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Old 02-15-2021, 11:01 PM   #1
OldCarNewTricks
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Default Still Can't Get this Thing to Start #2

My 1983 242 just doesn't want to cooperate. What I thought was just a fuse corrosion issue is no longer true. I had it running and driving for a total of maybe an hour over a couple days. Yesterday it stopped running while I was trying to air up the tires so I can finally drive it home.. grr, so frustrating.

I started with the AMM, added sleeves to the ICM pins that needed them and replaced the fuse holder with a waterproof one. Alot the wiring was replaced in the past, except for the light related wiring, alot of that needs replaced.

I wiggled the wires around the ICM and the distributor and it ran two seperate times for maybe 10-20 seconds each. Not sure if that's because I wiggled the wiring or if because of residual fuel. I can feel and hear both relays opening, they are both new, as well. What could cause the car to run, sitting stationary for 20 minutes and just die with no intention of starting again? Hall Sensor?

My distributor has a circular plug.

Also, the injectors are not receiving +12v to the Yellow/Red wires. When they had voltage, it ran.
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Old 02-16-2021, 12:38 AM   #2
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I would start with the basics. Get a can of starter fluid and spray it into a vac line in the intake then try to start the car. Does the car start and run on the starter fluid? If yes, you have a fuel problem so diag further. If no, you have a spark issue so diag further.
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Old 02-16-2021, 12:52 AM   #3
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injectors are not receiving +12v to the Yellow/Red wires.
Fuel pump relay must be energized. Pin #17 on 1984's ECU grounds out fuel pump relay when engine is rotating.
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Old 02-16-2021, 12:59 AM   #4
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Runs on starting fluid. And it ran extremely well when it was running.

So the injectors only receive +12v when the engine is turning? I thought they were to receive voltage whenever the car is on..
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Old 02-16-2021, 01:00 AM   #5
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Also, fuel pumps work. Fuel press. regulator still functions, etc.
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Old 02-16-2021, 01:17 AM   #6
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Rule number 1 did you change out the fuel pump fuse and clean the contacts?
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Old 02-16-2021, 01:23 AM   #7
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The only fuse I changed was the 25a main power. I've spun them in their holder several times and I've gone through and I've cleaned any corrosion I found.
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Old 02-16-2021, 02:31 AM   #8
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Quote:
Originally Posted by OldCarNewTricks View Post
Also, the injectors are not receiving +12v to the Yellow/Red wires. When they had voltage, it ran.
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Originally Posted by OldCarNewTricks View Post
Also, fuel pumps work. Fuel press. regulator still functions, etc.

If you're getting power to the pumps but not to the injectors there must be a break in the wiring. The pumps and the IAC valve get power from the same pole on the relay as the injectors. I'd suspect the junction where the 4 injector wires split from one.

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Old 02-16-2021, 10:15 AM   #9
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power to the pumps but not to the injectors
1984 diagram shows two electrical contacts in relay...one to the pumps and the other to the injectors. Two separate wiring paths, as viewed here.

OP Question - "injectors only receive +12v when the engine is turning?"

Answer - Correct

ECM activates a ground to the relay when the ECM detects engine rotating. When this ground is turned on by ECM, then the injectors and pumps should have 12 volts...if relay is working, and if relay has 12 volt pwr, and ignition switch is sending 12 volts to it. See diagram here.

Relay is under the passenger side dash...towards center console area. Fuse #13 must be good. Via 1984 diagram, there are three Yellow-Red wires coming out of relay and going to fuel pumps and injectors...with a test light, I'd check to see if 12 volts is on these wires when starter is cranked. Relays go bad.
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Old 02-16-2021, 10:19 AM   #10
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Footnote - With test light, check to see if Red wire(s) at relay have 12 volts at all times.
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Old 02-16-2021, 10:41 AM   #11
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A break in wiring would make sense. I've stripped off all the split loom in the engine bay, and all the wires look good. So I'll have to check for continuity on that wire from the relay to the injectors.

I had the injectors out with bottles taped on them before I got it running the first time. It's weird because the injectors has +12v to them when they actually started working, and this was without the engine turning.

I'll have to see if they get +v when cranking the motor.

I had already suspected relays, and they are both brand new Bosch units, although the factory ones were still OK.

I'll check all my fuses again.
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Old 02-16-2021, 10:42 AM   #12
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Red wires do have +12v. Definitely getting voltage there.
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Old 02-16-2021, 02:55 PM   #13
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Take the cover off the relay and verify that when energized the relay is making contact.
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Old 02-16-2021, 05:52 PM   #14
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Take the cover off the relay and verify that when energized the relay is making contact.
Better to use a jumper wire connected to Red and Yellow-Red wires on relay's receptacle...with male spades on this jumper wire to insert into receptacle's terminals, as I recall.
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Old 02-16-2021, 06:08 PM   #15
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Originally Posted by OldCarNewTricks View Post
The only fuse I changed was the 25a main power. I've spun them in their holder several times and I've gone through and I've cleaned any corrosion I found.


