Battery disconnected with driving
04-10-2010, 04:16 AM
#16
Rennlist Member
Medic,
In the combined spirit of patriotism and 928 obsession, I will drag my butt to the basement and demonstrate, photograph and post.
Give me 15 minutes or so.
In the combined spirit of patriotism and 928 obsession, I will drag my butt to the basement and demonstrate, photograph and post.
Give me 15 minutes or so.
04-10-2010, 04:48 AM
#17
Rennlist Member
Well more like 40 minutes.
This panel should look familiar. Its USA 83/4, in an 84 car with manual transmission.
Fuel Pump Relay position is XVII.
Pay attention to the pin size / orientation and the diagram on the relay. You are bridging 87 with 30.
30 is direct positive battery voltage, so be careful down there.
Pump will (should) immediately run and gasoline should recirculate through the fuel lines.
If it doesn't run, it might be clogged and you need to immediately remove the jumper. And, it defeats the ability to shut the pump down by turning off the car, of course, so its just for testing.
Sometimes they clog with a little tank debris that passes through the strainer that is supposed to be part of the discharge fitting at the bottom of the tank. (The fuel filter is located after the pump to protect injectors).
If you get a clunk or hum, but its not running, it might be possible to clear the debris by running the pump backwards, but you must be very careful. I'll let others explain best practice on that.
This panel should look familiar. Its USA 83/4, in an 84 car with manual transmission.
Fuel Pump Relay position is XVII.
Pay attention to the pin size / orientation and the diagram on the relay. You are bridging 87 with 30.
30 is direct positive battery voltage, so be careful down there.
Pump will (should) immediately run and gasoline should recirculate through the fuel lines.
If it doesn't run, it might be clogged and you need to immediately remove the jumper. And, it defeats the ability to shut the pump down by turning off the car, of course, so its just for testing.
Sometimes they clog with a little tank debris that passes through the strainer that is supposed to be part of the discharge fitting at the bottom of the tank. (The fuel filter is located after the pump to protect injectors).
If you get a clunk or hum, but its not running, it might be possible to clear the debris by running the pump backwards, but you must be very careful. I'll let others explain best practice on that.
Last edited by Landseer; 04-10-2010 at 05:52 AM.
04-10-2010, 08:51 AM
#19
Rennlist Member
Yes, I always pull the whole panel out and clean the fuse contacts and replace them with new VW fuses.
Could absolutely cause the problem!
Two nights ago I pulled this panel out. Just before dinner. Ate, watched Wheel of Fortune, Jeopardy and DWTS. Had a glass of wine, cleaned it, replaced it and was driving at 11:30pm.
It had been polished clean two years ago, but had debilitating corrosion on a small section that corroded the stoplight fuse and hence no lights.
Now the jumper lets you begin to isolate the problem, or at least discount other stuff. If the car runs with the jumper, but not without, you dive into the circuit deeper, but not the injector harness, AFM, distrib, green wire, etc.
Could absolutely cause the problem!
Two nights ago I pulled this panel out. Just before dinner. Ate, watched Wheel of Fortune, Jeopardy and DWTS. Had a glass of wine, cleaned it, replaced it and was driving at 11:30pm.
It had been polished clean two years ago, but had debilitating corrosion on a small section that corroded the stoplight fuse and hence no lights.
Now the jumper lets you begin to isolate the problem, or at least discount other stuff. If the car runs with the jumper, but not without, you dive into the circuit deeper, but not the injector harness, AFM, distrib, green wire, etc.
04-10-2010, 01:02 PM
#20
5th Gear
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Okay, I did the jumper, heard the fuel pump running, but the car did the same thing. Starts, then immediately kills...
I'm not sure if this is pertinent information but when I would turn the key I would hear relays clicking, so I removed them one by one and turned the key to see if it would still click.
First it was the power windows relay, I believe VI, the the EFI relay, something like XVII, then it was clicking in the center console behind the radio so I couldn't see where it was coming from at that point. The car didn't act any different each time I started it with the relays pulled.
