Fuel issue with 97 sport nautique

[Haterclothing]

So I head to the lake yesterday and going through my pre checks and found someone siphoned most of my gas! Pissed right? So I head to the lake and refuel only I used the next higher octane so I put 89 to top off with 87that was left in the tank. Didn’t think much about it at the time. Boat ran like a gem till about 1/4- 1/2 tank left while running at multiple speeds the boat loses all power then gets back on it then off and on sputtering and cutting out completely. Had to limp back home. what could this be? Fuel filter? Could it have ran through the 87 gas and started to run poorly on the 89? Has anyone ever experienced something similar? Please help!! Thanks

[wtrskrs]

You have a GT40? If so, the GT40 is supposed to run on 89, not 87. Regardless, the gas mixed, so that is not the issue (it will run with no problem on 87 sort term but I wouldn't long term). Unless there was some really bad gas, the filter wouldn't just suddenly plug up. Of course, the gas could have been dirty but it took half a tank to plug the filter up. Not likely though.

There are a number of possible issues (not all fuel related). And if you don't have a GT40 MPI engine, some of this may not apply.

If you have or can get access to a fuel rail pressure gauge, hook it up to see if you have 40+psi all the time (even when cutting out). If the pressure remains high when the engine is cutting out, then it it probably not fuel related (unless the injectors are not firing correctly), probably an electrical issue.

If the pressure is dropping, then it could be the low pressure fuel pump or the high pressure fuel pump. It could be the filter. It could be the screen mesh in the top of the tank pick up. It could be the fuel hose that suspends the high pressure pump in the fuel cell.

It could also be electrical; one thing being the kill switch going bad but not completely dead. Plugs, rotor, dist cap, high tension wires, etc. don't usually fail suddenly, but when was the last time all these were changed?

When you 'limped' home, I assume you were idling. How was the idle? Was it fine, but started to cut out when you gave it more throttle? If it let it idle for a while, could you then drive at speed for a while before it started to cut out?


A little more info will be helpful.

[SatherG230]

Could be a fuel issue, but not from mixing octanes. I only run premium non-oxygenated in mine. 93 octane. Did you use Stabil 360 Marine or Seafoam when you put her away for the season? Check filters, add some fresh good quality fuel and try again. Some Seafoam in the tank would be good, too. I would double the dose.

[Haterclothing]

Thank youSatherg230 and wtrskrs. I do have the GT40 motor. I recently purchased about a month ago and had a premium year service at my shop. I haven't changed anything except a new impeller and steering cable. Also when it limped home it struggled at first and would shut down but once I bit the bullet and didn't try to give any more gas it limped at idle for about 30 min back to the dock with no other issues. Also, the kill switch isn't hooked up I don think believe as it's in the glovebox. The lake I'm on is lake Meade and the chop can get very rough and I try to not even run it in such weather. The other day there was very little chop but on other days I could see some potential for jarring something loose.

[functionoverfashion]

First things first, drain the Fuel Control Cell (FCC) into a clear container, let it sit for a while and see if any water settles out to the bottom. If there was some water in the tank, it could have taken a while to cause an issue. If there's water in the fuel, you'll see some in the fuel you drain from there.

Just another thought (and given the age of your boat), there's a small piece of fuel line in the FCC that is known to crack and will cause some run issues - check that out if you take the FCC canister off to look at or change that filter.

But since it ran great for a while then suddenly ran poorly - on the first trip out for the season - my money is on water in the fuel.

[Haterclothing]

Thanks functionoverfation. That makes sense as the cap was left out after gas was stolen and it had rained the day before and I have no idea when gas was siphoned. Thanks!!

[SilentSeven]

+1 on water in the fuel.