Gas tank problem

[plan_a]

I have a Ski Nautique 196 -96 with a GT-40 engine. It don´t get any gas. We have located the problem to the tank after many hours troubleshooting. When we put the fuel hose into a gas can it sucks it up really fast. But putting it back onto the tank, just a small amount of gas get trough into the fuel cell.

What do you think?
How does it look like inside the tank?
Is there a valve or something that keeps the gas in the fuel line when the tank is empty that could be broken?

[DanielC]

RE: Gas tank problem

This is the fuel flow on a GT-40 engine in a 1997 ski, mine. Fuel in the tank is pulled from the tank by an external electric pump located on the front port side of your engine, by the FCC. At the top of the tank there is an anti siphon valve that will not allow fuel to flow until the pump is creating a vacuum in the fuel line. This pump should flow about 70 gallons of fuel an hour, and the excess gas is returned to the tank by another fuel line that goes back to the tank. About halfway down inside the FCC, the high pressure pump is located inside a fuel filter. It pressurizes the fuel rail to 39 psi. There is a pressure regulator on the other end of the fuel rail, and it returns fuel to the FCC, and the fuel is returned to the tank, or recirculated back through the high pressure pump.
Be sure to observe all the safety requirements about handling gas in your boat. Any spilled gas and its vapors stay in the bilge, and are explosive, and flammable. Do not work in a garage attached to your house. You do not want to lose your boat, and your house to a fire . If you are not sure of your ability to do fuel system service safely, take the boat to a shop that knows how to do this.
To check the low pressure pump, disconnect the return hose from the the FCC, the return hose is the only one held to the FCC with hose clamps, on the side of the FCC. Get a suitable container to catch the gas, about a quart. Turn the key on, DO NOT TRY TO START THE ENGINE! The fuel pumps will run for about 2 seconds, then shut off. You should see a good steady stream of gas. Clean up any spilled gas immediately! To check the high pressure pump you need a fuel injection pressure gauge set, and connect it to the schrader valve on the fuel rail. My boat wants 39 PSI, your boat may differ, the fuel pressure should be in the specifications on the decal on the top of your engine.

[plan_a]

RE: Gas tank problem

Very good description DanielC. All that works. If we fill up the FCC and turn the key it works for like 5 minutes. Then it dies. Both pumps (low and high pressure) works. The injection works. The only thing left in our troubleshooting is in the gas tank.
You wrote something about a anti siphon valve, how does it look?
Do you got a overview picture on the tank?
Any other ideas?

Thanks

[DanielC]

RE: Gas tank problem

The Anti siphon valve is on the top of the tank connected to the right angle fitting that goes down into the tank. When the fuel pumps are running, you will hear it buzz at fuel is drawn through it. it looks just like a normal fitting with a taper pipe thread on one end, and a barb hose fitting on the other end, but it you remove it, it has a spring and a check ball in it.
At around 920 hours on my boat, I had to replace the primary (external) fuel pump.
I have had to clean junk out of gas tanks on cars, because it collects around the fuel pickup in the tank, when the engine is running. The engine then dies, the fuel suction goes away, and the junk moves away from the fuel pick up, and it seems ok, until you run for a while, and then the junk collects and temporary plugs the pickup again.
I was also in a new boat of another brand, and the tank vent hose was kinked, and would not allow air into the tank, and the engine would run for a while, and then die. The tip off to this problem was a sucking sound when the gas cap was removed.
If you can run the boat safely with a fuel pressure gauge attached to it, that may also help you diagnose the problem.
If the safety lanyard loses connection, the fuel pumps turn off, and the engine will die. The fuel pumps run when the boat is being cranked, and if the lanyard connection is intermittent, the boat may start again, and run for a while, until the lanyard switch loses connection.

[richard]

Gas tank problem

A rare case may happen to your tank,that an air leak in the extention from the gas outhole to the lower part of the tank.

[plan_a]

RE: Gas tank problem

Thanks. I will look into it tomorrow. Sounds like it could be junk in the tank. If not, how can I the valve out of the tank?

[swooddc]

RE: Gas tank problem

There is a little filter screen on the fuel pick-up tube in the tank. mine was almost completely clogged, causing a similar problem. (97 gt40 with 1200hrs.) on some models you can pull the fuel pick-up without pulling the tank. should be simple to pull it and take a look.

[linebacker55]

RE: Gas tank problem

Could the vent line be clogged, and thus drawing a vacuum in the tank? Maybe spider webs and such after the winter?

[Rick]

RE: Gas tank problem

I think the pickup is clogged. Take the pickup out of the tank and clean or replace the screen at the bottom. Also replace the check valve. Order one from the dealer or SKIDIM and then look for it in the fuel line.

[plan_a]

RE: Gas tank problem

It was alot of junk in the tank. We cleaned it out and put a new fuel pick up in with a filter outside the tank. Now it works like never before. Was riding all weekend.
Thanks for helping. You guys saved our summer.
//Henrik

[jhersey29]

Anyone have advice for getting a very stubborn elbow out? I've tried turning the elbow that the pickup attaches to and wow it does not want to budge.
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