Volvo penta aq131a/275 wont plane out

muskopf8

Recruit
Joined
Aug 7, 2012
Messages
4
Help!! I have a 1988 Beretta success with a volvo aq131a/275. I bought the boat from my neighbor (it sat for 10 years) changed the oil and stern drive oil. Fist time out the boat performed perfectly. Second time out, right away WOT, the boat wont rev past 2000 rpm wont plane out. Since then, I have been reading forums and heres where im at. Compression check=160 psi all four cylinders new timing belt set timing and checked for timing advance with timing light, timing advances in spec. installed petronix ignition and flame thrower coil, went completely through carb and installed new gaskets and accelerator diaphram, carb seems to be fine. Engine starts and idles GREAT. Engine revs great in neutral (did so by disconnecting linkage and revving by hand at carb) Engine seems to be in GREAT running condition. so now im thinking maybe prop, prop spins straight seems fine, I marked the prop and checked for a "spun hub", no spun hub. I also tried a different prop my neighbor had which he had simply replaced trying to get more speed still same effect. Ive been told to check exhaust flapper, but I think this setup only has a flapper just above the prop not internal like my friends boat has? not sure, but I think there isnt one. I hate to give up on this, I feel its soo close to being a perfect litte boat for me. PLEASE HELP with any other possibilities. THANKS.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Volvo penta aq131a/275 wont plane out

What did you do about the 10 year old fuel?
 

muskopf8

Recruit
Joined
Aug 7, 2012
Messages
4
Re: Volvo penta aq131a/275 wont plane out

I hooked up a 12v fuel pump and let it pump into a bucket. First time out I put 25 gallons of 93 octane and a bottle of octane boost in it. We were out 5 hrs with 5 adults pulling a 3 man tube which consistantly would reach 30+ mph untill we loaded up and went home
 

trophy boat

Seaman Apprentice
Joined
Apr 23, 2011
Messages
41
Re: Volvo penta aq131a/275 wont plane out

Has it ran good since you changed the timing belt? One time I had the same issue and it turned out I had the new belt off two teeth. It ran perfect but not over 3000 rpm. The motor was timed right but the valves weren't opening at the optimum time.
Check anti siphon valve in the fuel pickup tube.
See if your fuel tank has a filter that might be clogged.
 

PiratePast40

Lieutenant Commander
Joined
Mar 21, 2009
Messages
1,734
Re: Volvo penta aq131a/275 wont plane out

In addition to all the above recommendations, do a close inspection to see if anything at all looks out of the ordinary. Double chack the carbureator and check to make sure the main jet is still seated properly. I've actually had one unscrew itself out of the carb body and fall into the bilge. Had the exact same symptoms that you're describing.
 

muskopf8

Recruit
Joined
Aug 7, 2012
Messages
4
Re: Volvo penta aq131a/275 wont plane out

I have replaced the fuel filter and fuel line from filter to fuel pump. The timing belt thing does interest me. This engine has three pulleys cam,distributor and crank. I purchased a ginuine volvo belt, so it had marks on the belt as well as the block. The cam pulley was pretty obvious with a mark on the belt and a slot right behind the pulley. The distributor, almost as easy with a mark on the belt and a notched bracket behind the pulley. However on the crank, I coundnt use the mark on the belt, only lined up the TDC mark with the mark on the block. Is it possible to be off, even though I used a timing light and i'm reading 6 degrees BTDC @ 850 rpm as read in the manual? I do alot of engine work on ATV's and i've expierenced a very simular issue with an engine being one tooth out of time. Just thinking if the top two pulleys line up with the marks on the belt and the #1 plug fires at the right time it has to be set right?
 

muskopf8

Recruit
Joined
Aug 7, 2012
Messages
4
Re: Volvo penta aq131a/275 wont plane out

Thanks Pirate. I will examine the carb closely. Last test, I did check that all three jets in the solex44 were squirting gas at WOT. Thinking about messing with the air screw next test and maybe take a new spark plug to see how it reads. Only thing is with it bogging down at WOT, i'm thinking its going to read rich no matter what. Does anyone know if fuel pressure could be an issue on this even though it's an old float and bowl style carb. which doesnt seem to be running out of gas?
 
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