I got a lil' problem that I hope you guys can help me with. Got a '98 promax, oil inj removed, running 40:1 oil. Problem is the motor killing on me at a 1200rpm or lower idle speed. When it does this, I go to the back and pump the fuel hose bulb up (the bulb is not collapsed) about 3 times and she fires right back up. Good to go for a while until I slow the idle down below 1200rpms. I can idle for about a minute or two below 1200rpms but then she'll kill if I don't speed up above the 1200. There is absolutely no miss, no nothing once boat is above 1200rpms all the way to the rev limiter. I am seeing a lot of fuel in the cowling pan, but nothing visible when the motor is running. It looks like there is some fuel running down the side of the fuel pump flange (that silver thing on the port side of mota). Any help is greatly appreciated. Thanks, Jarrod.
promax poor idle
- Thread starter jaybluez
- Start date
turn the key on (which should activate the pump) and check the fuel lines from the pump to the resevoir. once you find your leak run the boat again to see if the problem is solved. if not, i would check the tpi. i had a similiar issue, everytime i would slow down below 2000rpm the motor would kill but then fire right up.
I'll try that spanky. I changed the fuel filter yesterday. I pulled the old one off and pumped the bulb up to flush out the line there was a lot of air in there. I filled the new fuel filter up then installed. I idled the motor for about 3 mins and it did the same thing. Pumped the bulb up and it idled for 15 mins w/ no probs. The fuel pump is activated upon ignition, still no visible leaks until after I got it home. The leaks are very minor, it's actually seaping. I got a question about the 'fuel pump'. The fuel hose goes into a diaphram pump, then to the fuel filter, then to the electrical fuel pump. What is the purpose of the diaphram pump...or am I naming this incorrectly?
Darth VMAX
Well-Known Member
Dang!
When did you get a PM? I musta missed it when you got rid of your 280???
When did you get a PM? I musta missed it when you got rid of your 280???
JR
Active Member
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The fuel pump might have a bad diaphram or check valve. I would go through it/replace before it leans out and costs you a piston. Be sure and drain the surge chamber attached to your engine [where the high pressure electric pump is inside]. You might also blow through the inlet line with low pressure air in case there is trash in the surge chamber float while you have the chamber drained.
JR
JR
LOL, I snuck it in on ya Darth.
Thanks JR, this surge chamber w/ the high pressure pump you're talking about, is it safe to disassemble? Meaning can I undo the screws that hold the top half to the bottom half or should I not do that? Thanks again for the replies.
Thanks JR, this surge chamber w/ the high pressure pump you're talking about, is it safe to disassemble? Meaning can I undo the screws that hold the top half to the bottom half or should I not do that? Thanks again for the replies.