06 260hpdi issue

[Greenskeeter]

Hi all,

i have an 06 21i with a 06 250 hpdi. Been having a issue with it. Little back story. Bought the boat in November after it’s been sitting for a couple of years. Changed all of the fuel filters and strainers. Sent the injectors out to be cleaned and tested. Ran great for the beginning of the season. Now it’s acting up intermittently. Runs perfect for the first couple of miles then all of a sudden the rpms drop to around 3700 wot and it loses torque for lack of a better term. Hole shot goes to crap. Idle is low. Around 400-500 but in neutral it won’t rev. Just dies. Put it in gear And it’s fine. Just not full power. It eventually will get on plane but won’t rev past 3700 rpm. Let it sit awhile then it goes back to normal for a few miles then the cycle starts again. Replaced the LP fuel pumps thinking they weren’t supplying enough fuel to the vst but no luck. Anything else I should have done since the boat has sat or a while? Worst part about this is the closest lake I can run the gas engine is a hour away lol. Any input is appreciated.

[Nutoy]

Just taking a shot in the dark here, but it sounds like something(possibly a coil or CDI) is heating up and dropping a cylinder or two.

[Greenskeeter]

You know what. That would make sense about how it won’t rev in neutral but when I put it in gear it will do better. I’ll pull plugs tonight and see if any look weird. Thanks!

[MATZUO]

Hpdi will not rev in neutral, it's drops from 4 cyl to 2 cyl in neutral to keep u from damaging engine. Have you tried replacing all the mystery filters.

[Greenskeeter]

Right. But normally I can at least rev it without the engine shutting off. every single filter was changed beginning of season including all of the mystery filters.

Tonight i I pulled the vst and checked that filter. Clean.
did a compression test. Lowest was 106 highest was 110. Happy with that.
Changed spark plugs. Number 4 was very rich. Possibly a cylinder that’s dropping out.
Measured resistance across all 6 coils lowest being 3.0ohms highest being 4.1ohm. Not sure what spec says. Ran it in driveway for a bit and checked resistance after warming up. All rose but nothing looked crazy. May end up swapping the number 4 coil with another and see if the rich plug follows it. Injectors were just serviced this season.

[SkeeterJohn]

Was your gas treated could it be related to bad gas or water in the gas... did you also replace the racor filter in the boat?

Sounds like you're on top of filters and with good compression it points to a fuel issue somewhere. Do all the plugs look dry and clean?

[Greenskeeter]

Gas is always treated with marine stabil. Always 93. But this tank is 90 ethanol free from a place in ny when I was up at Cayuga, coincidentally where the issue started. Was planning on draining that gas out and fill with fresh before the next outing.

[87gtNOS]

search my posts...I posted a lot about the shift switches on the rail....

[Tonyc]

Injectors ever been serviced? Cleaned and flow tested? I had one that we caught, it was running lean.

[Greenskeeter]

Injectors done over the winter. All looked ok in their eyes with them. I’m having a guy tell me that it could possibly be the vst pump going out.

[Greenskeeter]

Changed the vst pump. Ignition coil #4. All new plugs. Fresh gas. RUNNING BETTER THAN EVER. I don’t care which one of those 4 fixed it. Just happy it ran like a top yesterday. Thanks for all the advice!!

[Nutoy]

Changed the vst pump. Ignition coil #4. All new plugs. Fresh gas. RUNNING BETTER THAN EVER. I don’t care which one of those 4 fixed it. Just happy it ran like a top yesterday. Thanks for all the advice!!

Good to hear you got it fixed.
If I was a betting man, I'd go with the ignition coil.

[87gtNOS]

Changed the vst pump. Ignition coil #4. All new plugs. Fresh gas. RUNNING BETTER THAN EVER. I don’t care which one of those 4 fixed it. Just happy it ran like a top yesterday. Thanks for all the advice!!

can you report back on how that plug looks now?

THX

[Greenskeeter]

I’ll pull it tonight if I get a few and let ya know. If she’s looking rich I’ll send that injector back out to get checked.

[onewalker]

following...

[JMouch]

I had a similar issue with a powerhead that sat up for over a year. When it was installed every single filter in it was changed, the plugs were changed, and 100% sure the gas was good. It ran awesome for about an hour or so then it was falling off and just not running good at all. Just because I've seen it act like that when the filters were plugging I went ahead and changed the 3 main ones again (even though they only had like 2 hours on them). After that she ran awesome! My assumption is that sediment / corrosion that was just laying in the engine since it sat up so long caused filter pluggage. Glad you got it straight though.