Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 M3W Fuel Pump Replacement

One more thing I should have mentioned.

If you keep dumping warm fuel into the bucket and re-circulating it, the temp. of the fuel should continue to rise... but it doesn't.
The flapper valve at the bottom of the bucket serves two purposes. If you put an empty bucket into the fuel tank, as in a new installation, the fuel from the tank bleeds into the bucket, through the valve.

When you turn the pump on, at the junction of the fuel return tube and the flapper valve is an integral venturi. As the return fuel runs through the return pipe by the flapper valve, it creates a low pressure at the flapper valve and sucks in some cool fuel from the tank.
Cool fuel from the tank is constantly mixing with the warm returned fuel in the bucket.

The fuel in the tank will never get hot. It's in contact with the large aluminum surface of the fuel tanks.

I used the fuel pump originally installed by Morgan in 2013. It has 6,000 miles of use on it. There are no markings or model numbers anywhere on the pump. it's a centrifugal vane pump. The pump that I will put back once the testing is done, is a Walbro gear-rotor design. A well known brand with a track record of reliability.
If the old original pump is still working when I'm finished, I keep it as an emergency backup.

which Walbro pump model?

The preferred alternative is the Walbro GSS342

You'll also need:

Convoluted pump hose heat-shrink 210mm: PFH0825 (for GSS342)
Pump wire loom: 22-615 (for GSS342)
Pump rubber foot 22-63 (for GSS342)

It's detailed in the Alternative Parts List, superbly managed by Planenut:

https://www.dropbox.com/s/gbrfaonbh9xqwan/Updated%20list%20250119.pdf?dl=0

The full thread:

http://www.talkmorgan.com/ubbthreads.php/topics/556001/Re:_M3W_alternative_parts_list#Post556001

thanks.... just in case

It finally stop raining in the San Francisco area.

I did several runs with a thermocouple on the output of the fuel pump. I used the original no-name fuel pump installed in my 2013 3W.
First run had 5 inches of fuel in the tank. The fuel gauge said 25% remaining. DON'T TRUST YOUR FUEL GAUGE.

45 minute ride up and down hills. Outside air temp. 56 degrees. fuel temp.out 65 degrees. Oil temp. 215 degrees

25 minute ride up and down hills. Outside air temp. 54 degrees. fuel temp.out 65.6 degrees. Oil temp. 205 degrees.

Filled the fuel tank.

30 min. hard ride up long twisty hill. Outside air temp. 60 degrees. fuel temp.out 67.5 Oil temp. 220 degrees.

30 min. ride, mostly flat terrain. Outside air temp. 63 degrees. Fuel out temp.69 degrees. Oil temp.200 degrees.


So, the fuel pump and fuel flowing past the engine does not significantly raise the fuel temperature.

The fuel is circulating through the fuel pump bucket and the fuel in the gas tank. The big slabs of aluminum that the fuel tanks are made of cools the fuel.
As outside air temperature increases, and the temperature of fuel in the tank increases, there will be a related rise in the temperature of the fuel exiting the fuel pump, but it's going to take an incredibly hot load of fuel to reach the maximum operating temp. of the fuel pump (approx. 150 degrees)

I don't know yet the whole story on fuel pump failures, but it is certainly not hot fuel over-heating the fuel pump.

The circulating fuel cools and lubricates the fuel pump. One sure way to fail the pump is to run out of fuel.

The fuel pump failure investigation continues.

Good info, thanks.

Thanks - great and refreshing to see some actual measurements! Facts almost always help displace urban legends...

It is interesting that the temp differential is significantly more with less fuel in the tank. Stands to reason certainly, but does indicate that fuel heating is real, although as you observe, probably not significant as far as a failure factor.

I wonder if the same differential would be found on a very hot, (say 95 degree) day and a long 3-4 hour run with a tank tending toward empty.

I'm leaving the thermocouple connected to the fuel pump. Maybe there will be a really hot day sometime this summer for further testing.
I will never run the tank near empty... because it's only an educated guess as to how much fuel is left. No fuel flowing through the pump will certainly damage it.

I get 25-29 mpg. When my set odometer reaches 200 miles, I fill up the tank. It usually takes about 7 gallons, leaving a 5 gallon reserve.

New here. Thank you so much for this. Got mine.not running and it seems as tho someone has messed with the fuel.lines. was trying tonfigure this out till i realized that the fuel filter wasnt actually a filter but a regulator. There was no restriction in the system without the filter