FUEL DELIVERY ISSUE. Video posted

[Bigdave196]

I own a 20' 1997 Blue Water MonteCarlo Bowrider with a 5.7L Volvo Gi 250hp Throttle Body Injected motor. Last year the boat ran great, and this year I cant get it on plane. It starts fine, but once under load it falls flat on it's face. I have just replaced both fuel pumps, and the fuel filter. The boat does NOT have the infamous fuel cell that the paint chips away from to clog the fuel pump screens and the screens were clean.. I have only 20-psi in the fuel line going to the TBI, I spent last night pulling the whole fuel system apart trying to find anything that makes sense. I checked the anti-siphon valve and you can barely blow air back thru it., it does not allow anything to go back through it. The tank was clean, and I replaced the fuel filter last night. I even pulled the (float bowl assembly) that the High pressure pump pulls fuel from apart last night to inspect that as well. PLEASE HELP!!

 

[tgell001]

if you find a piece of clear fuel grade tube, you can put it in various legs of the fuel system, run it and look for bubbles. if you see bubbles then theres a leak somewhere and you know where to go from there... just a thought, seems like youve covered all your other bases.

 

[Bigdave196]

if you find a piece of clear fuel grade tube, you can put it in various legs of the fuel system, run it and look for bubbles. if you see bubbles then theres a leak somewhere and you know where to go from there... just a thought, seems like youve covered all your other bases.

Once the fuel system hits the low pressure pump, all the lines are metal with threaded ends.

 

[Bigdave196]

https://youtu.be/2xDbmpZ8vk0

any ideas?

I even replaced the anti siphon valve with a strait tube.

 

[jerms234]

I can't view your video, it says its private...

 

[Bigdave196]

try it now.

 

[dypcdiver]

Have you checked the pressure regulator in the TBI assembly I believe there is a screen in there,. 20 psi sounds a bit low, the chart for the Gi shows 30 psi on the HP side. There are Schrader valves on the fuel lines for checking High & Low pressures, could be the LP pump not working correctly. Could also be an ignition timing issue.

 

[Bigdave196]

I have checked the fuel pressure at the Schrader valves the high side is showing 20 I'm going to replace the low pressure fuel pump again today because yesterday out on the water it made a lot of noise and got extremely hot. coming out of the hole the boat responds and acts the way it should until the engine gets between 2800-3000 rpm and then it sputters. as soon as I struggled back just a little bit the engine starts to build power again and if I gently ease up on the plane I can actually plane the boat out.