1991 Volvo 240 Intermitant fuel pump problems

yosef7 · Post by **yosef7** » 03 Oct 2013, 09:37

My volvo starts sometimes and not at other times. When I hear the pump (in tank) hum I know it will start. When I don't hear the pump it will not start. I have 4 different relays that I will switch out two are new. Sometimes switching works other times it does not. It is a roll of the dice as to what will power the pump. Both pumps are new. Good fuses. Relays ??? When it energizes the pump runs great. Can not find the radio sup relay on this 4door sedan. Seems to me the occurs during non fair weather times. Anything to hot or colder than 60 -75 degrees f. Thanks for suggestions. - Yosef

Post by **JDS60R** » 03 Oct 2013, 09:54

Hi Yosef,

If the pumps sometimes get power and sometimes do not ( humming vs not humming) we should look at the electrical feed to them. I'm not sure what you have done so this is what I suggest.

1. Clean the terminals at the battery as well as any fuses connections or relay connections.
2. Use an electrical meter or test light to follow the problem.
3. Each time the pump does not turn on break out your test light and work from the pump back to the battery to find out where it failed.
4. Consider the common culprits of, corrosion in connections, bad grounds, A failed or failing ignition switch not giving the turn on signal to the fuel pump relay, a bad relay or a bad pump ( yes- even some new pumps are bad but you will know this when it doesn't humm and you have power and ground going to it.

Post back what you are finding with the meter so we can help more.

yosef7 · Post by **yosef7** » 03 Oct 2013, 13:59

Thank you for this reply. I just got back and got in the volvo to try and start. It did not at first. I took the new relay and left the ignition to on. I (frustratingly) pushed it on and off a number of times. Then the Hum! Yes! It started and ran fine. I am going away until next Wed. I will look at the electrical feeds next. I have cleaned terminals , fuses and their holders... I was wondering about the ignition switch but thought that can not be it. How do I test for this? And if it is the problem / solution , is it difficult to change out?
Thank you, Yosef

Post by **JDS60R** » 03 Oct 2013, 14:41

http://www.volvoadventures.com/howtodof ... relay.html

http://www.davebarton.com/volvorelays.html

yosef7 · Post by **yosef7** » 09 Oct 2013, 08:10

Thank you for those sites. I will try some of the hints and helps, for jumping the fuses. After reading your posts I tried the test wire procedures. No power at fuse after the initial turn of the key. Power though when I first turned the key. That makes sence though. Dont know how to test the relay. Stuck my test light into relay with Key on. Some wires tested stronger (brighter light) than others. Is this the norm? How do I test relay.? I have four relays at this time. One new. All have worked at some point on this vehicle.

Later in day pump humed and no problems. So far it has started each time. Hate waiting for the non start.
Yosef

Post by **JDS60R** » 09 Oct 2013, 16:30

Here is Dave Bartons diagram with a supporting relay mod.

Just use the wire colors to help you diagnose. With a meter and some testing it should all test out until you find the problem.

Post by **JDS60R** » 09 Oct 2013, 16:39

So if you have a white fuel relay (LH) and 87/2 has 12 volts with the switch on, and in start, the pumps should operate (hum).

With ignition in position 2 (run)
Check 87/2 for 12 v if yes and pumps do not hum or get voltage (testing at pump connector) then suspect bad wire from relay to pump.

Check 87/2 for 12v - If NO then test inputs from computer and battery to relay as well as relay.

Post by **JDS60R** » 10 Oct 2013, 15:14

Posting for Yosef

Thank you. I went out this am and got a no hum. (No Start) Checked for power at # 4 fuse. Nothing. Could no jump it. Yellow / red wire. Can hear the relay click though. No power at the yellow /red wire at the relay. This is making me think I have an ignition switch problem. Just not sure.

After turning key on / off a number of times...... For no good reason at all with an older relay I got Hum. Started it up and ran around the block. Test light shows power at fuse #4 as well as yellow/red wire of the relay. No problems.

Parked, shut off. Turned key again and no hum. I will read the rest of your notes now.
yosef

Post by **JDS60R** » 10 Oct 2013, 15:46

OK - Red/yellow seems to be 77/2 which is the output to the pumps.

If you hear it click that means the ignition switch is activating the relay.

If the relay clicks and you have power at 30 (red) but no power at 87/2 red/yellow then relay is defective.

Post by **JDS60R** » 10 Oct 2013, 15:51

To set the relay place 12v across 85 and 86/2 ( with relay removed from vehicle)
85 12v
86/2 ground

It should click - If it clicks check continuity across 30 and 87/2 leave the relay power on with 85 and 86/2 as described above.

Also test 12V to 87/2 (wire) and see if pumps humm . (Connect a short heavy wire between 30 and 87/2 with relay removed from wires - you are connecting the wires from 30 to 87/2 - running power direct to the pumps.