# 7.3 Starting Problems



## redplowman

I will appreciate any help y'all might give with this problem!
I have a 2001 Super Duty with a 7.3 diesel with 118,000 miles on it. I am having a problem with it starting cold. We have replace the glow plug relay, all the glow plugs, checked the glow plug harnesses as well as ohmed out all the glow plugs through the harnesses. We are 99.9% sure the glow plugs are working but still no cold start. If we plug the block heater in the truck will start in about 30 minutes. Other items we have checked is the high pressure oil pump and fuel filter. Does anyone have any other ideas of what it might be. Thanks for looking!


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## White Gardens

redplowman;1606278 said:


> I will appreciate any help y'all might give with this problem!
> I have a 2001 Super Duty with a 7.3 diesel with 118,000 miles on it. I am having a problem with it starting cold. We have replace the glow plug relay, all the glow plugs, checked the glow plug harnesses as well as ohmed out all the glow plugs through the harnesses. We are 99.9% sure the glow plugs are working but still no cold start. If we plug the block heater in the truck will start in about 30 minutes. Other items we have checked is the high pressure oil pump and fuel filter. Does anyone have any other ideas of what it might be. Thanks for looking!


Not plugging it in.

....


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## redplowman

I wouldn't think I would have to plug it in at 20 degrees.


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## goel

Cycle the glow plugs a few times. Does that make a difference?

As long as mine is parked inside (unheated shop) it will start, And the block heater has not worked in a couple years. 

Now if its going to be colder than hill freezing over for a couple weeks straight I make sure it gets started regularly.


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## Milwaukee

Get volt multi tester and put on batteries do you see volts from 12.30 drop to 10.5-10.8 volts for like 5 seconds then creep up 11 volt stay for about 100 seconds if i remember.

Until engine had low compression or injectors tired. Had you try 5w40 synth oil? I used to run those in tired injectors it help very much in cold outside.


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## redplowman

The oil is the recommended type and cycling does not help. Do you think the injectors could be bad at such a low millage?


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## FordFisherman

Have you checked that the HPOP reservoir is full? Just a thought.


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## Milwaukee

redplowman;1606343 said:


> The oil is the recommended type and cycling does not help. Do you think the injectors could be bad at such a low millage?


Too many to list.

Not change oil on time, run on low fuel pressure, clogged fuel filter, and bad fuel can cause this.

When I had tired injectors it wouldn't start or had very bad romp. Switch to 5w40 it like you had new engine ever start -5oF with no ROMP.

Does it smoke when crank or none? If plug block heater for 20 mins does it smoke white?


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## FordFisherman

How does it run once its started? Try switching out the relay with a Fisher or Western relay. Had a Napa unit go bad on me in under a year. Just cause its new doesn't mean its good.


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## dfd9

Since the last time I replied on a 7.3 cold start issue I got bit, check the oil. lol

You shouldn't have to keep it plugged in, but it helps. 

Weird. 

Is your fuel draining back? Wasn't there an issue on diesels sometimes? Or something with the injectors, I'm too tired to remember.


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## redplowman

Oil was just changed, fuel filter does not look bad. It does blow out black smoke when it is cranking. The HPOP is full.


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## Milwaukee

FordFisherman;1606360 said:


> How does it run once its started? Try switching out the relay with a Fisher or Western relay. Had a Napa unit go bad on me in under a year. Just cause its new doesn't mean its good.


I use Boss's relay I think trombetta it was best one I can find that handle glow plug system.


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## diesel dave 04

Batteries are bad or the starter is drawing to many amps. (to slow of a crank speed with thick oil)


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## Milwaukee

diesel dave 04;1606397 said:


> Batteries are bad or the starter is drawing to many amps. (to slow of a crank speed with thick oil)


Check batteries terminals. Make sure they are 100% CLEAN.


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## redplowman

2 new batteries, I'm not sure about the starter. cleaned all the battery and ground connections!


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## Milwaukee

Where you in Michigan? 

U need scanner to find what exact issue with this one.


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## jmac5058

redplowman;1606382 said:


> Oil was just changed, fuel filter does not look bad. It does blow out black smoke when it is cranking. The HPOP is full.


