No power when I throttle down

[josieo]

I have a 1995 220 hp, Ford, 5.0L EFI, V-8 with a Cobra SX outdrive. I guess Volvo-Penta slapped their name on everything once they bought OMC. I recently replaced the alternator thinking that was the entire problem. The problem seems to be two-fold now. Out on the water last Sunday, boat ran great. Went out Memorial day, got out of the no wake zone, throttle down, and got on plane. I slowed down to let a friend catch up in his boat. When I throttle down to get back up on plane, I got no power and heard a loud popping like sound coming from the motor area. I had to idle back to the ramp.<br />This past weekend, ran the boat in the driveway, and gave it gas while doing so. Sounded great. Got to the marina and backed the trailer down the ramp. As I shifted into reverse to pull off of the trailer, same thing happened. No power, popping sound from motor area.<br />I'm looking for some direction. Is it electrical? What can it be? Thanks in advance for your assistance.

 

[Haut Medoc]

Re: No power when I throttle down

Water in fuel? Check water separator.

 

[Haut Medoc]

Re: No power when I throttle down

Also, the shift interrupter switches are different on OMC [as opposed to Mercruiser]. They only kill half the cylinders while they are engaged. Maybe yours is stuck. There are alot of people on this site who know more about OMC than I do, I'm sure you'll get some more replies.

 

[josieo]

Re: No power when I throttle down

New fuel separator a couple weeks ago. Pulled it off this past Sunday and it's clean.

 

[Mahoney]

Re: No power when I throttle down

Could be lean condition in carb. Wont notice it in driveway but under power you will.<br /><br />In the driveway you can try disconnecting the throttle linkage after the engine has started and snap the throttle open very quickly by hand from the linkage on the carb body(make sure to engage secondaries and see if you get a pop then)Don't leave it rev, just snap it open quickly a couple times.<br /><br />Keep face away from carb! If you get pops, then you are pretty sure its a lean condition engaging the secondaries, although it could also be an ignition issue as well. I had that problem and it turned out to be carb/fuel flow related.

 

[bigdaddyofhouse]

Re: No power when I throttle down

I had the same prob. last week,it turned out to be just a bad alternator.It would start fine but was a almost imposable to get up on plane.The motor was shaking and just wouldnt go over 3200 rpm's and progresavly got worst.<br />I would take a look and see how many volts are on your battery.Its a easy fix but a pricy one.

 

[Don S]

Re: No power when I throttle down

Water in the filter would be my first thought. Since filter is clean check the fuel pickup tube in the tank and the antisiphon valve for blockage. It's not the shift interrupt switchs because it doesn't have any. Volvo didn't just put there name on the Cobra, the threw away the insides of the drive and the complete ESA system and put in the cone clutch shift method, and added a dual prop to the line...... Nothing Like the OMC mess.<br />Also, I doubt a lean carb is the problem since you have EFI.<br />Since you already changed the alternator, check the voltage output, also check the cables. Loose or corroded cables will not work on the EFI, also have the battery load tested. Dead cell will take a charge but will show a big voltage drop to the computer.<br />Have you done a tuneup lately? Cap, rotor, spark plugs? Should be done every spring to prevent problems like you are having.

 

[josieo]

Re: No power when I throttle down