Newer Fuel Pump Seized - Help

[Michael D.....]

I purchased a 1966 230 sl which just had a lengthy visit at the mechanics shop.  On the list of repairs was a replacement of fuel pump and drain tank with sediment.  Shortly after the work was done the owner had some health issues and the car sat for about 8 months with out starting. When I bought the car, I shipped the car non- running to my MB mechanic who diagnosed rusty fuel tank and seized fuel pump.  I suspected when i bought the car the fuel tank was shot and needed to be replaced due to the tank being drained and sediment found.  I thought I would be able to salvage the fuel pump though and figured the tank screen was plugged from sediment.  Has anyone unseized a fuel pump, I suspect this one has less then twenty miles on it?  Any ideas what caused it to seize?

[ja17]

Hello Michael,

The electric fuel pumps are fairly easy to free-up.  You can first try spraying some penetrant into the fuel openings and letting it soak.  Hook up 12 volt power source (Caution, be careful there is no fuel present, sparks !).   You can even try reversing the wires since this is a DC motor and can run backwards.

If it still does not free up, the lower cover on the pump can be removed by removing the small screws. At this point you will be able to turn the rotor and fee-up the pump. Be careful not to loose the tiny woodruf key on the pump shaft.

While your at it, the intake fitting for the electric fuel pumphas a filter screen built into it. Remove and clean it while your at it.

[Michael D.....]

Thanks for the suggestions I will give it a try.  Any idea why it would have seized up?  Do you think this caused any permanent damage?

[114015]

Hello Michael,

Eight months is ususally not a long time ago that the pump (hopefully) ran the last time if it really did ...

1) However, it is well known that old fuel can gum up (some sort like a gel or epoxy) and sticks together everything. I once destroyed a pump because I did not pay attention to that. :'(  But this is unlikely if the pump already ran 8 months ago.

2) Is the pump really new or is it only "refurbished"? 

3) If the inlet filter screen is missing dirt, especially rust can enter the pump chamber and clog the rotor.

I recommend not to try to run the pump electrically and try to free it more than a very few seconds. You will destroy the armature (ask me how I know ...)
Better follow Joe's advice.

Best,
Achim

[ja17]

Micahel,

Rubbing Alcohol, seems to be the best thing to quickly desolve fuel varnish.  Caution, it is flamable. You can use this for clean up if dried up fuel is the issue. Penetrant, like WD40 will work on rust. Check the screen built in the tank drain also. These can become completely clogged with a tough coating of fuel varnish also.

[230slhouston]

Hi Micheal,

I had a fuel pump sitting for 20 years and seized, totally. I stripped and soaked it in marine clean, a POR 15 product. This stuff is magic, it removed all the varnish, Pump is as good as new and works fine. I also used it to free up the float as well. Soaked it for three hours. It also works now.

I am sold on this stuff even for parts celaning. It is $21 a gallon. Anyone know and equivalent that is cheaper?

Regards
Maistran

[Travis71280]

I used Super Clean and some old toothbrushes on mine and it worked great at disolving the varnish. Be careful with using it on aluminum parts too long though if you let it set for long periods of time though, dont ask how i know. I did use the POR-15 product when I cleaned and relined the gas tank and i highly recommend it.