If the oil was no changed its whole life with the right oil the HPOP will make the injectors fail prematurely . Even having fresh oil will not improve this condition . I think its injectors from bad oil. There are fue diesel motors that use HPOP injection system but the 7.3 is one of them. Theres a guy on you tube that shows you how to change the HPOP oil on a 7.3 this can sometimes get your injectors to work better.I think his name is Powerstroke help from Georgia.


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## Milwaukee

jmac5058;1606422 said:


> If the oil was no changed its whole life with the right oil the HPOP will make the injectors fail prematurely . Even having fresh oil will not improve this condition . I think its injectors from bad oil. There are fue diesel motors that use HPOP injection system but the 7.3 is one of them. Theres a guy on you tube that shows you how to change the HPOP oil on a 7.3 this can sometimes get your injectors to work better.I think his name is Powerstroke help from Georgia.


^ Here one word for you. Stop believe what he say. Every words come out his mouth is blah to get you fall in his gimmick words on youtube.


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## TLK380

Check your fuel filter.
I changed mine and after removing it i saw about 1/4 " of debris on the bottom of that can.
If it gets dirty again real fast then check your fuel tank for delamination.
Hope that helps.


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## brad96z28

On a few trucks I have fixed that had bad glow plug relay I could not get the computer to send a signal to the gp realay until I cleared the code in the computer. This code will also not out on the ck engine light.An easy quick test that will tell you your probelm. Next cold day dont plug it in. Turn the key on and run a scrwedriver across the 2 large terminals on the gp realy for 20 sec then try to start it.then you know if realy is not working, weither its bad or not getting the propper singnal some more testing will be needed. This will point you in the right direction. You can pm me if you want any more info. Its a fairly easy system.


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## brad96z28

jmac5058;1606422 said:


> If the oil was no changed its whole life with the right oil the HPOP will make the injectors fail prematurely . Even having fresh oil will not improve this condition . I think its injectors from bad oil. There are fue diesel motors that use HPOP injection system but the 7.3 is one of them. Theres a guy on you tube that shows you how to change the HPOP oil on a 7.3 this can sometimes get your injectors to work better.I think his name is Powerstroke help from Georgia.


The hp oil pump oil mixes with the oil in the crank case anyway. changing the oil in the hpop is a prety big waste of time.


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## brad96z28

redplowman;1606382 said:


> Oil was just changed, fuel filter does not look bad. It does blow out black smoke when it is cranking. The HPOP is full.


If the filter was a problem it would not effect the truck only when its cold.


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## Milwaukee

brad96z28;1606965 said:


> If the filter was a problem it would not effect the truck only when its cold.


Reason I say fuel filter is when they RUIN injectors. When injectors go bad they wouldn't start until plug for 30-1 hour.

Since he say plug for 20 mins it start. Going think it related to glow plug system issue.


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## sparksrides

I'm having a little trouble with my 99 if i don't plug it in and it all started when my fuel heater wen't bad, it was a dead short and keep popping ecm fuse so I unplugged it and it stopped popping the fuse and the truck started but now if i don't plug the truck in and it sits for 24 hrs cold it don't want to start. I have to give it a tiny shot of either and it fires right up, just make sure when using either to let the glow plugs cycle before spraying and only a tiny spray.( you probably know this but...) I've seen too meany people ruin a diesel with too much either anyway hope this helps but i could be wrong, I just know my truck and it might not be the case with yours but its worth a look


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## diesel dave 04

I still say starter to slow of a crank speed when the oil is thick!


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## brad96z28

sparksrides;1607048 said:


> I'm having a little trouble with my 99 if i don't plug it in and it all started when my fuel heater wen't bad, it was a dead short and keep popping ecm fuse so I unplugged it and it stopped popping the fuse and the truck started but now if i don't plug the truck in and it sits for 24 hrs cold it don't want to start. I have to give it a tiny shot of either and it fires right up, just make sure when using either to let the glow plugs cycle before spraying and only a tiny spray.( you probably know this but...) I've seen too meany people ruin a diesel with too much either anyway hope this helps but i could be wrong, I just know my truck and it might not be the case with yours but its worth a look


You dont need to use ether in a 7.3 powerstroke and its a bad idea. I never ever had to plug mine even at 0 temps. I also had my fuel heater unplugged never made a difference in starting But helps keep it from gelling in the bowl. The glow plugs stay on for about 2 min even though the light goes off .


