gt40 issues after getting hot

Ok here it goes... picked up a 1995 nautique w/ gt40 set up. The PO had trouble with it he replaced high pressure fuel pump, and both sensors temp, oil pressure. One head was also replaced after a rivet from the spark arrestor fell out into the head and got stuck in a valve. I replaced both relays, and the low pressure pump. I tried switching out the electronic box in the heat sink no luck. Note: I have a spare parts gt40 so there is really no problem with part swapping.
I tried to clean the anti siphon valve also but since it is right next to the return it is impossible to get out although I did pull a little gunk out. Fuel pressure was around 38 according to the PO.
Yesterday I took it out once again ran great for 20-30 mins then started sputtering like lack of fuel or vacuum leak. I turn it off and no start (separate issue starter would not turn no click either. Think I have a bad relay/solenoid) So after a few minutes I did get it started but still poor idle and running rough. Lastly I did here a sound from the gas tank almost as if gas was flowing back or maybe air escaping from tank. I did not think of taking gas cap off till later.
Any ideas ?
Thanks again
DC

Thanks Pete, but I got plenty of juice after it cools down it fires right up. I haven't had a chance to check but I think I have a corroded connection or need new starter relay. I think that it is the simple problem (getting it started) . Running rough is the bigger problem I think I may need to pump the gas out and get new.

I have a 95 GT40, just purchased in January, took a couple months to get the bugs out since it sat most of 20 years in a garage with no use.
A couple odd things about the GT40, when first used it would run great then run really bad, so bad I was worried I would have to get towed back to the dock. Changing all the fluids including the engine Oil and filter, changing the fuel filter and removing and cleaning the safety kill switch by the gear shift and changing the Impeller and Thermostat fixed mine. The system checks for oil pressure and coolant temperature.
If it does not like the signal from the Temp Sensor and the Oil Pressure sender it puts your engine in limp mode. It will run terrible but limp you home. ( designed to limit engine damage ) Doing the above mentioned work eliminated my issues. All basic stuff but it helped.
I really can't say which item helped the most since I did them all at once. I suspect the coolant sensor since my boat would run at 160 until you worked it hard and then idled, after the hard run and now at idle it would creep up towards 190. Never more but that was enough.
After the new thermostat and new raw water pump impeller it is constant at 160 with no variation.

Have you checked the little hose in the fuel cell? And the fuel pressure regulator?

I can here the fuel pumps running. But thats what I am going to do pump the fuel out, and clean all connections and see what happens. Just hope to get it done before cold gets here.
Thanks
DC

The early 95's ran two fuel pumps, a Carter P4070 supply pump and right above the supply pump is the high pressure pump. Both are mounted at the rear passenger side of the engine. The Fuel Cell design newer applications are mounted on the front passenger side of the engine block. I have seen many posts about the hose in the middle of the fuel cell failing. Good idea to change it now and be done.