Poor acceleration - 2005 Volvo 5.0L Gxi

[Brian K]

I have recently experienced poor acceleration from my Volvo 5.0 L Gxi 270HP (Fuel Injected) on a Four Winns H200. I have a Hi 5 SS 21P SS prop. I have 60 hours on the boat. When new it would pull really well - but now the pull out of the water is painful - just no giddy up and go. Top end is normal and no hesitation problems once at higher revs. Just getting low end torque and getting the prop spinning seems to be the issue.
I took it to the dealer who replaced the Fuel pump and spark plugs - but that didn't help. They said everything else looks good - as per the computer - no error/fault codes. On an older engine I would suspect the Vacuum advance or points - but there isn't one on this boat (I don't think). I tried a 17P Hi 5 SS prop and of course that helps alot but revs alot higher (yes rev limiter works). I burn regular fuel (manuf recommendation) and change the oil, oil filter and fuel filter every season. I'm tired of taking it to the service depot ($$$) but don't want to start replacing things on a trial and error basis.
Would Premium fuel make a big difference?
Any other suggestions on things to check would be appreciated.
Thanks

 

[Don S]

Re: Poor acceleration - 2005 Volvo 5.0L Gxi

What's the full model number of your engine, or better yet, the Volvo SN?

And no, you don't have a vacuum advance or points. You have an MPI engine very similar to an automotive engine.
What is the max WOT (Wide Open Throttle) rpm of your engine when you get it up on plane?

 

[rodbolt]

Re: Poor acceleration - 2005 Volvo 5.0L Gxi

are you noticeing any black soot accumulating on the transom?
any smell of rich running at low speeds?

 

[Brian K]

Re: Poor acceleration - 2005 Volvo 5.0L Gxi

Serial number of motor is 3869255. There is another number that might be it also - 4012138528.
The drive unit is SX-M 1.60 3868891 4202123038. (Sorry I'm getting these numbers from my Blackberry and didn't put in alot of desc) The repair shop didn't like this drive ratio and suggested that Four Winns should have put in a higher ratio end???
I don't see any soot or anything resembling too rich an exhaust. I don't see anything that looks like a problem - no smoke. No leaks of water or anything (oil) in the bilge water funder the engine either. I realize there is no vacuum advance as this is an MPI - it just feels like the Vacuum Adv hose is disconnected - like the giddy up is gone. WOT is probably limited by the rev limiter and is very gentle and tough to notice it kicking in but it is 5000 RPM and top speed is around the 42-45 MPH range and strangely enough is roughly the same with both the 17P and 21P props although this doesn't make sense. It seems once the boat is up to a higher RPM, it acts fine - it's just getting there with a skier on that is the problem - throtle position sensor perhaps? With no skier on accelaration seems fine of course alot more peppy with the 17P than the 21P.
I did a compression test a while ago - don't have the numbers handy but I remember that all cylingers were pretty much the same. What should compression be?
Have changed the spark plugs 3 times - with the expensive ones so I don't want to do that again.
Brian

 

[Don S]

Re: Poor acceleration - 2005 Volvo 5.0L Gxi

Put your original Volov prop back on and see how it does.
When you go from a 17 to 21 pitch prop and they both do 5000 rpm, you could have a faulty tach or underpropped.

 

[Tail_Gunner]

Re: Poor acceleration - 2005 Volvo 5.0L Gxi

You can hit 4900 with the 21 pitch prop? if i am reading this right the 17 bangs the rev limiter very lighty or hard to hear it....This may sound overly simple but you may have some bad gas going on..aka knock sensors retarding the timing.

 

[Brian K]

Re: Poor acceleration - 2005 Volvo 5.0L Gxi

1) I didn't get a Volvo prop - the dealer said the 21P Hi 5 was a better prop and simply did an exchange. I also ought a 19P 3 blade alum as a spare and it is awful even when the boat ran fine.

2) I appreciate the bad gas comment and wondered about that too. In the spring I'll try to burn it as low as possible and then refill with prmium. The manual says regular - but a friend told me to use premium. He has a Malibu and says the Malibu manual says Reg is OK but he says Prem works much better.

So basically you're thinking bad gas because of the WOT I get with both props. I haven't noticed any knock - but I guess if there is a knock sensor I wouldn't hear it anyway. As far as the rev limiter on the 17P - I don't feel it limiting RPM's and the repair shop confirmed that I wouldn't feel it but figure it must be active to get since I can get to 5000 with the 21P and the 17P should be much easier so must be active.
Thanks for the help - I hope it's as simple as this!

 

[havasuboatman]

Re: Poor acceleration - 2005 Volvo 5.0L Gxi

Just out of curiosity...
The longer we own a boat, the more crap we tend to accumulate. If your boat is loaded down with gear you "might need" it's real easy to end up with a couple hundred pounds of stuff.
If you do keep your boat loaded, pull everything out and stack it next to your boat, you might be suprised to find you found your lost hole shot.