Fuel Pump Relay - Can I please have an overview?

One of the things that will make me nervous on my first road trip will
be the fuel pump relay. My 1987 740 GLE (non-turbo) has 200,000 miles
and I would like to inspect this.

I have read how it may require soldering.

Can someone please give me a quick run-down on exactly where it's
located and what to look for as far as any symptoms?

Thanks!

 

Pull out the ash tray to get to the fuse panel. Now pull the small cover
off around the cigarette lighter and you'll see a screw which you can
remove, now the little cubby hole (or equalizer if you have that option)
will come out and you should have a clear shot of the fuse/relay block.
I forget offhand where on there the fuel pump relay is located but it
should show it in the owner's manual if you have that, normally it's a
white rectangle. Pull it out and look at the bottom, you should see how
the base clips into molded tabs on the outer casing. A small flathead
screwdriver can carefully pry to pop the cover off. Inside you will find
a small circuit board, look at the soldering on the bottom of this,
especially at the heavy connections of the plug pins and the actual
relay assembly. If they look dried or cracked, it's advisable to reflow
them. To do this heat the joint with a soldering iron and feed some
rosin core tin/lead solder into the joint until it all flows and you get
a nice smooth fillet. Remove the iron and the joint should cool and
harden with a relatively shiny surface.

 

Perfect! Thanks!

 

While you are at it clean the contacts, especially one closer to the middle
with 600 abrasive paper. Fold a piece of it on it self and cut a small
sliver from it. Using tweezers I insert this double sided abrasive in
between the contacts and work them smooth.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

I also received a tip to drill holes in the cover for added
ventilation. I may do this. When I bought the car a few weeks ago I
drove (limped) it home at night with the lights on. Then a couple days
later - no lights. Turns out a couple fuses were blown. 2 - 20 amps.
Then the lights, radio and windshield wipers worked again.

So, I need a full diagnostic, but wasn't sure how to access the relays.
Now I know.

 

Well, because I don't think the owner serviced this car for the last
several years, I just found a brand new relay on eBay for $15, so I
bought it and will have it either as a back-up, or will replace the
existing one if it looks like it needs to be replaced.

I guess it's $15 peace of mind...

 

Since many contacts are palladium plated, prefer the old standby of kraft
paper (like lunch bags are made from). It will burnish off the residue
without scraping down to the base metal, which can oxidize.

Mike