FCC getting HOT and triping 15 amp breaker

[ebjratliff]

Hi all, first post! I have a 2000 Ski Nautique with only a 155 hours on it. During every outing on the lake, I run the boat for a while, off/on, idling, start/stop and every now and then the boat will not run because of no fuel going to it. The 15amp breaker on the rear of the engine trips. It never has a problem once it is running, only after I turn it off then back on. The FCC canister is very warm, and also the low pressure pump is a little warm. I was told that it could be the hi-pressure pump, which i ordered a replacement, or the return line is clogged. I have no clue how to examine/test that. I was looking for any feedback!

[DanielC]

Basic GT-40 fuel system operation:
There is a low pressure pump. This is a pump you can see, below the alternator.
The only job this pump does is to keep the FCC full of fuel. There is a second hose, on the side of the FCC, that goes back to the fuel tank. This hose cannot be crimped, kinked, or plugged. Gas must freely flow through this hose back to the gas tank. This hose it at the top of the FCC, so any air, or fuel vapor can vent back to the gas tank, and the FCC stays full of fuel.

There is also a high pressure fuel pump, it is inside the FCC, and inside a fuel filter. The pump and filter are about halfway up, inside the FCC, to allow any water in the gas to settle into the bottom of the FCC, and be drained out by the drain plug on the bottom of the FCC. The high pressure pump supplies the fuel rail, that feeds the eight fuel injectors. There is a pressure regulator on the end for the fuel rail, that bleeds fuel back into the FCC, maintaining the correct fuel pressure. This fuel may go back to the tank, or back into the high pressure pump.

If the FCC is very warm, I would suspect the hose going back to the gas tank is not allowing gas to flow freely back to the tank. If it was, the warm gas would just go back to the tank, and the cool gas from the tank would keep the FCC full, and cool.

If your low pressure pump is trying to push fuel back in to the gas tank, and cannot, it would seem to me that the low pressure pump would be working a lot harder, that would make it run warm, and draw more current, and tend to make the breaker trip.
It is also possible that your low pressure fuel pump is going bad, and just drawing more current.

To check the hose going back to the tank, just blow into it. I would get a fitting, and a short piece of clean hose, and attach it to the tank return hose, to avoid touching gas hose with your mouth.

I would not suspect the high pressure pump, unless the engine fails a fuel pressure check.

You can download the GT-40 engine manual from this site, in the downloads section.

[NautiBrophy]

Let me know what you find out I'm having a similar issue w/ my 99...

[ebjratliff]

Thank you so much for your reply. A wealth of info! To clarify things for me, the low pressure pump is responsible for sending the fuel back to the tank during idling. This is through the LARGER hose on the top of the FCC. I have attached a pic to be sure.

My stupid question is that is the LP pump is dong its job of supplying gas to the FCC, (since I never have any issues while the boat is in gear), then it might be reasonable to believe the issue might be a clogged line back to the tank? Or does the pump require more psi to pump the gas back to the tank during idling, and the pump has weakened?

Thank you so much!!

[ebjratliff]

More confused!
Troubleshooting so far...
1. Removed the return hose from the top of the FCC and blew through it. It took quite a breath, but it did go through and didn't seemed clogged. I even felt some air coming back after I stopped blowing (I did move my mouth first!)

2. I removed the FCC and it was completely full of gas. I inspected the inner top where the FCC screws into. and it was clean and free of debris. The filter is new, but does not fit snug onto the HP pump, but it all seems in good working order and condition.

3. I put the FCC back on and turned on/off the boat a few times to fill the canister back up with gas. Instead of hooking the return line back up, I put a 12 inch hose on it and ran it into a bucket.

4. I started the engine (I have the flush kit installed) and let it idle. The gas started flowing into the bucket as it should. Not real fast, but enough.

So, my only assumption at this point is that the LP pump is too weak to push the fuel back to the tank??

Any advice would be helpful!!