7.3 Cold Start Issue
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7.3 Cold Start Issue
Hi guys,
I'm kinda new here and bought a 2000 F350 at the beginning of this year. I never really had any problems until now. It starts fine if I leave it plugged in but when I go to leave work after it sits for 9 or 10 hours and it's cold outside, around or below freezing, the engine cranks just fine but it sounds like it fires once then just keeps cranking. The only way to get it to start is to turn the key off and try again. Sometimes it takes 2 or 3 tries to get it to start. Also, once it does start it smokes a white ish smoke for maybe 10 or so seconds then clears up and doesnt smoke any other time. Never smokes when plugged in. I've tried waiting about a minute after the wait to start light goes off and it doesnt seem to make a difference. Changed out glow plugs, used brand new motorcraft ones but didn't make a difference. From searching around a little I tried unplugging the ICP sensor and cranking but it didnt seem to have any effect so I dont think that's the issue but I may be wrong. Hoping for some input from you guys as to what may be the culprit. My next guess would be CPS.
I'm kinda new here and bought a 2000 F350 at the beginning of this year. I never really had any problems until now. It starts fine if I leave it plugged in but when I go to leave work after it sits for 9 or 10 hours and it's cold outside, around or below freezing, the engine cranks just fine but it sounds like it fires once then just keeps cranking. The only way to get it to start is to turn the key off and try again. Sometimes it takes 2 or 3 tries to get it to start. Also, once it does start it smokes a white ish smoke for maybe 10 or so seconds then clears up and doesnt smoke any other time. Never smokes when plugged in. I've tried waiting about a minute after the wait to start light goes off and it doesnt seem to make a difference. Changed out glow plugs, used brand new motorcraft ones but didn't make a difference. From searching around a little I tried unplugging the ICP sensor and cranking but it didnt seem to have any effect so I dont think that's the issue but I may be wrong. Hoping for some input from you guys as to what may be the culprit. My next guess would be CPS.
Postmaster
Joined: Nov 2015
Posts: 4,807
Likes: 125
From: Colorado Springs
Welcome to FTE.
I would start with checking to make sure the GPR actually works based on what you stated. See the video. How long are you consistently leaving the key on BEFORE trying to start the truck? Keep in mind that the WTS LIGHT has ABSOLUTELY NOTHING to do with the GPR. Think of the WTS light as the time it takes the fuel pump to prime the system. The GPR will keep the glow plugs activated for up to 2 full minutes. The white smoke at start up is normal. If you haven’t already switch to 5w/40 synthetic it will help with the cold starts. A lot of us in the 7.3L forum are running Triax oil, the 7.3L really seems to like it. I really think your issue may be with the GPR. If it’s dead, by a Stancor GPR and you’ll never have to worry about it again.
Remember ONLY OEM sensors in these trucks...
In the future post here: https://www.ford-trucks.com/forums/forum31/
I would start with checking to make sure the GPR actually works based on what you stated. See the video. How long are you consistently leaving the key on BEFORE trying to start the truck? Keep in mind that the WTS LIGHT has ABSOLUTELY NOTHING to do with the GPR. Think of the WTS light as the time it takes the fuel pump to prime the system. The GPR will keep the glow plugs activated for up to 2 full minutes. The white smoke at start up is normal. If you haven’t already switch to 5w/40 synthetic it will help with the cold starts. A lot of us in the 7.3L forum are running Triax oil, the 7.3L really seems to like it. I really think your issue may be with the GPR. If it’s dead, by a Stancor GPR and you’ll never have to worry about it again.
Remember ONLY OEM sensors in these trucks...
In the future post here: https://www.ford-trucks.com/forums/forum31/
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Joined: Dec 2018
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Thanks for the advice. I never though about the relay. I just checked and have 12.66 Volts on the left, same as the battery, and 11.5 on the right when the key gets turned on. Does this mean the relay is ok or is it bad since the voltage is dropping? I usually wait about 30 seconds after I turn the key on. I did not realize the wait to start light did not have anything to do with the glow plugs. Only got home an hour ago so I will try in the morning when it's cold and leave the key on for about 2 minutes and see.
Tuned
Joined: Dec 2018
Posts: 330
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If your PS has a hard time starting when cold, it's probably the glow plugs and/or relay and/or the wiring harness(es).
