GT40 Won't stay running.

[jchristian]

Had boat out for the first time yesterday. (Impeller was replaced by dealer when they winterized it in the fall.) Fired up the boat, ran it for a few minutes at the launch, impeller drips slightly...Took it out for a ride anyway. Ran fine for about 15-20 min and then quit. Would fire, start up, and quit. Or would start up, run for 30 sec and then quit. Would love any suggestion on where to start troubleshooting. Battery is older...maybe not enough volts?? Have read could be bad kill switch (with lanyard), fuel relay(s), distributor cap, plug wires, fuel pump, and maybe some more...

[functionoverfashion]

If it ran fine but now runs and dies, the first thing I'd check is the fuel itself, this being your first time out for the season. Put a small clear container under the fuel canister, aka Fuel Control Cell aka FCC and drain a bit out of the bottom - it's a 7/16 plug I believe. Let it settle in the clear container (give it 30 minutes even) and see if there's any water. That's a place to start.

[glassywaters]

See if your getting fuel on the rail...are both pumps priming when you turn the key?


Sent from my iPhone using PLT Nautique

[Cadesun]

I had that happen on the old '98 super sport. I replaced the kill switch and it solved the issue.

[functionoverfashion]

I had that happen on the old '98 super sport. I replaced the kill switch and it solved the issue.

Agreed, this is probably the right place to start troubleshooting. Fiddle with the switch and/or bypass it temporarily to see if it solves the problem. If it's running fine all of the time that it's running, and suddenly just quitting at weird intervals, that's a very likely culprit.

[Jholly87]

There is also a capacitor in the ECM that can go bad. It gets hot after running awhile and then it starts messing up. It mimics fuel like symptoms. Cuts out when running. Can cause starting issue also till you let it cool off for awhile.

Kill switch is by far where I would start though, super easy to check..

[Aaren22]

Jholly87.....How can you tell if the capacitor is bad?

[Jholly87]

Jholly87.....How can you tell if the capacitor is bad?

On mine when I took apart the ecm it was obvious by looking at the circuit board that the capacitor had gotten hot enough to basically un-solder itself. I had another ecm out of my other boat that I put in and it ran great. Another thing was when it was running with bad ecm/capacitor my fuel relay would constantly be switching you could feel it if you held relay in hand while it was running, as soon as I swapped ecm it quit.

Also I have not tested it yet but I bought a variety set of capacitors (making sure the exact one I needed was included) for like $10 and soldered it in, so hopefully that fixes it!

[jchristian]

Thanks for the responses. It was the low pressure fuel pump. Replaced and so good so far.

[charlesml3]

Thanks for the responses. It was the low pressure fuel pump. Replaced and so good so far.

Good deal. I'm sorry for your troubles but I do appreciate you coming back out here and updating us with the solution. We all like fixing things and having these posts "closed out" is always good. Someone else will likely run into this same problem and this information will be helpful.

The behavior you described is typical of a failing LP pump. It can pump some fuel, but not enough to keep the FCC full. As the boat runs the FCC keeps getting behind until the boat just dies out.

-Charles