8.1 Volvo, stumbles in mid to high RPMS, will not get on plane

[The Dark Side]

Long story short, port engine ran fine during sea trial (fall 2020), then boat sat for 1 year while work was completed on starboard engine. Then we took it for a sea trial in late fall (2021) after starboard engine work was completed, and now port engine does not get into mid or high RPMS. Seems to stumble and lots of gas fumes coming from exhaust (running rich??).

Fuel pump replaced (made noise during initial sea trial), fuel injectors cleaned, did compression test and all cylinders had good compression.

Boat is a 2008 Larson with 259 hrs.

Thoughts?

 

[PlayDate]

What was wrong with the Starboard engine?

Volvos are pretty reliable GM engines. If you have gas at the exhaust.....you either have too much gas going into the cylinder or you aren't burning it. Time to pull the plugs and see what they tell you. Hopefully it will just be a bad spark plug wire or a fouled plug.

 

[mrsrobinson]

Bad fuel in that tank since the boat sat for a year?

 

[Jimmy Buoy]

Replace the plugs. 8.1's eat the things and that's the symptoms.

 

[firecadet613]

Plugs / wires then I'd look at fuel. If the boat has twin tanks, can you run it off the other tank?

 

[The Dark Side]

What was wrong with the Starboard engine?

Volvos are pretty reliable GM engines. If you have gas at the exhaust.....you either have too much gas going into the cylinder or you aren't burning it. Time to pull the plugs and see what they tell you. Hopefully it will just be a bad spark plug wire or a fouled plug.

previous owner did not like to replace the manifolds and risers....got water leakage and internal corrosion and replaced with a new long block. Port engine internals looks good with no corrosion though.

 

[The Dark Side]

Bad fuel in that tank since the boat sat for a year?

tanks were about 1/4 full in fall of 2020. We filled with new fuel in spring 2021 and added fuel treatment, so do not think fuel is the issue. Starboard runs fine.

 

[The Dark Side]

Plugs / wires then I'd look at fuel. If the boat has twin tanks, can you run it off the other tank?

I think plugs and wires are old, will check those next. It has twin tanks with a crossover, but I cannot switch tanks for the port, if that makes sense.

 

[PlayDate]

I think plugs and wires are old, will check those next. It has twin tanks with a crossover, but I cannot switch tanks for the port, if that makes sense.

Generator runs okay on the Port Tank? If so.....plugs/wires are the first thing on the list.

 

[dvx216]

A compression test at this point would be a good thing to do.

 

[paulswagelock]

Plugs and wires, 8.1 are notorious for eating them up.
Start with plugs, if still exists, replace wires.
Injectors were cleaned, but were they flow tested?

 

[Wanderer 290]

Doesn’t the 8.1 have coil over plugs ignition ?

 

[Jimmy Buoy]

Doesn’t the 8.1 have coil over plugs ignition ?

Individual coils near each of the plugs using shorter plug wires than typical distributor run engines.

 

[The Dark Side]

just to close the loop on this, the problem was clogged injectors. They eventually flow tested them and found a couple that were acting like a fire hose. Boat was sea trialed this week and ran great!