor you put in a used one or new. Your old distributor also has a pick up coil in it that sends a signal to the ign module when to fire. The best thing for you to do is use a flow chart from a shop manual to diagnous the problem. Just for shits and grins, check the ign fuse in fuse block too

When you put in the new distributor did you use the old ignition module or did you use a new one?

Is there any spark from the coil at all?

Where did you check for power and the pulsating ground? At the ignition module or coil? Hope this sparks and idea.

The engine is showing oil pressure and the distributer was complete with pick up coil and module. I have power to the coil but NO pulsating ground. I had a friend look at it and he seems to think the new module is bad. I remain sceptible. The distributer has a lifetime warrenty but I can't swap it out till Tue.

well I changed the distributor out for another one and still no spark..I'm about at my wits end.

Have you checked to make sure the engine grounds are good, they are usually bolted on the intake or front of the engine.?

You seem to have the power but never any mentioned the grounds?

Anyways good luck, keep us up to date and we'll get you through this, I had the same problem, and it turned out to be a bad pick-up coil, also I had not connected 2 ground cables after swapping the motor, these wires are usually all (BROWN) and connect all together.

SO look for the BROWN wires, if you have no ground, you will have NO SPARK!

Mr.Rob

Lic Mech Auto/Truck/Trailer!

I've double checked the grounds..maybe ok..working on a whim I changed the prom from my old computer to the new one but no luck. I'm thinking I blew part of the computer so I'm swaaping mine to a co-workers truck to see if I'm right........Prey I'm right!

Check again your grounds. You need to have a good ground from the engine to body and engine to battery. Is your injector pulsing? Most of the time people neglect the ground during engine swaps and it is as important as the positive. Remember the ignition is ground fired.

FINALLY!! After inspecting another 4.3 I noticed that I had two wires crossed on the coil..I feel stupid.

Cool beans... You gonna keep the new distrbutor?

Check again your grounds. You need to have a good ground from the engine to body and engine to battery. Is your injector pulsing? Most of the time people neglect the ground during engine swaps and it is as important as the positive. Remember the ignition is ground fired.
Every 4.3 gm I look at have two plugs that will only go on one way. Did you cut the wires and splice them wrong?

Every 4.3 gm I look at have two plugs that will only go on one way. Did you cut the wires and splice them wrong?

yeah, your right! To the poster, how did you manage to hook up the plugs wrong when they are keyed? Did you splice them?

when I removed the motor the wires comming from the wireing harness to the coil was brittle and busted. Just didn't keep it simple.