New Fuel Pump not running off started engine

[NewerBoater]

Hello,
I posted before about my '97 Volvo Penta V6 4.3 GL(PLK?) - cannot locate the model number - not starting well, just cranking. We determined a bad alternator and fuel pump, so I replaced those along with the relay, but now it is stalling after running for about 15 secs. The fuel pump is feeding gas off of the battery (took the line off and verified), so I get it running fairly easily, but it seems as soon as that initial gas burns off the engine dies out as the fuel doesn't seem to be continuing once it switches over to the alternator. Looking at boards and diagrams its looking like it could be a diode or possible oil pressure sensor? Can anyone point me to things to help diagnose with the volt meter before starting to replace more parts one-by-one? Looks like the Don S. fuel guide requires the engine to be running for several mins to run tests

We looked at the carb, but seems to be functioning ok.

old post: http://forums.iboats.com/forum/engi...50-starting-trouble-locating-the-model-number

 

[Dave-R]

The fuel pump has 2 power supplies. When cranking the engine, the starter supplies the power. When the engine is running, the alternator supplies the power. There is a diode in each supply to keep the each supply from back feeding the other. The loss of the alternator supply sounds like what you have. When starting, the pump fills the carb bowl, then after 15 seconds of running, the bowl is empty. You can remove the fuel relay and jumper the pump to run. Then the pump will run until the jumper is lifted. If the engine will run, I would think your problem is with the alternator supply. Good luck. Dave-R

 

[NewerBoater]

Yep, thanks for the response, Dave, looks like I had the 'green' wire not connected. I hooked it up to the 'EXC' connection on the alternator and we're back in business in terms of running.

Now, curious if that is the correct wiring as I am seeing conflicting diagrams. The green arrow is where I attached the green wire, which already has a purple and RED wire. I am wondering if it needs to be move to the location of the gray arrow, but am not clear which connection that is (L2?), even though that is where it looks like it 'should' go according to the penta manual I have. I am confused because when i pulled the old alternator off the green wire was disconnected, otherwise I marked and moved the wires exactly as before. This is an aftermarket alternator, but has the same setup as my stock Mando.

(sorry for poor quality, larger photo wouldnt upload)

 

[NewerBoater]

Ended up going with the green to the L2 position, i still have an additional purple wire (pictured in the bottom left) that is not connected but everything seems to be functioning correctly. Any further input on wiring would be appreciated.

 

[bruceb58]

Purple wire goes to the EXC terminal and there is likely a jumper form that that goes to the S terminal

If its a purple/white wire you are talking about, that goes to the P terminal and that goes to your electric choke.

 

[NewerBoater]

Makes sense, with your response and affirmation from: <http://forums.iboats.com/forum/boat-repair-and-restoration/electrical-electronics-audio-and-trolling-motors/9988403-replacement-db-electrical-alternator-wiring> i'll run the purple capped wire to 'P'.

Thanks!

 

[bruceb58]

As long as its purple with a white stripe!