1990 Golf GTD, (yes, a real one...lol)
Went start it yesterday and while cycling the glow plugs, the light comes on steady for a few seconds, then begins to blink.
The fact that it wouldn't start is leading me to believe that glow plugs aren't working... I'm getting the smoke out of the exhaust after cranking for a few seconds. Any ideas? I've read that the fuel-water separator at the tank will cause a blinking GP light if it's full of water, but would that cause the GPs not to cycle?
Unfortunately I need this car at the moment, so I'm having to resort to using a shot of starting fluid to get it going. (I know, I know...) I'm off on Monday, so I'll have time to work on the car then.
Also, is there a way to "jump" the glowplugs from the battery so I won't have to use starting fluid?
Use WD 40 instead of starting fluid in a diesel.
I have jumpered directly to the GPs via the fuse block using 10AWG or jumper cables. GPs should withstand ~1min energizing (or more if Duraterms).
a blinking light is water separator, drain separator good, press in fuel fill vent while and after draining. use a catch can. after draining try glowing now, if doesn't fully glow you ll have to troubleshoot glow plugs. in the interim you can jump glow plugs. I wouldn't use a fluid in the intake, jump plugs (carefully, don't make sparks at battery end, and don't ground out on plug/rail side.).
Jump a wire from the battery to the glow plugs. Aligator and battery clips on the end.
It's better than using starting fluid.
Using starting fluid with good glow plugs is a bad idea, good thing they weren't turning on.
You might have a bad ground wire connection on the relay.
Starting fluid has knocked out pre cups, if you need the car don't use it. WD 40 works
1990 Golf GTD, (yes, a real one...lol)
X2
The fusible link in the glowplug control box has blown or cracked.
follow the glow plug bus bars back to the bulkhead, there should be a plastic box with a cover, pry off cover and there should be a piece of tin held on by two allen bolts. This is the fusible link, costs pennies or pfennigs whatever. Replace and enjoy. They are a bit fragile though, so buy two.

X10 on not using ether. Unless persued by a herd of zombies.
A yard of heavy guage copper wire, hold one end to the 12v battery post and with the other end touch the glow plug bus bar for 10 seconds then jump in and start her up before the plugs get too cold. If the wire is too thin you will burn your fingers, if you make a spark at the battery, it might blow up, don't blame me if it all goes horribly wrong. The full wrath of a car battery can be quite impressive.
A jumper cable works great for that.
Sorry for not closing this out.
It turned out to be the fusible link in the glow plug control box on the firewall, it cost me $0.60 to replace.