Need to know compression or what's the problem

[dre0256]

I have a 1996 four winns horizon 200 with a 302 5.0 volvo penta, I've lost 2000 rpms from 6500 WOULD to about 4500 WO if am lucky and from 50 mph to 35 mph, on cylinder 8 I have 100 psi, 7 100, 6 110 and 5 125 psi on #1 100 psi also, can't get the plugs out on 2,3 and 4 (another project) so is the psi too low? What is it supposed to be? Any and all help greatly appreciated.
Thanks Dre

 

[alldodge]

I have a 1996 four winns horizon 200 with a 302 5.0 volvo penta, I've lost 2000 rpms from 6500 WOULD to about 4500 WO if am lucky and from 50 mph to 35 mph, on cylinder 8 I have 100 psi, 7 100, 6 110 and 5 125 psi on #1 100 psi also, can't get the plugs out on 2,3 and 4 (another project) so is the psi too low? What is it supposed to be? Any and all help greatly appreciated.
Thanks Dre

To many things do not add up for this old guy in your statements
6500 rpm for a 302 is to high and the engine would come apart?
Seeing compression numbers on cylinders other then 2,3 and 4 are OK but we need the others. Need to get those plugs out
125 is good but the 100 and 110 is a bit low unless your in a high altitude area

 

[dre0256]

Am in Maryland, I had the boat out again today and am starting to think it might be a fuel problem, at WOT after taking off it was athe 3k rpms, but as it got going it would surge (like getting gas then not) then eventually I went up to about 5k rpm and then back down but kept surging up and down. So am thinking its a fuel issue... any thoughts??? And yes I know I need to get them other plugs out...

 

[alldodge]

Am in Maryland, I had the boat out again today and am starting to think it might be a fuel problem, at WOT after taking off it was athe 3k rpms, but as it got going it would surge (like getting gas then not) then eventually I went up to about 5k rpm and then back down but kept surging up and down. So am thinking its a fuel issue... any thoughts??? And yes I know I need to get them other plugs out...

With this issue I also would think fuel. Start with fuel filters both the main and the one at the inlet to the carb. After they are clean and you still have issues next I would look into carb clean/rebuild and fuel pressure

 

[dre0256]

It's EFI not carburated.

 

[alldodge]

It's EFI not carburated.

Thanks much for that, sorry but having a time with someone else for days saying he had a carb and just found out 5 minutes ago he has TBI. Also sorry to deviate from your issue.

When were the filters last replaced? Can you get a hold of a fuel pressure gauge to determine what it is. My though is your loosing pressure from a reduction in fuel and maybe do to a restriction.

 

[dre0256]

Filter changed like year and a half ago and yes I have a fuel pressure gauge. I plan on changing filter tomorrow, checking lines for any restrictions and I can also check the psi. Any idea what the fuel psi is or should be?

 

[alldodge]

From what I can find your engine should have 2 pumps, the low pressure should be 3 to 7 psi, the high I'm seeing 35-45psi. As a non-VP expert hope a more knowledgeable person comes in to advise.

Other things which can cause the issue are MAP or TPI sensors

 

[dre0256]

Ok I checked the fuel psi and it's at 40 psi, so now am thinking it might be one of the sensors MAYBE

 

[dre0256]

And I also changed the fuel filter

 

[alldodge]

Was sure hoping a VP guru would come along and advise, with the not happening, Start by getting those other plugs out and measure compression.

I would then recommend checking to see if there are any codes showing up during an engine scan.

 

[jerryjerry05]

The fuel with ethanol destroys old hoses.
Replace with e-resistant.
The tank vent might have a bugs nest in the line??
You could have junk in the fuel pick up?
There is an anti-siphon valve in that tank too.
One piece of crud stops the little ball from moving.
Any water in the tank?
Any water will rust the spring in the anti-siphon valve.

Also the coil when it goes bad will do what your describing.
Start and run and go back and touch the coil.
If it's too hot to keep your fingers on then it's bad.