Voltage on glowplug busbar is low?

[Matteo]

 
Hi Volks, I have a 1990 1.6 non turbo. Ran great, then would not start period. Timing belt is newer and still intact. The glow plugs looked very old, so I replaced them. When I took the bus bar of the glow plugs it fell apart. So I made another one by flattening out a 5/8ths piece of copper tube, drilling holes in the appropriate places and sliding the rubber covers back in place. Still would not start. Took out the volt meter and got 10.6 volts on the busbar at where the power from the 50 amp connects. 12v at the input to the 50amp fuse and 10.6v on the output of the 50amp fuse. I removed the fuse and cleaned the corrosion off of it, including the posts, fuse and copper screws. Hooked it up, 12v on both sides. 12v at end of cable that connects to bus bar, but as soon as I attach it 10.6v. Bus bar is not touching anything it can ground too, other than the glow plugs. Replace negative battery terminal connector, cleaned the post, cleaned engine at ground point. Turns over easy, so it is pulling amps.
Is there supposed to be a drop in voltage at the bar? Not sure where to go with this.
Matt

[the caveman]

Where exactly are you putting the lead from your meter when you read he 10.6 V ? I assume are you testing voltage as the key is turned,the glow plug circuit activated. Where ever you are placing the lead, test upstream at the next junction  and see what you get. It's possible it's just the voltage dropping as the glow plugs are pulling current. I never tested glow plug circuits that way, all i care about is approximate 12 v at the buss bar and full current [ 28 A warm, up to 48 A cold].Do you have a clamp ammeter you could use? That's the only real way. If then you are seeing the full current, then stop worrying, and get to the next project.

[fatmobile]

Put one lead on the positive of the battery and one on the buss.

The glow plugs draw alot of power, the battery voltage it dropping too when you connect the plugs.

See what the drop in pressure/volts is between the battery and plugs,.. probably isn't much.

Battery might be old.

[Baron VonZeppelin]

It sounds like your glowplug circuit is doing fine.
You'll get a voltage drop at the buss when the plugs are energizing - like 10.5-11.5 volts i think.
Its going to vary from car to car.

Check to see if your fuel solenoid is working.
That may be the probo.

If you are cranking and cranking trying to start the engine - you would start getting white diesel fuel clouds out the exhaust - IF the glowplugs were NOT operating, and the fuel solenoid IS operating.

So IF you are not getting white diesel fumes out the exhaust after say 3-4-5 tries of cranking for 10-20 seconds each time (cool down periods between those crankings) ... then your fuel shut-off solenoid on the injection pump "may" be the problem.

With the key switch ON in RUN position, go underhood and pull the wire lead off the solenoid - and reattach. You should hear / feel a click in the solenoid each time you do that. Its not definitive, but good place to start.

You can also remove the fuel solenoid, take it apart, remove the plunger, reassemble, reinstall. That makes it FULL ON all the time. And that is a definitive test of the solenoid. HOWEVER, you will have to choke the engine out in 2nd or 3rd gear with the clutch/brake to shut the engine off - when it cranks/runs.

Another cheat test for glowplugs would be to run a good gauge piece of wire from the battery positive - to the bussbar - and try to crank engine like that. I've used piece of wire, and even one side of a pair of jumper cables.