Apparent Fuel system issues

[cedarcreek216]

There are a lot of things that can be wrong, I agree. I have ruled out bad gas, as it's happened three separate times with fuel from three different places, only one on the water, which it actually ran through perfectly fine. I guess I'll keep dealing with it until the dealer finds the solution.

[Need-a-nautique]

Fuel Filter

DanielC

According to my manual, the only fuel filter is in the FCC. Mines a 97 like your's. Is there another filter somewhere in the line from the tank? I just replace the H.P. pump, filter, fuel pump relay, and the ecm relay, and still have the same problem the origional poster has.

[DanielC]

On a 1997 GT-40 the only fuel filter in in the FCC. However, it you look back at all the post I made, there is a screen inside the low pressure fuel pump.

I did have a weird electrical issue with a 1998 Ski Nautique I work on. When I recommissioned it to the season two or three years ago, it started right up, ran for about 30 seconds, and stopped.

When a GT-40 dies, and will not start, here is the first thing you do.
You lift the engine cover, and turn the key to the run position without starting the engine. You will hear the fuel pumps run for about two seconds. Go and do this the next time you are in your boat. Get familiar with this sound. If you do not hear this sound, your boat is not going to run. It may start, and run if you hold the key in the start position, if this happens, check the safety lanyard. The safety lanyard is part of the fuel system circuits. Shutting off the fuel supply to an engine is a more reliable way to kill an engine, than killing the ignition. This feature is overridden by the starter being engaged.

If you do not hear the fuel pumps run, check for power on pin 30 of the cube "Bosch" relays. Pin 30 should have power on both relays.

Back to the 1998 ski Nautique I had that died. There are two circuit breakers on the panel on the back (flywheel) end of the engine. The 60 amp breaker is the main breaker. The 15 amp (or 20 amp) breaker is the fuel pump breaker. The 15 amp breaker gets power from the 60 amp breaker. Rather than take the wiring harness apart, I just made a jumper out of an inline fuse link, and used that to get power from the main breaker to the fuel pump breaker. I use a 15 amp fuse in the jumper. That way, if you happen to jump to the wrong side of the fuel pump breaker, you still have circuit protection for the fuel pump circuit.

To review, GT-40 cranks, and no start, listen for the fuel pumps to run for about two seconds when the key is turned on. If no fuel pump noise, check for battery voltage at pin 30 of both cube relays. If no voltage, you have some electrical issues to deal with.
If you hear the pumps run, time to check the pressure at the fuel rail, 39 plus or minus 3, key on, engine off.
Check also the output of the low pressure pump. You should have 5 or 6 PSI, and about a quart of gas every 15 seconds.

Here is my thread on checking the fuel pressure on a GT-40:
http://www.planetnautique.com/vb3/sh...=Fuel+Pressure

Here is my thread about relay connections:
http://www.planetnautique.com/vb3/sh...=Fuel+Pressure

You need to download the GT=40 service manual from this site.