Port motor is giving me trouble. It will fire off occasionally, run like complete **** and shut off (if I can even get it to fire). I am an old school setup - thunderbolt IV, MSD Blaster ignition coil, single Holley carb setup.

So far I have swapped my MSD blaster, thunderbolt ignition, and carb from one motor to the other with no luck.

Unbolted the MSD rev control box with no luck.

I cleaned the distributor cap the other day - carbs are full and pump gas whe I pump the throttle. No water in the oil or cylinders - I've pulled all plugs and found nothing unusual.

Could I have a ground problem? Problem in my ignition switch(which is a little finneccky)? I do believe one battery to be bad, but I'm using it on ALL battery position to overcome that concern......

Motors only have about 20 hours on them and have run fine up until now......

Thanks for any suggestions.

+12 Volt at coil (key on)?
Are you getting spark at plugs?

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Hook it up to a test can and try running it. 6 gallon outboard cans work great.

I assume so - timing light is firing so I assumed that it was getting spark to the plugs

After a shut down. Pull a plug to see if wet or dry. Should give you a hint on fuel or spark

Saw you cleaned the dist cap. . If you got some carbon tracking inside the dist cap, it can't be fixed. You'll have to replace the cap. Try swapping dist caps.

I think I am going to replace the cap - I had buildup in each terminate that was close to 1/16th of an inch deep

I have to fix the hatch reservoir first so I can get the hatch up - always something.

Start with the basics. Replace dist caps and rotors.

Change out the sensor in the dist. and check for water in the fuel water separator..