1991 Ford 302 5.0 HO omc stern drive engine backfiring under load only not in neutral

[NewbieAtownsam]

1994 Chaparral 2130 Just bought the boat! Filled boat up with 89 ethanol free gas! Po had engine rebuild with paperwork included and told me engine had 40 hours on it! LiL rough to start but starts and idles ok and revs up ok no back fire! But when I got go in drive anything over 2,000 rpm’s it backfires and bogs down and than it will stall and rough to restart than rough to restart than when restarted in neutral it idles but eventually stalks than if idling to go to “drive” it stalls! I haven’t changed the fuel filter yet but I’m going to see if that’s the issue! Backfiring though? The tank seemed low when I filled up put 30 gallons at least! Haven’t done anything to boat because figured 40 hours on rebuild boat should be up to par! Guess not! Any help in the right direction is appreciated! Before I have to break out another thousand! Thank you!

 

[kenny nunez]

When you remove the filter dump it into a clean bucket. If there is water you will see it separating from the gas.

 

[NewbieAtownsam]

Ok so that’s a start! Thanks

 

[NewbieAtownsam]

When you remove the filter dump it into a clean bucket. If there is water you will see it separating from the gas.

Do you think if there’s water in there that would give me my symptoms of backfiring under load but not on idle in neutral?

 

[Bondo]

Do you think if there’s water in there that would give me my symptoms of backfiring under load but not on idle in neutral?

Ayuh,..... That's a sign of going lean, for whatever reason,....