Crusader 6.0 dying once hot

[Scott892]

My port engine has been dying once it's hot. Starts fine and runs at power no problem. but when I come back to idle it will die. After it gets hot the fuel pressure drops from 55 to 25 PSI .

So I did the most obvious, replaced the high and low pressure fuel pump, replaced all fuel filters, replaced fuel pressure regulator and relays. Still happening, didn't fix it.

Mechanic was kinda stumped and said his next move would be to insulate the entire port fuel line as he speculated that perhaps it was overheating and boiling the fuel causing vapor lock.

I've already spent $2K on this so I really don't want to keep guessing. Any ideas? It's a Crusader 6.0, 2007 with about 550 hours.

[RobGunn]

Kinda sounds like vapor lock. Did this issue just start recently, or has it been a issue from day one with the boat? Something changed...? Maybe look at fuel tank vent also, may be plugged and causing tank vacuum?

[Scott892]

Rob, thanks yeah I agree. The mechanic checked the fuel tank pick up and said it was welded to the tank so he couldn't remove but cap vent is an idea.

I'm not original owner and it's been doing it for the 3 years I've owned it but gotten worse. First year was only couple times so I just shrugged it off. Pretty much happening every time I take it out now.

[Viper]

Run it off a remote tank before doing anything else so you can determine if it's a problem with the fuel delivery system on the boat side. If you still get the same thing happening off the remote tank, then the problem is with the motor. Be safe when doing this, and ventilate.

Insulating the fuel line without taking some readings or inspecting things carefully might be a waste of time and money. It can also be caused by a restriction in the suction line such as a collapsed line, a kink, extra filters on the suction side, fuel monitoring accessories, etc. If one of these is the cause, insulating won't do a thing except empty your wallet more. Before they ASSUME anything, they should take a vacuum reading and take temp readings to see if vapor lock is even a consideration. If it's a vacuum issue, then insulating won't do a thing, but it would make a difference if temp readings point out that the compartment/fuel is getting too hot.

[Scott892]

Thanks Viper. Good ideas. This boat has separate fuel tank for each engine. I think it's definitely a fuel starvation issue as it otherwise runs fine and we clearly see a drop in fuel PSI before it quits.

[Viper]

Source of the post..... replaced all fuel filters.....

Is your low pressure pump attached to the side of the Fuel Control Cell or is it mounted away from the FCC?

I take it your application does not have the Oberg fuel filter (hockey puck type assembly)? If it does, did it get addressed?

[bud37]

Source of the post Rob, thanks yeah I agree. The mechanic checked the fuel tank pick up and said it was welded to the tank so he couldn't remove but cap vent is an idea.

That sounds odd....those fittings are screwed into the welded bung but can be removed. Be careful the threads are aluminum and may have become galled previously.

Did your mechanic check the anti siphon valve? I think the port engine has a much shorter fuel feed from the tank than the starboard side.