Volvo 240 (1989) Fuel pump relay - pull to start

[blb...@atlantic.net]

My '89 Volvo 240GL has a peculiar problem which started about three years
ago. Occassionally, the engine won't start. It apparently gets no fuel.
Through alot of trial and error, I found that if I pull the (what I
believe to be) the fuel pump relay and re-insert it, the vehicle will
usually start again. There does not seem to be any particular pattern as
to when it won't start - however, the problem is getting more frequent.
Naturally, I went to shops and they told me the relay was bad - but I
don't buy that anymore (not after the third one!)

I do notice that when I pull the relay and re-insert it, after cranking
about two seconds one of the relays in the module (there are actually two
small pcb mounted relays in the white case) clicks and activates and then
the engines starts. When the engine doesn't start, there is no click. I
guess my question is "what makes the relay click. Could this relay be
controlled by an electronic module somewhere which becomes loaded down in
such a way so that its output driver can't come on to activate it - until
the load is removed (opened). Or, is there a sensor (such as engine
rotation) which activates it. I notice two electronic modules under the
passengers compartment (under and behind the glove box). Would changing
one of these help (if so, I probably replaced the wrong one - because I
still have the problem).

Does anybody have experience with this type of failure before?? Need help.

Thanks

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[Boris Mohar]

I had apparently same problem with my 740. The fuel pump relay is
soldered to a small circuit board and the whole thing plugs in. The
fault was a cold (read poor, cracked, bad etc. ) solder joint at the
armature (body) of the relay and the circuit board. This is due to
the fact that iron does not solder as easy as copper and that the iron
armature has to suck up quite a bit of heat before it reaches proper
temperature, else cold joint. Unplugging and plugging in the module
flexes the circuit board and re establishes the connection
temporarily. Use flux core solder (electronic) to re solder the
armature and all other connections . I wonder how many "bad" fuel
pump relays are out there. This question was posted here few times in
various forms. I also wonder how many good fuel pumps have been sent
to the dump due to this. There is a strong and distinct odor that
comes out of the exhaust when ther pump relay is not working and the
engine is being desperately cranked. Could someone explain this?

Regards

Boris Mohar

VIATRACK printed circuit designs

[W Li]

Our extended family has 5 240's. The only consistent defect is the fuel
pump relay located on the firewall behind the glove compartment. I have
replaced three of them, all after 100K miles. It is a cheap fix, that
seems to work. They relay costs somewhere aroung $30 from Volvo. Good
Luck!