so the boat was cutting out on me and I had fuel in the oil for the sea water pump so I sue my fuel pump was bad and changed it. the boat seemed idol better and so I thought my problems were solved. took the boat out today and it is better but I cannot get it off idle. it does fine in neutral or seems to but under power if I get it much of idol it cuts out. it will cut out and pick back up then cut out and pick back up in a ventually overloads and backfires a little.

it is almost rhythmic but not consistent. I have check battery cables and connections to be sure everything is tight.

the only other thing to add is it seems that there is a large sucking sound
Any thought
oughts

Vacuum Leak??

when is the last time you changed your water seperator filter?

It could be a vacuum leak, but what all is vacuum on these as I am not very familliar.

I have a brand new fuel water seperator, it is still last years fuel which I am going to figure out how to drain out. I added some sea foam and Heet the other day.

Where is my flame arrestor, and anti-siphon device as I can not find them. I have a K&N if that makes a difference.

The first post was a mobile post from the lake so here is an up date. It starts right up, idles fine and even revs up and holds in nuetral without trouble. It will rev up under load just off idle to about 1200-1500 rpm then it starts to cut out. It will cut out almost die, then pick back up. If I do not let off it will rev back up and then almost die, eventually it acts like it loads up and backfires a little. I could smell fuel the extra fuel after a while but nothing is leaking.

It would just keep going like this and not die.

Carb or MPI/EFI ?

Timing not advacing? Causing it to dump a ton of fuel in the carb,when you try to give it throttle, but not advacing the spark to burn the extra fuel...which is why ya smell extra unburnt fuel..

On stock engines there is a screen/filter behind the carburator inlet fitting , have you looked at that? And if not stock new holleys used to come with the little bronze filters, they lasted about 5 minutes in the boats, would not pass any moisture at all.

ok sorry guys I have the MPI so no carb. I hooked up some diagnostic software and no trouble codes.

I wonder if this could be caused by a bad connection at the oil pressure sender. I rode around today while it did it checking and listening. The only real thing I noticed in the guages was that my oil pressure all over the place. I wonder if a bad sensor or connection is sending it into safe mode and back.

The sucking sound is most likely your IAC valve (idle air control)--its a good thing to hear the sucking sound.
I had the same thing occuring (boat idling good but going into safe mode under load) in my 1994 Powerquest with a 454 mag EFI (385 hp)...My engine vacuum was disappearing under load. It took months of diagnostic (replacing all sensors, having all the fuel injectors flow tested etc) before we finally figured out that it was a bad MEFI 1 control module/computer. Half my engine was shutting down under load.

So would that show up on a diagnostic scan?

Also was your going in and out, mine shuts down then comes back up.....back and forth