Change the fuse for the fuel pump and take sand paper to the contacts before putting in a NEW fuse.

If you haven't done that you are missing the #1 starting/no start issues with our early model Volvos...

I carry those fuses in my car in case I see a Volvo on the side of the road, I've sent quite a few happy people on their way after doing the steps outlined above.

Simple and at least gets that out of the way.
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Old 02-16-2021, 06:16 PM   #16
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Change the fuse for the fuel pump and take sand paper to the contacts before putting in a NEW fuse.

If you haven't done that you are missing the #1 starting/no start issues with our early model Volvos...

I carry those fuses in my car in case I see a Volvo on the side of the road, I've sent quite a few happy people on their way after doing the steps outlined above.

Simple and at least gets that out of the way.
WELL, it can't hurt to do! Thanks for the suggestion.

Also, the relays are brand spanking new Bosch units. The old ones, with the covers off, still worked just fine. I am keeping them as backups.
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Old 02-17-2021, 02:30 AM   #17
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Originally Posted by OldCarNewTricks View Post
WELL, it can't hurt to do! Thanks for the suggestion.

Also, the relays are brand spanking new Bosch units. The old ones, with the covers off, still worked just fine. I am keeping them as backups.
Ya it's a no cost five minute box check in terms of trouble shooting - but you'd be surprised how often that is the cause of no start issues.

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Old 02-17-2021, 03:41 AM   #18
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Quote:
Originally Posted by OldCarNewTricks View Post
WELL, it can't hurt to do! Thanks for the suggestion.

Also, the relays are brand spanking new Bosch units. The old ones, with the covers off, still worked just fine. I am keeping them as backups.
Do not use sand paper on contacts. A fine brass wire brush will remove the corrosion without damaging the contacts. Any paint store/hardware store carries them.
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Old 02-17-2021, 11:25 AM   #19
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WELL, it CAN hurt to do!
Good shout there 2manyturbos. I believe I have one of the brass brushes in my tool box. And I've got some fuses on the way.
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Old 02-17-2021, 07:43 PM   #20
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Well, I switched the fuses. No luck there. However, I purchased a Bentley manual recently and it has been helpful. I tracked the issue down to the ECM not providing ground to the injectors. The relay is functional and provides 12v to the injectors.

So I'm guessing maybe a bad hall sensor isn't picking up engine rotation?
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Old 02-17-2021, 10:17 PM   #21
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My 78 242 ran like absolute crap and I did a lot of troubleshooting for 3 months, never found the problem. Comprehensively ruled out fuel and spark problems. When I was pulling out all the unnecessary wires from the loom for my LS swap, I found the culprit. One wire was broken right where the main harness goes though the firewall, solid blue wire I think went to the Lambda system (hard to remember now). All the other wires looked perfect. So 1 broken wire could be your issue.

Before that, I had a lot of problems with the fuel pump relay burning up. I wired a modern 30A relay next to it to run the fuel pumps, just used the original relay to turn the new one on.
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Old 02-17-2021, 10:32 PM   #22
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Do you have a test lamp?

Does it run on starting fluid? (click my sig)

Spark, injector pulse, fuel pressure, compression, ignition and cam timing. Something is off.
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Old 02-17-2021, 11:09 PM   #23
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Yes, it runs on starter fluid. It sat for approx 6 months, and before that, ran fine. It's got to be corrosion or something...

I'm just not sure why it would run so nice for 20 minutes the other day and suddenly shut off. It was idling while I was airing up the tires, so I wasn't moving anything around.
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Old 02-17-2021, 11:53 PM   #24
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Now that you have a Bentley Bible say what it lists for the test for the spark signal going to the computer. Remember, I described it to you in a PM. If the ECU is not getting that signal it will not turn on the injectors. If it is getting that signal and you’re not getting any injectors to fire, that indicates a bad ECU.
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Old 02-18-2021, 12:16 AM   #25
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Now that you have a Bentley Bible say what it lists for the test for the spark signal going to the computer. Remember, I described it to you in a PM. If the ECU is not getting that signal it will not turn on the injectors. If it is getting that signal and you’re not getting any injectors to fire, that indicates a bad ECU.
The Bentley says to test that the ECU is receiving RPM signal, to connect the test probes to connector pin 4 and ground. It should receive ~8v when the motor is cranked.

During my inspection of all the interior wiring, I did notice what looked like corrosion on the ecu. I removed the board from the casing and found that moisture had made it's way into the case during the time the 242 sat. I gently cleaned the corrosion off. So, I wouldn't be surprised if it ends up being the ECU.
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