i had the same problem with one motor shut down and would not start(no fire), long story short after spending 630.00 on new dist.and hours of trouble shooting come to find out it was the tach wire that was bad. the motor fired right up until you hooked the tach wire up and it shut right down. thanks to jetmech for all his help in finding the problem.

Blower motors with carbs, msd coil, reg. ignition. Motors crank only. Nothing is unplugged. All breakers are in good shape and operating correctly.

What is your reg. ignition? Need 12vts at coil.

Is there a control module somewhere? In the distributor or a separate unit? There a number of different systems out there. Until we have a better idea as to what you have we are going to have a hard time helping you.

A couple of pictures might help

Had a distributor sensor go out on an HP500 a few weeks ago. Motor would just crank and crank and no spark. It was the old style with the studs on the sensor and when I pulled the distributor to prime the engine the studs loosened. These were HP500's with Thunderbolt ignition.

Small update:

I have used a test light on the coil, i have fire at the positive and the negative side of the coil, but still no fire at the plugs. Any suggestions?

What is the shape of the dist. cap and rotor?

did you pull the tach wire off? check my last post, we had the same and it was the tach.

dist. sensor ....Its under the rotor in the dist. These go bad all the time in the merc thunderboat 4 ing. system..

Yep, distributor sensor if T/bolt IV. I have a couple of distributors and am local if you need help.