jwurl

I am replacing my engine and upgrading my fuel system to 1/2 fuel line. Has anyone had a look at their fuel tank to see if a 1/2 line can be attached at the tank. What size is the fuel pick up? Is there a check valve on the fuel line leaving the tank? I do not want to pull my floor up to see that it can not be done. Thanks, Jeff Wurl

LAKE EFFECT

I know on my 311 and my 353 both tanks were made by the same supplier(Florida Marine, I think), and they used 3/8 NPT bungs welded into the rear of the tanks. The pick ups were 3/8 NPT 90degree fittings with a 1/2" pick up tube inserted in them. You should be able to remove the 3/8 NPT to 3/8 hose fitting and put on a 3/8 NPT to 1/2 hose fitting. If your running an electric pump do not use any type of checkball fitting, as the electric pump can not suck thru it properly.

If the stock motor used a mech fuel pump, Formula probabally used a check valve. Is there no access panel to the p/u and sending unit?

LE

C_Spray

iTrader: (2)

My 2000 382 with EFI seems to have check valves in it, as the fuel does not run back into the tank when I disconnect the lines from the engine.

Do you really need 1/2" lines? A 3/8" line will feed a LOT of horsepower - it's the equivalent of a dash 8 Aeroquip line.

axapowell

I re-plumbed my 353 last year and went with (dash) -8 all the way from the top of the fuel tank to the carb. Removed the check ball barbed fittings and replaced it with a 3/8" to -8. Earl's braided Ultra Flex 650 -8 is .536 ID, just over 1/2".

As a side note, you should consider the Keith Eikert high volume mechanical fuel pump and the KLM replacement fuel water separator. The fuel pump upgrade is all ready fitted with -8 fittings (3/8" to -8) and the separator is 3/8" pipe. Both upgrades from the stock 1/4" openings!

Dave

LAKE EFFECT

I can only speak for my 353, but under the rear seat there is a access panel held down by 4 screws, and there is also a round screw on access panel in fwd bilge bulkhead. Both give easy access to the rear of the tank.

C Spray: Does'nt Merc use a mech and electric pump on there EFI engines? Would explain the check valve. Also the gas line might drop down from the p/u thru the bulkhead then up to the motor, not letting gas easily drain back to the tank.

IMO, I'm all for big fuel lines. I made two 5/8" pick ups from #10 fittings I was able to secure to the tank thru the sending unit hole, #10 to the engines, then used the two 3/8 NPT bungs for the #8 return lines.

LE

C_Spray

iTrader: (2)

These are Volvo/Innovation 600's with two SX electric pumps; one for low pressure and recirculating cooling and the other for high pressure delivery. Maybe that's why...

No matter how high I lift up the gas line above the level of the tank, it doesn't drain back, so there must be check valves in there...

Axa - According to Earl's, Ultraflex has a larger ID than most standard -8 lines, which have an ID of .44". Interesting.

I suppose that it doesn't hurt anything to run large fuel lines, but it seems like a lot of effort...

jwurl

I have not checked for an access panel under the rear seat. I hope there is one under there. I am running 1/2 inch line all the way to the intake and then a #6 return line. I am also running a Harden high flow 1/2 inch water seperator and a aeromotive billet filter for the pump. By the way, the pump is an Aeromotive 1000. The boat was originally a 415 502 with an electric fuel pump only. The new engine is a 540 with a 500 efi intake with the new Tyler crockett intake with the throttle body on top. AFR heads,RM marine Kinetics custom cam,Crane roller lifters and rockers, and much more. It will be on the dyno sometime in December. Hoping for close to 700HP. Jeff Wurl

LAKE EFFECT

I dont know if check valves are still being used. My 311 was oringinal when I put on electric fuel pumps, and I had pressure/flow issues untill I removed the check valves. I bought my 353 with modifications, and if there was check valves, they were removed before I got them.

jwurl: Sounds like its going to be a fun combo. Good Luck.

LE

C_Spray

iTrader: (2)

Woof! What drive?

Do you have the original top off of the intake manifold? I might have a buyer for one.

Are there any pictures of Tylers setup?

jwurl

I am running an XR drive. There is a youtube video of the Tyler Crockett 500EFI intake system on line. The original intake top has to be sent back to TC for a core. Jeff wurl