[T3] Mechanical Fuel pump kit

Jim Adney jadney at vwtype3.org
Thu Dec 14 10:01:56 PST 2023

On 14 Dec 2023 at 9:16, Joe Plowick III wrote:

> I have a T3 mechanical fuel pump that I would like to get a new diaphragm
> for.  It's a Brosol pump with a 4 screw top cover.  Do they make kits for
> these?  The pump is in good shape and works, but the diaphragm is starting
> to stiffen up after sitting and won't push fuel any more.  Taking it apart
> and moving it a little usually gets it working again.
> https://ibb.co/8cZsTnz

It's possible that the problem is not with the diaphram, but with the check 
valves. Clean any dried gas residue off them, or they can stick and not work.

I don't know much about the mechanical fuel pumps, but, in general, old 
rubber parts that were in contact with gasoline for a long time tend to get 
quite stiff if they are allowed to dry out. The first thing I would try would be to 
let the diaphram soak in gasoline for a few days, to see if that helps.

If that works, reassemble the pump with some grease on the non-gasoline 
side, to help keep some petroleum oil in contact with that side of the rubber.

I don't recommend just flexing the rubber to soften it up; that's more likely to 
break it.  

I don't know if a kit for a different maker would fit. And those kits are getting 
scarce. You might have to resort to buying a new pump.

I have some silicone diaphram material if you'd like to try making your own. 
This came from Russ, years ago, and should be quite good, but you'd have 
to cut and punch it to shape, and do the rivet in the center.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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