97 GT40 starts, dies and pops 15AMP fuse at engine

[skihartwell]

I began having problems with the engine dying about 30 seconds after it starts. The fuel pump relay is doing it's job of triggering fuel to the system as I can hear it juice up and the engine starts. It appears the fuel is burning off and then the engine starves for fuel and the 15AMP red button breaker kicks. You have to shut the ignition switch off, then reset the breaker and the engine will start right back up and die again after about 30 seconds. Any suggestions as to what this could be?

[DanielC]

I am going to suspect your low pressure pump is starting to go bad.

You have two fuel pumps in your system, the low pressure pump, and the high pressure pump.

The only job of the low pressure pump is to keep the FCC full of fuel.

The high pressure pump keeps the fuel rail supplied with fuel, and the pressure regulator bleeds any excess fuel back into the FCC, to keep the fuel pressure in control.

Your engine will run without a low pressure pump, until the fuel level in the FCC drops below the high pressure pump. Then it dies.

I have heard that when a low pressure pump starts going bad, it starts to draw more current than is normal. This could cause the breaker to trip. when the breaker trips, the engine should die immediately, because the high pressure pump is also powers by the same breaker.

[skihartwell]

97 gt 40

Thanks for the reply. I was beginning to come to that conclusion after reading a few other posts with similar problems. One thing that may or may not be strange is that the engine did the same thing memorial weekend and then cleared up, like an intermittent situation. It ran all day long after dying several times after about 30 seconds of run time. In any event, I will secure a low pressure pump and give this a try.

[DanielC]

I take care of 1998 Ski Nautique with about 1400 hours on it.
A few years ago, a connection in the wire harness between the 60 and the 15 amp breaker on the engine went bad. The 15 amp breaker is for the fuel pumps, as you know by now, so the fuel pumps would not run. Rather than completely remove the wire harness, unwrap it, find the break, repair it, and put it back together, and possibly do more damage in the process, I just put a short fused jumper between the two breakers, with a 15 amp fuse.
This year, when I recommissioned the boat, and turned the key on, the 15 amp fuse blew. I replaced the fuse, and it blew again. I put in a 25 amp fuse, and then the fuel pumps ran. I then pulled the 25 amp fuse and put a 15 amp fuse, and the fuel pumps ran, and test started the engine.
On the advise of an experienced independent marine mechanic, I replaced the low pressure pump. A fuel pump starting to go bad will draw more current, before it finally fails.

A fuel pump is just a DC electric motor turning an impeller pump. A DC electric motor has a commutator to switch the windings on the motors armature, to make the motor run. The commutator wears out, and the brushes slowly wear, and the motor loses efficiency. As the motor loses efficiency, it draws more current.

[skihartwell]

97 gt 40

Thanks for all the advise. I ordered out the low pressure fuel pump this am. I was also advised by a mechanic to start the engine, pull one of the wires from the stud on the LPFP and see if the fuse trips. NOPE.. So, this was an easy way to diagnose the problem. Interesting however, that the engine idles fine, when the LPFP is deactivated. I would suspect this would not last too long and vapor lock would soon be an issue. Thanks again for all the great advise.

[mtrader]

Hi DanielC ..I have a 98 nautique gt40 and I’m stumped….I went to turn on the boat yesterday and it didn’t start. I had noticed a while back the key ignition seemed faulty so I took it apart and noticed one of the post had broken off completely. I realized that if I bridged it the boat would start. Problem is the starter stayed running but I didn’t know how to stop that so I disconnected the white cable at the starter and the starter stopped engaging. I was going to tape off the end of that cable so it wouldn’t spark or anything but as I went to get the tape the boat turned off. When I went to try and start it nothing happened. It seems like there is no power to the starter or something since I can’t get the motor to turn or even hear the starter engage. I took off the starter and tested it at the battery and it’s still working. I am ordering a new ignition switch but in the meantime I can’t even hot wire this thing to get it to start. I’m totally lost….any suggestions?

[JimBoat]

I have a 2002 SANTE with GT-40. I think the same thing is happening to me. Last time I tried to start it, the engine would run for a few seconds and then the 15A red breaker button would pop and the engine stopped. To get it to start, I would have to hit stop on the control pad, push in the breaker, and then it would start again, run for a few sec, pop the breaker and stop. I recently had the boat serviced because there had been water in the fuel system. The high pressure fuel pump had failed and needed to be replaced. I’m now thinking that the low pressure fuel pump is starting to fail.