2009 4.3 gxi-j cant get it over 3k rpms

[2009 stingray]

i have this boat that will not get out of its own way. and its kicking my ass, i hope someone else has had a similar issue.
it feels llike i have 6 fat guys sitting in the rear of the boat.
the engine has 150hrs on it, the fuel pump module was replaced due to low pressure and noise, the screen on the regulator was clogged with paint chips and removed for the c clip bulletin. the fuel injectors were replaced and the fuel rail flushed out.
the engine was tuned up: cap, rotor, wires and plugs.
this issue was present before these parts were replaced.
the engine idles fine, revs in neutral.
there are no codes and the only thing that looks strange on the scan tool is the cam retard is -4.5
i am at a real loss on this one and any help is very much appreciated.

 

[Scott Danforth]

New to you boat or a new problem?

Compression numbers?
Fuel pressure?
Changed fuel filter and inspected contents for pure fuel?

Trim setting when taking off?

 

[2009 stingray]

new

New to you boat or a new problem?

Compression numbers?
Fuel pressure?
Changed fuel filter and inspected contents for pure fuel?

Trim setting when taking off?

new to me boat,
haven't run a mechanical compression test but did one with the scan tool and all cylinders reacted the same.
fuel filter new with module, fuel sample taken and looks clean and is fresh.
tryed the trim all the way down on take off and 1/2 way up, both same results. and every setting in between.

 

[Scott Danforth]

Pull the plugs and get compression numbers

Hook up mechanical fuel gauge and read pressure both at idle and under load

 

[ESGWheel]

In addition to above, here are some of off the wall thoughts:

• Validate the throttle plate fully opens when the throttle is fully forward.
• Is there lots of belt dust all over the engine compartment? The flame arrestor may be restricted and needs cleaning. Try running without it.
• Does it rev in neutral above 3k?

 

[2009 stingray]

In addition to above, here are some of off the wall thoughts:

• Validate the throttle plate fully opens when the throttle is fully forward.
• Is there lots of belt dust all over the engine compartment? The flame arrestor may be restricted and needs cleaning. Try running without it.
• Does it rev in neutral above 3k?

throttle plate is wide open @ fulll throttle, no belt dust, flame arrestor was not in place for testing. yes it revs in neutral

 

[alldodge]

Agree, check fuel pressure, should be 50-60 psi

the fuel injectors were replaced

With ones direct from VP or somewhere else?

 

[2009 stingray]

fuel pressure is @ 42psi with regulator connected and 48 with vaccuum line off.
compression range is 155-165 on all 6
the injectors were replaced with new gm injectors, same part #
i am going back today to check the fuel pressure with a different gauge to confirm findings, i am also bringing a can of gas and will feed the pump from this tank to see if the anti siphon valve is causing an issue.

 

[Scott Danforth]

Your fuel pressure should be higher

Running from a separate can is good

If you bought injectors off eBay, they are usually counterfeit

 

[2009 stingray]

Your fuel pressure should be higher

Running from a separate can is good

If you bought injectors off eBay, they are usually counterfeit

yeah i am retesting with a different gauge to confirm pressure readings cause it shoudl be between 50-60 psi so ill see what developes

 

[2009 stingray]

ok, back from testing, new test gauge reads 48 with regulator connected and 54 with the vac line off. seperate fuel tank made no difference. i stil lthink the fuel pressure should be higher yet i am prety sure these regulator as set for 52psi bypass so if thats the case, how can the pressure get past that?

i got the boat up on plane. but out of the gate she is a dog, very sluggish. once up on plane, i had the rpms top out @ 4200 and speed up to about 40mph. based on the dash. the top end is fine for this boat.
lots, i mean lots of porpoising. like i was in an ocean, meanwhile this is on a calm lake. i am wonding if the bottom has too much growth on it and needs a good scrubbbing. the boat is in the lake the whole summer, no trailer so i dont know what it looks like. i asked a neighbor to look at it when i drove past and he said it was bad but who knows how bad is bad?
i am having the boat pulled out and cleaned by the local marina next week and see what that does cause truthfully, it heels like i am dragging around a cynder block when i am trying to get up on plane.

 

[alldodge]

ok, back from testing, new test gauge reads 48 with regulator connected and 54 with the vac line off.

i got the boat up on plane. but out of the gate she is a dog, very sluggish. once up on plane, i had the rpms top out @ 4200 and speed up to about 40mph. based on the dash. the top end is fine for this boat.
lots, i mean lots of porpoising.

If gauge is accurate then there is no issue with pressure

Porpoising is caused by to much trim out, or to much lift. If you trim it full in against the transom and it's still porpoising, then look at load placement and just what prop is on the boat?

Next check your timing
if you have the flat type cap check timing and also replace cap

 

[2009 stingray]

If gauge is accurate then there is no issue with pressure

Porpoising is caused by to much trim out, or to much lift. If you trim it full in against the transom and it's still porpoising, then look at load placement and just what prop is on the boat?

Next check your timing
if you have the flat type cap check timing and also replace cap

This engine hasn't been touched in years. I don't see how the timing can be off when the distributor is a lock down 1 position clip in other words you can't adjust it and still be bolted in unless it was pulled and shaft rotated.

 

[2009 stingray]

I'm also hung up on that cam retard spec of negative 4.5
Anyone have this reading on their unit?

 

[cyclops222]

The porpoising. Bilge full of water ?

 

[2009 stingray]

The porpoising. Bilge full of water ?

Empty

 

[alldodge]

The flat style distributor cap can and does cause issues. The motors timing is controlled by ECM, and the ECM assumes the dizzy is exactly where it should be. There is a service bulletin indicating for low on power that the dizzy should be marked, then moved 1* in each direction to see if power improves.

Not saying this is your issue, just a possibility.

VP uses the cam sensor on the HSV distributor where Merc does not.
I don't see the -4.5* retard as an issue, but would compare with crank timing

 

[ESGWheel]

Any thoughts as to the engine not coming up to temp or the ECM is not seeing the correct temp and limiting fuel?

 

[alldodge]

Just to clarify, this is not a new to your boat, and it use to run great?

 

[2009 stingray]

Just to clarify, this is not a new to your boat, and it use to run great?

boat ran great earlier in the season, it has sat a while, lots of rain and busy schedule. finally got out to run it and this is where i am at