Think I found my fuel pressure problems...

« **on:** June 26, 2009, 06:00:34 PM »

I pulled the fitting off the top of the fuel tank and there is a check/ball valve inside that only lets fuel out of the tank and not back in. This one is very hard to suck through. I'm pretty much positive this is my problem.

So do I need this fitting or can I just run a regular fitting without a check valve?

« **Reply #1 on:** June 26, 2009, 06:17:20 PM »

That is an anti-siphon valve. It should be spring loaded closed. As you discovered, vacuum from the fuel pump opens the ball valve. When the engine stops, the ball valve closes preventing fuel from draining back into the tank...in theory it makes starting the engine easier becuase there is always fuel in the lines.

If working properly, it should not be the cause of any fuel pressure problems.

p-jet

« **Reply #2 on:** June 26, 2009, 07:29:43 PM »

Grab a standard 90 and throw it back in there.

Ball check valve what

maybe im the only one that has never had them in my tanks, but it does make sense....

« **Reply #3 on:** June 26, 2009, 07:33:51 PM »

It seems very restrictive to me. It takes alot of effort to open that check valve. I installed a standard 90 in one tank and left the other the way it is with the anti siphon valve. I have reinstalled the clay smith mechanical pump and ran -8 steel braided line from the fuel water seperator to the pump (steel braided line is addicting I can see alot more in my future $$$). I am going to take it out tomorrow and see what happens (weather permiting).

I will report back with my findings. I'm hoping this is finally the fix...

« **Reply #4 on:** June 26, 2009, 07:34:43 PM »

Quote from: Ultra460 on June 26, 2009, 07:33:51 PM

It seems very restrictive to me. It takes alot of effort to open that check valve. I installed a standard 90 in one tank and left the other the way it is with the anti siphon valve. I have reinstalled the clay smith mechanical pump and ran -8 steel braided line from the fuel water seperator to the pump (steel braided line is addicting I can see alot more in my future $$$). I am going to take it out tomorrow and see what happens (weather permiting).

I will report back with my findings. I'm hoping this is finally the fix...

Good luck

« **Reply #5 on:** June 26, 2009, 07:35:47 PM »

On most boats, the fuel system pump or filters are below the level of the top of the fuel tanks, so if there happen to be a leak in the fuel system, it can literally fill the bilge area with raw fuel by siphon...extremely dangerous, if nothing else, hard pipe a ball valve onto the 90 and turn it off when the boat is not in use...(prefer a check though) it's the law.

The newer anti siphon valves are a lot better design with a very light spring, IMHO, I would put in a new one... $:-\$

GT

« **Reply #6 on:** June 26, 2009, 08:10:02 PM »

Quote from: GT Jets on June 26, 2009, 07:35:47 PM

On most boats, the fuel system pump or filters are below the level of the top of the fuel tanks, so if there happen to be a leak in the fuel system, it can literally fill the bilge area with raw fuel by siphon...extremely dangerous, if nothing else, hard pipe a ball valve onto the 90 and turn it off when the boat is not in use...(prefer a check though) it's the law.

The newer anti siphon valves are a lot better design with a very light spring, IMHO, I would put in a new one... $:-\$

GT

Where can I find a newer style high flow vavle?

« **Reply #7 on:** June 26, 2009, 08:17:13 PM »

I think NAPA can special order them (through Balkamp), but here is what your looking for...

http://www.moellermarine.com/aftermarket/fuel_systems/valves/

GT

« **Reply #8 on:** June 27, 2009, 09:12:36 PM »

Update...

Just got back from the lake (perfect day) and I think I found all or part of my fuel pressure problems. Anyways I have the clay smith mechanical pump reinstalled. I had one tank with the anti siphon valve still in place and one tank with just an open 90 degree fitting. On the tank with no anti siphon valve in place I was able to get a consistent 12 psi before the regulator. When I switch over to the other tank the pressure would drop down to the usual 5-6 psi.

So now onto the new problem... With no anti siphon valve in place the fuel before the pump must have been draining back into the tank when the boat was off and was causing problems. After sitting for an extended period of time the boat would start, have 0 fuel pressure, drain the float bowls and die. Then I would have to turn the motor over for a good 15-20 second to build up pressure again before it would restart.

So isn't it ironic that I finally found the problem but I am gonna be forced to run them anyways...

Any suggestions? Am I the only person that has run into this problem before?

« **Reply #9 on:** June 27, 2009, 09:51:37 PM »

Quote from: Ultra460 on June 27, 2009, 09:12:36 PM

Update...

Just got back from the lake (perfect day) and I think I found all or part of my fuel pressure problems. Anyways I have the clay smith mechanical pump reinstalled. I had one tank with the anti siphon valve still in place and one tank with just an open 90 degree fitting. On the tank with no anti siphon valve in place I was able to get a consistent 12 psi before the regulator. When I switch over to the other tank the pressure would drop down to the usual 5-6 psi.

So now onto the new problem... With no anti siphon valve in place the fuel before the pump must have been draining back into the tank when the boat was off and was causing problems. After sitting for an extended period of time the boat would start, have 0 fuel pressure, drain the float bowls and die. Then I would have to turn the motor over for a good 15-20 second to build up pressure again before it would restart.

So isn't it ironic that I finally found the problem but I am gonna be forced to run them anyways...

Any suggestions? Am I the only person that has run into this problem before?

Something is really wrong, the reason I am saying that is....Where is the air gap coming from, I think you have an air leak in the section of hose between the tank and the pump. otherwise ther is no reason for the fuel to pull back from the pump.....you need to find that leak.

GT

« **Reply #10 on:** June 27, 2009, 10:36:06 PM »

an electric fuel pump solves all those problems...

« **Reply #11 on:** June 28, 2009, 09:32:22 AM »

Quote from: GT Jets on June 27, 2009, 09:51:37 PM

Something is really wrong, the reason I am saying that is....Where is the air gap coming from, I think you have an air leak in the section of hose between the tank and the pump. otherwise ther is no reason for the fuel to pull back from the pump.....you need to find that leak.

GT

How do you go about finding an air leak?

It's not just draining back cause I'm not running the check valve/anti siphon vavle on that tank?

« **Reply #12 on:** June 28, 2009, 11:18:37 AM »

Quote from: Ultra460 on June 28, 2009, 09:32:22 AM

How do you go about finding an air leak?

It's not just draining back cause I'm not running the check valve/anti siphon vavle on that tank?

How would it drain back if there was no air gap?, It doesn't make sense...Is it just the one hose going from the tank to the pump? are those hoses new (or AN)? Leaky fuel filter? I don't know.

Maybe try to pressurize the inlet side of the system...

Something is really wrong, the fuel pump is literally just two check valves and a diaphram, the fuel, once primed, should not drain back unless air was being introduced somewhere.

GT

« **Reply #13 on:** June 29, 2009, 08:15:08 AM »

I had a similar problem and took the stainless line off between the tank and fuel pump (electric). Capped one end and pressurized the other with air compressor and stuck the hose in a bucket of water. The entire length of hose bubbled through the steel braid. The rubber inside had dried out so bad that the pump couldn't pull the fuel from the tank. Bought a new hose with teflon inside and haven't had a problem since.

Ultra460

Think I found my fuel pressure problems...

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