350 Mag fuel pressure

[Jpettinat]

Took boat out this morning with pressure gauge and meter attached. After about 5 minutes voltage dropped to 0. I connected a second ground wire to the pump , still no voltage. Jump power from another source and boat tan fin back to dock. Took the plugs out of the ECU and examined them, they look fine, took relay off and switched it dith another one. Still no voltage to pump. Tried turn batteries off and back on still no voltage. Hopefully now i can locate problem since its not coming back on.

 

[alldodge]

Check your fuses on the motor

 

[Jpettinat]

Did that all good

 

[alldodge]

Need to find out if the PCM is removing the ground to the relay, or your missing 12V to the relay. The pic is from a 2006 manual 555 ECM, so colors may or may not be correct.

The Green wire coming from pin A19 and goes to coil of fuel pump relay (g). ECM applies ground and relay closes and transfers power to fuel pump. Power to the relay comes from the main power relay (I). The MPR is energized when key is first turned ON and there would be the fuel pump and beep turn ON by pin A22

 

[Jpettinat]

I don’t believe that is the correct wiring disgram for my boat. Mine is a 2010 350 Mag and the ICU is square with three plugs going into it. The fuel pump relay has three pink wires and one green with black tracer. When i turn key on two of the pink wires to the relay show voltage.
motor # 1A628103

 

[alldodge]

Agree, but that's why I said colors may not be correct. This is a 555 ECM and you have a PCM 09 I would think

Anyway, so your getting power with key ON and would get power to the other pink if the relay closed (green/black wire is grounded by PCM) and this would send 12V to fuel pump. Just need to know why the PCM is not supplying a ground.

If the motor thinks it lost oil pressure it will kill the fuel pump ( or at least I think it does) muc

Motor needs to be scanned for codes

Put meter on black/green wire and other on ground. If no voltage is found (shouldn't find any) then switch to ohms and see what kind or resistance is found. Then try to ring out the wire

 

[muc]

If the motor thinks it lost oil pressure it will kill the fuel pump ( or at least I think it does) muc

The only reason the PCM 09 would remove the fuel pump relay ground is if the PCM loses it's RPM signal.
Low/no oil pressure will set guardian.

AllDodge has you troubleshooting in the right direction. If it's not the wires, only thing left is the fuel pump relay driver in the PCM

For future reference, the fuel pressure regulator for this engine is on the top of the FSM. The part on the fuel rail doesn't regulate the pressure. It acts more as an dampener.

 

[QBhoy]

Is this the original engine ? Don’t suppose it’s a new engine 350 mpi trying to use the ecu from a previous 305 mpi ? Just a thought I had.

 

[Jpettinat]

All dodge, whats the FSM ?

 

[Jpettinat]

The fuel pump relay has four wires pink, Green/blk tracer, Pink /yellow tracer and a Pink/green tracer. I have voltage across the pink and Green/blk tracer. When relay is energized i have voltage to the Pink/Yellow tracer which goes to pump. Think my issue is in the plug that connects to pump. I’ll clean that up today and if weather holds up, take it out on water to see if there is improvement.

 

[Jpettinat]

AllDodge, that regular was also changed when I rebuilt the pump.

 

[alldodge]

The fuel pump relay has four wires pink, Green/blk tracer, Pink /yellow tracer and a Pink/green tracer. I have voltage across the pink and Green/blk tracer. When relay is energized i have voltage to the Pink/Yellow tracer which goes to pump. Think my issue is in the plug that connects to pump. I’ll clean that up today and if weather holds up, take it out on water to see if there is improvement.

With relay not energized there should be 12V on the Pink and Green/Blk because the Green/Blk has not been grounded by the PCM. Power travels thru the magnetic coil in the relay and out to the Grn/Blk. When the Grn/Blk is grounded the relay is energized.

What is happenig is the PCM is either not grounding because of not getting RPM signal (as muc mentioned), or the ground is not being done because there is a bad connection between Grn/Blk or the PCM needs to be repaired

 

[Jpettinat]

I cleaned the fuel pump connector with vinegar and salt then neutralized it with baking soda. Spent about three hours on the river , didnt skip a beat. Thank you all for your support!