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

Planenut and I have got together to produce these instructions on how to replace the standard (Landrover Discovery) fuel pump with a more reliable aftermarket pump. There seem to have been quite a few failures recently so this is a recommended upgrade, especially if you have long trips planned.

M3W Fuel Pump Replacement

Please let me know if you spot any mistakes or have suggestions on how the document may be improved. It will shortly also be available via the Morgan Three Wheeler Club web site.

Wouldn't it be an idea for MMC to convene a forum of some of the more knowledgeable owners like yourselves to sort out some of these unnecessary niggles? Eight years too late, maybe, but there are still easily avoidable build issues.

Well done Ian and Andy, looks like an excellent set of instructions 👍

Great work guys

What an excellent write up on how to change an intank fuel pump. Ian and Andrew deserve high marks for taking the time to explain this procedure.

Questiioon, did you comsider any other pumps?

Another question , and perhaps an old guy question, I have been a carburetor guy for a lng time and never had to service a fuel injected vehicle, so why is it necessary to put the pump into the tank? All you young guys probably know why but I can only theorize.

I am not sure the pump needs to be in the tank. However you need the proper pressure with fuel injection. I know with my '05 Harley it turned out a had a little leak in the line inside the tank, but I would only notice kind of a stall with acceleration.

Just thinking out loud, but does it dump the extra pressure back into the tank?

I believe it helps cool the pump

Yes, that is true. Also, having the pump & sender on an assembly probably makes sense in a mass production environment?

Cooling the pump,, never thought about that! I would bet it is especially true if the pump was in the engine compartment.

Since the M3W is pumping a cool liquid (fuel) I have difficulty seeing how it could get to hot, BUT if it is leaking pressure inside the tank then that is a real problem because you cannot see it happening unless you have a tank pressure sensor. Does Morgan M3W have a tank pressure sensor?

In real old cars there was the fuel pump located inside the engine compartment and it generally was mechanically actuated. It also had a fuel filter bolted onto it in the form of a glass fuel bowl that could be observed and cleaned as necessary. These things could get hot and cause what was called a vapor lock and ruin your day, or at least until the system cooled down enough to allow the pump to work again.

Morgan must have put it in the tank to save time with an off the shelf item locally sourced. If the fuel pressure and flow spec could be met with an external pump I would think that much better from a maintenance and replacement viewpoint.

Also if the tank was clear of anything except a pickup tube then a nice drain cock to bleed off condensate could be installed :-)

It does dump the unused fuel back to the tank. If you look at the injectors, you see a line to each one which appears from the back side of the engine. It would be normal carburetor logic to figure each injector has its own feed. Then you notice that there is a fuel line between the two injectors. What you have is a pressurized loop that comes from the tank, thru the injector housing and back to the tank. The ECU signals the injector when to turn on and when to turn off. It is much more precise then the Bing CV carburetors on my old BMWs and pretty much fuss free when all the pieces work.