Troubleshooting Engine Stutter/Momentary Loss of Power

[JBehrens]

Hi all, just got back from Lake Powell and was experiencing a strange issue with the boat that hasn't been seen before. When underway, the engine would randomly get boughed down (almost like it was starving for gas or miss-firing), loosing anywhere from 200rpm to 750rpm for about a second then returning to normal. It would sometimes be repeated for say 25-30 sec. This event was completely random, boat would run for say 15-20 min straight with no issues then have ~5 minutes of the random power loss events. I'm really not sure what would have caused the issue.

Things to note:

• High altitude impeller installed for Powell
• First tank of gas was clear 87 (no ethanol) normally the boat is filled with regular 87 up to E10
• RidSteady installed on boat
• No engine error codes

Troubleshooting Steps Attempted:

• Disconnect RideSteady (no change)
• Check Spark plugs (all looked normal, nothing dirty)
• Checked battery connections

So what could I check next/what might this be? Bad gas, broken fuel injector? Any help or ideas are appreciated. Thanks!

 

[tdonoughue]

1) Just because it works, change the spark plugs (I know they look fine, but you would be surprised what that fixes...).
2) Check the air intake. I had a piece of soundproofing flying out and blocking mine, which caused for an interesting diagnostic session...
3) Bad or contaminated gas is possible. Thrown in some Stabil 360 or Sea Foam (can't hurt).

Also, I doubt it is the battery connections...

Let us know the results!

 

[Scottintexas]

Cleanout hatch safety switches, tape a nickle on them to push them down more

 

[JBehrens]

Ok, I shall give those a go. You think the safety switch would cause the boat to not completely shutoff?

 

[tdonoughue]

Absolutely. Has happened before. The boat hits chop and that hatch lifts a little, cuts the engines a half a second second, then the boat settles, hatch pushes down a little, engines come back on...

 

[JBehrens]

Absolutely. Has happened before. The boat hits chop and that hatch lifts a little, cuts the engines a half a second second, then the boat settles, hatch pushes down a little, engines come back on...

Interesting, I'm not sure if that is happening as when it looses RPM it stays there for a moment. Worth a shot though.