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## rob1325

My 2000 7.3 had same problems and it was idm module in driver side wheel well. I'm just throwing this out there.


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## 7.3 Plower

sparksrides;1607048 said:


> I'm having a little trouble with my 99 if i don't plug it in and it all started when my fuel heater wen't bad, it was a dead short and keep popping ecm fuse so I unplugged it and it stopped popping the fuse and the truck started but now if i don't plug the truck in and it sits for 24 hrs cold it don't want to start. I have to give it a tiny shot of either and it fires right up, just make sure when using either to let the glow plugs cycle before spraying and only a tiny spray.( you probably know this but...) I've seen too meany people ruin a diesel with too much either anyway hope this helps but i could be wrong, I just know my truck and it might not be the case with yours but its worth a look


Do not use ether on a 7.3 it's a terrible idea. The glow plugs remain on for long after the wait to start light turns off. If you truly feel the need to use ether disconnect the glow plug relay then proceed.

That being said using ether is asking for low compression issues and that's a whole nother mess.

If the truck is starting poorly then romping after startup your injectors could be bad. Poor maintenance can do all sorts of funny things to a HEUI system. When my injectors started going bad the truck had a tough time starting in the cold unless plugged in and when it did it would romp badly and have a slight miss until warm. I'd lean towards worn injectors due to lack of maintenance but that's just me guessing like everyone else in the thread. Sounds like you have a pretty good idea of what's going on being that you checked the HPOP reservoir oil level replaced your relay ohmed your harness etc


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## redplowman

Well, thanks for all the replies, we took it to dealership today and here is their take on it.

They said they would start with replacing the injector harnesses at $360
Then if that didn't fix it, the injectors are bad. $3000

Just what does everyone think of that? Does that seam realistic of just a wild ass guess.

They say the oil is the culprit and changing oil type wont work.


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## Milwaukee

redplowman;1615196 said:


> Well, thanks for all the replies, we took it to dealership today and here is their take on it.
> 
> They said they would start with replacing the injector harnesses at $360
> Then if that didn't fix it, the injectors are bad. $3000
> 
> Just what does everyone think of that? Does that seam realistic of just a wild ass guess.
> 
> They say the oil is the culprit and changing oil type wont work.


SMH you should have told where are you in Michigan plus find someone with scanner.


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## dfd9

I'm thinking you'll be $360 lighter in the wallet and still be having the same problem.

First problem: You took it to a dealer.

Second problem: You took it to a dealer. 

If they are guessing at it and can't give you a diagnosis, they are parts changers and have no idea what they are doing. 

As Milwaukee stated, you need to have someone scan it while its running, starting hard, etc. This is not some guess by numbers problem. Especially when the numbers are coming out of your wallet. 

Where in MI are you? 

Find a good diesel shop that knows what they are doing rather than playing with your money. 

PS Third problem: You took it to a dealer.


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## clark lawn

They should be able to pin out the harness and tell you if its good or not. If the harness or the solenoid on the injector failed then oil has nothing to do with that. Sounds like they are just throwing parts at it.


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## diesel dave 04

if it was a harness it would be bad all the time not just a cold start issue. I have seen bad injectors cause a no start cold do to sticking try some oil addative like rev x and see if it helps if so then i would say injectors.


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## BlindViper

On the glow plug relay there is 4 terminals, 2 small,2 large. Take a screwdriver and short the 2 large terminals for 20 seconds. Try and start the truck if it starts your relay needs to be replaced. The 7.3 is rated to start at -20 deg without being plugged in. If it starts when plugged in its a 99% of the time its a glow plug issue.


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## plowguy43

How do you short it with a screwdriver? I want to try this with my 7.3


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## Milwaukee

plowguy43;1616894 said:


> How do you short it with a screwdriver? I want to try this with my 7.3


Look at glow plug relay it look like starter solenoid it closer to turbo. Stick screwdriver on 2 Big studs. It bring ALOT amps it will turn screwdriver glow red.


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## brad96z28

BlindViper;1616793 said:


> On the glow plug relay there is 4 terminals, 2 small,2 large. Take a screwdriver and short the 2 large terminals for 20 seconds. Try and start the truck if it starts your relay needs to be replaced. The 7.3 is rated to start at -20 deg without being plugged in. If it starts when plugged in its a 99% of the time its a glow plug issue.


