Just rebuilt OMC 5.7L '92 Four Winns stalls with any amount of throttle

We just put 15K in all new floor & rebuilt engine in our '92 Four Winns 225 Sundowner. Very frustrated that it stalls out with any attempt of acceleration! The repairman says it's due to the gas that sat in there for almost 2 years & we just need to treat it with Startron. Had we known that flushing the tank wasn't in their plan of repair work, we would've requested that it be done. We maybe had 1/4 tank of gas in there. The boat starts beautifully, and runs fine when idling, but as soon as we throttle up she stalls out. We did as instructed & filled the tank & treated with the Startron yesterday & it ran worse than last weekend. Could barely get her on the trailer because it kept stalling even when idling. Repairman says keep running & treat again. Says it'll be $500 for them to flush the tank (which we just put $100 worth of gas in). Very frustrated at this point, any advice is appreciated!

Hi, sounds like the carb. accelerator pump is not adjusted properly or the shift interrupter switch . try a new repairman!!
Charlie w

Hi, thanks for your advice! The carb was completely rebuilt, but perhaps some adjustments need to be made. Because it runs fine in their shop, they don't feel there is anything else wrong other than clearing out the old gas. Going to run up today & dump more Startron in & maybe try to take her out a few minutes. I agree, if no improvement we'll be looking for a new repairman!

I would check the supply lines from the tank. If they are the old ones then they may have been attacked inside by ethanol in the fuel. If that happens the inside of the hose breaks down and clogs the line. That would be where I'd start looking at the fuel starvation problem.

o2batsea said:

I would check the supply lines from the tank. If they are the old ones then they may have been attacked inside by ethanol in the fuel. If that happens the inside of the hose breaks down and clogs the line. That would be where I'd start looking at the fuel starvation problem.

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X2 and switch to Sea Foam

Good news! After we overdosed with Startron, she ran great! Still a little rough with full throttle, but didn't stall out at all! Headed up tomorrow. Hopefully the problem is fixed! Thanks for the advice!!