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DeltaDog
05-09-2015, 07:53 PM
I've got an old 22 Donzi Classic, 454 Mercruiser with a Bravo One drive. I have an intermittent problem. The motor runs great most of the time, but sometimes at or near WOT the motor starts cutting out until I back off the throttle. If I don't back off, the motor will actually quit. Sounds like fuel starvation to me but I'm not sure where to start trouble shooting it. I've replaced the fuel filter. It has an Edelbrock carb. Weak fuel pump? Anyone had similar symptoms?

Sidney073
05-10-2015, 09:34 AM
Install a fuel pressure gauge at the carb, it should maintain 7 psi or more with the engine running at any throttle position. If it drops below 7 psi, say 3 - 4 psi, you have a weak (or insufficient flow rating) fuel pump. If it maintains 7 psi or above then the carb needle & seat may be too small for the engine demand.

Morgan's Cloud
05-10-2015, 10:32 AM
The lowest tech suggestion of all ...
Make sure your gas tank vent isn't blocked in any way from dirt or corrosion.

That little tip I first picked up from the good folks here . It's free and only takes a few minutes but it has the potential to save you a lot of expense and aggravation.

Pismo
05-11-2015, 08:55 AM
The lowest tech suggestion of all ...
Make sure your gas tank vent isn't blocked in any way from dirt or corrosion.

That little tip I first picked up from the good folks here . It's free and only takes a few minutes but it has the potential to save you a lot of expense and aggravation.

Even lower tech, just remove the gas cap to check for vent blockage.

DeltaDog
05-11-2015, 09:54 AM
thanks guys, sounds like good advice.

Morgan's Cloud
05-11-2015, 01:21 PM
Even lower tech, just remove the gas cap to check for vent blockage.

OK, I like that . You can work on my boat anytime ! :biggrin.:

Pat McPherson
05-11-2015, 02:57 PM
Fuel pressure is a good place to start.
My 502 with 750 Edelbrock seems to run fine with about 6psi. My stock Carter electric fuel pump is internally regulated so I've not ever messed with it. The pressure doesn't ever seem to drop even at 4600rpm...