2019 f300 fuel pump.

[bc545571443]

Hello,

My new to me2019 f300 will not start.

Verified fuel delivery, new fuel, swapped line from running motor. New, strainer (looked good) VST filter (was shot) float was stuck as well which is now good.

When I turn the key on the port motor (running motor) fuel pump primes.

The STBD motor does not prime. I put a meter on the harness output and no voltage. Verified 12v on the other running motor. The Fuses are all good in the fuse box and verified power at the HP pump fuse.

Can anyone think of anything else obvious before the boat goes to the dealer next week?

[boscoe99]

What about the fuel pump relay?

Is power getting from the fuel pump fuse to the relay?

Is the relay closing when the key is turned to the ON position?

If you feel the relay closing is power getting across the relay to the wiring to the fuel pump?

[oldmako69]

Please post the solution when you get it.

[bc545571443]

I attempted to find the fuel relay in the drawings or on the physical motor. I see the relay box located below the fuse box with several relays all labeled with the same part number.

Because they were all the same PN I did move them all down a slot and the last to the first to see if it traveled. No luck.

[bc545571443]

Please post the solution when you get it.

No problem!

[boscoe99]

If you have electrical power to the fuse, don't stop there. Check from the fuse onward all the way to the fuel pump connector.

[99yam40]

need to know where both meter leads were placed also

[boscoe99]

OP seems to have stalled out. He got to the fuse and appears to have given up.

If he got voltage at the fuse then I would hope he can figure out how to measure voltage down the line.

He is over on the "other" site getting great advice. Two posts about checking the kill switch.

[99yam40]

sounds about right for over there

[bc545571443]

Haha I was hoping for Allboy over there to give me guidance.

I am hoping to try and chase down the voltage issue later today.

I haven’t checked continuity of ground from the plug to the block which would be easy to rule out. I did try to swap the starter relay with the fuel pump relay and I still get starter and no pump.

[bc545571443]

To 99yam40

When I tested for power at the harness I just did voltage straight across the plug.

I really need to ring out the ground cable in the plug. It’s next up on the list.

when I checked at the fuse block I went from the fuse holder to ground cable from battery.

[boscoe99]

To 99yam40

When I tested for power at the harness I just did voltage straight across the plug.

I really need to ring out the ground cable in the plug. It’s next up on the list.

when I checked at the fuse block I went from the fuse holder to ground cable from battery.

The ground lead for the HP pump is not grounded except for a couple of seconds when the key is turned on. Then once the motor is up and running the ground will be there.

Best to test from R/Y wire to the pump to a good ground on the block.

Summary - R/Y wire should have voltage with the key on. The black wire will normally not have a connection to ground if the motor is not running. The fuel pump relay applies battery power to the R/Y wire. The ECU applies the ground to the black wire when the ECU wants the pump to run. The ECU wants the pump to run for a few seconds when the key is turned on. Once the motor is being cranked and then running the ECU will then again ground the black wire.

[bc545571443]

Excellent description- thank you. Will check out soon

[bc545571443]

The ground Rings out.

If I measure VDC across the R/Y harness lead to the HP pump and a known ground I get an increase from 0V to about .15VDC for the few seconds when I turn the key on.

[boscoe99]

Haha I was hoping for Allboy over there to give me guidance.

I am hoping to try and chase down the voltage issue later today.

I haven’t checked continuity of ground from the plug to the block which would be easy to rule out. I did try to swap the starter relay with the fuel pump relay and I still get starter and no pump.

Allboy would be a fool to post at that joint.