The white smoke is a giveaway that the pre-heat system is not functioning properly, and is leaving you with unburnt fuel in the cylinders.
Replacing either of these components is not a difficult job...it took me 4 hours to change out the glow plugs on one side, then only 2 on the next...and I had to replace the wiring harnesses too!
Use ONLY Motorcraft glow-plugs...the Bosch have a tendency to swell, and then are impossible to remove without taking the head off.
Go for the cheapest part first....the relay.If that doesn't fix it, disconnect the wiring harness and check the resistance of the glow-plug pins to ground (don't remember which ones they are...easy enough to Google it).
If the resistance of each GP is good, then it is probably the harness....they tend to burn up and melt under the heavy draw. You should be able to see if there is an issue when you unplug them.
The harnesses are the second least-expensive/time consuming repair.
If worse comes to worse and you need to replace the GP's...do yourself a favour and replace ALL of them as well as the harnesses and GP relay....that will eliminate any further cold-start problems for the next few years.
Good luck, keep us posted on your progress.
Edit: I just went back and re-read your post....didn't realize that yours was a 2000. Mine was a '97 so I don't know if the ease-of-replacement will apply to your vehicle as it did to mine.
Regardless, the process of elimination should be the same.
The white smoke is a giveaway that the pre-heat system is not functioning properly, and is leaving you with unburnt fuel in the cylinders.
Replacing either of these components is not a difficult job...it took me 4 hours to change out the glow plugs on one side, then only 2 on the next...and I had to replace the wiring harnesses too!
Use ONLY Motorcraft glow-plugs...the Bosch have a tendency to swell, and then are impossible to remove without taking the head off.
Go for the cheapest part first....the relay.If that doesn't fix it, disconnect the wiring harness and check the resistance of the glow-plug pins to ground (don't remember which ones they are...easy enough to Google it).
If the resistance of each GP is good, then it is probably the harness....they tend to burn up and melt under the heavy draw. You should be able to see if there is an issue when you unplug them.
The harnesses are the second least-expensive/time consuming repair.
If worse comes to worse and you need to replace the GP's...do yourself a favour and replace ALL of them as well as the harnesses and GP relay....that will eliminate any further cold-start problems for the next few years.
Good luck, keep us posted on your progress.
Edit: I just went back and re-read your post....didn't realize that yours was a 2000. Mine was a '97 so I don't know if the ease-of-replacement will apply to your vehicle as it did to mine.
Regardless, the process of elimination should be the same.
Postmaster
Joined: Nov 2015
Posts: 4,807
Likes: 125
From: Colorado Springs
Thanks for the advice. I never though about the relay. I just checked and have 12.66 Volts on the left, same as the battery, and 11.5 on the right when the key gets turned on. Does this mean the relay is ok or is it bad since the voltage is dropping? I usually wait about 30 seconds after I turn the key on. I did not realize the wait to start light did not have anything to do with the glow plugs. Only got home an hour ago so I will try in the morning when it's cold and leave the key on for about 2 minutes and see.
Palumma Car Charger, 5V/3.6A Dual USB Port Safe Smart Quick Car Charger Adapter with LED/LCD Display Battery Low Voltage Warning Volt Meter Car Battery Monitor (Black)
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Started fine today (about 30°F) after leaving the key on for right around 2 minutes. No smoke either. I had always thought the wait to start light was for the glow plugs. I think I'm going to do as you said you did Colorado350 and wire an led to show when the glow plugs are on. Thanks guys for all your help and sorry for being such a noob.
Laughing Gas
Joined: Mar 2015
Posts: 885
Likes: 2
From: Pittsburgh
Thanks for the advice. I never though about the relay. I just checked and have 12.66 Volts on the left, same as the battery, and 11.5 on the right when the key gets turned on. Does this mean the relay is ok or is it bad since the voltage is dropping? I usually wait about 30 seconds after I turn the key on. I did not realize the wait to start light did not have anything to do with the glow plugs. Only got home an hour ago so I will try in the morning when it's cold and leave the key on for about 2 minutes and see.
Quickly measure the voltage on the post opposite the "always hot" large terminal between chassis ground and this post. This is the post that feeds the glow plugs. If your voltage measurement there is less than .2 volt lower than the "always hot" post, the relay is beginning to have the contacts burned from arcing. Otherwise it is working fine and you may have a glow plug problem.
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