2001 305 motor

[gas57]

Just had my 2001, 305 Mercruiser 2 barrel carb motor completely rebuilt, the first motor had less than 200hrs. on it and the freakin oil sensor broke while going down the Connecticut river and knock knock too late , but that's another story, my issue is that at idle it sounds really smooth but under a load I have loss of power, it really bogs down when you throttle up, and also it backfires every once in awhile when you throttle up. I can only get about 3500rpm's where as before I was getting about 5000rpm's. Everything is brand new with this motor including the wires, cap and plugs. The block was magnafluxed, all new rods and pistons, cam and new cylinder heads. I have read several posts about this and was hoping that someone who has had simular issues with there 305 could shed some more light on this problem. I have put dry gas into the tank, fresh gas, new water gas separator, 2 of them. If the wires were crossed could the timing still be set correctly? The mechanic is a personal friend who put this motor together, he has been a licensed mechanic for 40yrs. I don't think that he would make a mistake like that but I guess it wouldn't hurt to check timing and firing order. Also is it possible that the electric fuel filter could be faulty? I'm just guessing here so any further info would be greatly appreciated!!

Thanks

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[Don S]

Re: 2001 305 motor

With the backfiriing, I would guess a possible fuel lean condition. Possibly from an air leak in a fuel line or a plugged pickup in the tank.
You can test it with a vacuum guage Like This or just hook up a remote tank (outboard tank) directly to the fuel filter on the engine and eliminate the boats sytem and see if it does it.

 

[gas57]

Re: 2001 305 motor

Thanks for your input!

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[gas57]

Re: 2001 305 motor

On the carb, there is a single set screw, I adjusted this screw 1-1/4 turn, does that sound correct?

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[Don S]

Re: 2001 305 motor

That is a preliminary adjustment for the IDLE MIXTURE. has nothing to do with higher rpm.

 

[gas57]

Re: 2001 305 motor

Just wanted to give an update on my issue, well very basic and simple, the 6 & 8 plug wires were reversed, haven't put a load on it yet but I'm pretty sure that will resolve my lack of power problem, man I feel sorry for my mechanic, he'll have a long day on tuesday, the guys in the shop have no mercy, oh well he's a freakin chrysler mechanic. Hee Hee!!!

Thanks for all the help, this site has great info!
Much Appreciated, special thanks go to Don S, thanks bro!!

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