M/C solenoid

[Richard Cooper]

I am still unable to find the problem with my M/C solenoid. When I disconnect the plug from the solenoid on the carb and run power from the battery directly to the solenoid ( the part that is actually in the carb) I can make it "click" every time I touch the ground wire to ground. But, when I hook it up the way it should be the solenoid does not work and the car runs VERY rich. I have replaced the computer two times and just replaced the PROM and still, no good.
I am running so rich that when I change my oil it really smells like gas. I seem to have power at the plug end too, but nothing happens when I plug them together. Its like it is not switching the power on/off like it is supposed to do. Does anyone have any ideas that I could try? Thanks in advance.

 

[Richard Cooper]

OOPS

Sorry, I am talking about my 81 coup.

 

[sixty9vette]

Have you tried jumping the test strip under the ashtray? Not sure if the test pins are orientated the same on all L81s, but on mine it's the first two on the left side. You can also tell since there's no separator between the connectors. Anyway, turn on the ignition (don't start car) and jump those test pins and you should hear it clicking (you can also read your trouble codes by doing this). If it starts clicking, the likely cause of a rich condition will be a bad or out of adjustment TPS (throttle position sensor). The voltage should range from around .45 to .85, and spec'd at .56. If the voltage is high, the computer thinks you're at or near WOT, and produces a rich condition. Your idle quality will be very poor and will vary up and down. You can easily test the TPS with an ohmmeter and it should vary the resistance 'very smoothly' as you move the TPS plunger up and down. If it jumps around or has dead spots, the TPS is shot.

 

[Richard Cooper]

Chris81,
I did jump out the test pins and I get a code 23, it is an open in the M/C circuit. But I'm not sure where. That is why I changed the computer and PROM. Thanks, any more ideas?

 

[sixty9vette]

Just a few quick questions... Have you shorted the test teminals, then cut the ignition on and still no clicking? Have you checked the voltage at the M/C dwell lead? Do you have the Shop Manual or have you seen or gone through the standard checks to perform?

 

[Richard Cooper]

81Chris
Yes, I shotred the test terminals and turned the key to the on position(engine not running) and there is no clicking. I also tested the voltage at the dwell test lead and got 6.4 volts. I do not have a manual. I have been playing with this for almost one year now and keep giving up, the car runs like this, but is VERY rich. I traced all the wires from the computer and they seem to be Ok. I believe that the ground wire is the one that is supposed to do the switching for the M/C solenoid. I thought the computer was bad, but I have tried a used one and then bought a new one and still the same, no clicking. Maybe the wires do not go directly from the computer to the M/Csolenoid. Maybe they go someplace else first and this is where the problem is. Thanks a ton for your help.

 

[sixty9vette]

Ok, we'll start with the 6.4 volts. BTW, this is out of the book, 'cause I have no been-there-done-that answer here. There's a series of checks if 'Over" 10 volts as well. Good luck

If under 10 volts:
Disconnect M/C solenoid.
Connect test light from sol. connector battery terminal to ground.

If Light Off:
Check for open B+ circuit to solenoid


If Light On:
Connect test light between sol. harness connector terminals. Do not use voltmeter. Then...
1) If light On
Remove numbered term. ECM connector. Then...
1a) If light off - replace ECM
1b) If light on - Repair ground in wire from solenoid to ECM terminal 18
2) If light off
2a) Check for an open in wire from M/C sol. to dwell connector. If not open, it is a faulty M/C solenoid connection or solenoid.

 

[Richard Cooper]

81chris,
I did the tests and it seems to be "repair ground in wire from solenoid to EMC terminal 18." I am not sure if this wire goes from solenoid ground directly to terminal 18 or to some other switches, relays or anything else first.
I removed the numbered terminal and stripped a small piece of wire from terminal 18 and checked for power there. I had power there so I spliced a piece of wire there and ran it to the other end at solenoid and STILL NOTHING. This is why I think this wire #18 may go some other place first and then to solenoid. Thanks again for all your help.

 

[Yoda]

Richard,

Looking at my shop manual wiring diagram..
on the ECM terminal "U" should have a Black/White (blk/wht) wire the correct ID is 450.
The text at the bottom of the wiring diagram in the ECM Module says for Terminal "U" "ECM PWR GRD TO ENG GRD"

There is a common ground from the terminal off the test plug under the ashtray that shares it's ground with "Vehicle Speed Sensor" and the "Park Neutral Relay" (Both for Automatic Transmissions ONLY)

"R" terminal on the ECM should be an "Orange" wire and this is Continuous Battery Power.

Don't know if this helps or not, but it appears to me that you should be able to lift the blk/wht wire from the ECM and have continuity to ground, almost a direct short or very little ohms, have you tried to ground at Terminal "U" at the ECM?

Good Luck.

BudD

 

[Richard Cooper]

Rare81
I think you have hit on something. This problem started with my "check engine" light coming on. When I read the codes ( don't remember the numbers) I got the one for the M/C solenoid and also one for the vehicle speed sensor. I went after the M/C solenoid because the car runs very rich all the time and has since I got it 4 years ago. I had the carb professionally rebuilt, but it did not help. I smell gas in the oil every time I change the oil.
I am getting a 1981 repair manual for Christmas. I'm kind of done for the winter because I do not have heat in my shed. I could not afford a garage for $9,000 plus then I would have to pay tax on it every year so I bought a wood shed. It's one of those that is already make that everyone sells. Its 12ft X 24ft. It works fine, even has 2 windows and the floor is made of 3/4" plywood with 4X4's every foot on center, but no heat.
Well, thanks a million for your help. As soon as I can I'm going to check terminal "U" at the EMC. Thanks again.