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1992 240 cranking but not starting. Fuel pumps and relays okay.

AwesomeTreehouse

New member
Joined
Jun 6, 2015
Location
Portland, ME
So I'm looking for a little guidance on this. I've been driving along with no issues or warning signs of things crapping out. I had gotten a full tank of gas, drove for about 12 miles. Stopped the car. Started again. Drove another 12 miles. Stopped the car. Now it will crank over but not start.

For some context I have a new in-tank fuel pump. New fuel filter. New fuel pump relay. Tested the main relay and it's working. Tested the fuel pump by jumping between fuse 4-6 and that was okay. Checked all fuses and they're okay. Tried starting with the MAF unplugged and that didn't change anything. I also cleaned the grounds on the intake manifold. I also noticed that the OBD wasn't giving me any codes. No 1-1-1 from either terminal. It just lights up for as long as I have the button pressed down. This led me to wonder if it's a problem with the ECU.

THEN I tested the ECU according to the Bentley service manual and boom. The only test to fail is the first one. ECU power supply from ignition switch. (Every other test was fine.)

So I'm a little unsure where to go from here. Can I assume that this is a problem with the ignition switch its self? Or is it probably just a break in the wire at some point?

Any advice would be greatly appreciated!
 
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Check the fuses. 1992....does it have a fuse holder by the battery? This powers the computers and fuel pumps.

The EFI/fuel pump relay is powered from B+. Get a test light and crawl under the passenger side and make sure it illuminates at the thick red wire to ground. It's a large white relay.
 
I'm nearly certain it does not have the fuse by the battery. I think Volvo stopped using that fuse a few years prior to my year.

In a way I wish it did because it seems to have the same symptoms of that fuse being blown.
 
Do some basic diag using a test lamp and a wiring diagram. Figure out if the computers are missing power or ground. Just because OBD says they are dead doesn't mean they are. Maybe the diag box is broken.

Ok so the car doesn't start!? Ask yourself is it sprak or fuel and how can I determine this?

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Ok so have you looked at a wiring diagram and traced the circuit?

If you apply 12v manually to this pin do your computers power up?

Also, no offense, but it's really easy to misread diagrams and to do electrical tests incorrectly.


Do you have power at the EFI relay like I asked about in a post 4?
 
Try new spark plug leads, or at least a set you know are good.

Had a 1991 and a 1992 245 with B230's, both were running (roughly) before purchase.

The second didn't start when I got it, checked fuses, spark, fuel. Ended up swapping over the leads and it ran fine. (Leads were making spark, but must of been too weak to run?)
 
So it was in fact the connection from the ignition to the ECU. After testing the ECU and finding that the only failure was power supply from the ignition switch I used a jumper wire from fuse 6 (Could have been any fuse. Just need 12v) to the ECU power supply and it started right up. Upon further inspection I found that the connection at the ignition switch was not great.

Now it's running great and the OBD is back to functioning as it should. Thanks for the insight everyone!
 
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