SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: torvald68 on June 22, 2011, 11:46:45 AM
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Need some help trying figure out my problem. 1978 Nordic pickle fork. Fresh 454 with a 177 B&M blower. Newly rebuilt Holley 850 dbl pumper. Bassett header. Took boat out for 1st wet test seemed to run fine under normal driving. The minute you stab the gas the boat backfires and shuts off. Boat has a berkely pump with a place diverter. People are saying the carb is too rich others are saying too lean. I really need help. Any good info you guys can send will be greatly appreciated. Timing is static at 26 deg full advance. Fuel pressure is set at 6psi. Blower is capable of 5-7lbs of boost.
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fuel psi, float levels?
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Back fire out the carb or exhaust....
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Timing sounds like it's too retarded. Adjust it at idle by hand until it runs smooth. then roll into the throttle. If your carb is to fat normally the motor will just die, same if it's to lean.
The beav
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sorta sounds like a vacuum leak!!!! :banghead:
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Pull a spark plug and let us know the color.
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If it's up the carb, it sounds like way to little acc. pump. Put on 50cc pumps and she'll pop no more :D
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I broke an input shaft on my 14-71 about 3-4 years ago. Motor would start, run, show 6-7 lbs boost, you could wing it as much as you wanted out of the water(no load). When loaded, it would pull to only about 2400 rpm, (not quite on plane), backfire and quit. It would start right up after that though. Added fuel pressure gauge where I could see it, replaced carbs with borrowed units, checked the blow-off valve, replaced the entire ignition, plugs, wires, dist, hotwired the ign directly to the battery, tried a small fuel cell of known new fuel, with a different electric pump, and it was the input shaft..... It was broken at enough of an angle that it would turn the rotors without much load, but when the boost was higher than 6-7 lbs, it would distort the front gear cover enough to slip for a few revolutions, just enough to kill the motor. The motor could windmill it, with help of the broken shaft, to 5500 rpm with no load, but under load there wasn't enough air to run it. Craig from BDS claims to only have heard of that twice in 40 years. Check your shaft and gears, by hand everything felt fine on mine, no extra slack or anything. We finally put a block of 2x4 between the rotors and could slip the shaft with a 1/2" drive ratchet fairly easily. New shaft, and no issues. I still have both parts of the old shaft. Good luck. TIMINATOR