Volvo Penta 5.0 running rich - loss of RPM's

[bkhitchens]

1994 Four Winns Vista 278 with two 5.0 Ford carbureted motors.

My port engine seems to smoke a lot at times with a thick, black smoke. It reeks of gasoline when idling and for a while after shutting down. I recently rebuilt the carb (2bbl Holley). Since replacing the carb it still smokes and smells. At WOT I am not achieving the 4200 rpms that it had easily achieved before the rebuild. There are no gas leaks.

The engine idles a little rough, which is one of the reasons for the rebuild. It had been starting well and running well at WOT before the rebuild. It does not use oil at all. I believe that the carb was rebuilt correctly. I did the other one last year with no problems. It still starts well.

My questions are as to why I am getting the rich condition. Could it be ignition related? Timing, possibly? I am also wondering why I am not getting my max RPM's. I am currently having trouble getting on plane. Could I have replaced the throttle cable incorrectly? It just doesn't seem as if I am achieving WOT.

Any guidance is appreciated. Thanks

 

[Bondo]

Re: Volvo Penta 5.0 running rich - loss of RPM's

1994 Four Winns Vista 278 with two 5.0 Ford carbureted motors.

My port engine seems to smoke a lot at times with a thick, black smoke. It reeks of gasoline when idling and for a while after shutting down. I recently rebuilt the carb (2bbl Holley). Since replacing the carb it still smokes and smells. At WOT I am not achieving the 4200 rpms that it had easily achieved before the rebuild. There are no gas leaks.

The engine idles a little rough, which is one of the reasons for the rebuild. It had been starting well and running well at WOT before the rebuild. It does not use oil at all. I believe that the carb was rebuilt correctly. I did the other one last year with no problems. It still starts well.

My questions are as to why I am getting the rich condition. Could it be ignition related? Timing, possibly? I am also wondering why I am not getting my max RPM's. I am currently having trouble getting on plane. Could I have replaced the throttle cable incorrectly? It just doesn't seem as if I am achieving WOT.

Any guidance is appreciated. Thanks

Ayuh,... Rebuildin' a carb is at Best a 50/50 shot,... even in a carb rebuild shop...

You Still have a Carb problem...

Do these motors have mechanical fuel pumps,..??

If it went Bad, it'll flood the motor, through the over-flow tube...

 

[bkhitchens]

Re: Volvo Penta 5.0 running rich - loss of RPM's

Yes, they are mechanical fuel pumps.

 

[bkhitchens]

Re: Volvo Penta 5.0 running rich - loss of RPM's

Okay, are we on to something. I have often noticed gas (I thought it was oil at first but have no drive leaks) in the water behind my boat. When I rebuilt the carb I noticed a passage into the main body that obviously had discharged gas into the manifold through the main body, but was not through a pump discharge nozzle. I am guessing that this is where the gas smell is coming from. I smell gas after shutting down but didn't see any leaks around the engine. Am I smelling gas running into the carb/manifold or gas in the water, or both. Could the gas be making it's way through the exhaust system that fast? Or would it be from when it was running? Is my only choice replacing the carb or is there a fix? Please help, you have definitely piqued my interest. Thanks,

 

[Technologic80]

Re: Volvo Penta 5.0 running rich - loss of RPM's

Are you positive its a carb issue? Have you checked to make sure all the cylinders are firing? When was the last tuneup or compression check?

 

[bkhitchens]

Re: Volvo Penta 5.0 running rich - loss of RPM's

This past weekend I checked the timing, spark plug wires for spark, etc. I also found that the linkage on the choke was set wrong and was not allowing the choke to open fully. It seems to have helped with the running rich.