4.3l bogs out on WOT

[CaptDuck]

Long time lurker, first time poster here!

I have a 2003 Mercruiser 4.3l in a Bayliner 1850 open bow. Engine serial number is OM375871 and it is a 2bl MercCarb. It has about 200 hours if that.

This past weekend i decide to take if out for the first time since last year. I gave it a once over before we left. Hooked up the muffs and she started right up. Oil looked good and everything appeared to be good to go. I get to the lake and she fires right up. I put along to get away from the no wake zone and then decided to opem it up. Well no go, she just bogs down flat on her face.

From what i have been reading on here it could be the oil pressure switch. I did the jumper thing and it started up and is spitting out fuel. I reconnected the wire plug to switch and she still runs. I am going to go ahead and buy a new switch. I pulled the water/fuel seperator filter and it was gunked up. I replaced it. Drained all the fuel and put in fresh fuel. I know the pump is working as i disconnected fuel line to carb and plenty of fuel comes out of fuel line. I will pull carb and clean it up just to be on the safe side.

Anything else i should check? How about the ignition coil?

Thanks in adavance.

 

[CaptDuck]

Re: 4.3l bogs out on WOT

I tried to work on it somemore this afternoon. I noticed no fuel was coming out but i could hear the pump working. I disconnected the fuel line from tank to water/fuel filter and i could barely get any suction. I connected fuel line from tank to pump and she pumps out plenty of fuel. I pulled the filter off and it is full of fuel. But it is just not getting up to the carb. I wonder if the base of the water/fuel seperator is clogged up. Could that be possible? Or could it mean pump is getting weak?

 

[JJJ]

Re: 4.3l bogs out on WOT

I'd try cleaning the fuel separator first and see what happens, could even be a plugged filter again if there is that much junk in the tank.

 

[CaptDuck]

Re: 4.3l bogs out on WOT

The tank is clean. I took out all the old gas and cleaned the tank. The put fresh gas in it. I did discover another fuel issue. When i took the water/fuel seperator filter and housing off. I noticed the fuel line going from filter base to the fuel pump was stripping out on both ends. Not make a good tight seal. So that may be why the pump is not getting fuel from filter. It is leak air into the system. I making a new stainless steel line and new fitting with flared fittings on both ends. Hopefully that will solve that problem.

 

[CaptDuck]

Re: 4.3l bogs out on WOT

Well it appears that my problem has been solved. I made new fuel line out os stainless tube and recoonected fuel pump amd filter. Turn the key and she had plenty of fuel flow now. I will verify it on Sunday when we head to the lake. Now on to my Tach not working.

 

[Bondo]

Re: 4.3l bogs out on WOT

I noticed the fuel line going from filter base to the fuel pump was stripping out on both ends. Not make a good tight seal.

Well it appears that my problem has been solved. I made new fuel line out os stainless tube and recoonected fuel pump amd filter. Turn the key and she had plenty of fuel flow now. I will verify it on Sunday when we head to the lake. Now on to my Tach not working.

Ayuh,..... It don't take much of a vacuum leak to shut down the fuel system,...

good luck,... I think yer probably in good shape now,... if anything, check, 'n change the filter again in a few hours run time...

 

[CaptDuck]

Re: 4.3l bogs out on WOT

Ayuh,..... It don't take much of a vacuum leak to shut down the fuel system,...

good luck,... I think yer probably in good shape now,... if anything, check, 'n change the filter again in a few hours run time...

Yeah i noticed that. But glad i hopefully found the problem. I ran it fro a little while on muffs and she was purring like a kitten. I will change out filter again half way thru the season. I don't use it all that much. As i usually out on my 100' commercial fishing boat more than on my pleasure boat! Something wrong with that!!!!!!

 

[CaptDuck]

Re: 4.3l bogs out on WOT

UPDATE.....Well my problems wasn't solved after all that. I took it out again today. It ran a little better than before. But after about 10 minutes it started doing the same thing. so i broke out the jumper wire for the oil pressure switch. Put it in place started her up and she ran like a scalded dog. So i have ordered a new oil pressure switch. And that should take care of my problems. I put the wires back in place to verify and she did the same thing. So i think am safe to say that it is the oil pressure switch.