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Fuel pump suction thru anti siphon valve 1998 200 hp

sbklf

Contributing Member
"My tank is in the hull and the fuel line is uphill all the way to the motor (1998 Merc 200 HP carbed outboard). I installed new 3/8" fuel line with a primer bulb nearer to the motor (12' from the tank). Once primed, no problem but when shut off, the fuel in the line drains back into the tank. I Installed an anti siphon valve and it still drains back to the tank. I could blow backwards thru the valve so it is not positive shut off (not sure if is supposed to be?).

Couple of questions:

-I read about outboard motor fuel pumps having trouble with the added suction head with anti siphon valves, is this the case with Mercury fuel pumps?
-Will the motor run long enough on the fuel still in the bowls to allow the fuel pump to draw fuel thru the empty line and re-fill the bowls?
-If it will, can I remove the anti siphon valve?

Thanks, Kevin"
 
Sounds like you have a bad pri

Sounds like you have a bad primer bulb. There is a ball in them that acts as a check valve and prevents fuel from flowing backwards to the tank. You really don't need the anti syphon valve. A primer bulb is one of the few things I highly recommend using OEM part for. Ones like sold in Wally World is junk.
 
"Install a spin on water separ

"Install a spin on water separating fuel filter on the transom and a ball type shut off valve onto the tank side of the filter. Simply shut off the valve at the end of the day, gas can't leak back."
 
IBN has it right--the primer b

IBN has it right--the primer bulb should not allow that to happen. Better replace before it bites you. Wal Mart sells them cheap (and they are good stuff).

Jeff
 
"If the primer bulb is not sus

"If the primer bulb is not suspended properly it will not shut off and it will allow fuel to pass past the check valve. Before replacing, ensure it is hanging with the engine end higher than the tank end. I would still install a filter and a ball valve. many insurance companies want to see proper fuel valves installed in the event of fire or spillage into the environment."
 
"That should not make a differ

"That should not make a difference since the check valved is extremely light and spring loaded. Replace that bulb and you'll be fine..

Jeff

PS: I once had a bulb where the outlet check valve froze closed, shutting off the flow. Drove me nuts 'til I figured it out. Not uncommon, from what I've heard. The simplest things can get you."
 
"12 feet is a long way.just a

"12 feet is a long way.just a suggestion,install a low pressure electric fuel pump at the tank end,would help priming,help prevent backflow [ when turned off],and take the load off the motors fuel pump."
 
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