Volvo 4.3l no power.

[xsyourrides]

Bought 2004 Campion 565i boat with 4.3 gxi-g volvo penta efi engine. I have no history on the unit as I bought it from repo auction. The block,heads and manifolds where cracked. I removed the engine had it rebuilt. The engine shop built one with flat top pistons and bored 0.030" said it would give me 19hp more? I installed,ran it in the shop ran like kitten with no load on the engine.Took it out yesterday for break in run, but no poor. it doesn't bog or knock just extremely slow in building rpm and max rpm is 3800. if you back it off to 2500 or 3000 rpm and punch it nothing at all happens,then few seconds later it will slow build rpm to 3800. I checked the prop it has 21 pitch prop witch is ok. Starts like dream and very snappy throttle responds with out the leg engaged. Gets up on step very nice. But serious dog on the water. Pulled the spark plugs nice med brown. Its got me puzzled any help or ideas would be great.
Thanks
Ps.I have ran mercury engines and had lots of problems with anti-syphone valves in the fuel tanks restricting fuel to the engine is this problem for volvos?

 

[achris]

Re: Volvo 4.3l no power.

Sounds like you need to drop a couple of inches (at least) off the prop.

Chris......

 

[xsyourrides]

Re: Volvo 4.3l no power.

The only thing I can get off the prop for numbers is 3850313 which when I googled it , it came up 21 pitch 14.5"

 

[Don S]

Re: Volvo 4.3l no power.

If the prop worked before, it should be fine now.
With all the engine work, I would be looking a something done wrong, missed, loose, adjusted wrong or ....................
Timing, fuel lines, vacuum leaks, valve adjustment and the list goes on.
All needs checked out before you even think about a prop.
You should be seeing 1000 rpm more, and you aren't going to get that with prop size.

One other thing, the fuel mapping in the ECM is for a 4.3 with standard pistons and bore, and whatever else was changed.

 

[bomar76]

Re: Volvo 4.3l no power.

The block,heads and manifolds where cracked. I removed the engine had it rebuilt. QUOTE]

Trying to figure out how you had a cracked block rebuilt.

 

[xsyourrides]

Re: Volvo 4.3l no power.

Sorry I didn't rebuild the damaged one. Found core and reused my rods cam crank. I ask engine shop about the fuel mapping on efi With flat tops and he said it wouldn't make differance but it's got me worried.the only thing I can come up with is the anti syphone valve very hard to open

 

[Don S]

Re: Volvo 4.3l no power.

The answer to your question is very easy. Hook up an outboard fuel tank to your engine. See if it runs ok. If not, then it's engine side. If it runs great. You have a problem in the boats fuel system. Either an air leak or a clog. There are tests for that too in the Adults only sticky.