4.3 GL-D Electrical Issues

[PutMeOnTheWater]

These are the numbers on the engine cover sticker.
4.3 GL-D
3869251
4012141889

Took the boat out Saturday. Pumped the throttle a few times and it started right up, ran for about 10 seconds and died. Couldn’t get it started afterwards. My mechanically inclined neighbor took a look.
1)The fuel pump relay tested good
2) the pump above the fuel filter ran when power was given below the relay

He looked something up and said the relay should get its signal from a switch that is hooked up to an oil pressure sensor. We found an oil pressure sensor on the top of the motor but couldn’t find a switch. I’ve only had this boat a couple months but I’ve always had to manually pump the throttle a few times to get gas into the carb to start it. Also I’ve never heard the fuel pump prime when I switch the ignition to on. His going theory is the main fuel pump that’s on the tank has not worked since I got the boat because the switch that is supposed to send the signal to the relay was removed or never installed when the engine was swapped (I was told the engine was swapped when I bought the boat, but don’t have any more info). He said the filter may need to be replaced or maybe the accelerator pump is worn out from doing all the work. We’re going to change the fuel filter and see if it starts. Just trying to see if this makes sense to anyone here and if anyone knows where this switch between the oil sensor and the fuel pump relay is supposed to be.

 

[PutMeOnTheWater]

The engine was swapped before I bought the boat and I’m trying to figure out what these go to. One I think is a ground wire, the others I don’t know. We think there something that’s supposed to connect to the oil pressure sensor that is missing. I recently added a Bluetooth adapter to the factory radio’s cd port input. While installing I realized the remote and power wires were all connected together so disconnected and connected them separately. The radio worked fine until I started the boat, then it had what sounded like electrical interference coming from the running motor. I assume this has to do with the ground?

These are the numbers on the engine cover sticker.
4.3 GL-D
3869251
4012141889

Thanks for any insight!

 

[alldodge]

I'm going to merge your wiring threads because while it is 2 different wiring issues they are both wiring issues, and this will help others keep up with issues

The second pic seams to be coming from the exhaust and is a Tan wire. Might be Tan/Black and if so it goes on the exhaust overheat sensor. There is one sensor on each exhaust

The first pic might be for bonding and has had a piece of black wire attached to it. If so it's goes to ground

This is a V8 but wiring for sensors is the same.

 

[alldodge]

Your friend is thinking about a Merc and VP does wiring different for the fuel pump. When cranking the Yel/Red wire sends power from key thru Yel/Red wire to a diode and then to the relay. When cranking power energizes the relay and turns on the pump

Once running, power is removed and relay is energized by the alternator sending power thru another diode to keep relay energized

 

[PutMeOnTheWater]

Your friend is thinking about a Merc and VP does wiring different for the fuel pump. When cranking the Yel/Red wire sends power from key thru Yel/Red wire to a diode and then to the relay. When cranking power energizes the relay and turns on the pump

Once running, power is removed and relay is energized by the alternator sending power thru another diode to keep relay energized

Got it, so when actually cranking, it should trigger the relay?

 

[alldodge]

Got it, so when actually cranking, it should trigger the relay?

Yes
Here is a close up, Red/Yel cranking, Green running