I guess I'll go run to autozone and pick up some replacement fuses, some of mine do look a little decrepit (most of the white ones)
Thanks again so far for all of this good info
I'm not sure if this is pertinent information but when I would turn the key I would hear relays clicking, so I removed them one by one and turned the key to see if it would still click.
First it was the power windows relay, I believe VI, the the EFI relay, something like XVII, then it was clicking in the center console behind the radio so I couldn't see where it was coming from at that point. The car didn't act any different each time I started it with the relays pulled.
I guess I'll go run to autozone and pick up some replacement fuses, some of mine do look a little decrepit (most of the white ones)
Thanks again so far for all of this good info
04-10-2010, 02:38 PM
#21
Rennlist Member
I've had this happen when there is low voltage at the fusebox and also when I've had a bad engine ground.
The low voltage has occured when there was a low battery.
It also occured with the ignition switch was bad.
It happened another time (twice, actually, once on 32V, once 16V) when there was a melted wire on the back of the panel drawing voltage off some of the circuits.
And it happened another time when I had corosion hidden beneath the plastic cover on the battery ground cable. It had continuity at the sensitivity I measured with the digital voltmeter (ohms scales) but under load would not provide sufficient capacity to ground. Replaced it with an Advance auto generic strap.
The bad engine ground was one to the top of the engine grounding the brains and other electronics on the 85 car to the engine. The terminal was clean, but a bit loose, and the wires into the ring terminal were corroded.
Sounds incredible, I know, but I'm reviving cars that were given up for dead, so issues are multiple. In all above cases I had clicking in various relays.
Stick with it! I say do all grounds and clean all electrical contacts, then move from there directly to coil voltages, etc.
You can use a 3 way jumper on the AFM relay/fuel injection relay ( XVI , shown with the green dot diagonally above the FI relay to the left): 87 to 87 to 30 or 87 to 87a to 30 depending on how the relay is labeled. This is has been a culprit many of us, even when all other electrical systems aren't perfect. Actually, this is what I would try now.
The low voltage has occured when there was a low battery.
It also occured with the ignition switch was bad.
It happened another time (twice, actually, once on 32V, once 16V) when there was a melted wire on the back of the panel drawing voltage off some of the circuits.
And it happened another time when I had corosion hidden beneath the plastic cover on the battery ground cable. It had continuity at the sensitivity I measured with the digital voltmeter (ohms scales) but under load would not provide sufficient capacity to ground. Replaced it with an Advance auto generic strap.
The bad engine ground was one to the top of the engine grounding the brains and other electronics on the 85 car to the engine. The terminal was clean, but a bit loose, and the wires into the ring terminal were corroded.
Sounds incredible, I know, but I'm reviving cars that were given up for dead, so issues are multiple. In all above cases I had clicking in various relays.
Stick with it! I say do all grounds and clean all electrical contacts, then move from there directly to coil voltages, etc.
You can use a 3 way jumper on the AFM relay/fuel injection relay ( XVI , shown with the green dot diagonally above the FI relay to the left): 87 to 87 to 30 or 87 to 87a to 30 depending on how the relay is labeled. This is has been a culprit many of us, even when all other electrical systems aren't perfect. Actually, this is what I would try now.
04-10-2010, 07:51 PM
#23
Rennlist Member
Rennlist Site Sponsor
The '83 has two ignition resistors, one @ 0.4 Ohms and one @ 0.6 Ohms.
The power to the coil goes thru the 0.6 Ohm resistor during cranking, and thru both during running. If the 0.4 Ohm resistor fails, the engine will run as long as the starter is operating, but will die almost instantly when the starter drops out.
Turn the ignition switch on, and check for voltage on Terminal 15 (small black wire) on the ignition coil. If there is no voltage, suspect the resistor.
The power to the coil goes thru the 0.6 Ohm resistor during cranking, and thru both during running. If the 0.4 Ohm resistor fails, the engine will run as long as the starter is operating, but will die almost instantly when the starter drops out.
Turn the ignition switch on, and check for voltage on Terminal 15 (small black wire) on the ignition coil. If there is no voltage, suspect the resistor.
