Re: 502 EFI Intake Limitations
 

Brett at Aeromotive said you should not return the fuel to the fuel filter/separator (the way mercruser does) that's what heats up the fuel thus needing a fuel cooler. Returning the fuel to the tank directly eliminates the need for a fuel cooler. It also helps in preventing fuel pump cavitation.

Re: 502 EFI Intake Limitations
 

My fuel fill is in the front of the boat, so returning to the tank is not a real good option.

Smitty, where did you get the cooler from and how does it mount (engine or stringer mount)?

Re: 502 EFI Intake Limitations
 

I bought the cooler from Tyler Crockett for around 100$,I think I saw one in cp perf catalog for same price too.I have cooler mounted in the discharge hose from raw water pump on left hand side of motor (as you face it from the front) near the motor mount. I am also returning fuel to a tee before the suction side fuel filter (between it and the suction from gas tank),everyone says its not "ideal" BUT there is no good way on my boat to return extra fuel to the tank and I have no fuel pressure issuse even at the 950 hp level,Smitty

Re: 502 EFI Intake Limitations
 

Mine is in the front as well. If you look where your pickup is coming out of the tank in the back you'll notice an extra plug where you can put your return. A "T" before the suction side of the pump will guaranty premature pump failure. And that always results in a piston melting... Been there done that.. :mad:
correct Pressure doesn't mean you have correct volume. learned that the hard way too. I increased my draw tube to 5/8" and got rid of the "T" and returned to the tank. There is really no easy way to go around this problem, sure The "T" works, but it will fail eventually. I got about 80 hrs on mine before it happened.

Re: 502 EFI Intake Limitations
 

Here is another post that talks about kinda the same thing.
It also has links to how some of the guys returned there fuel to the tank. OSO post

Re: 502 EFI Intake Limitations
 

Another post.
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fuel pump plumbing

Re: 502 EFI Intake Limitations
 

I know what your saying but my fuel tank has no extra fitting and getting to the filler neck to cut in a return tee is also nearly impossible without removing top half of my hull.I have a fuel filter that holds 1 qt of fuel between the suction side of my pump and the tee where my fuel returns. I'm also running two regulators back to back,one holds the base pressure,the other overtakes the first when boost referencing,and I'm reading fuel pressure off the excess in the charged loop returning the extra fuel from the rail to first regulator. If there wasn't enough volume the pressure wouldn't be there or regulator would close down more,its not ideal but it works and my fuel pump longevity has never been a issue. I been using this set-up for about 350 hours with no problems and I'm currently supporting 950 hp,Smitty

Re: 502 EFI Intake Limitations
 

Sounds like you got it work out for your app. :p

My main point is that you have to be careful and not think that having the right fuel pressure means you have the right volume of fuel. They don't work hand in hand.
For example if you have a 1/4" fuel line with 50 lbs of pressure, And a 5/8" fuel line with 50 lbs of pressure.
Sure the pressure is the same, but the volume of fuel coming out of the 5/8" line will be a lot more than the 1/4" line with the same pressure.
With a regulator you will always get the pressure in the line to be whatever you set it at because that's what it does, but it doesn't mean it's suppling the volume of fuel needed. :p :p

Re: 502 EFI Intake Limitations
 

Kanookstar,I saw your thread on making a bigger pickup tube with a bulkhead fitting,excellent idea, plus a return fitting could be plumbed to the original pick-up at same time. If I get ambitious this spring I may follow your advice,Smitty

Re: 502 EFI Intake Limitations
 

Just too bad I did that after melting #6 piston.. :D My home waters are kinda small, so the high speed runs were short and quick. It was when I went on a big lake with room to spare did I run just long enough to starve the engine of fuel Volume and .... well we know the ending of that story. :rolleyes:
Summer is almost here. :drink: