Electrical help 83SC

[Mookster]

I have a '83SC that is hesitating/bucking intermittenly as a result of an electrical interuption.

The first symtom was the O2 relay suddenly would start clicking and thus stalling the auto. When I replaced the relay the problem was resolved for a few months.

Resently the relay, again, to begen to click and the car would buck/hesitate. The car has not stalled like the first time.

I have attempted to garage test the wiring. One time I shook the battery cables gently and the fuel pump relay clicked and acted funny. I then checked/cleaned my connections at the battery and cleaned and reconnected all the grounds. When I shake the wiring now the fuel pump relay does not click.

My problem with the hesitation appears to be electrical in nature and diagnosed by the O2 sensor relay clicking when the car bucks/hesitates.

The battery is a Porsche battery and is 2 1/2 years old. The voltage is 13.8 volts when the car is running. The car starts without a problem.

Is problem the sign of an alternator/voltage regulator going bad?

Any ideas or suggestions before I am forced to take the car to the local wrench?

Thanks in advance.

[filou]

First of all, to find out if regulator or alternator is bad, do one easy test :
Before you crank motor, check voltage at battery and note value.
Now start your car and check voltage : is it higher and study ??? It is better if you use a digital voltmater (even a cheap one will do).
If you o2 realy is clicking, it's mean that his power supply is irregular.
Have the proper wiring diagram for your car and check power supply for O2 relay. Go upstream from relay (before the relay). One thing
i want to make sure : it is because of the clicking of O2 relay that the car hesitates and NOT the reverse, right ????
At least, you found what causes the car to hesitate like that !!!!!
Keep us posted.
Truly, Filou.

[diy83sc]

If you are going down the charging route, try this thread, with the first reply by cleaning the 14 pin connector.

Correct alternator Output

[autobonrun]

It's always difficult to troubleshoot from a description, but after looking at my Bentley manual, I think Filou is correct when he questions whether the Oxygen Sensor relay you hear is a symptom of the problem and not the cause. I would guess you are either losing power to the relay or the ground circuit for the relay. The ground for the oxygen sensor relay is directly connected and is probably not the problem. You can quickly verify the ground wire is tight.

The power supply side of the oxygen sensor relay is more complicated and is where I think the problem lies. According to the Bentley manual, the power to the Oxygen Sensor relay comes from contact #30 of the Fuel Pump Relay. If you lose the Fuel Pump Relay, then you lose power to the Oxygen Sensor relay (and the warm up regulator and the supplementary air valve). Loss of the fuel pump would explain the bucking you are sensing, moreso than the oxygen sensor relay. I just think you can hear the oxygen sensor relay since it is under the seat and the fuel pump relay is up front. I'm thinking the problem is in the fuel pump circuitry.

First, check to see if the fuel pump relay is in tight. Power to the fuel pump relay comes from fuse #16. Make sure it is in tight, the wiring snug and neither are corroded. If the fuse is old, just replace it to eliminate this as a cause. A crack in an old fuse element can lead to intermittent loss of power across the fuse. The next time your car starts hesitating, stop and replace the fuel pump relay to determine if it is bad. You should have a spare fuel pump relay in your car anyway so if you have to purchase one to do this test, it will not be a waste of money. I think short term you can use a regular relay in place of the fuel pump relay since the only difference (as I understand it) is the fuel pump relay contains a protective diode.

The ground side of the fuel pump relay goes through the airflow sensor contact. So the loss of this contact would lose your ground connection causing the fuel pump relay to drop out as well. By the way, this fuse 16 that feeds the fuel pump relay is also connected in the circuit to the RPM Limiter switch, the tach, and the CDI ignition control unit. This gives even more credence to double checking this fuse.

This should give you a few specific areas to test before you have to take it in. Good luck.

[Thack]

Every time my car bucks it is the ignition. Water got in my distributor once. If your igntion cuts out then your car thinks it's running rich. Which could trip your O2 sensor. Maybe a primary wire to the coil is loose? Just an alternative thought. O2 sensors go "out" sometimes and the car just runs rich, not bucking. At worst maybe a backfire. Let us know what happens.

Mike

[widebody911]

I went to start the 911 this eve - nothing. It wouldn't turn over at all, and the speedo would just flick a little when I turned to the start position. I was in a hurry so I took my bus, and pushed the 911 into the (old ) garage when I got home.

My first guess was the starter, but it's farly new. I put the car in the air (side note: when lifting one side of the car, make sure the opposite door is shut, or you risk bending your original Westfalia roof rack and scraping the paint on your door. Ask me how I know) and all of the connections looked fine. I cussed at them a little, and then went to try and start it again. Not only did it not start, but now it won't shut off! I disconnected the battery and came in to write this.

What's a good way to tell if it's the tumbler portion that failed, or the electricals?

[filou]

you said that your speedo flick a little when you turn key to start (cranking) position. You are having a high resistance in your circuit due perharps to worn out contacts and bad mechanism of ignition switch.
Some time it works, some time it don't.
Can you disconnect your switch and "hotwires" the car to see if it is the switch that is bad ??? Be meticulous and number the wires with tapes or label them.
Let me know, filou.