Loses power at 2000 RPM

[SharonAnne]

Boat started losing power at the end of last summer (2015). Had carburetor rebuilt. This season we began by having fuel filter changed - but it still would not go fast. Had engine compression test and numbers were fine. Cleaned out air vent to gas tank. Tried running it with gas cap off - no luck. It doesn't stall, starts up every time. I Last guy told me he'd have to cut through the hull to access gas tank. Did not do that. Boat was put away in storage last week.

What else could this be? So frustrating. Any thoughts?

[mjk1040]

It would be helpful if we had the year, make and model of the engine. May have to pull the pickup line out of the tank and check. Fuel pump issue? Check timing? Throttle cable going all the way open? Carb rebuild may need adjustment? More engine info and even a picture of engine will help. I'm sure someone on here will walk you thru things to check. Mike

[SharonAnne]

It is a 1989 Carver Montego 2557. It is powered by a Volvo Penta 5.7L AQ271DP. Also replaced fuel pump last year as part of trouble shooting. Replaced throttle cables as well.

[g36]

Timing, distributor not advancing fully or at all

[SharonAnne]

What is the fix? Does the boat need to be out of the water to repair?

[SharonAnne]

Sorry, misread. It wont go above 2000 RPM at full throttle.

[bud37]

Agree with all the above and here is one more.

Did your mechanic check the anti syphon valve, which should be located at the fuel line outlet from the tank, looks like a brass fitting, it has a spring and a check inside and can become plugged restricting fuel flow.

[g36]

Source of the post What is the fix? Does the boat need to be out of the water to repair?

i dont know if you were referring to my post on distributor timing or another? i'll put this here regardless, if mine are you familiar with timing a engine? you could run it out of the water if supplying cooling water to the engine but if winterized no. easier to do in the water since you could then take a ride. but if curious you might take the dist cap off and at least take a look inside at the rotor and twist it a little (it wont go far ) and make sure it snaps back from the spring tension on it. if its stuck or wont snap back then that will need to be looked at at. my trojan i had before my carver had the same issue your having and the springs were totally rusted away. just a thought.

[Viper]

Source of the post

i dont know if you were referring to my post on distributor timing or another? i'll put this here regardless, if mine are you familiar with timing a engine? you could run it out of the water if supplying cooling water to the engine but if winterized no. easier to do in the water since you could then take a ride. but if curious you might take the dist cap off and at least take a look inside at the rotor and twist it a little (it wont go far ) and make sure it snaps back from the spring tension on it. if its stuck or wont snap back then that will need to be looked at at. my trojan i had before my carver had the same issue your having and the springs were totally rusted away. just a thought.

++1
Pretty sure your model has an electronic pick up but mechanical advance system. As mentioned, check the base timing first, then the advance timing to ensure it's actually working. You can visually inspect the mechanism by removing the rotor and pick-up assembly. The mechanism will be under there. Chances are it's rusted, preventing it from moving freely and the springs may be toast. Pretty common problem for this symptom though not the only cause. Simple enough to confirm though before you start getting into all kinds of other areas and parts replacement. If it's the distributor I'm thinking of, parts aren't available from Volvo anymore so you'll need to find a dealer or distributor repair shop that may still have OEM springs in stock or aftermarket equivalents. If you take it to a rebuilder, make sure they are experienced with marine units so that they're maintaining a marine advance curve and not switching it to an automotive one. Worst case scenario; upgrade to an electronic distributor with no mechanical advance system.

[km1125]

Are you sure you replaced all the fuel filters going to that engine?

I'm not familiar with that particular engine, but I know on my engines and on my friends engines, they both have multiple filters in the fuel line. I have the main ones before the fuel pumps and one on the inlet to each carb. The ones at the carb don't look like a filter, they look like a fitting on the fuel line. They are actually small filters inside the fitting (I have crusaders with carbs).