1999 7.3 Powerstroke

Truck is high milage, 410,000. Last summer replaced all injectors, high pressure oil pump, injector pressure regulator, injector wiring harness, and all glow plugs. When below 30 degrees if I do not plug in the truck, it will not start and run. Batteries are one year old, crank speed is good warm. During cold cranking I have white smoke from tailpipe, I also notice the crank speed increase, I assume from the fuel in the cylinders. I have an OTC scan tool but have not checked injector pressure during cold cranking. I also can perform an injector test with this tool but have not done it cold. I'm wondering if the engine is just worn out to the point that the compression won't fire at the cold temps. I have limited diesel experience, especially diagnostic. I run Stanadyne additive, NAPA 15-40 oil, Motorcraft filter.

I recently discovered this site and would be greatful for any diagnostic direction.

Welcome to SOS!!

410K miles- WOW!!

Are you hearing the loud click of the glow plug control relay when you cycle the key to run? Do you see the dash lights and interior lights dim when the wait to start lamp comes on? Do you hear a buzz under the dash when you are starting cold?

I replaced the glow plug relay. I do not see any voltage drop on the dash guage and the wait to start cycle is pretty short. I estimate the wait to start cycle when cold is about 8-10 seconds. I have not checked voltage output from the relay, by the time I get to it the wait to start cycle is over. Thanks for your time.

www.thedieselstop.com is a much better place to research.

The knowledge and time given by fixxer impressed me enough to ask a question, then this morning I got off my duff and did some investigating. I recorded the following: Intake air temp 36, Oil temp 36, Trans temp 36, Manifold air temp 97 degrees. Cranking speed 133-139 rpm, injector cont pressure during cranking 2300/2400 psi, injector duty cycle 34%. All this was during first start attempts without plugging the truck. The glow plug cont time shown was 99 seconds, the glow plug control was 99%, lamp time was 10 seconds. The truck would crank, blow white smoke, but not run. After starting the truck and driving in datastream mode, the manifold air temp only changed 5 degrees. I'm guessing this sensor is bad and since it is showing 97-102. Is it possible this is keeping the glow plug circuit from coming on. I also had two codes P1249 / P0471 - Wastegate control valve performance & Exhaust presure sensor circuit. When cold at times the truck will lay down and blow heavy black smoke. It clears up when hot.

Syd, that's a good site but know we have fixxer22 on the board who is a ford diesel tech. Its nice to ask a tech directly. Alot of us have this truck and I for one love learning about the diagnosis of these problems.

Boat 1 I am having that same trouble truck runs great just a little hard to start when temp is below 30deg. have to plug it in. I too tried testing solenoid by myself and always cycles off before I get out there. I am thinking I have a couple bad glow plugs.
So I am waiting to see fixxer's reply to your thread.

My glow plugs are only 6-7 months old I think they are OK, the relay is a couple of weeks old. I saw no voltage drop at all when I first cycled the key, wait to start light came on like usual but clearly nothing was happening. The truck's computer has decided it wants me to move to Florida, I'm definately considering it. Give me a blower motor I'm comfortable, these diesel thingy's are just screwy. :willy_nilly:

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Originally Posted by Sydwayz

www.thedieselstop.com is a much better place to research.

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Why Fixxxer is a Ford Master certified diesel tech, whats better than that?????

Could you also please verify the coil side off the glow plug relay for me. I assume one signal wire should be 12 volt with key on, and the other side is ground controlled by the PCM. When the glow plugs are called the ground is made by the PCM, when not called what should this side read? I'll bench test the relay to make sure it functions. Thanks.

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Originally Posted by Magic Medicine

Why Fixxxer is a Ford Master certified diesel tech, whats better than that?????

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My bad guys. I didn't know about Fixxxer. Thanks for being here Fixxxer.

But let's not burn him out!

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Originally Posted by Boat1

Could you also please verify the coil side off the glow plug relay for me. I assume one signal wire should be 12 volt with key on, and the other side is ground controlled by the PCM. When the glow plugs are called the ground is made by the PCM, when not called what should this side read? I'll bench test the relay to make sure it functions. Thanks.

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You are going to want to make sure the relay can carry a load. The glow plug system requires a very high ammount of current. I have had properly functioning relays that could light a test lamp but could not carry the load. most of them were just repaced and the terminal was overe-torqued and cracked the contact in the relay itself. Not saying you did it wrong. does your vehicle have the tandem relays indicating that it has an intake air heater as well?

Yes it has tandem relays. Am I correct in thinking that one side of the coil circuit is 12 V with key on, the other side gets a ground from the computer. I'm going to look for a call signal in the morning once everything is cool again. Thanks.

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Originally Posted by fixxxer22

You are going to want to make sure the relay can carry a load. The glow plug system requires a very high ammount of current. I have had properly functioning relays that could light a test lamp but could not carry the load. most of them were just repaced and the terminal was overe-torqued and cracked the contact in the relay itself. Not saying you did it wrong. does your vehicle have the tandem relays indicating that it has an intake air heater as well?

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I agree, had this same issue, your response was my problem, mine was also a late 99, if he has 2 relays it will be a late 99 I am sure, if it is ealry with no intake heater they run like chit cold..

I plug mine in all the time under 35-40, jst hate the sound of them starting cold... I have 362,000 going strong!

I also plug mine in nitely. it's a 2000 F-350 4WD 7.3 w/ 129,000 miles...Only problem I've had is the + wire broke off the alternator. I used vice grips to hold it in place.