Please Help - Electrical Problem
 

OK, here' the deal.

'71 914, 1.7L

I drove down from Nor-Cal 2 weeks ago (to LA) through a bad storm that caused the landslide on 5 at the Grapvine.
I had to divert to 101 through SLO and Malibu.

I got to my new place just fine; but the next day, I am driving along and then the motor cuts out like a ligth switch; and then kicks back on again. Off, on, off, on. For the first week, it would restart just fine. But now, it will barely run for more than 10 seconds before it cuts.

I have replaced:

1) Head Temp Sensor
2) Ignition Switch
3) Fuses on fuse block
4) Checked the Black round relays on the fuse block and in the relay board; they all seem to check out.
5) Condensor
6) Points
7) Spark Plugs
8) Spark Plug Wires


When I:

Turn the key to the first stop, power come's on, I hear the Fuel pump prime the system.

I twist to start, the starter spins the motor.

I have unscrewed the fuse panel and:

when I shift it around, I can get the engine to stay running,
but , for the life of me, I can not figure out were exactly the problem is.

I have a Multimeter.
I have the Haynes manual.
I can read a schematic; although this one leaves a lot to be desired.

I am guessing, as this is typical German wiring; that there is a common "postive" wire that is shorting somewhere in the dash or at the panel.

Obviousely, too much moisture ushed its way in along with a couple of gremlins.


thanks to all!!

Dave B.

Check all your grounds?

I would think that it would take more ground to start the car than to keep it running. Have you checked above the panel for any broken/cut/burned wiring? Any chance one of the tangs on the block is loose? I would look on the schematic for the wires that lead to the fuse block that would have a direct effect on ignition and look at all of those first. You are obviously close to the problem if you can effect it by moving the block around.

Check your ignition switch. While the car is running juggle your keys and see if your car cuts out. You also may have your coil wire shorting to ground killing your spark. The instantaneous nature of your problem definetly sounds like something stopping your spark from happening.
Grounds on engine block-
Coil wires-
ig switch-

If the ground wires on your block open, your injectors will stop working.
Thats all I can think of off the top of my head. Someone else will fill in the blanks I'm sure.

Mike

Check for a grounded wire...

Funny story, my father in law gave me my 914 because of an electrical problem that would kill the lights or the radio or the ignition or whatever it felt like killing. I had 25 or so little boxes of German fuses that came with the car! So I dealt with the problem as I was restoring the car to running condition as best I could. One day I decided to knock out that new carpet kit project that he hadn't. I have a 74 2.0 liter with one of those center gauge consoles. As I was removing the console for the carpet I discovered a tangled mess of wires by the heat flapper lever. The wires were bouncing off the the lever! Probably 4 or 5 pairs of wires over the top of each other. I taped them all off and haven't had a problem since.

My 914 died one day in a storm. Had a devil of a time trying to fix it. It did turn out to be one of the little black relays in the engine compartment, though they all looked fine. Try removing all of the black relays and relocating them to a different spot. If this fixes the problem then one of them is bad. The seal on the bottom breaks and water gets inside and they go to hell (happens after a rain). If that doesn't fix it try checking the fuel pump. If the car is turning over just fine, but not staying running try going underneath the car and tapping the fuel pump with a ratchet. If that fixes the problem then you need to replace the brushes on the fuel pump (which BTW are not replaceable) So then it is time to get a NEW (or rebuilt) fuel pump. If none of that works call Brad Roberts and just throw a 6 cylinder in there! hehe

-Chris

hey thanks guys!!
 

I will give it all a try!

...and let you know how it went.

Still searching
 

>Big ground just to left/above fuse panel, >10mm nut, multiple lines.

Checked this, its fine
Also re-did ground harness @ engine block.

though I found fault with the wire that is jumpered at the ufse block from the ignition to the relay board.

I clipped each side and ran a fresh wire; still same problem.

I have a couple of Q's someone might be able to answer:

1) the Fuel pump; it primes when teh key is turned from off to on.

How does it do this? Is the FI comp spinning it until a certain pressure is reached?
Or does it spin it for a set time before the starter is engaged?

When does the FI comp tell it to start up again?

Since I dont see an Electrical Fuel pressure sensor, How does the FI know anything about Fuel delivery? I gues it just works by tables. Obviousely not a closed loop; more like an "electric" mechanical fuel injection.

thanks again guys

The FI runs the pump for about 1.5 seconds when the key goes from "off" to "on". The pump also runs while the starter is cranking, and also when the trigger points in the distributor are opened and closed fast enough. (Something like 200 engine RPM.)

The FI is not closed loop, it simply figures out what it thinks you need and opens the injectors for that long.


So, is the starter cranking?

If so, are you getting spark?
How about fuel?

--DD

Bash555,

Try this; Pull the 3 black wire terminals off of Fuse S8 and clean all of the connections and reinstall. See if this corrects your problem.
Good luck,
Phil