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1988 Volvo 240 No Start

J

Juster

New member
Joined
Sep 8, 2020
Hello guys! I'm all to the Volvo world. Recently picked up two Volvo 240s for pretty cheap. One runs and drives fine but the other one doesn't. For the one that doesn't run been trying to figure out what's wrong.


My issues fuel pump won't prime at all. Was originally told by the previous owner that it just needs the fuel pumps changed. So I changed the in-tank one as well the main pump also down below the driver side door.

When I have the key on the on position it doesn't prime at all. While cranking fuel does shoot out from the fuel line. I also used a jumper cable on fuses #4 and #6 to test the pumps and they do turn on. (In tank and the main one)


After that I checked the fuel fuse in the engine bay the 25 amp fuse that is known to go bad on Volvo's. That checked out good also. With a voltmeter both leads read 12 volts same as the battery.

Then went to check the Fuel Pump relay below the passenger glove box. Changed it out with my other Volvo 240 which is starting and running fine still nothing.

Went out and picked up an ECU from the junkyard switched them out and still nothing.


Another thing I noticed is at every single injector I'm not getting any power at all with the key turned to the on position.


At this point, I'm uncertain to what else to check. Seems like a fuel issue still. But spraying starter fluid only the car will run fine until it stalls because of fuel. So forsure I'm getting spark.
 
hessam69 said:
Not all cars prime the fuel pump with the ignition in KPII
Click to expand...

Well, that solves that issue then. My issue would be not getting power to the injectors then. Not too sure what to check been checking grounds all day and cleaning them still have no luck.
 
There are two main relays, one for fuel pumps and another for IAC, injectors, etc. I think they are both underneath passenger side dash. If you are not getting power to injectors, the relay is probably dead, but check to make sure it is getting power too. In fact, check the fuses and make sure they are all clean with no crust on the fuse holders.
 
adamdrives said:
There are two main relays, one for fuel pumps and another for IAC, injectors, etc. I think they are both underneath the passenger side dash. If you are not getting power to injectors, the relay is probably dead, but check to make sure it is getting power too. In fact, check the fuses and make sure they are all clean with no crust on the fuse holders.
Click to expand...

Was looking for a really can't find anything rather than the fuel pump relay (6 pin one). Changed the ECU back with the old one a now getting (0.31-0.43v) through the injector wiring. Completely lost to what to check. I'm picking up a new 25 amp fuse and holder and replacing that to see if anything changes.
 
How long did the car sit non running? There is a possibility that all of the injectors are clogged if it sat long term and the fuel turned to varnish. I've seen 1 injector get clogged on my old 744 after sitting maybe a year or 2. So any longer than that, it's worth pulling them. I would first use a noid light and check for injector pulse while cranking. That will be a useful test to determine whether or not they are functioning.

Also, what was the part number on the junkyard ECU, was it for sure from an LH2.2 car like yours?
 
adamdrives said:
There are two main relays, one for fuel pumps and another for IAC, injectors, etc. I think they are both underneath passenger side dash. If you are not getting power to injectors, the relay is probably dead, but check to make sure it is getting power too. In fact, check the fuses and make sure they are all clean with no crust on the fuse holders.
Click to expand...

That is not true. On a Turbo 740/940 there is a second relay that powers the injectors (aka Radio interference relay)

You need to get a wiring diagram and a test lamp. I suspect the fuse holder at the battery is corroded. It powers up your EFI/Fuel pump relay, which is a dual relay. One circuit powers the fuel pumps, the other circuit powers up the MAF, etc.

Is the MAF powered up? Blue/yellow wire. Start there and report back. If it's NOT powered up, I would be looking at your EFI/Fuel Pump relay/circuit.
 
Well checked the MAF wiring as I was told. Getting like 0.30 to less than 1v of power with the key on. Checked the power from the fuel realy and getting the battery voltage from two points.
 
A test lamp is used to measure power circuits. 12v can show on a meter, but be a "weak" 12V that won't operate a circuit. It is rare, but I have seen it happen. In this case, if your fuse holder by the battery is corroded, you could see 12v on a meter, but it may not illuminate a test lamp.

At this point you know you need to do additional circuit diagnosis at the relay. Here is an easy one. Pop the cover off the relay and pinch the contacts closed. You should see battery voltage at the MAF and injectors at that point. Pinch the other contact closed and you should hear the fuel pumps operate.


OR create a jumper and power up the fuel pump wire and the EFI wire at the relay for the same result.

It sounds like a bad relay. You can do the 10 min of additional diag, or fire the parts cannon. With my money, I prefer to do the diag.
 
Redwood Chair said:
It's the fuel pump relay, even when it isn't the pump relay it's always the pump relay.
Click to expand...
You speak the truth.

When my cylinder head failed on my 940, the fuel pump relay spontaneously failed at some point while the car was sitting. When I went to start it for the first time, it wouldn't start. It cranked beautifully, but would not make it past that point. I wasn't getting power to the pumps, so the second thing I did after checking fuses was pull the relay and try to revive it.
I did everything I could to that relay: reflowed the solder, cleaned the contacts, even sanded the terminals. It looked perfect by the time I was done with it. And nothing. For a while, I was convinced the failure was somewhere else in the system, but couldn't find any other problems. My girlfriend kept telling me to buy a new fuel pump relay anyway, repeatedly, so eventually I did. Car started right after I installed it.

Can anyone explain what could have failed? The only part in the relay that looked capable of failing easily was an 8-pin DIP, but how could that have failed while the car was sitting unused?

And Juster, check the terminals in the relay socket too. The relay can generate enough heat to damage itself or the socket.
 
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