I have a 67 GMC truck that I built and installed a 93 6.5 turbo motor in. My question is basically this. Do the glow plugs need to on for a period of time after the truck first starts in the morning? When the engine is cold it starts fine with about 5 seconds of glow, but it smokes like a chimney until it gets up to about 150 degrees. It was suggested to me to hold the glow plugs on when the truck is cold, and this will not destroy the glow plugs because there will be fuel to help cool them. My glow plug system is operated by a dash mounted switch (spring loaded to release so I don't leave them on). What do you guys think? Mind you I have most of the stock wiring harness in use from the 67. The glow plug relay and wiring is actually from an 89 6.2 truck. Brand new glow plugs, fully rebuilt motor with brand new pistons, rings, bearings, marine injectors, and the IP flow has been turned up. IP has a military grade hydraulic head. Here is a link to the build thread on the 67-72 chevy truck (http://www.67-72chevytrucks.com/vboard/showthread.php?t=290922) forum for more details.

What glowplugs are you using? If your using ACDelco 60Gs then it sounds like your not letting them heat up enough. I know if i only do 4-5 second of glow my blazer may start but it's really smokey. If i give it 10 seconds of glow, it starts much better and there's much less exhaust smoke.

Possible problem with cold start timing advance or whatever it is called on the mechanical injection pumps? Warming to 150 seems rather long to totally blame glo plugs

I forgot to mention that the second solonoid on the IP is tied into the glow plug relay. As suggested by the guy that WAS helping me. I forgot to mention that. Any suggestions on what that sol. Does would be awsome. I'm at the point where I'm figuring this all out by myself.

I reread the post about the second plug on the ip being for timing advance. If this is true what is the "on off" switch for that? Should I consider a timer and second switch for that, or set up an on off sol for that controled by a temp sensor?

marine injectors, Bad