Surging/power loss- where to start?

[rulong]

I have a 1993 - 4.3L Merc Alpha 1. Sometimes I loose power or it surges after it warms up and been running for a while. It is more noticable if I am using or start to use other auxilary items such as the bilge pump, blower, stereo, light, etc. My voltage indicator never does show 12, it is always around 10 or 11. When I turn on any other electrical components the voltage indicator needle drops. If I drop the throttle and idle along it seems to pick back up for a bit. The battery is fairly new and all connections seem to be good and clean. Can the problem be the charging/electrical system, would that cause a loss of power/surging. If something is shorting out can this be the culprit. I'm thinking it maybe the alternator which is not providing the correct charge? Or is it a fuel related issue?

 

[spktho]

Re: Surging/power loss- where to start?

It sounds to me like a fuel issue--if it does it without using other accessories also. Any black smoke on the transom when you pull the boat out? Check the choke adjustment. Then you could trace the electrical issue.

 

[Haut Medoc]

Re: Surging/power loss- where to start?

'Surging' is generally a fuel issue.....
'Cutting out' is usually an electrical issue.....
In your case, I would start with changing the water separating fuel filter, checking the screen at the inlet on the carb......
For the electrical, I would check the connections, not only at the battery, but at the block ground (earth)...
Check the alternator connections, & pull the large 'cannon plug' apart & inspect for corrosion.....
The volt meter should never be below 13 volts with the engine running on a healthy charging system....
If none of the above helps, take the alternator out & have it checked at a shop....
There are specific tests outlined in the "adults only' section at the top of this page for both fuel & charging systems, check 'em out if the visual inspections I gave you don't help.....