Fuel line I.D - 454/8.1

The fuel lines on my 454's are 3/8" I.D. which it had from the factory. I replaced all of them with the exact same aeroquip hose when I bought the boat and that worked fine. The 8.1 install manual specifies 1/2" I.D. which raises a few points:

1) The fuel pump cooler/inlet is 3/8" so that limits my flow at the pump regardless of what I do

2) If anything, I think the 8.1's will require a little less fuel than the 454's


I really won't know the NEW fuel line layout until I get the engine installed but I'll likley need to make up new lines regardless. Should I just stick with 3/8" or bump up to 1/2"?


thanks
Bob

I'm inclined to agree with you...the intent is to minimize the pressure drop in the suction side...so if the pickups are 1/2", you can't maintain 1/2" up to the pump. with a 3/8" restriction in the factory line, they must be concerned about sustained elevated RPM condtions...I'm thinking you are likely to see them.

In the return types, you can easily exceed the consumed rate...but with the returnless types, the average consumed is the averaged delivered...

I'd say minimizing the pressure drop would be a good thing but I wouldn't spend extra unless it is needed....a vacuum gauge at the suction side of the LP fuel pump will tell you what you need to know...

Do you know if the new system on the 8.1L's is a return system, or a returnless system? If it is a return system, you shouldn't need a "fuel pump cooler," correct?

After returning to have access to my 'library', the install guide I have states they want to see less than 2 in Hg pressure drop at the fuel pump inlet.

also of note, they recommend a shutoff solenoid in lieu of the classic anti-syphon valve, if required.

Guess the big concern is if you have the return type of fuel system...should be able to determine by inspection or S/N...

sorry guys, I've been working on the boat and shooting for Monday install of @ least one of the new engines. These are early 8.1's, returnless with just the single fuel pump and cooler. Off topic, both of my coolers are new, the pumps were fused to the inside of the coolers because the aluminum pump bodies were so corroded. If anyone has this setup, I would strongly suggest trying to remove the pump from the cooler proactively. The coolers are not sitting on the shelf and I had to have them made by "MR Cool" who now makes all the Crusader oil/fuel coolers.

If a pump failed during the season, it would have cost me 3 weeks of boating. Fortunately, I was in my garage so not a big deal. I managed to save one of the coolers and will buy a spare pump (which is just an automotive pump made by Pierburg).

Bob