We have a 1988 f250 4x4 that we just put the engine out of our old 1991 f350 in It is a 7.3L. It has cold start issues. I replaced the o'rings and return lines on Sat. I has an e-pump on it so we primed the system and it started really well but the temps where way up close to 70 F. So I though maybe we had fixed it. Went to start it Sunday after lunch and it wouldn't start temp 35 F. I had had the block heater on a couple of hours. Got it to hit once and it had a lot of white smoke. never got it to run. I tested all the glow plugs before the install all tested good. The glow plugs do the 10-15 sec then pulse after that.
Here is my plan of attack. (Supposed to have 10-15 inches of snow tonite) I think there is a possibility that the connections for the glow plugs on the fender well is poor I will hard wire those tonite. A test light on the (left) drives side showed bright while glow plugs where on. Right side where dim. Does each wire server a side. Will replace the glow plug relay. I still think there is some air intursion in the fuel system will replace the line from the return line header to the fuel tank.
Anything else I should do to try and eliminate the hard starts.

 

If you are getting white smoke, you have fuel.
What you are lacking is enough heat.

88 and up engines had two wires from the starter relay to the glow plug relay, but they attached to the same terminal on both the starter relay and the glow plug relay, so at that point it was just a dual path for the electric to flow through.

After it leaves the glow plug relay, one wire does the left cylinder head, one wire does the right cylinder head.

Any connection in the glow plug system that is not clean and tight will cause hard start problems.
Glow plugs with to much resistance are also making less heat than the should be, again hard start problems.
Optimal resistance is .5 to 1 ohm per glow plug.
At .5 ohms, that is 288 watts of heat per glow plug.
At 1 ohm, that drops to 144 watts per plug.

 

Well that is where am going next. I haven't checked the Gp's with an Ohm meter but I did test them with a test light and they all passed. Will do the ohm meter thing. They are all motorcraft Gp's What I saw last night was when I tried to test for voltage at a Gp My fluke meter when OL (over limit) don't understand that. Had 13.36 volts at battery. I have made up the the power wires to the relay as hard connections soldered. Relay is brand new. Will trace voltage out farther. Once again thanks for your help.

 

Any chance you had the meter set to manual ranging instead of auto ranging?

 

The saga now continues I made a complete new glow plug harness I think that issue is now corrected. Wts to start light works as outline good 15 seconds then the clicks. Fuel appears to be an issue. It would not start opened schader no fuel. And this was with the e pump running. pulled filter less than 1/2 full WTF. Appears to be sucking air from somewhere. Tank pickup is in good shape from when I had tank down last weekend. I will now replace the line from the tank to the E-pump. I did manage to get fuel pummping and primed the system. Still no start by then the batteries where getting low. Will try again after I replace the fuel line.