Hey guys, I have a 460 in my boat, its a drag boat. It has a Holley 650 Double Pumper, pretty standard, mechanical secondaries, no choke. The other day I'm cruising along and it back fires through the carb which it has never done. Its done that now a couple of times and then all of a sudden began running extremely poor and cutting out and I noticed gas leaking out of the accelerator pump on the primary side. Would backfiring cuase this? What would cuase the backfiring as well?

Thanks guys

Andrew

 

Sounds like the power valve ruptured, not too hard to check and replace.

 

Well I took it all apart to check the power valve - it doesnt have one, it has a plug. Why would it not have one? Could I put one in it? Also how do I find what model of carb I have? Could a backfire cuase the accelerator pump on the primary side to start leaking?

Thanks

Andrew

 

Don't know if backfire would rupture accelerator pump. I would check float level or condition of needle/seat. Unusual it doesn't have a power valve. Absence of one is usually reserved for all-out racing engines.

 

It doesn't have a power valve because you really don't need one on a boat. The power valve is so that you can run the carb leaner at low rpm's and under a load, it opens up to allow more fuel in. Usually, when not running the power valve, the front jets are about 10 sizes bigger than what you would run with a power valve. Since most boats are run under a load, there is no need to have one, just plug it and run the larger jets, this way, if it does backfire, it won't start flooding and leave you stranded in the moddle of the lake.
I would say that the leaking accel. pump is just a coincidense. The backfiring could be an unrelated problem all together. I would look into the ignition first. Plugs, wires, cap, rotor, etc. Also check the fuel filter for restricted flow.

 

Thanks for the help guys, I bought a kit a put all new gaskets and seals throughout including new accelerator pumps and am off to the lake to test it.

Andrew

 

Good luck to ya.
Jimmy