Need some help with fuel pump relay
 

I own a 240 1993 with B230FD engine.

It has some trouble with the fuel pumps and/or relay.

Problem began with the car not starting, but could start and run fine the next day. The problem increased, and the relay was replaced.

But the same problem came back after a short time, and then the main pump was replaced. Then the car would run fine for short time, but the problem came back again. It might never really disappear. Can't know for sure. I continued use the car, but one day, a couple of years since the problem first occured, it also stalled along the road. That had never happened before. And it would not start again. The relay was replaced once agian, and the car started. It worked fine but as usual the problem quickly came back, and worse than ever. Now it often will not start, and it sometimes stalls every 500 meters.

During this period, sometimes I could start the car by disconnecting the relay and reconnect, sometimes just by knocking on it. And the car always starts when bypassing the relay.

So: Does the car destroy relays? (yhey visually looks fine inside.)
Can the problem relate to insufficent grounding or ECU?
Can it relate to the pre pump? (would I for sure recognize a faulty pre pump while driving?)

Finally; since I am not familiar with reading wiring diagrams I would be very thankful if someone tells which connectors to have voltage or ground with ignition on, and with car running, and where there will be otherwise in the most common cases.

Are you sure that it is a fuel issue? When the car doesn't start, can you hear the main fuel pump run when you turn the key to the II position? It should run for a second or so when the key is turned to the II position. I make a habit of listening for this every time I start the car.

Also, I don't see anything about replacing the in-tank pump. If it isn't functioning it will place extra load on the main pump wearing it out prematurely.

Can you pull codes on your car?

I tried to keep the stroy short, and it might have become a bit too short....

When the car does not start, the main pump is silent. Every time. So the reason the car does not start is located in the relay.

But why does the relay fail, and is the problem the relay itself?

I would like to determine for sure why the relay does not click, and an advice wether I should replace the in-tank-pump (pre pump) and/or other components or not regardless of what the multi-meter says about the relay when it is failing?

There has been no codes to read so far.

Cheapest and easiest way to start searching for the fault is to first change the fuelrelay. Faulty fuel relays is a very very common problem with Volvo 240,740 and 940. its the solderpoints that crumble. Open it up and redo it.

Thanks for responding all of you!

I already have opened the relay and cant see anything wrong in the soldering. The contact surface on one of the relays has a small nob, but that can't be the issue since the relay is silent. Can it be the inductor?

I have two spare relays available, but do not wish to use them until I have located and fixed the source of the problem.

Therefore I need som guidance regarding the function of the relay and how to determine what has failed when the relay becomes silent.

Was the replacement relay a genuine Volvo relay or an aftermarket? I have read on the forums here complaints about poor quality of the aftermarket relays. However, I have no experience with that.

There was some years that contained a "pink label" ECU that over time would have problems supplying the signal to the fuel pump relay. If your car has the original ECU, I would expect that it should not have the pink label. I believe the pink label ECUs were discontinued in 1990 and a "white label" ECU used that solved this problem. Check your ECU anyway just in case the previous owner had installed the ECU with the pink label.

This is what happens when you turn your key
1.Startermotor
2.Cranksensor starts
3.Ignitionamplifier box goes in
4.fuelrelay clicks
5.signal to fuel pump
6.fuel comes to be fired.
So if you get fuel then there is nothing wrong with the crank sensor,fuel relay or pump although fuelrelays sometime malfunction because of poor/faulty solder points inside.

that pink label ECU was on like 1985 or something early LH 2, not an LH 2.4 1993.

with LH 2.4, that power up sequence is slightly different.

1) key on, ECU and ICU are turned on, fuel pumps run about 1 second to prime things then stop.
2) key to start, starter motor turns over engine, cranks engine, crank sensor tells ECU its moving, so ECU turns fuel pumps back on.

note, btw, the 'fuel pump relay' is actually a double relay inside, one half powers the ECU and injection, while the other half powers the fuel pumps (and OX sensor heater).

With temperature expansion/contraction the solder joints crack, which can be hard to see without magnification. You can reflow all of the joints with a soldering iron on the dead ones to see if they come back to life.

Also make sure fuses 4 and 6, and the holders are clean.

