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B21 Kjet low idle, no power, '78 242

I followed the procedure in Section 2 Group 24 Fault tracing Oxygen sensor feedback system, its the only one that has electric tests starting on page 6.
D1: Grounds are connected
D5: I do not have power to terminal 8 so go to F1
F1: No voltage at either terminal
F2: Voltage present
F3: Voltage, but only 6.4 mv
F4: Voltage across both terminals, only 0.9 mv but if its still voltage I guess
Diagnosis according to the results of this test are defective relay.

Sound about right? I'll start looking though my boxes of relays for another haha
 
I have not checked the ignition timing yet, have to get ahold of a timing light. I will check the O2 voltage then as well, I'm sure its older an 25K miles.
 
2turbotoys said:
I followed the procedure in Section 2 Group 24 Fault tracing Oxygen sensor feedback system, its the only one that has electric tests starting on page 6.
D1: Grounds are connected
D5: I do not have power to terminal 8 so go to F1
F1: No voltage at either terminal
F2: Voltage present
F3: Voltage, but only 6.4 mv
F4: Voltage across both terminals, only 0.9 mv but if its still voltage I guess
Diagnosis according to the results of this test are defective relay.

Sound about right? I'll start looking though my boxes of relays for another haha
Click to expand...

F3: No voltage. F4: No voltage

In the terms of this 70's troubleshooting, millivolts wouldn't budge the meter needle, hence "no voltage."

Here's what I've seen before. The voltage to terminal 86 of the lambda relay (step F3) gets power from the fuel pump relay same as does the aux valve heater. If someone put the wrong type of relay in for a pump relay, there won't be any power there even though the pump turns on. Just a wild possibility the same has happened to you. Those DPST relays are not common at the store.

Actually, your 78 should have the electronic fuel pump relay, so that #86 should be wired to 87b on the k-jet fuel relay.
 
Last edited:
240CIWiring.jpg
 
Was the engine running when you made your measurements? (I don't have the diag procedure here.) The fuel pump relay senses the tach signal from the coil and won't turn on until engine starts cranking, or running.
 
hiperfauto said:
Lambda sond is a separate system.
Click to expand...

Sorry, Ian, didn't mean it as a critique. We in the 49-state arena didn't get lambda-sond until
'80. Indeed, the book (NCF 78) does show the two systems as if they were separate.

bobxyz said:
Was the engine running when you made your measurements? (I don't have the diag procedure here.) The fuel pump relay senses the tach signal from the coil and won't turn on until engine starts cranking, or running.
Click to expand...

Very good point. The troubleshooting chart does look as though it was based on the old relay with the airflow switch. Step B2 disables it.
 
Ok, I have to go back to F3 then, and also check for voltage at 87b on the k-jet fuel relay. Thanks!

No the engine was not running, the manual just said turn the ignition on, which I took to mean the key position.
 
2turbotoys said:
Ok, I have to go back to F3 then, and also check for voltage at 87b on the k-jet fuel relay. Thanks!

No the engine was not running, the manual just said turn the ignition on, which I took to mean the key position.
Click to expand...

If you have 12V at 87b on the k-jet fuel relay when it runs, and the noise of the engine is distracting, you could shut it off and just stuff a jumper bridging pins 30 and 87b in place of the k-jet fuel relay to deliver battery to the lambda relay and the heaters in the aux valve and cpr.
 
I went back to F1 with the engine running. Ended at F5 having voltage, solution is to repair wire from CI system fuel pump relay to sensor system relay terminal 86. I pulled the fuel pump relay out to see which terminals are which, reinstalled it, and now have no fuel pump again. I guess it might be in the wiring, it all looks good so far, gonna get a flashlight and see if I can see anything.
 
The relay to socket connection is VERY tight and the relay pins are directly connected to the circuit board inside. The printed circuit board is only good for a couple removals/reinsertions. A very common problem solved by removing the relay cover and reflowing the solder between the board and the connecting pins.

Even if you cannot see a break in the solder it doesn't hurt to do that.
 
Well I found why the pump wouldn't work...
2JSlZ0Dl.jpg

Yes that is wrapped in electrical tape, and the wire for 30 is arcing to the relay...I suppose that could burn the relay up? The fuel pump relay socket has obviously gotten warm, as the hole for the relay position 30 wire is not the correct shape anymore haha. Jamming the wire in deep allowed the car to start, but no voltage from 87b still.

Ok, I'll make the jumper. I think I should fix the relay socket first, as the engine keeps shutting off, the contact on 80 is terrible.

Anyone have a decent fuel pump relay socket?
 
2turbotoys said:
...

Anyone have a decent fuel pump relay socket?
Click to expand...

If you want to "restore" the car, yes, get a new plastic housing. But you can make it reliable with new terminals crimped on wire cut back to where it isn't crispy even without a new housing. I think Dave Barton has the sockets on hand, and I bet Ian and Eric can find one for you too.
 
This housing is beyond repair, I'll think about it for the night. I guess it really doesn't need the housing if I shrink wrap the terminals or use shielded ones. I'll probably go that route for now, I'll do it in the morning and then continue the troubleshooting. Thanks!
 
I popped the cover off the relay (KAE 3.302.200) and it seems fine except for what appears to be an accidental little solder bridge, here's a pic:

hLCn4rNl.jpg


Think that shouldn't be there
 
Seems like we need to get you a Striebel relay. The Kaehler relays aren't that great, unfortunately. Both of my turbo cars have early 1235337 relays installed. 245Ti has one from a late '79 car (black plastic case), and 242Ti has one from a '78 with the metal case. Both have the desirable brass terminals.

When I first picked up the 242 from a friend in 2016, the relay was a Kaehler from iPd. Car would start, then immediately die, as if the CPR was bad. Except that it would never run longer than a second. Discovered I had a used Striebel K-Jet relay in the cargo area of our old '92 245 when I drove that car over to check the 242 out. Swapped relays and it fired right up, no problem. Ran perfectly fine until I kicked the relay while disengaging the clutch and stalled the car out. Relay coil on that one was loose. But it at least ran and had normal power until I did what I did. Popped another in and everything was good.

If it turns out you need one, I have a spare late model green Volvo/Striebel relay that works. Can send that your way.
 
I would greatly appreciate that if it is the correct relay! My brother came up with a great heavy duty solution using a a heavy duty dpdt relay, but it would be easier to get a factory one. I don't want any more junk, the above pics are of a relay that has about 15 miles on it...

Just for fun I dug the relay I replaced out of the trash, and the failure point is obvious, even if I hadn't circled it in red

3J2r9Xnl.jpg


Pm coming your way, thanks!
 
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