Loosing fuel pressure

[Last Mohican]

I've got a fuel pressure issue. This is on a 25' Sleek Craft Ambassador with a 455 and a jet drive. It will run great for 10 - 15 minutes at 3200 or so then it just peters out. The fuel pressure falls completely off to 0. After is sits (get towed) for 10 - 15 minutes it will fire right back up and the fuel pressure will return to ~ 6 lbs. This is a mechanical fuel pump and a Q-Jet carb. It has a new water separator and all new rubber fuel lines. The tanks are aluminum. My gut feeling is there is sediment in the tank that gets suspended and after 10 minutes or so it manages to pack the sock on the tank pickup. Once the boat dies is sloshes around and the sediment falls off the pick up and it is fine again. Wash, Rinse, Repeat. It has done this pretty consistently on every long haul I have made with it. It does just fine if I stick to short runs. I have tried popping the fill cap to make sure the tank is venting but it makes no difference.

In conversation with another boater at the lake this weekend he said he had the exact same issue and it was the same style water separator. He said he bypassed it with just a regular inline fuel filter and it resolved his issue. He said he fought it for a long time before finally getting it resolved.

The tanks are tabbed in with glass and I don't think I can get the pickup out without removing the tank. The plan is to bypass the separator with a filter. If that does not fix it I am going to borrow a portable fuel cell from a friend and use that instead of the on board tank. If the borrowed tank fixes it I know I have an issue in my tank. If not it has to be the pump.

Anyone have any other suggestions? I'm all ears.

 

[Last Mohican]

Re: Loosing fuel pressure

Fuel pressure issue is fixed!!!! Made a run across the lake and back non stop yesterday evening. The fuel pressure never fell below 5 lbs. The water separator was definitely the issue. I bypassed it with an inline fuel filter and all is good now. Thought I would post up just in case anyone else finds this post with a search.

 

[Alpheus]

Re: Loosing fuel pressure

You said it had a new separator on it but did you try putting a new filter on it since you installed the system? You may have had water and or sediment in your tank and the separator did its job but got clogged up real quick in doing so...

 

[NHGuy]

Re: Loosing fuel pressure

Buy two or three separators if you have the throw away cartridge type. Use em til clogged & change em. That's better than debris in the carb inlet screen.
Or if you want to be proactive get some jerry jugs and a low pressure pump to suck the fuel out through the separator system. That's one way to polish it up.

If it keeps loading the separators with water you could get one of those clear bottom separators that can be drained. Eventually you will get to just gas!