Volvo penta 1993 434a v6 alternator help? Fuel pump? , please, please help!

[win-or-bin]

Hi all
i have had a few issues with my boat recently and thought today I had finally got to the bottom of it after pulling my hair out with a fueling problem that believe it or not turned out to be a faulty batch of brand new pumps!! Now when I start the boat it starts fine runs for around 30 seconds then cuts out, on my dash I am getting no output from the alternator, output staying below 12v when running. Clearly there is a problem and am going to check the output from the alternator tomorrow with multi meter I just wondered if there was anything else to check? I think the problem is when the boat starts power should come from the alt to run the fuel pump but this isn't happening? Relays? Anything else, really want to get this put to bed.
Thanks for any help

 

[alldodge]

Do think you have the issue found. The ALT does power the fuel pump after so many seconds. Also check the diodes

 

[win-or-bin]

Thanks for taking the time to reply, how do I check the alt diodes? Do you know of any other wiring etc I could check, don't have access to any boat shops so need to do everything myself and don't want to miss anything
thanks

 

[win-or-bin]

Ok,
Checked the Alternator today, no change in voltage when the engine is running, so, is there a way to check if the regulator on the ALT is faulty or the ALT itself? Big difference in price between a new ALT or just a new regulator
Thanks in advance

 

[alldodge]

The diodes are inside the regulator. You can replace the regulator pretty cheap in most cases

 

[alldodge]

Got this thread mixed with another, but alt answer is the same. The diodes I mentioned are in near the fuel pump relays. Diodes get check using the diode scale on the multimeter. When probes are connected on each side it will read high resistance one way and low the other. Since the ALT isn't working the best chance right not this is the issue