Won't start with full fuel tank

[jseadoo]

My 03 155 will not start if the fuel tank full. Fuel pump seems dead.
Starts and runs fine if I drain fuel down to a third of a tank.
What's happening?

 

[clegg]

Try running it with the gas cap loose or off. Sounds like a tank ventilation issue.

 

[jseadoo]

The fuel pump doesn't power on if it's submerged in gas.

 

[ski-d00]

The fuel pump doesn't power on if it's submerged in gas.

The fuel pump is at the very bottom of the pickup so it is always submerged in gas. The problem is that the tank is not venting well enough. As stated above, leave the gas cap off or very loose and I'll bet it runs fine. When there isn't enough air in the tank, it can't vent quick enough to keep itself running. Your check valve in the vent line isn't working or your vent line is plugged up. Simple to fix/replace.

 

[jseadoo]

Thanks but, it doesn't power up when the key is applied if gas is above a half tank. Low gas and it powers on when the key is applied.

 

[ski-d00]

So you've tried it with the gas cap off? It's possible you have a connection problem that shorts the wires out when you have a full tank. Pull the fuel pump and should be a simple fix.

 

[jseadoo]

I'm not familiar with the components of the fuel pump assembly. Will remove and have a look. Any advise welcome.

 

[jseadoo]

Update: I reassembled the pump assembly with new connector and cleaned contacts on the pump itself. Filled it up. It went 300 yards and died. BRP dealer sold me an OEM pump assembly ($840 CDN plus tax). I installed the new pump assembly. Pump does not power up.

 

[POPPS]

Pull the connector,,,attach meter on volts dc,,,apply key,,,see if voltage appears at the connector,,,forget what the voltage should be?

 

[depami]

Try unhooking the fuel level sensor.

 

[jseadoo]

Thanks everyone. All sorted out. The ground to the fuel pump is supposed to be provided by the ECU but it's broken. I supposed a direct ground to the brown-pink wire. It works but Check Engine is on the display.
Anyone know how to get rid of check engine?

 

[ski-d00]

Fix the code that it's throwing

 

[mkov608]

The fuel pump is a ground-side switched circuit controlled by the ECU. Power comes from the MPEM. If the driver in the ECU goes bad, the fuel pump will not run. I had a fuel pump driver fail in an ECU last week, but a freaking ECU is expensive, so I ran an alternate switched ground wire to the fuel pump. It works like a champ, however it will set a P0231 fault (fuel pump shorted to ground) DTC from now on.