Brad Christy

Ian,

I had a sagging issue once in our first boat. It had a mildly warmed over 454. We replaced a Holley 650 (how the boat was set up when we bought it) with a Holley 750, thinking it would fix the fuel starving issue. Took it out, and, while it ran better, the sagging came on much quicker with the new carb. We left it at the tech overnight. Came in the next morning to find him standing on his head in the storage area under the rear seat. When he came out, he handed me the tank check valve and said, "Found it!" I was completely packed with 20 yrs of crud and fairly well corroded. We dropped the boat back in the water and it ran like a scalded cat for as long as we wanted to keep the fun stick stabbed to the firewall.

You said you've got one tank, but two lines coming from it. It wouldn't be much of a stretch to suggest both check valves went south at the same time. Especially if you got a batch of bad gas. Might be worth looking into.

Thanks. Brad.
Model Machine and Precision LLC
(937)545-8991

imartin

Thanks Brad et al!

I think we all agree ita a single common issue affecting both engines. Its so odd that it does this after a few hours out on the water with varied use ranging from some high speed runs to anchoring. Then, she just decides to act up. Both times has been after being anchored off for an hour or less, then she flops.

For the tank. In the back, is two separate fuel lines off of elbow, one to each engine.. then there is a fuel sending unit. Thats all I can see...

No vacuum or or sound that I could hear from the gas cap.

F-2 Speedy

iTrader: (6)

are you saying 2 lines off a single pickup ?

SB

iTrader: (1)

Yes, please Speedies question answer !

imartin

I see two separate fuel lines that go to two separate elbows from the tank. Dont know if or where a fuel pick up would be and if so, common to both engines. Hmmm

Just turned keys on, both engines reading 6psi for fuel, when they should be closer to 40psi. No fuel leaks that I can smell or see or feel. First time this happened was before I changed fuel filters, so I can rule out fuel filter change...

AllDodge

iTrader: (1)

Battery voltage above 12?

imartin

yes. like 12.8 or so. I think was like 13 when running yesterday...Fresh batteries of 12 mos ago

AllDodge

iTrader: (1)

something that kills both motors at the same time, its either electrical or , out of gas maybe

edit: remove the filter is it full?

imartin

agree! Last time, yes both fuel/water separators were full. Didnt pull the new ones off today, but boat ran well for a good while yesterday till the petering out at the end. on trailer, fuel reads 67 gal. In water, more like 55-60 or so. Good amount of fuel in her. Im going to go get about 35 gallons of Ethanol Free fuel, see if that might blend in a make a difference.

Keys on, now getting 38 psi and 10 psi for fuel pressure, engine respective. Electric fuel pump active when key turned, so seems to be ok.

AllDodge

iTrader: (1)

If it happens again pull the filter. I'm thinking its fuel related.
You had 11 psi on both, then a few more key cycles and pressure comes up. Could be the filter was not full, but cycling some more they filled back up. If filter is full then the pump is shutting off