Mechanical Fuel Pump FAQ (under construction)

[tjones02]

I have collected a few pictures here... and will add more in time...

http://s121.photobucket.com/albums/o236/tjones02_bucket/Parts%20is%20Parts/Fuel%20Pumps%20Mechanical/

There are basically two different types of mechanical fuel pumps that were used on '02s. The '02 fuel pumps have 8mm inlet with 6mm outlet hose fittings, and one that has 8mm in and out hose fittings that is a performance upgrade......

#13 31 1 252 506 Pump is defined by its lever type operating mechanism that is below the mounting surface and the 8mm inlet and 6mm outlet hose fittings. This pump was used on single barrel and 2002 TI's before mid '72.

#13 31 1 265 192 The operating mechanism has a pin and coil spring that stick out of the mounting surface. This pump was used on 2 barrel '02s from mid '72 on.

#13 31 1 260 677 was used on the carbureted 6 cylinder M30 motors and is defined by the lever type operating mechanism, its ability to clear most side draft intake manifolds, AND its 8mm inlet AND outlet hose fittings, thus it has a greater volume capacity while having the perfect pressure for running many different types of carburetors on the M10 4cyl engines. M30 6cyl engines that used this pump had 170 to 190hp and dual carburetors. This is THE mechanical pump to use with side drafts on modified performance engines!

Picture of the two different operating mechanisms. Thank You Bob Yee, from this old thread!

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,301879

There are two different fuel pump push rods for 2002's. Early longer ones are for the "506" early pump and the "677" M30 engine types. This is the push rod for all the BMW mechanical fuel pumps that have the lever type operating mechanism that is below the mounting flange.

The two part #'s for the pushrods are...

#13 31 1 250 398 is 107mm long. Most of these have a narrow section in the middle of it. This is the push rod for all the BMW mechanical fuel pumps that have the lever type operating mechanism that is below the mounting flange. These longer pushrods are for the "506" early pump and the "677" M30 types.

#13 31 1 255 727 is 88mm long. This shorter pushrod is for the "192" and all the pumps which have the pin and coil spring mechanisms that stick out of the pump mounting flange.

#11 11 1 721 614 is the insulator block With gaskets on it.

#113 127 311 is a VW number for the gasket to reseal an old insulator block, you'll need two of them.

#13 31 0 075 752 is for the insulator bushings, use two (2).

To mount the pumps use two of the above bushings, two wave lock (not split lock!) washers and two 8x1.25 x 12mm wrench size nuts with a dab of blue loctite (13mm nuts don't work as nice in the tight space around the pump). Some try and use nyloc nuts but I find most of the time that the studs are not long enough to grab properly into the nylon. Try and not over torque the nuts as the bushings are fragile.

If your cylinder head doesn't have the provision for a mechanical fuel pump I suggest this Pierburg unit part# 7.21440.51.0 . They are specifically rated for the fuel pressure that our carburetors require, thus do not need an external fuel pressure regulator. And they are very quiet, especially when compared to a Facet pump. (SSF sells these Pierburg pumps as replacements for early carbureted Porsche 911's)

http://www.wilmink.nl/pierburg/brandstofpomp_oldtimer_ombouw.pdf

In addition to this electric fuel pump I suggest wiring it with an RPM sensing relay like that from an early E21 320i fuel pump relay part# 12 63 1 277 245, or this VW relay that has a built in fuse holder (15A) part# 321 906 059C . All these relays need to work is a tach signal from the coil. Even Tii's can be wired with one of these relays to make them safer.

This post has been promoted to an article

[gruizer]

Thank you Tom, for doing such a detailed write up.

I was going to post a question here but I just realized this was in the under construction area, so I will move my question to the General section.