502 dies, or spits and backfires as soon as i puit it in gear

[502procharger]

ok, i was setting up a procharger on my boat (502) , the carb i had for the system ran ok but was a bit lean in a few spots. i am having nickerson build me a carb, and will not have it for a week or so. i removed the carb box for the procharger system and replaced it with my old carb. i left the areomotive fuel pump i had installed for my procharger and just reduced the pressure to about 7-8 pounds. It starts, runs, and revs fine. As soon as I put it in gear( under load) it spits sputters, backfires and pretty much will not even run. if i do get it to stay running i can only idle, or a bit above or it backfires. what the hell is going on? did i knock a wire loose? i messed with different fuel pressures, but nothing helps. it would be a great running boat if i just never put in into gear. please give me some advise. if anyone out there has a msd ignition for sale for this 502 please let me know

[DEL51]

I would check the timing.If the engine is not advancing the timing, this will occur.Also, the distributor could be wrong.It may be one tooth off or more.Check your wiring harness for loose connections and if you are using an msd ignition double check the 2 little output wires from the distributor to the msd box.If these are reversed it will cause problems.Check the plug wires and coil wires.Make sure the coil wires are not reversed.Check the voltage output to the ignition and the associated ground connections.Good Luck!
[This message has been edited by DEL51 (edited June 09, 2002).]

[502procharger]

i did not touch the distributor, coil or change any of that stuff. it was running great, i slapped the old carb back on while my new one was being built, and this started happening. i never changed my timing even when i added the procharger. it ran great both with this carb (before i put the blow through procharger carb on, and with the procharger blow through carb. i feel it is electrical, and not fuel related though. maybe i hit or knoked something loose when i removed the carb box and carb for the procharger setup. i have the stock ignition system on it. any other ideas on what could be hapening. what would stop the timming from advancing? as always any input is apprieciated.

[Costello]

Are you running through a pressure regulator? If you are, try removing it and going direct from the pump while running the boat under load. It may be that the regulator is restricting your flow to the point that under load you are running out in the bowls. It happened to my deal on Friday.