I said to do that in post #20 but people sometimes refuse to take good advise


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## plowguy43

Milwaukee;1616903 said:


> Look at glow plug relay it look like starter solenoid it closer to turbo. Stick screwdriver on 2 Big studs. It bring ALOT amps it will turn screwdriver glow red.


Geez I had a brain fart there. Yes I get it now, should've re-read it before i posted.


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## NBI Lawn

Funny, I was going to ask about hard starts. Went to a dealer today to look at a 99 7.3. It was 33 degrees today and it wouldn't start. They sprayed starting fluid in it to get it to start! Yeah I know, not a good idea. Being it's at a dealer it's hard to get any answers or any real maintenance history. Not sure about glow plugs or anything so I don't know where to start for a price.


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## dfd9

NBI Lawn;1617048 said:


> Funny, I was going to ask about hard starts. Went to a dealer today to look at a 99 7.3. It was 33 degrees today and it wouldn't start. They sprayed starting fluid in it to get it to start! Yeah I know, not a good idea. Being it's at a dealer it's hard to get any answers or any real maintenance history. Not sure about glow plugs or anything so I don't know where to start for a price.


If I saw that, they'd probably be wondering why I was ducking and hiding.

Idiots.


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## plowguy43

NBI Lawn;1617048 said:


> Funny, I was going to ask about hard starts. Went to a dealer today to look at a 99 7.3. It was 33 degrees today and it wouldn't start. They sprayed starting fluid in it to get it to start! Yeah I know, not a good idea. Being it's at a dealer it's hard to get any answers or any real maintenance history. Not sure about glow plugs or anything so I don't know where to start for a price.


If you want to PM me the VIN I can run an OASIS on it, but you'll only get what was done at a dealer.

Once it started did it have a ton of blue smoke? Did it clear quickly or continue blue? If it didn't clear quickly its a sign of weak injectors. Otherwise, it could simply be a Glow plug relay, or the plugs themselves. Not very difficult or expensive to fix.


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## redplowman

I am on the west side of the state near Grand Rapids. The glow plug system has be checked very thoroughly, we put all new glow plugs in, checked all voltages on the harness, and even jumped the relay. Hey, how long should the fuel pump run when the key is turned on. This runs about 20 seconds and you can hear air surging through the lines! Keep the info coming, I really appreciate all of it!


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## White Gardens

redplowman;1618870 said:


> I am on the west side of the state near Grand Rapids. The glow plug system has be checked very thoroughly, we put all new glow plugs in, checked all voltages on the harness, and even jumped the relay. Hey, how long should the fuel pump run when the key is turned on. This runs about 20 seconds and you can hear air surging through the lines! Keep the info coming, I really appreciate all of it!


If you think you are hearing air, then it sounds like you you have air intrusion somewhere in the fuel system.

..........


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## Antlerart06

redplowman;1618870 said:


> I am on the west side of the state near Grand Rapids. The glow plug system has be checked very thoroughly, we put all new glow plugs in, checked all voltages on the harness, and even jumped the relay. Hey, how long should the fuel pump run when the key is turned on. This runs about 20 seconds and you can hear air surging through the lines! Keep the info coming, I really appreciate all of it!


You must have good ears to hear air surging in a fuel line I don't even hear my fuel pump run on my 99 7.3
If you cycle the glow plugs 3 times with temps below 30 degrees should start right up 
You said it starts with plug in for 30mins It takes a good hour or 2 to heat the coolant up to shut off the engine block heater 30 mins the coolant still be cold
If you have air in the lines it wont start or even run with air in the lines 
So plugging it up doesn't remove air from lines 
What I do on my 7.3 I'll plug mine up 12 hrs before the storm 
You start it and heater putting heat out means its warm ready to work Jump in and go I don't have to wait for it to warm up

Sound like you better take to a pro let them look at it or buy a gasser


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## redplowman

How about the fuel pump running so long (20 seconds) is this normal?


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## FISHERBOY

what about injector seals?, i just started changing my top end oil in the HPOP(fall 2012) in both trucks and what a difference, the oil really was like glue , both trucks hav always been well taken care of


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