AQ120b Starts fine, stalls after a couple minutes of load.

[agomes1]

Hi I have a 1979 Bayliner with a volvo penta 4 cylinder aq120 I believe and a volvo outdrive on it. When I start the engine either with muffs or in the water it starts up fine at first. If I keep it in neutral I can rev up just fine as high as i want. Once I put it into either gear, it will run alright for a few minutes at a low speed then putter and die out, or if i try to speed up it dies right away. Once it stalls it seems like it ran out of gas. If I try restarting it right away it will not start, but if I let it sit for a couple minutes with the fuel pump running it will start right back up and keep driving slow and do the same thing in a couple minutes. The guy I bought the boat off of replaced the original pump with an electronic pump so since it seemed like it kept running out of gas I jumped the fuel pump relay just to keep it on while motor was stopped to get back to shore.

 

[captmello]

Re: AQ120b Starts fine, stalls after a couple minutes of load.

the electric fuel pump, can be fine, but it needs to be wired correctly and safely.

it sounds like a fuel problem to me as well. clogged line, clogged filter, clogged tank pickup, carb...

It sounds like the previous owner was having troubles and installed the electric fuel pump to try to fix it. Instead, why not figure out whats wrong.

Safely pull the fuel line off the carb and run the pump. Is it pumping gas? should pump quite a bit in just a few seconds.

Safely!!!

 

[agomes1]

Re: AQ120b Starts fine, stalls after a couple minutes of load.

the electric fuel pump, can be fine, but it needs to be wired correctly and safely.

it sounds like a fuel problem to me as well. clogged line, clogged filter, clogged tank pickup, carb...

It sounds like the previous owner was having troubles and installed the electric fuel pump to try to fix it. Instead, why not figure out whats wrong.

Safely pull the fuel line off the carb and run the pump. Is it pumping gas? should pump quite a bit in just a few seconds.

Safely!!!

I believe he did the right thing hooking up the pump. He did set it up so it only comes on when their is oil pressure. As far as clogging goes it seems to not be clogged when i pull the fuel line off of the carburator. I was thinking maybe the pump wasn't powerful enough for it. The reason I am saying this is because it seems like the few minutes I leave the pump running with the engine off it seems like the water seperator filter is filling back up and then it runs for a few minutes (i'm thinking while it is wasting the fuel in the seperator filter) and then it shuts off once the filter is empty. Not 100% sure if this is accurate because i'm not a professional mechanic but that's what i'm thinking. I can't think of anything else. Also if i let it sit for a longer period of time with the engine off and pump on it seems that i am able to accelerate a little more then usual (not full throttle but more then minimum) without shutting off. Either way after a few minutes of driving it does shut off, it just takes a bit longer and lets me go a bit further at very very low speed.

 

[Maclin]

Re: AQ120b Starts fine, stalls after a couple minutes of load.

There could be an air leak somewhere between the suction side of the pump and the fuel inlet in the tank. Have you tried a separate small fuel tank from an outboard to feed the fuel pump? That could isolate a problem in the plumbing and filtering components.

You could also have a problem in the electrical circuit with wiring or the oil pressure switch. Some have hooked up a momentary switch that will feed the fuel pump directly just for startups and situations like yours.

Seeings as how the original mechanical pumps work ok for those engines there is more than likely a problem that was never found and the electric fuel pump is masking and/or band-aiding.

 

[agomes1]

Re: AQ120b Starts fine, stalls after a couple minutes of load.

There could be an air leak somewhere between the suction side of the pump and the fuel inlet in the tank. Have you tried a separate small fuel tank from an outboard to feed the fuel pump? That could isolate a problem in the plumbing and filtering components.

You could also have a problem in the electrical circuit with wiring or the oil pressure switch. Some have hooked up a momentary switch that will feed the fuel pump directly just for startups and situations like yours.

Seeings as how the original mechanical pumps work ok for those engines there is more than likely a problem that was never found and the electric fuel pump is masking and/or band-aiding.

I'll definitely give the seperate gas tank a shot. Haven't tried that. The only thing is that it only does it in gear in the water so I'm trying to figure it out somehow before I put it back in the water. Any ideas?