Just gone thru total re-build of HP500 (including carb).
During timing (out of the boat), engine popped. It showed on the timing light. Made some adjustments and did not see it again until under load and testing in water. Problem starts around 2000RPM. Engine pops, tach fluters down and it happens intermitent but consistently. Runs fine at high idle in gear and out. Swaped module, coil, coil wire and carb with other engine. Going to check grounds and Oil pressure shut off...Any other ideas?

With Memorial day coming, any help would be greatly appreciated.

Dan

I would check the plugs. Possibly a cracked plug. Unless you look at them very closely, you may not see it.

Check the plug wires real good. If you have another set you may want to throw them on. A bad wire will usually only show up only under a load.
Eddie

If it is when you first start to give it the gas, check the adjustment of your accelerator pump. Sounds like you are under load already, so this may not be it. Thought maybe a lean miss-fire? Go with the ignition check up. Good advice!

Dave

I was doing some rejetting this weekend and I found when I went up in jet size to the point it was too fat, the motors would start popping... right after 2500 rpm's.... pull a plug and look and see how they are burning.

It was the Distributor Module...Ran great...Thank you for the feed back....