New Owner-Backfiring and Oil Pressure
 

I just purchased my first Mariah. I finally got it in the water today. It ran strong for about 10 minutes then started hesitating, losing power and backfiring. I am going to check fuel filter, plugs etc. Wondering if there is a common problem with this boat that will help me look in the right direction. It has a Merc Alpha One 4.3 litre. Thank you so much!

Re: New Owner-Backfiring and Oil Pressure
 

I had a similar problem with my 496. It was the boost pump which brings the fuel from the tank. It sounded like it was starving for fuel, then it would start popping. Where your fuel line comes into that pump, disconnect and see if there are any obstructions in the screen filter. It could be clogged like mine was and will eventually burn up. The boost pump on mine is to the left of the motor on the outside. Good luck!

Re: New Owner-Backfiring and Oil Pressure
 

On the same note...does anyone have any idea why my 496 would plane out, then when I get to 3/4 of throttle after running, it starts backfiring, but no hesitation like it's a fuel issue. Just had the boost pump replaced this year, and the main fuel pump last year. Both are supposedly good, but wanted to see if anyone had any starting points to look at.

Re: New Owner-Backfiring and Oil Pressure
 

I would check to make sure that the choke butter fly valve on top of the carb is opening fully as the engine warms up. If it is stuck in the closed position it will run good when the engine is cool then like garbage when it engine temp comes up. Check the manuals section for adjusting it. Another possibility is that the ignition coil is getting bad. They sometimes work well when they are cool, then start causing misfires when the engine heats up. There are other possible causes, but these are the first/common things that come to mind.
Happy Boating
Dan

Re: New Owner-Backfiring and Oil Pressure
 

It ended up being the plugs. Took the old ones out and one of them was fouled because of the previous fuel pump issue causing it to run lean. Bought me some new NGK plugs, and $90 later she ran great! Thanks....