the ground on the port side rear stud.

no anti siphon valve to be found from the tank 90 to the fuel shut off Valve or at the fuel filter housing

So I took the boat out today, same deal. Took scanner with me, and fuel psi tester. When I get up and running and start getting around 4,000 rpm and above I lose about around 20psi, fuel pressure will fall off to mide 20’s. I’ll attached the video I took, can’t watch the pressure just suddenly fall off, and that’s when the boat starts breaking up. So I believe I’m looking at fuel pump issue, or reg. Both of which I’ll probably replace since I’m down there.

Can I replace just the fuel pump on the fuel cooler? I’ve read both thing you can replace just the pump, others says pump and cooler?

video posted few posts down

Never-mind, can’t post videos on here I guess

go out and run the boat again,but this time w/ a separate gas container.eliminate all the fuel hose in your boat.

Agree w/s30

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I only have about 20” of rubber fuel hose, from tank 90° to my shut off valve and another 10” of hose from shut off to the filter housing. From filter housing it’s hard line hose assembly

lol, yea that. Wasn’t thinking last night.

Also pulled the sending unit out, looked in the tank and pick up, which is just a stainless tube straight down. When I had the fuel hose off the barb I feed a long zip tie through until I could see it poking out in the bottom of the pickup in the tank. Pulled the full hose off the bard at the filter housing a blew a little air back into the tank, had the wife Verify air was coming out the breather vent as well.

Looks like it could be creating a vacuum in the tank, have you checked the vent hose to be sure its clear, loosen the gas cap while running to see if it picks back up, maybe you covered this I just scanned the post

I put some air back through the hose from the filter housing and air is pushing out the breather next to the filler port

The hose could be collapsing internally when it under suction from the fuel pump. If the fuel line hoses have never been replaced, they need to be strictly from a safety point anyway.

Like was said, it would be a good idea to run a remote tank. If the pressure does the same thing, then its the cool fuel pump. The pump by itself is NLA from Merc, but there are lots of aftermarket ones available for $100ish. Merc only sells the complete Cool Fuel for like $900

i just replaced the rubber line from the tank fitting to the filter housing. There is less than 3’ of rubber 5/8” line total. Hose maybe has 15 hours on it.

Update.

Replaced the fuel pump, and new regulator since I had all of that out 2 weeks ago, finally was able to run the boat, and back to running great. 5100 rpm, fuel pressure was steady 47-48psi and ran great!

Good to hear! Can you share the pump model number and where you got it, please? I'd like to have a spare pump but don't want to pay Mercruiser the big bucks for the whole Cool Fuel module.
Thanks!

I ordered this pump and regulator. I had to cut the top off the new regulator to put my Hardin adjustable set up on. I also bought a tube of super lube silicone heat sink to put on the pump side that contacts the metal plate. Fuel pump kit came with o rings and screen for the fuel cooler as well.

https://www.highflowfuel.com/qfs-oem...RoCbhcQAvD_BwE