2004 25 lsv 8.1 motor shutters after ruining for 25 minutes

[Nobodyrides4Free]

Boat runs for about 20 to 25 minutes and then acts like it goes into limp mode. Started last fall, so I replaced the timing sensor and plugs. Thought I had it fixed after it ran for about an hour. Put the boat on the boat ramp to warm enough to change the oil this spring.  Then it started again, boat ran for 25 minutes shuttered and died. Took it to boat dealer showed a map sensor code. But while hooked to fake Lake it would not do it. Replaced map sensor took boat out to the lake and started to do it again. Took boat back to dealership and no code. Have to take it back on Friday so they can look at it again. Any help or somebody has an 8.1 Vortec with same issue,  please help. Search forum and didn't find same symptoms I'm having. Rick

[Nobodyrides4Free]

After checking all wires connections,  replacing fuses, put boat on fake lake in driveway,  

Guess what? No issues.  Took boat to lake and  IT ALL STARTED AGAIN....pulled hoses on oil cooler and intake just to be sure, also cleaned throttle body.  STUMPED!!!!

[Idaorr]

When you run it on the fake lake are the rear hatches open?  Maybe struggling for air? If it gets hot and we have been surfing for long sets, mine will stumble coming off throttle to quickly, but turn blower on and it clears it up. Is the boat new to you or have you had it a few seasons? Just throwing some ideas out there. What things are different from being on the water or fake lake?

[Nobodyrides4Free]

It doesn't matter what you're doing surfing skiing or just driving the boat. It bogs down like someone is pulling the throttle back to neutral and then it might take off again. Sometimes it just sputters and dies. One of my mechanic friends at work suggested check in the vent line to the gas tank in the screen in the fuel tank. The boat set for a couple of weeks last September so there's a good chance mud daubers got in the vent. Going to check it tonight. And then take it to the lake probably tomorrow night. Thanks for your input

[justgary]

27 minutes ago, Nobodyrides4Free said:

It doesn't matter what you're doing surfing skiing or just driving the boat. It bogs down like someone is pulling the throttle back to neutral and then it might take off again. Sometimes it just sputters and dies. One of my mechanic friends at work suggested check in the vent line to the gas tank in the screen in the fuel tank. The boat set for a couple of weeks last September so there's a good chance mud daubers got in the vent. Going to check it tonight. And then take it to the lake probably tomorrow night. Thanks for your input

Open the fuel filler cap when it happens to see if the tank "gasps" for air.

If that's not it, check the fuel pressure while it is lugging.

[Nobodyrides4Free]

My friend is bringing fuel pressure test gauge in the morning so I can check it.  Tonight in pulling floor piece up to check tank and vent hose.   He suggested Pulling the gas cap to.... Had boat to lake the last 3 days trying to check  it.  Hopefully I find something tonight!

 

[justgary]

I have seen fuel hose that lost chunks from the inside and created a blockage.  I could blow through it the wrong way very easily, but not in the direction of flow. 

[formulaben]

Do you have individual coil packs or a large single coil on that engine?

[Nobodyrides4Free]

Individual coil packs 

[Nobodyrides4Free]

Finally got it fixed.  After pulling floor and checking all hosed, I didn't find anything wrong.  

My friend brought his fuel pressure tester gauge.  Hooked it to fuel rail and started engine.  Wow,  140 psi to fuel rail.  It should be between 40 and 60. Tapped on rail regulator, didn't change anything.  Tapped on fuel regulator valve beside fuel pump and gauge bounced,  tapped again and again.  It finally dropped to 60! Motor ran smooth! Went and bought new regulator at auto zone for 54.99. After we cross referenced part number, bought a regulator for a 04 Volkswagen pasat.  Delphi from oriellys was 180.00. Installed new part and took to lake for test run.  Boat ran great! No miss our stuttering after 20 minutes or any hour.  Ballast her up and ran her.  Everything good.  Engine was getting over loaded with gas and out could not get enough air mixture and killing it.  Have to change oil again because it smells like gas! 

Thanks for all the input guys.  I appreciate it.