They do make an isolating battery switch, seems like a waste of dough though, Just use the battery switch in the #1 position for the engine, and install your isolator normally, that way if your cranking battery gets low due to a proplem you have instant jumper cables by the flick of a switch

 The nice thing about having the switch is you can turn off the power to the boat, if you do it this way you will need to install a second smaller circut breaker and switch from the "stereo" battery because you will need to hook the stereo right to the battery terminal (does that make any sense?).

I am having some issues with my 4150 750 DP.  The engine is on a stand, so I can't test under load yet.  The carb has a 6.5 pv in the primary, no pv in the rear.  The engine is pulling 10in hg at 900 rpm.  The carb has 73's primary and 81's in the rear with 30 cc acc pump.

When the engine is at idle and I roll the throttle it sounds fine, but if it is at idle and I stab it, it falls on its face and then back fires.

Any suggestions as to what is going on and what to possibly do??

Thanks

I was talking to my freind this morning and he has to replace the mechanical fuel pump on his houseboat this weekend.

He proceeded to tell me something shortly thereafter that made we want to smack him in the back of the head.

He told me the "marine" fuel pump was way to expensive for his 130hp 152" I4 "Iron Duke" (the little Chevy II) and that he was just going to buy a rebuilt Kragen special and go up there and put it on. I told him it had to be a "marine" approved pump with an SAE J117 sticker on it to be safe/legal because it has failure protection on it that literally kills the engine if it fails.

He then tells me the fuel pump costs $118.00, so I said "and", he then tells me he can get a Kragen special for $58.00, so I handed him $60.00 and said I'm buying your stupid life. He just smiled and handed my money back. He said he had to go order the "marine" pump.


In a closed engine compartment boat, do NOT ever cheat when it comes to USCG rated fuel/electical parts for the boat, this was a house boat that sleeps 12, think about that for a second...


A marine specific fuel pump (mechanical) has two diaphrams, one that pumps fuel into the bowl of the carb, and another heavier diaphram that floods the engine if the primary fails, killing the motor and ultimately the fuel flow. That is what that clear or yellow hose to the flame arrestor is for.

Sorry for the rant, but seemed relavent.

Hey speedy,
I think I remember you posting in a different thread that you were having this same trouble (the engine would want to stall comming off of plane) and the problem was the power valve was too big and not closing??