HP fuel pump questions

[ajcatman]

2003 Suzuki DF140. I'm trying to get answers as to why my HP fuel pump is not running. I don't get the 3 second run when I turn on the key. I checked the terminal, I had 12v at the lead but no continuity on the ground. I spliced in a separate ground wire and the pump ran, started the motor and ran for 2 or 3 minutes then killed. Now I'm showing 4 volts at the lead. Where could the voltage have gone. I'm showing 12.6V at the battery. Does the ECU control the ground to the pump? If so, why don't I see it when I turn on the key?
I have the online service manual but it doesn't go into detail on any of the questions I asked.
The motor left me stranded on two consecutive trips. It started and ran great but wouldn't run after a few hrs of fishing. Since the last tow in, the only time I've gotten the motor to start was when I spliced the ground.
Any suggestions???

[artdf175]

Are you experiencing any other power issues?
You might check power connections in the "white wire" that feeds power to your remote controller/ignition switch
This is a source of power to the ECU
If there is a connection going flaky it could be causing other problems
I'm out of town without a electrical schematic at the moment
If there are no other replies will get back in s couple of days
Art

[ajcatman]

None that I'm aware of. I have the electrical schematic from the service manual but it doesn't give me much info. I'll check the wiring later today. The white wire, where does it go? I've read a lot of forums and the white wire is notorious in many posts. It's difficult to trace because everything is so congested.

[artdf175]

My white comes off a power lead from my Main battery switch
In my case the spliced connection from that short power lead was a real irritation with intermittent power failures until it finally quit
Depending on how your boat is wired this wire can go to the helm and power up your dash instruments with a lead then running to the ignition switch or directly to the ignition switch with a completely different source for the helm
This wire also has an inline fuse built into it
A lot of times connection look perfectly good from the outside but have corrosion on the inside

[ajcatman]

I did some electrical checks and what I found was my voltage to the fuel pump is low. If I put pressure on the harness to the ECM the voltage raises to battery voltage. I'm not quite sure which wire feeds the pump but I do know that if I get the harness in a good spot, the power is constant. It changes with any slight movement of the harness. I think this is why sometimes it will start but motor vibrations causes the connection to fail. Running out of daylight today, I'll do some more checking in the morning.
In the meantime, has anyone seen this phenomenon?

[ajcatman]

I guess I need to check if the low voltage is common to all the gray (hot) wires. It's something that I just ran across on the wiring schematic.
Does anyone know where the power to the Joint Connector comes from? Looks to me like it comes from the starter motor relay on the white wire. My diagram is small, difficult to see.

[redlowrey]

Battery voltage will flow to the ignition switch through a white wire in the loom either from the starter soliniod main battery connection, or fused directly from battery pos. When you turn the key on, battery voltage will flow back down the loom through a gray wire to the main relay coil and to ground inside the ecu. When this happens the main relay contacts will close and battery voltage will flow to the fuel pump, injectors, ignition coils, and so on. Pull the plastic cover off the front of the ecu, pull it forward and let it hang, then you will see two relays, the one on the left is the starter relay the one on the right is the main relay, check to see if the connector is not on properly. With the fuel pump when you turn the key on battery voltage will flow from the main relay to the fuel pump then through it to ground in the ecu for three seconds, if it doe's not see a signal from the crank sensor it will remove the ground. The ground in the fuel pump is duty cycled. To check the ground in the ecu connect up a low powered test light to battery positive, put the test light probe on the black and white wire on the connector get some one to turn the key on , the test light will light if there is a ground. there.

[ajcatman]

Got it solved. The gray wire supplying 12V power to the JOINT CONNECTOR on my main wiring harness had some corrosion. Cleaned it up, established a good contact and she's purring like a kitten.