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Greetings! I'm back with hard-start problems on my 240DL.
My conclusions are that the car will start just fine when,
with the ignition key in pos.I, the fuel-pump relay clicks
and I hear the fuel-pump buzz for a second or so. If this
doesn't happen, sometimes I'm lucky and the car will start
(the fuel-pump relay will click) anyway when I turn the key
on pos.III. Otherwise, it will take several attempts before
the car finally starts. So I have spent the last few days
trying to understand what is needed for the fuel-pump relay
to click. From the wiring diagram (Fig. 13.225) on my Volvo
240 Haynes manual, it looks like the thing should be very
simple: it needs some voltage between term.15 and term.31,
and between term.31b and term.31, of the relay. The question
is, how much? With ignition key in pos.I, I have 12.5 V
between term.15 and term.31, and 1.1 V between term.31b and
term.31. Apparently this is sufficient, because the relay
clicks. I'm not sure of the voltage between term.31b and
term.31 when the relay won't click (I checked, but I don't
remember the figures).
All the previous applies assuming that the fuel-pump relay
is working properly internally. I replaced it a week ago,
but I'm having a continuous problem of relay overheating.
So I cannot exclude that the symptoms are due to the fact
that the new relay is dying as well...
If the relay is working well, and since I have full voltage
at term.15, I suspect that the voltage at term.31b might be
barely sufficient to trigger the relay. According to the
wiring diagram, term.31b should be connected directly to
term.1 of the ignition coil. However, the resistance is
zero only with the key in pos.0. If I turn the key in pos.I
the connection between term.31b and term.1 opens completely!!!
I don't understand that, because even for later models the
wiring diagrams always show direct connection between those
two terminals... At any rate, I also checked the voltage at
the coil's LT terminals. Shouldn't be 12 V or so? I only
get 6.6 V with the key in pos.I, and it drops down to 4.6 V
with the engine running. (BTW, even with that, the relay
clicks and the pump buzzes.) I don't have a clue of what's
going on! I checked the coil's resistance (both LT and HT)
and agrees with the factory specifications...
Any suggestions will be greatly welcomed! Thank you!
Roberto
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