Interface between spark plug threads and head

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Nov 8, 2015
It has been a while since I have been able to work on the 97 cruiser I purchased last year with a blown headgasket. Some history.. Replaced headgasket first time and would not start. Ended up being a problem with very little compression due to a warped head. So ended up having to pull the head back off and replace with a new one. Every thing is back together and having a problem with spark at the plugs.

I can pull the coil wire off from the dist cap and place near the intake and it will spark. Plugging it back into the cap and removing plug wire #1 and checking for spark from cap output to ground produces a spark. Checked resistance in the wires and they are all fine. Placed plug into the wire and there is spark.

It has to be a problem with the plug grounding through the head, but I have tried adding jumper cables from the negative terminal of the battery to the intake and body with no success. The plugs continue to get covered with fuel and I have purchase 2 sets at this point. The indication that there is no spark at the plug in the head is by using a timing light on the wires. I have tested it on another vehicle and it works properly.

Has anyone experienced this problem before? I used a very small amount of never seize on the threads of the plugs. Could this have an impact and if so, what should I do to clean this out?

Components that are new include: coil, dist cap, rotor, wires and plugs.

There is a factory ground strap that goes from the body (near the heater valve area) to the passenger side of the head. Make sure that is there and intact. Make sure you have the factory ground cable that goes from the battery to the fender (in the battery compartment area) and of course the heavy ground from the battery to the block.

Given the head bolts to the block with all those head bolts I can't imagine that even without the factory ground strap mentioned above that your would have a spark issue. But, make sure you have it in place.

Antisieze is not an issue either, most of us use it on the spark plug threads - just don't foul the electrode area.

Ok, found a past picture I've taken:


George, I have the ground cable installed that you have pictured. The negative battery terminal lug looks to be the original.

When I installed the head, I used studs instead of bolts. I dont think this should make a difference though.
Well then you have a good ground path more likelier than not. So as per inkpot I'd be looking at everything to do with timing. Make sure the distributor is set properly as per FSM. You wouldn't be the first to have the distributor set wrong versus 1st cylinder TDC on the compression stroke...

I'll second what Inkpot said, i think you've got a timing problem, recheck the position of the timing gear, Also check that your distributor is not 180 degrees out.
Finally had a chance to work on this again with some success?

1. Remove plug 1 and use compression tool to find compression stroke. Checked position of rotor in distributor and it was correct.
2. Rolled engine over with starter to see how much compression was present (150 psi). (Fuel is now in all cylinders.)
3. Removed compression tool and replaced plug 1. Disconnected injectors 1,2,4,5,6 (3 was not accessible with the throttle body on). All I was going for here was to check if plug 1 would make the timing light go off to ensure spark wasn't going away due to plug being fouled by fuel. Upon rolling the engine over, it started and ran for several seconds until it no longer had fuel in the cylinders.
4. Checked 1,2,4,5,6 injector plugs for 12V and continuity checked each of the trigger wires back to the ecu. Also continuity checked to 12v and ground to make sure they were not shorted in the harness.
5. Plugged in all injectors and tried to start with no luck.

Getting closer to running I hope. Any suggestions for next steps?

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Yes the ecu is bolted in place, however the ecu ground is found on the intake.

The plugs are fouled again. Too much fuel? This has been the problem for a while now. I am unsure what action to take at this point. If the problem is too much fuel, what causes this? The only thing that changed in the fuel system is the fuel filter during the head gasket replacement.
So, maybe the ECU thinks the engine is running BEFORE you start it, so it fires the injectors and drowns the plugs before to activate the starter?

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