04 Mobius XLV issues

[treverspence]

I have been having an issue with my boat since the end of last season and I was hoping someone would have some input on possible cause. The boat runs fine for 30-45 min then it will start to shutter and loose speed if I ease the throttle back to idle it returns to running fine and I let it idle down the river for a few minutes then take off again it runs fine for 5 minutes and shortly thereafter it does it again. My mechanic & I recreated the issue in the fall of last year with a fuel pressure gauge hooked up and even during the shuttering the fuel psi stayed a steady 60 psi so that leads me to believe it's not a fuel delivery issue. So next we changed the spark plugs, wires, rotor, dist.cap & coil to eliminate those as issue but I have taken the boat out twice this year & it has the same issue. Any input would be greatly appreciated, I have taken it to my closest Moomba dealership H2O watersports in Dothan AL but it will be a couple of weeks before they can get to it.

[treverspence]

Nobody has any input?

[sivs1]

for $30 and 30 minutes change the fuel filter and dump a can of seafoam into the gas tank. I just did this Sunday and actually primed the fuel pump with seafoam while the filter was off. Runs great now.

[drb59]

My last boat was a Malibu Response and I was having a similar isssue but my dealer could not recreate. It seemed like my tach would jump up when this happened and he thought he may be related to that. Also check your temperature guages as it seems like once you cool everything down it runs fine again (for a while).

[mmandley]

I have been having an issue with my boat since the end of last season and I was hoping someone would have some input on possible cause. The boat runs fine for 30-45 min then it will start to shutter and loose speed if I ease the throttle back to idle it returns to running fine and I let it idle down the river for a few minutes then take off again it runs fine for 5 minutes and shortly thereafter it does it again. My mechanic & I recreated the issue in the fall of last year with a fuel pressure gauge hooked up and even during the shuttering the fuel psi stayed a steady 60 psi so that leads me to believe it's not a fuel delivery issue. So next we changed the spark plugs, wires, rotor, dist.cap & coil to eliminate those as issue but I have taken the boat out twice this year & it has the same issue. Any input would be greatly appreciated, I have taken it to my closest Moomba dealership H2O watersports in Dothan AL but it will be a couple of weeks before they can get to it.

What part of the country are you in?
Does this only happen when its hot out or all the time?

My first thought is Vapor Lock issues.

You will show fuel rail pressure but its not liquid pressure, its vapor so the injectors can fire it off and make power.

Go recreate the problem and then pour cool or cold water on the fuel lines at the filter and pump, problem goes away then you have vapor lock.

If this isn't your issue then I would be leaning towards a ECM issue when its hot or an injector control issue.

[treverspence]

Thanks for the input as far as fuel filter it was the first thing I changed I also run a bottle of stabil in every third tank not sure how that compares to seafoam. I live in SW Georgia so yes it gets hot here but I had the issue in late October when the water was very cool. I don't think it is vapor lock but I could be wrong boat is at the shop now it will be a week or two before they can check it out. If it was Vapor lock then if I depress the Schrader valve on the fuel rail I shouldn't get liquid gas right?

[ranger098]

I had something similar happen in my mastercraft last year... turned out to be water in the gas. what happened was it would run fine until the fuel went down to a certain level then it would start burning gas and water.. it would even "jump" into running well, then back to poorly as the engine burned either gas or water. It may be kind of a bitch to do, but take your floor out, get a clear plastic cup and take a sample of your fuel from the gas line opening at the top of your tank. the water and fuel will seperate pretty quickly and youll know if that's your problem. I could be backwards on this, but im pretty sure the water will be at the bottom and gas at the top of the tank.

Just something to consider!

Also, what engine is in it? is it MPI, or TBI?

[treverspence]

Ranger098 The shop I have the boat at will be doing a gas test hopefully that will be the issue so the repair bill wont be too high!