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rebuilt 5.7 boat engine, pings, backfires and stalls under heavy load

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Old September 27th, 2021, 9:12 AM
  #11  
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+1
low fuel pressure will not cause predetonation
Old September 27th, 2021, 11:41 AM
  #12  
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Hi tech2,
I'm pretty sure we both know what detonation is, but how about helping me out with what is predetonation ?
Old September 27th, 2021, 4:01 PM
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am i making up a word..lol

pre ignition. thank you for the correction.

Last edited by tech2; September 27th, 2021 at 4:05 PM.
Old September 27th, 2021, 5:11 PM
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Originally Posted by chs marine
the fuel pump was checked and even though the pressiure was fine, i installed a new carter pump as well as a new anti siphon valve, then i ran it on an external tank with fresh gas,
The issue to me is two fold. I'd suggest working one first instead of both at the same time. If the fuel pump is delivering to the carb, but the engine is stalling, cannot maintain higher load rpm's, look at the float drop in the carb. I am not familair with your setup, but this is indicative of fuel starvation. Predetonation, timing.
Old September 27th, 2021, 6:20 PM
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Originally Posted by hanky
A couple of things,
If the dist is one tooth off , could produce performance problems.
Usually when starving for fuel, engine just doesn't have the guts to deliver. Possible fuel volume problem.
Your best bet is to start from the beginning and confirm dist is installed correctly then set timing to spec.It has to be removed and done correctly from the start.
We agree low fuel will starve engine , run lean and misfire .
The problem sounds like spark is not getting to where it is supposed to be at the right time.
please explain to me how a distributor that is movable can be 1 tooth off? if its off and you set the timing correctly, isnt it then corrected? and if not, how do you know you have it in the right way?
Old September 27th, 2021, 6:24 PM
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Originally Posted by kevinkpk
The issue to me is two fold. I'd suggest working one first instead of both at the same time. If the fuel pump is delivering to the carb, but the engine is stalling, cannot maintain higher load rpm's, look at the float drop in the carb. I am not familair with your setup, but this is indicative of fuel starvation. Predetonation, timing.
the engine is stalling, im my mind, is because the knock sensor is sending signal to adjust a timing to reduce knock and it is adjusting it to a point it stalls out the engine. maybe im wrong on this theory but i know if i pull back on the throttle before is backfires, it will not stall out.
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