Fuel Pump Failure and Revival

[Stevester 500E]

I have a W124 M104. Car sat close to a year without being started and I did not put a fuel stabilizer in the tank.
No surprise the car didn't start. Fuel pumps don't prime, they are dead.

Is there a way to revive them or do I need to replace them?

What exactly cause the pumps to go bad under this circumstance. The same thing happened to a 1998 Ford Explorer of mine years back.

 

[gerryvz]

Likely the fuel dries out and leaves a crusty film in the pump(s), freezing them from the inside. There are two different types of pumps for the M104 W124s -- although the very vast majority use the early style pumps (same as the E500E). Confirm with the EPC which style your car takes. Best to just get new pumps via AutohauZ or Amazon, they seem to have among the best prices, around $100 apiece. Bosch only.

I've never really heard of reviving these rotary-style pumps, though you could try by banging them with a hammer and seeing if they come back alive. Also, check that they have power at the fuel pump relay.

Good luck !

 

[gsxr]

Try forcing +12v to the pumps first, and tapping them (gently!). If they don't spring to life... probably need to replace them.

Note that if you source good used pumps, they may leak slightly from the body ends. If so, monitor closely and see if it goes away within a day or two. New are $90 each from Amazon:
https://smile.amazon.com/gp/product/B000BZIDP8/

I don't know what causes the failure, but with fuel stabilizer, they are usually OK for at least a couple years of storage. If possible, turn on the ignition to run the pumps once or twice per year, just to keep the internal parts moving.

 

[Bogeyman]

Careful banging on them - hit them too hard and they will leak.

 

[gerryvz]

Perhaps use a rubber mallet instead of a metal hammer.

 

[JC220]

I have a W124 M104. Car sat close to a year without being started and I did not put a fuel stabilizer in the tank.
No surprise the car didn't start. Fuel pumps don't prime, they are dead.

Is there a way to revive them or do I need to replace them?

What exactly cause the pumps to go bad under this circumstance. The same thing happened to a 1998 Ford Explorer of mine years back.

Is it a 300E-24 model or the later 320E / 320CE etc?

I ask because the MAS relay on the early CIS 300-24 models is a very common failure and can die without warning like yours did.

 

[LWB250]

Perhaps use a rubber mallet instead of a metal hammer.

Just be sure to put out that heater you're beating before doing this.

Dan

 

[gerryvz]

JC, it would be a 1993-1995 car with the 3.2-liter M104 (HFM injection).