Here is where I am at:
Bought the 89 7.3 truck dirt cheap. The guy that had it HATED it with a passion. Complained it would never start without ether or being plugged it.
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First thing I did was replace the glowplugs with beru/motorcraft. Then I noticed that the gp relay was cracked and replaced that. Replaced the fuel filter. Replaced old injector return lines. Replaced oil sending unit, installed an after market oil pressure gauge as well (45 lbs cold idle, 60+ lbs cold revved, 42 pounds hot idle, 60 pounds hot revved). Changed oil & filter. Flushed engine/radiator and install new anitfreeze. Install electric fuel pump in front of front tank, before line runs up to motor. Beat head on wall.
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Here is what I still have:
GP only stays lit for 4 to 5 seconds before light goes out. Truck rolls over 5 to 10 seconds, chugs once (maybe). Hit plugs again, mash throttle, then hold at half, full, where ever. Truck will roar to life after 5 to 10 seconds of cranking. Keep in mind, there is NO HESITATION once it starts. No missing, no hunting, no hessitation, just an IMMEDIATE and beautiful diesel rattle.
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Here is the scoup.
Odemeter shows 84,000 miles. Truck is rusy and the body is beat up. Had a gooseneck and 5th wheel hitch and homemade steel combo box rails and headache rack (HEAVY and thick steel). A couple of stockyard and cattle hauling decals and permits. Every stinking oil change sticker from the Ford dealer is on the cab ceiling (no cloth, just steel, this truck has no options, its not even an X, just a f250) There are 27 stickers. My math shows that if the oil was changed every 3k miles, the miles are about right. If the oil was changed every 6k miles, it would have about 180k on it. Either way, it should run great.
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This is the last thing I did:
Pulled the schrader valve core out, connected a rubber line going to a clear container. Hit the key, waited for gp (4 to 5 seconds) and watched the container. The first 1 to 1 1/2 seconds there was nothing, then the fuel came out, clean, no air. I cranked for 5 seconds. During that time, a very foaming fuel came out the line for the duration of the cranking. In 5 seconds of cranking, I had maybe a cup of diesel fuel in the bottle. This seems a fair amount, but the foam raised an eyebrow.

Now, once running, this truck has all kinds of power and does not seem to smoke, black or blue. Its a 5 speed and will chirp the tires in 2nd gear. (4.10 axels) I am very impressed for the power, I just cant under stand why it starts so hard.

I cant find any signs of fuel leaks or weeping, I have the box off right now and the front tank is damp, all over. The rear tank is solid rust. I had to cut the gas cap off (plastic cap was siezed into the rusted metal neck) to get the box off. I assume the rear tank leaked bad.

IS THIS starting problem normal ?

 

Do you still have the mechanical lift pump on the front of the engine? it sounds like you are getting air into the supply lines, 10 secs of cranking is purging the air out

 

replace any metal lines that look questionable going to the lift pump and definitely replace the lift pump, (they are cheap and can make a big dif). Make sure the gp harness is still good where it hooks to the gp tips.

 

Did you change the glow plug controller? Not the relay on the fender, but the controller on the back of the engine. Your glow plugs should stay on for 13 seconds with first cold start, 4-5 seconds is not enough.

 

I would double check the connections on the fuel line of the electrical pump.... I think your sucking air in... what are the fuel levels in the tank(s) being used at or below 1/4 full.

 

glowplug has been replaced, glow plug harness has been checked. Original mech lift pump is still in place. Fuel level is below 1/4 tank.

I would like to eliminiate the mech pump, now that I have an electric pump in place, UNLESS there is good reason not to.

I still have original steel lines. I will check them out tonight and see how bad they are.

Am I to understand that the foam pouring out of the schrader valve is not good ? Remember, it only foamed when the engine was cranking.

 

But you still haven't said if you changed the glow plug controller. But oh well, who needs the darn thing anyway.

 

glow plug controller (relay) was the 2nd thing listed that I changed. The starter relay is on the firewall, the gp relay/controller is at the rear of the block. The starter solenoid works fine.

 

Is there a temp control unit that controls the gp time ?

The reason I ask is the gp light is the same (4 to 5 seconds) unless the engine is hot (run for 10 minutes or more), then it only stays lit for 2 or 3 seconds. Could there be another bad sensor somewhere ?

The fast (cold) idle solenoid works ok, when I start the motor, it idles high for several minutes then will quiet down.

 

Unless your truck is different, the glow plug controller is at the rear of the block. The glow plug relay is on the r/s fender. It is not a starter relay, although it resembles one.
The controller tells the relay when and how long to turn on.
Like I said though, they may have changed it. Mine was an '84 6.9. I have a '92 7.3 now, but I haven't worked on or looked the GP system to see if it's the same or not.

 

as far as I know, the glowplug controller is solid state and contains the relay. It looks kind of like a starter solenoid, but cost plenty more. I also have the glow plug schematic in front of me and it only shows the gp controller for a 7.3.

Also, for future referance. I have checked each and every gp on my truck and each plug gets power and gets hot.

 

is your fuel return bypass still hooked up?? it goes from the passenger front injector return to the top of the fuel filter housing. if it is still there, disconnect the line fron the filter housing and plug it with a brass pipe plug. then cap off the line, and your cold start problem should go away. this was an update that ford recomended in 89 or 90 due to air leaks in the return lines back draining the fuel filter back to the tank when left to sit overnight. parking on a good hill with the motor facing downhill is also a way to tell if this is the problem. with the tank at the same level as the fuel filter, it will not backbleed, and start rite up in the am.