Funny little thing, What is it?

[Randy Naylor]

Not sure what this is. It is in a gas boat, Any body know what it is?



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[P THOMAS]

water pump

 

[camaroboy383]

yep....thats what its used for i supppose... the part itself is a fuel pump..most likely off a garden tractor or similar...

alden

 

[toyotatruckin]

Ill third all above

 

[Randy Naylor]

how does it work?

 

[RodneyPierce]

if I had to guess, i would say pulsation from either the crank case, or the exhaust pressure

 

[toyotatruckin]

His guess is correct, one line should come from someplace on the engine case or the intake manifold the other two lines are inlet and outlet for water

 

[Ron Olson]

It's vacuum operated usually using a line coming from the carb isolator block. Once the boat gets up to a certain RPM or speed, water pressure will take over from the rudder or pickup tube. It's not generally used in racing boats but more for clutched motors where people can fire them up in the water (not recommended) or low speed passes where the boat isn't going fast enough to push water through the cooling system.

Randy, it looks like you've got yourself an oldie there with the Homelite in it. Compare it to an old 550 can motor on 1200 mah Ni-Cad's in today's world of gas boats.

 

[Randy Naylor]

Thanks guys. I have two customer/friends Gas boats I am building them for fun runners. I do Nitro and Gas now and then but not as much as Electric.

Am I right thinking the top line goes to the carb isolator block inlet and the lower ones go to the water inlet and out let?

And is the carb isolator block inlet the one on the bottom of the carb? I will post some pictures later. Today is my time in garage and around house.

 

[Ron Olson]

That sounds right.

 

[El Zorro]

This is a Mikuni fuel pump. Cost about $20.00. I used one of these on my C Stock hydroplane engine ( Yamato 102 ) to utilize a remote fuel tank instead of the gravity tank that comes on the engine. It operates off of crankcase pressure. Very simple device that worked great for me. If you notice the picture to the left of this there is no tank on the outboard motor on the 74-E hydro. The tank is in the bottom of the boat near the transom, putting weight ( about one gallon of gas ) that would normally be on the top of the motor into the bottom of the boat, greatly helping the boat in the corners. In the fuel pump picture in the first post, the lower left outlet goes to the carb ( fuel out ); the upper right outlet is for fuel in, and the center connection is for the crankcase pressure to make it all work. Racing the Outboards is lots of fun if you keep the shiney side up................

Dick Tyndall

 

[Tim Kish]

This is a Mukuni fuel pump. Cost about $20.00. I used one of these on my C Stock hydroplane engine ( Yamato 102 ) to utilize a remote fuel tank instead of the gravity tank that comes on the engine. It operates off of crankcase pressure. Very simple device that worked great for me. If you notice the picture to the left of this there is no tank on the outboard motor on the 74-E hydro. The tank is in the bottom of the boat near the transom, putting weight ( about one gallon of gas ) that would normally be on the top of the motor into the bottom of the boat, greatly helping the boat in the corners. In the fuel pump picture in the first post, the lower left outlet goes to the carb ( fuel out ); the upper right outlet is for fuel in, and the center connection is for the crankcase pressure to make it all work. Racing the Outboards is lots of fun if you keep the shiney side up................

Dick Tyndall

Dick check you PM's.

Tim K

 

[Rigged]

Thanks guys. I have two customer/friends Gas boats I am building them for fun runners. I do Nitro and Gas now and then but not as much as Electric.

Am I right thinking the top line goes to the carb isolator block inlet and the lower ones go to the water inlet and out let?

And is the carb isolator block inlet the one on the bottom of the carb? I will post some pictures later. Today is my time in garage and around house.

You dont want to pull from the pulse port going through the isoblock. You are robbing pulse from the carb, which is needed for the carb to operate correctly.

Either tap into the runner itself, or if you look on the cylinder, you'll see a threaded boss that goes into the transfer, drill into that and pull the pulse from there.