The pink label ecu affected 1990 240 models.

ah, yeah, 1990 240's, duh.

fyi, a decent ECU reference table, seems to be fairly accurate, applies to 240 and 7/9's

Engine ECU

So; this is my current reasoning: Since jumping the relay always brings the fuel pump to life, power on connector 30 always beeing present and wiring from connector 87/2 to the fuel pump is confimed. If my car does not have a pink label ECU I can be quite sure that there is no issue related to grounding.

In situations where the car does not start, there is also no 1 sec priming. This indicates that the problem is not relatet to absence of signals from crank sensor, ECU etc.

That leaves me with the relay itself and the possibility that the cracks in solder joints are invisible to the eye. Both the relays used as replacement the last year was marked "Hungary". Of the two spare relays I have left, one is Hungarian and one is German.

Assuming that the reasoning is correct, this raises the question; do I have a problem with the in-tank-fuel pump that causes the main pump to overload the relay, or are the Hungarian relays so crappy that they are likely to break down after a few months?

It could be that the cracks in the solder joints are not visible to the naked eye. I always inspect under a magnifying glass or a soldering station microscope (at work). Most of the time, the cracked joints are where the relay is soldered to the circuit board. Try re-flowing anyway to see if that helps.

I agree with your logic on the crank sensor, etc.

Ignition Module Alternative
 

I've read all the feedback from other experienced owners/mechanics. It appears that they've covered all the fuel & electrical fault tracing. The only contribution I can add is try switching out the ignition module. I had intermittent starting/driving occurrences w. my 240/740T/940T wagons where the car would just shut off when driving sporadically, and eventually not start later-a gradual effect. I checked all suggestions mentioned from relays/fuses/main/in-tank fuel pump, filter, fuel rail, etc. Then I switched out the ignition modules, w. Bosch or Hugo brands & solved the problem immediately. Both the fuel relays & ignition modules failed on my vehicles between 150-200K miles. My 240 sedan was 1980. PC

and I've got way over 500K miles total on several volvo redblocks, and never a problem with the ignition modules. these cars wer 1987 and newer, for what /thats/ worth. the 87, with 400K miles on it, has an issue right now with the ignition wiring harness, but it appears tob e wiring or the connector to the ICU.

Today I have installed a power switch in the panel to open / close the circut over connector 30 and 87/2 on the relay, and a light that will go dark if the circut breaks. Now I can test drive the car and still be able to get back to base if the car stalls by turning on the switch, and the light will tell me if the car has lost current over 30 and 87/2.

I have ordered a new in-tank-pump, a used ECU and a used ICU, and as mentioned I have two spare relays. That should cover the needs for spare parts.

But I intend not to use those parts before I knoe for sure what caused the problems. I have therefore checked the relay with a multimeter and studied some wiring diagrams. ( It turns out that my -93, build in -92, is wired like a -92.) Now I have an idea of how things should be when the car is ok (today it is ok), and hopefully that knowlegde will help me locate the error the next time the car stalls or refuses to start. I guess the will happen quite soon.

Pump check
Remove fuse #4.
Jump from fuse #6 to #4 left side: main pump starts. OK
Jump from fuse #6 to #4 right side: in-tank-pump starts. OK

Relay studie - Based on diagrams and various website reading.
1 = 87/1: 12V to ECU and 85 when igniton pos 2. OK
2 = 86/2: Ground from ECU_20 to EM 2 when ignition pos 2. OK
3 = 30: 12V. OK
4 = 86/1: Gruond from ECU_21 til EM1 when ignition pos 2. Has 12V when ignition 0 and 1, and 1.25V when ignition 2 and engine running.
5 = 87/2 12V to fuel pumps for 1 sec when ignition pos 2, and steady when engine running. OK
6 = 12V for EM2 from 87/1 when ignition pos 2 and EM has closed. OK

Thing are working and I am starting to understand the concept, but what have I misunderstood about 86/1??

And does the relay depend on any feedback from ECU in order to click? In other words: will there be heared a click from the relay if the ECU is toast?

If any others have a similar problem; the answer was not the relay, fuse or pump. 20cm from the relay there is a connection point in the wire harness. This connection point can only be seen on some editions of the wiring diagram. The wire between the relay and the fuse box is going through and the connection occasionally failed. Every time I touched the relay the connection moved a bit, giving ok connection for short period of time, leading me to the wrong conclution that the relay itself was the problem. Case closed.