Volvo Penta 4.3gl running rough under load

[HumanoidTyphoon]

I am having a problem with my 1998 Volvo Penta 4.3gl. It has the Volvo Penta SX outdrive. I'm going to do my best to describe what is happening and what I've done so far to trouble shoot it. First the problem. I took the boat to the lake about 2 months ago. Started fine and ran strong. Started cutting across the lake and after about 10 to15 minutes I noticed it would hesitate or loose propulsion every once in a while. What I mean by that is you would just notice the boat slowing down. Almost like the boat was shutting down. Then it would start going again. It eventually just went awa . I assumed it was bad gas. I took the boat out a few days later and never had an issue. Well I took the boat out a few days ago. Everything injustice described happened again. Only difference is it started getting worse. Quite a bit worse. It started idling real rough when in gear. Real rough. Anytime you are in gear it starts vibrating and running terrible. Out of gear. No troubles. So I slowly got the boat back home. Pulled the plugs and checked compression on all the cylinders. They were all between 150 and 165 . So I pulled the rear drive unit. To see if the issue was coming from the drive. Everything looked good back there. My guess is either a carb or spark problem but I would like to hear what you guys think. Way more knowledge hear then I could hope to have.

 

[Bondo]

Ayuh,..... Welcome Aboard,..... Sounds like a fuel delivery issue to me,.....

Pull the fuel filter, 'n examine it's Contents, for anything but clean fresh gasoline,.....

 

[HumanoidTyphoon]

Thanks for the welcome. I will take a look at the fuel filter and replace it.

 

[Saline Marina]

It would also be worthwhile to remove the distributor cap and look inside. Make sure the carbonaceous center post isn't worn to nothing. Also check for signs of corrosion. Another check is to run your fingers down each spark plug wire looking for chafing or cuts. If you feel a divot there is probably a problem. Sometimes the original wire routing gets compromised over years of working by feel to find the drain plugs on the side of the block each fall.

 

[HumanoidTyphoon]

Saline Marina. You were spot on. I've been away for work. Got home and replaced the distributor, wires and plugs . Set the timing and she's back to new. Not sure what exactly the problem was but it was one of them. Guessing the distributor. It was pretty bad insid . Thanks for everything guys.

 

[cptbill]

While the possibility exists that it could be fuel usually roughness under load is a sign of Spark plug wires or dist. cap or rotor maybe spark plugs

 

[Lou C]

Saline Marina. You were spot on. I've been away for work. Got home and replaced the distributor, wires and plugs . Set the timing and she's back to new. Not sure what exactly the problem was but it was one of them. Guessing the distributor. It was pretty bad insid . Thanks for everything guys.

thanks for reporting back. Usually its the contacts on the dist cap. The plug wires you can check with an ohmmeter for not more than 1000 ohms per foot. They rarely go bad. Plugs, I usually will clean as in the old days but if really fouled replace.