Dead fuel pump

[Jowe]

Las weekend, I was about to adjust my idle during warm up. The procedure needed a lot of engine starts and stops. After a while, I couldn't understand why the engine started to stumble and finally didn't start at all, until I noticed the fuel pump buzz from back was gone. I checked the fuse #4, but I realised that the old pump was stone dead .
I have now hoisted the car and started to dismantle the cover shield around the (early, long style) pump. But when I was about to pinch off the fuel feed line from the almost full tank, I felt it was very stiff, so I didn't wanted the risk to crack it. Any suggestions on how to proceed? Should I pump up the petrol from the filling end instead?

The next question is about what to do with the pump. For the moment, I don't know exactly the failure cause since it's still on the car. Though, I have noticed that a rebuild kit is sold by vintageeuroclassics. If I order now, I will save some time until I have been able to remove the pump. Should I go for that, not at least for preventive matters

[twistedtree]

You have the older tall pump that is correct fro that car.  Later cars have a short pump.  If you get a rebuild kit, be sure it's for the correct pump.  Alternately, you can retrofit a short pump, and it will require an adapter bracket.  I'd replace all the soft hoses while in there.  It will give you some extra peace of mind.  You might just have to bite the bullet and drain the fuel tank.

[scoot]

Unless you have old gas in the tank, I wouldn't drain it.  If memory serves me correctly the tank has a forward fitting and a return fitting, both connected with rubber hoses and hose clamps.  I would make two short hoses with new fuel line.   Have the car elevated enough that you can work under it with a 5 gallon bucket, and stick a appropriately sized bolt into one end of each of the two temp hoses.  Loosen the hoses one at a time from the tank and when they start to move gas will start dripping on you.  At this point you can probably pull the hose off and put your thumb over it, and then as fast as possible put the temp hose over the fitting on the tank.  Gas will be spilled, but that's going to happen regardless. 

Do you have any idea what the fuel tank level is right now?  If it is high then draining the tank is a big mess, and you end up with containers of gas that you don't know what to do with.   If the tank level is low it is much easier to drain, but still makes a mess.

[Jowe]

Today, I bought three cheap 20 litres spare tanks and a siphon and sucked up most of the petrol. Next is to go under and remove the hoses, as Scoot proposed, and pick up the last drops with a funnel. I have also ordered the pump renovation kit today and new hoses as well as a new seal for the tank filter, which I also intend to clean, while the tank is empty. Many thanks for all support. I'll keep you updated about the progress, guys.

[Jowe]

Pump is out, steam cleaned and bench tested. It actually spinns! If it runs with intermittent failure or not, I'm not sure. I will check the current on the cables that connects to the pump. To eliminate any other causes, is there any possibility that the key lock switch that engages the pump may be fault?

[Jowe]

Have opened the chambers and the top of the motor. The impeller chamber was nice and clean. The inlet and outlet chambers were covered with what look likes soot. Hmm, could it come from the motor, I asked myself . Opened the top end of the pump motor. I was like a coal mine... 

[Jowe]

The rebuild kit is now fitted to the pump after thorough cleaning. New bearings, seals, washers and screws. I had the local Bosch electrical service to remove and refit the bearings. The pump was tested with diesel and the pressure and volume was within tolerances. So, I mounted the pump on the car with new hoses and clamps, as well. The engine starts and runs as expected. However, the noise from the pump is awkward and very high. Should I've done any greasing in it? Or anything else that I might have done wriong?

[Benz Dr.]

I assume you installed new brushes? I can't say for sure but it might wear in and stop making a lot of noise. They always make some noise, which is normal, but it shouldn't be too loud. I've found that varying pitch in the sounds they make is never a good sign.

[Jowe]

Yes, the bushes are also new. I let them work in for a while and see if any change occurs eventually.

[wwheeler]

Both tall pumps I have had (W111 and then W128) both made louder, variable pitched whining just before they went out. I had new brushes installed in one of them to no avail. Don't be surprised if you have to replace it soon.

[Jowe]

Both tall pumps I have had (W111 and then W128) both made louder, variable pitched whining just before they went out. I had new brushes installed in one of them to no avail. Don't be surprised if you have to replace it soon.

Do you mean that the new brushes will not last any long? Anyway, the noise is annoying louder compared when before I renovated the pump. However, now I have winterized the beauty and will not fire her up until spring, with an intermediate warm-up drive on a dry winter day. As Benz Dr. suggests, the brushes will wear in over time, and that is what I'm putting my bet for.

[wwheeler]

Not sure about the brushes. I just know that on both, once they started whinning, it never stoppped.

[Jowe]

However, the noise from the pump is awkward and very high. Should I've done any greasing in it? Or anything else that I might have done wriong?

Last week I took the pump out from the car, disassebled it and put it together again, but now even more carefully and testing with power before tightening up. So far it's was spinning very well. However, when I mounted the pump back on the chassis I found the top of the pump to touch the chassis. Obviously, the rubber mountings in the renovation kit were too short. I fixed this by shimming up and made enough clearance for the top. Most likely this was the actual source of high noise.