VP 5.7 TBI bogging down

[Berkley1]

Hope to get some advice on why my VP 5.7 TBI it is in a wellcraft Martinique 2600 and it is not running at peak performance back story this year replaced both exhaust manifolds and risers went back in the water everything ran great was getting anywhere from 25-28 MPH one day came in filled the tank next trip out ran tops about 10mph more throttle it would bog down sometimes I will see the speed increase get up to 20 MPH I checked the fuel pick up screen is clean changed the fuel water separator emptied the filter contents in a jar clean as a whistle. pulled the spark plugs all looked good. I believe its a fuel delivery issue would it be the pump or the fuel pressure regulator or something else. when I find the sweet spot on the throttle she will run all day at 10-12 mph.

signed frustrated.

 

[Scott Danforth]

did you check fuel pressure? if not, check it
is the spark arrestor clean?
if you have a crab cap on the distributor, change it.

 

[Berkley1]

I cleaned the flame arrestor going to check the fuel pressure this afternoon I believe it should be about 15psi correct? Will also check the distributor but it is about 8months old changed last year.

 

[alldodge]

I cleaned the flame arrestor going to check the fuel pressure this afternoon I believe it should be about 15psi correct? Will also check the distributor but it is about 8months old changed last year.

Should be 30 psi with TBI

Take the fuel filter off and dump the contents into a clear container to make sure there is nothing but clear clean gas

 

[Berkley1]

Yea did that gas looked pristine the engine idles fine just under load I'm getting the problem

 

[Lou C]

You checked the fuel pick up screen but did you also check the anti-siphon valve?


Also, a good way to rule out the engine fuel system is to run the boat on a separate outboard tank with fresh gas, if it runs good then, you know it's not your EFI system or ignition system, it's something in the boat fuel system.
Probably best to do that first, because it reduces wasted time and fixing things that aren't broken!

If you do this, just be careful with the fuel line connections, I put a shut off valve on mine to be on the safe side.

 

[Berkley1]

I did check the ASV all good