2003 Ford Expedition Fuel Pump Relay (R303) Damaged

[Martynka]

Did that fix resolve this problem? Did you encounter the same issue with the R303 relay again?

If you ask me - yes, it help and I use standard 30A relay, not "mini 20A" ( in my opinion 20A is overrated for this relay to work long time )

On my profile I have a question:
"Hello. I was just curious why you think the problem is the fuel pump?"

Because your relay is rated for 20A. Fuel pump need to work about 15A. If your pump's motor starts to seize and has greater resistance, then the pump's power consumption increases. If rise above 20A can destroy your relays. If relays is melted after 20 years it can be because overheating, but after few days ?? For me it means:
- too much current flow through the relay
- factory damaged relay
- damaged/overheated relay solder pads

"Is there a way to check if the fuel pump is causing this issue before replacing the fuel pump?""

You can measure pump power consumption with multimeter device with 20A current probe possibility. You need to connect the meter probes in series with the pump power cable from the relay and start engine. You will see power consumption of your fuel pump. It will be good to drive and observe. Sometimes current rise with temperature and it need time.

If you observe that high current is not your problem, check solder pads on PCB. Look on my photo with pin description and remember:
- PIN 30 ( main power sypply ) is solder to circiut from bottom side
- PIN 85 and 86 ( relay coil supply ) are solder to circuit from bottom side
- PIN 87 ( pump power supply ) is solder to circuit from upper side - it means that you need to use more tin and heating time to make good contact. If you don't do it right, the pump will not start or stop working. Maybe this is your problem.

 

[mggmgm1]

Sorry it is not clear. What did you do to resolve your problem? Did you solder a 30 amp relay or did you replace the fuel pump?

 

[Martynka]

Did you solder a 30 amp relay or did you replace the fuel pump?

I use 30 amp relay because it is standard car relay ( normal size ).
My fuel pump workf fine. Power consumption is lower than 20A.

I wrote you why I think that it can be fuel pump... but first need to check current for pump, and soldering new relay on PCB.

 

[mggmgm1]

Ok thank you for clarifying my question. Do you know how I can test my fuel pump if the R303 relay is damaged and allowing no current to go to the fuel pump?

 

[Martynka]

Do you know how I can test my fuel pump if the R303 relay is damaged and allowing no current to go to the fuel pump?

You can check it with engine off and broken relay.
You need to bypass battery + with power supply for fuel pump. Now I don't have electric diagram but try to find.

 

[mggmgm1]

Oh thank you so much, I hope you are able to locate the diagram, I really appreciate your assistance!

 

[whtbronco]

You can put in a temporary wire, jumper, to provide power to the fuel and circumvent the fuel pump relay. If the fuel pump runs you have isolated the fault to the factory relay. Run a wire from a constant or switched power lead to the output wire from the relay. The output wire is green with a yellow stripe, the below pic has a wire inserted into the connector.



External relay:
https://www.amazon.com/APIELE-Water...xvZ0NsaWNrPXRydWU&th=1&tag=expeditionforum-20


Here's the circuit board relay connection points once you get the old fuel pump micro relay out of the way.






The info and pics above are from ExpeditionForum threads.

 

[whtbronco]

 

[Martynka]

I hope you are able to locate the diagram

You need to find "dark green/yellow" wire. It is wire from relay to the Inertia Fuel Shut off switch and from switch to the pump.

Because on junction box you have "few" wires and is not to easy located "dark green/yellow" one, the simpliest way to check fuel pump is use "Inertia Fuel Shut off switch". It is switch in trunk on left side behind plastic cover. it is connected to "dark green/yellow" wire from relay side and "pink/black" from fuel pump side.

If you take long wire from battery + and connect for one of this wire pump start to work. If you have current metter you should connect one probe to the battery, second to one of this wire. Pump will start and you can read power consumption.

If you prefer to use wire from junction box, I can go to the car and check where is connected.

 

[mggmgm1]

Hello Martynka. I would do this to test if the fuel pump is pulling too much current?