RPM drop between 2300-2400 while under acceleration.  The boat climbs from idle and once it hits 23-2400 rpm is dropps approximately 150-200 rpms and runs rough. If there was enough throttle applied it will climb past but if I leave it at that rpm level it will continue to run rough. Same thing happens at 2900-3000rpm. Then when back at the dock I shut down the engine and restarted it and I had to give it some throttle to get it to start at that point it seemed to idle properly. Its a fuel injected engine which shouldnt need throttle in start up? Right? 

 

Any ideas?

How old are the fuel lines and filter? Do you have access to a fuel pressure gauge? I'd start there, then pull and inspect the disty and rotor. They go to hell and cause weird issues. 

I would put a timing light on it and see if it is advancing. If it has a distributor it will have a spark curve module and when those fail you don't get any top end. Check the fuel first of course.

7 minutes ago, Carlos Danger said:

I would put a timing light on it and see if it is advancing. If it has a distributor it will have a spark curve module and when those fail you don't get any top end. Check the fuel first of course.

It is low on top end now that you mention it.

31 minutes ago, Kivalo said:

It is low on top end now that you mention it.

If memory serves it should go from 6 or 8 btdc to 30 ish but don't quote me. Either way it should advance.

26 minutes ago, Carlos Danger said:

If memory serves it should go from 6 or 8 btdc to 30 ish but don't quote me. Either way it should advance.

Im not mechanic amd dont have access to a timer so if its more in depth than plugs/wires Im gonna have to call someone. I break shit, not fix it.

WHAT??!!!

 

 

 

 

WHAT?!!!!!???

 

fuck...

Fuel. Absolutely fuel. Or wires. Do you get zapped if you touch the distributor?

8 hours ago, Kivalo said:

Im not mechanic amd dont have access to a timer so if its more in depth than plugs/wires Im gonna have to call someone. I break shit, not fix it.

Would dropping it off the trailer give it a jolt and bring it back to life ? LOL Where is Ben the boat mechanic when he is needed ?

1 hour ago, Frostynuts said:

Would dropping it off the trailer give it a jolt and bring it back to life ? LOL Where is Ben the boat mechanic when he is needed ?

He's never going to shake that mistake. I'm in the same boat after sinking a measly drone.

15 hours ago, Crnr2Crnr said:

WHAT??!!!

 

 

 

 

WHAT?!!!!!???

 

fuck...

Wow...what an adrenaline rush

On 5/27/2024 at 9:01 AM, ckf said:

He's never going to shake that mistake. I'm in the same boat after sinking a measly drone.

The funny part is there are only some very minor scratches in the hull near the transome, barely more than surface scratches. I bet your drone incedent was more expensive! Plus I blamed it all on my brother on facebook. 

On 5/27/2024 at 12:48 AM, Whiskey Tango Foxtrot said:

Fuel. Absolutely fuel. Or wires. Do you get zapped if you touch the distributor?

I was wondering tho, woukd it be wires considering it happens at specific RPM ranges??

1 hour ago, Kivalo said:

I was wondering tho, woukd it be wires considering it happens at specific RPM ranges??

Put it on prop dyno and start screwing with things 

33 minutes ago, Not greg b said:

Put it on prop dyno and start screwing with things 

I think if I releve the head gasket presure buy losening 2 bolts that shoud do the trick! Too much oressure is bad for your health!!

2 minutes ago, Kivalo said:

I think if I releve the head gasket presure buy losening 2 bolts that shoud do the trick! Too much oressure is bad for your health!!

When I worked at a boat repair place we would put weird problems like yours on a prop dyno and figure them out pretty quick as we could change things in the shop with it under load. 

For starters, pull all the plugs, and compare the burn pattern, and color of tip area. That might help you at least find out which cylinder it is. Could be bad wires breaking down, could be a bad plug.

8 hours ago, Kivalo said:

I think if I releve the head gasket presure buy losening 2 bolts that shoud do the trick! Too much oressure is bad for your health!!

Do a compression check & leak down test,

Add some liquid fuel system magic in a bottle.

Check Finnegan pins for wear & tear.

 

On 5/27/2024 at 12:48 AM, Whiskey Tango Foxtrot said:

Fuel. Absolutely fuel. Or wires. Do you get zapped if you touch the distributor?

Fuel be my thinking also. Had an old bike that had similar symptoms and it was a bad fuel pump. I’d rule out the cheap easy stuff first though plugs filter so on

12 hours ago, Kivalo said:

I was wondering tho, woukd it be wires considering it happens at specific RPM ranges??

Does that have a flat cap with wires coming out from the sides?

On 5/28/2024 at 10:51 PM, Kivalo said:

I think if I releve the head gasket presure buy losening 2 bolts that shoud do the trick! Too much oressure is bad for your health!!

Did you find the problem?

Here,s the problem !  LOL