Thunderbolt IV ignition problem
 

I did a tune up on my '89 with a 350. Installed cap,rotor,plugs,wires, and ignition sensor. I now have a miss and can smell a good amount of fuel through the exhaust. I am also noticing the volt gauge and tach are acting "jittery". Put a timing light on the #1 wire and had no light. Started moving it to other plug wires and would get the light to work on 6 or so wires.. Maybe a ground problem?? Thanks for the help.

Check that you have a good clean ground from the Thunderbolt ignition box...had that problem once.

I've had similar issues that were due to a bad pickup in the distributor.

Used to be a good piece, then merc quit building the triggers. Now the triggers come from China, and they are junk. Get several, keep spares and change the trigger. I removed 6 distributors last year, now run msd ready to run.

Where did you buy the parts and what brand ? EBAY ???

I see no coil mentioned ? When was that last changed ? I would buy a new quality coil as well.

On the ignition sensor under the rotor that has the black ground wire with the eyelite on it - run a jumper wire and clip that wire, then run the rest of the jumper wire to the negative on your battery that the engine side uses. This always is a good way to test weak and or bad grounds on marine apps.

Did your problems go away ? if so you need a better ground.

Double check plug wire order on dist cap

I replaced the the coil already and the new sensor in the distributor is Sierra brand. I like the ground jumper idea and will give it a try later. Thanks for the input everyone.

Plug wire order is good

no possibility a six cylinder rotor/shutter was put in ,is there

That's what I was thinking. Make sure you have an 8 cylinder tone wheel under your new rotor. If they sent you a 6 cyl you can take the wheel off your old rotor if you still have it. they are attached with screws. They don't wear but the rotors come with new ones.

Bup, no sheet. The triggers are no longer dependable? I am all hot to keep my TB V so I can have the knock sensing. Wish they would just do it right.