we have ran many engines on a test stand we have built to test run the engines before they go in the boats. and every time we do this i fight for three days finding spark and then all of the sudden bang they always start. i am have a hp500 i am trying to get going now and we just cant get spark out of it. 5 months ago when the engine came in from shipping we checked it for spark and it had it no prb. we put power to the starter post, neg to the flywheel housing stud, and 12v to the number 5 pin on the connector (purple wire) and jumper the start and it was fine. we did the same thing last night and no spark at all. the coil with the key in the on pos. has 12v on the + and - side off the coil is this right? i have seen this every time we do this test stand b.s. anyone have any idea what i am missing?

check your grounds, did you just paint the engine ? check there if you did and I'm sure you did...Rob

i did not paint the engine yet its right off the shippers truck for the most part. i will go and clean all of the grounds tonight. but if there was a bad ground would it crank? it cranks fine and i have power to the coil just no spark.

What ignition are you running ?

Probably still ground wire. If MSD box, ground that too! This drove me nuts on a stand also!!!!!! Look at the diagram for MSD. That's how I found it.

The TB ignition module CASE has to be grounded as well. I mounted one on the transom and it took me 2 days to figure out why I didn't have spark.

its a stock thunderbolt ignition. i will check all the grounds tonight. i dont understand how it had spark 6 months ago when i got it and none now. i have changed nothing on it

thanks guys, its was bad grounds on the ingition advance mod. cleaned them all up with 100grit sand paper and she fired rite up. man i love this site!

grounds are the # 1 issue with electrical issues !!!!