donzi matt

iTrader: (1)

If you keep finding water in the fuel, it is time to pump the tank. You have found something wrong, fix that before looking for the next thing that may be wrong.

Obviously some sort of contaminants are residing in your fuel tank, perhaps there is algae at the bottom blocking the pickup.

SB

iTrader: (1)

x 2. My thoughts earlier in thread.

BUP

iTrader: (9)

o ring seal around the gas cap and fuel vent are 2 big sources of water entering you fuel tank. They are often missed as the source. rain and or washing the boat or waves splashing up against the vent and or gas cap. The oring in the gas cap rots out or is missing causes the those water sources to enter.

oreokid220

So it appears this is either I) something clogging the line in the tank or II) vapor lock from the fuel line resting on water pump circulating hose as everyone is saying that the water seporator being full will not cause this issue of a momentary fuel pressure drop.

I have replaced all gaskets last year to fuel cap as well as the sender unit on top of the tank. Vent is clear with a 90 degree down tube with a hood as well as the boat cover to protect them all when off the water.

blue thunder

Years ago I replaced the fuel sender on my scarab and unknowingly did not have the gasket sealed properly to the tank. I power washed the cockpit floor and the draining water flowed right into the tank via the sending unit. Another time I injested water through the vent in heavy seas. I learned that time the importance of having the hose that hooks to the vent loop upward above the through hull vent a good six inches or so before going to the tank so that it is self draining when water is forced into it. I am curious what type of fuel pressure gauge you are using? If one at the carb I believe they have accuracy issues when they get warm.

oreokid220

I have a fuel pressure gauge right before the carb. I have swapped it out with others and they all seem to be accurate. I also checked and the sender has a new rubber gasket and the vent has been looped since day one.

I am wondering if:

I) It is water in the fuel which seems it would be odd that it is a problem happening every so often. I cant find a clear answer on if a water seporator with water in it will cause a drop in fuel pressure to almost 0psi and then when dumped the fuel pressure will jump back to 6 psi.
II) If there is a problem with the pickup where air is being pulled in and causing the drop in pressure.
III) Can the fuel line running from the filter to the carb resting on the water house cause vapor lock because I have heard several times vapor lock resulting in a fuel pressure drop will only happen before the mechanical pump and not after?

Tonight I am going to pull the pickup tube and inspect, pump the tank to see how much water is really in there, and move the fuel line away from the water hose on the engine. I will be out this weekend and curious to see the resutls.

Anybody have any true answers on some of the questions above.

buck35

Vapor lock that I have dealt with occurs after you have been sitting a while, and you get a good heat soak.upon restart engine stumbles and dies.

SB

iTrader: (1)

Answer for #1: I already answered it. Water will not block flow and cause psi to go to 0. It can however make the engine stall (water doesn't combust) which then causes 0 psi since motor not running.

Answer for #2: Most definately. You would be far from the first to run into this issue. Although rare per person, it's not totally uncommon in the boat forums. A bunch of pick up tubes have been found with small cracks that of course will let air in.

Answer for #3: Yes, you can still run into vapor lock with heat after the pump. It probably won't cause the pump (mechanical) to air lock and not pull fuel unless the heat travels down the fuel far enough.

I have seen it turn the fuel going into the carb as a 'frothy mess'. 1, it makes the fuel/air micture coming out of the carb lean and hard to run, and 2 I have seen it able to raise the float and cause the N&S to close with more air than fuel in the bowl. Again, it will run like schit first and then shut off.

oreokid220

Never an issue at restart. Everytime we will be crusing at aroin 3,500-4,000 RPM and the boat will fall right off the RPMS like the key was turned off and either stall or drop to a smooth idle, however, the fuel pressure gauge will show little pressure. Try to get back on plane and the motor will stumble. Shut the mototr down, spin off the fuel water filter, dump out contents, replace, and start right back up with strong pressure the rest of the way. This process only take 1-2 minutes. Is this excess water in filter reducing fuel pressure or is there air being sucked in a line somplace causing lower fuel quantity?

oreokid220

Thanks for the answers SB. The odd thing is the engine will idle fine and wouldnt be the wiser if i wasnt watching the fuel pressure gauge. It is when trying to run the RPMs up it stumbles and falls off. The fuel lines, filter, or pump have never felt hot to the touch so vapor lock seems like less of a concern. Also the motor is only off for a moment which is not a significant cool down time for vapor lock. Maybe it is a small amout of air from somplace getting in. It just seems so odd that the pressure will fall to almost nothing and then after the filter is dumped and replaced it will all be ok for the rest of the day. One would think if significant water in tank it would happen more frequently right?