I have logged somewhere around 700-750 miles on the rebuild. I've been daily driving it for the last couple weeks. It runs strong, builds boost quickly, EGTs are in check, all the vitals are in spec, very happy with it so far. The only thing I've been fighting with is difficult cold starts. The injection pump was rebuilt by a reputable local shop and new injectors. All the return lines, caps, o-rings, fuel lines, etc are new. I replaced the mechanical lift pump with a Facet Duralift conversion. The batteries still test out strong, the starter was rebuilt by my father in law. When I cold start it I let the glow plugs cycle 2-3 times, at the same time the electric pump kicks on priming the system. When I go to crank it over, it seems to spin over plenty fast. I hold the throttle wide open, it coughs and spudders. When it finally starts after 2 or 3 tries, it lopes and runs rough and smokes like crazy. It eventually smooths out and runs good. The only things I can think of is the main cable to the starter needs to be replaced, defective injector(s), or something wrong with the injection pump. Any ideas?

 

You didn't mention the actual glow plugs-- sounds like you have 2 or 3+ dead ones. Dead glows will short-cycle the glow plug relay, the more dead the shorter the cycle. Also cause hard starts, white smoke, and loping.

They could also be disconnected or have broken wires, same result.

 

Yup; it's glow plugs. Get the system working correctly as best you can.

You can always setup a manual pushbutton on your glow plug relay; try manually activating it for a few seconds and see if that helps.
Make sure that the glow plugs themselves are good first, though.

 

They are/were fresh glow plugs (Motorcraft) I'll have to check the wiring harness as well. Makes sense now that you mention it. The wait to start/glow plug light does work, you can hear the relay click on and off. I also added a secondary indicator light to verify that the relay system is functioning. I guess I took for granted that new glow plugs mean, they work. Thanks guys

 

Y'know, I'm still not sure but I'm running into a similar problem on my current truck.
I had a dead glow plug for a while, so it glowed a bit too short and was hard to start. Replaced with 8 new glow plugs(tested them all) and... now it just clicks.
Not sure whether something's not connected correctly, or the resistances are wrong or what. I haven't played with it yet.

 

Definitely double check the harness. I put brand new plugs in my 88 and still acted like only 5 were working. Checked the ones that came out, all worked, 1 was a little weak. Havent dug the harness out of it yet.

 

Kind of an update, I had some time after work to check things out. All 8 glow plugs tested out good. With the glow plugs disconnected, I ran a jumper wire between the two posts on the relay and checked for power at the glow plug connectors. That checked out good as well, one thing I did notice one of the retaining tabs was broken on one of the connectors. I plugged everything back in and made sure all the connections were secure. I cycled the glow plugs one time, 3/4 throttle and cranked it over. It spuddered a little bit and fired up, high idle running smoothly. I had the shop warmed up to 45- 50 degrees, I am thinking that might be why it started easier. I'll have to do a cold start tomorrow after work, see what happens. I don't know what else it could be if this doesn't fix it. Literally everything on this engine is new.

 

How did you test the plugs?

 

I used a test light, gator clip on the positive terminal and touched the probe to the terminal of the glow plug.

 

I did another cold start this evening. I had to crank it over with my foot to the floor and it started. When it did fire up, it ran smooth and no smoke. So I'm thinking the glow plug system is working fine. One thing I did notice is the inlet side of the injection pump is leaking fuel into the valley pan and running down the back of the engine. With it running it drips very very slowly. I'm thinking this is the culprit. If I let the pump prime up it seems to mask the problem. Any thoughts?

 

The slow drip when running is a sure sign of internal tolerance failure, in my experience. However if it's truly at the inlet it may just be a poor fit at one of the *three* connections right there.
(Fuel supply line "olive", brass supply-adapter-to pump body o-ring, and the brass or body itself if there is a scratch too deep to be sealed)
The most common failure by far is the olive.

However if it's not that then it's internal and needs a full rebuild.
Does it also have a hot-start problem? Like you drive 15-30 mins, park and come back 20-30 mins later and it's hard to start?

 

It generally hot starts good. Sitting for 30 minutes, it might have to roll over an extra time or two. The IP has been very recently rebuilt. I really hope I don't have to get it done again.

 

Yeah really, what a pain. Could be an injector line too, sometimes they just aren't quite right and take an extra bit of elbow grease.

My favorite trick is a little mirror on a stick so you can look under the IP while it's dripping. Helps a ton to narrow it down.

 

That was my next plan of attack, I'm pretty sure I have it narrowed down to the fuel inlet area. Those little mirrors are my best friend in the shop, I have 3 or 4 of them. I'm thinking I'll go in there and double check all the lines and fittings, make sure everything is tight. I absolutely HATE leaks of any kind, makes my OCD go crazy. Lol

 

Well I located the fuel leak, it's the 90 degree barbed fitting for the fuel between the fuel filter housing and the injection pump. I tried tightening it, helped a little bit but still leaking. Is there a product that I could use to seal the threads on the barbed fitting?