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Starting problem with a twist

2K views 27 replies 3 participants last post by  Rockabillyrider 
#1 ·
Okay so as a lot of us 7.3 owners most of us have had starting problems. Mine is like the others. So I have a 2002 excursion 7.3 meaning I have the stupid glow plug control module. I had to rebuild my glow plug harness for a few broken wires. Replaced all the glow plugs recently trying to fix my problem had multiple that where trash. Problem still here I also replaced my valve cover gaskets in case the harness was bad plus I had a small leak. So my truck still won't start haven't replaced my glow plug control module yet while I was testing to see if I got power to the connector at the valve cover and while probing the outer 2 wires on each connector I found before pulling my key out of my pocket and getting off the truck I had set the other probe on the battery and found I had a constant 10.2V going to each glow plug all the time. Is this normal or is something up please help. I also need to do injectors soon as I did a buzz test and 4 where weak sounding so please help me guys. I have searched and searched for this and found no info about it being normal or not
 
#2 ·
First, realize that Glow Plug operation is NOT required to Start. In fact, at temps above @50F it's hardly noticeable. This time of year, I doubt you need them at all and has nothing to do with your No Start.

Next, 4 Loud, and 4 Quite (or noticeably quieter) is Not normal. You have a problem there... ;)

Usually this is about the UVCH (valvecover connector) but you've replaced those - right? So next Id be thinking IDM but you would certainly have an IDM code - do you? What are you using to retrieve codes and do the Buzz Test?

As for the Power at the plug. This is with the Key OFF? At 10.2v it sounds like the GPs are ON though and that would certainly kill your batteries pretty quickly.

So, lets go over the usual No Start List;


WTS Light? - do you get it when you first roll-on the key? (shows the computer is running)

Can your scanner read Cranking RPM? If so, make sure you are reading over @100rpm (shows the CPS is good)

Is there fuel in the fuel bowl now? Does it refill after cranking? (open the drain level to check) Look above the pass ft tire, you'll see a 3/8" metal tube, against the motor that ends there, it's the drain for the bowl (yellow lever you slide to the side). Get a cup, open the lever, drain the fuel bowl, look at the fuel, close the lever. Then, turn the key to the ON position (should hear the pump) for 15 secs. Drain the fuel bowl again, whaddya got?

Can you hear/feel the pump running (below the dr seat, against the framerail)

Could the fuel gauge be giving a bad reading? (Below 1/4 tank?)

Is it cranking fast enough? - it won't even TRY to start if cranking too slowly.

Is your truck "chipped"? If so, remove it as a Test.

You can unplug the ICP sensor, as a Test, so the PCM sets a default value for the IPR to run on.

Did you check the plug and sheet metal nut going to the IPR? That nut can vibrate off and allow the solenoid going over the valve to slide around. The wires going to the IPR can get brittle, crack, and short together. Make sure the plug & wires look in good shape.
 
#3 ·
Noralph

Forgot to mention a few parts about it when the key is on I get 12.xV threw the harness. Also my truck like others will only start when it's plugged in and I still get a slight rough start when it's 80 degrees out and the truck has been sitting in the sun. Also I have on replaced my cps as far as sensors go. I have not replaced the valve cover gasket and harness. I believe that goes all the way to the outside where the glow plug harness plugs into it.

My injectors are noticeable quieter I know I need new ones just want to make sure that will fix my problem if I do them

I do not have any codes anymore after I rebuilt the harness. Although my current way of checking is a Bluetooth one connector and the torque pro app. Also what I use for my buzz test

I do get my wait to start light when I turn the key to the on position

I am pretty sure my fuel bowl is getting constant fuel as when it's running I never have problems but the pressure does increase while running. But I will check that right now and let you know shortly same for the fuel pump but same for that.

I have tried unplugging my icp sensor and no change although it is covered in oil and also needs replaced.

Not sure if it is cranking fast enough issue or not never heard a good cranking 7.3 this is my first power stroke and none of my friends have diesel because they are lame.

I will go check the wires for the ipr the bit did not come off but the connector wiggles, not sure if that's normal for the sensor or not

And thanks for your help and anyone else that chimes in I could use some help it's not my Dailey driver since I have a work truck but it would be nice to not plug it in to get it to start
 
#5 ·
So I checked the fuel bowl and fuel rail pump and both are fine, my scanner app thingy says while cranking my rpms are above 100 will have to recheck when the engine is cold. My glow plug coil duty is at good when the eot sensor is removed since the engine is hot will also have to retest tomorrow after work.

I checked for fuel pressure threw my app but it says no data same as eot sensor the scanner app also has an option for glow plug bank left & right and gives me an amp reading but both say 0 also some codes did come back but they are all left bank glow plug codes that where not there for the past 2 days since finished the harness but now they are back might be because of my gpcm

So any ideas on the constant voltage going threw the harness?
 
#6 ·
I'm afraid I'm not that familiar with the GPM system and whether or not the voltage you find there is normal. BUT, if it's not draining the batteries, let's put that aside for now.

I'm still thinking about the Buzz results and the UVCH. You say "I also replaced my valve cover gaskets in case the harness was bad". This would mean you Have replaced the UVCH connectors as they are integral with those gaskets.

From what you've described here's what I'm concerned with;

The Buzz results show you have an issue with driving 1/2 the injectors. I assume the 4 quite ones are on the same bank? (the buzzing follows the firing order then does all 8 at once 1-2-7-3-4-5-6-8)

You have to plug it in to start. Maybe that is what's making you concentrate on the GP system because it's Cold Starting related but that's not at all why plugging in helps. It's about the OIL and heating/thinning it. How many miles are on those injectors? Plugging in "cures" bad injectors sometimes.

-> http://www.swampsdiesel.com/files/7.3LInjectorDiagnostic.pdf

So while you may have GPM & GP problems, you need to resolve the starting problem first and your injector issues are the likely cause (either the injectors themselves or the driving of them by the IDM or connections or BOTH)
 
#7 ·
Noraplh

Then yes I did replace those uvch, I could remember if it plugged in or went straight threw to the outside of the valve cover.

When I get home from work tonight I will run all the tests while the engine is cold and let you know what happens.

I am concerned I brought it into the shop so the could check why my tuner stopped working and they came to the conclusion that it was either the tuner or I needed a flash on my pcm or a replacement pcm. I sent my tuner into edge and they tested it and that is good but have not had time to go further with that.

I will ignore the glow plug system for now I might just replace the gpcm since I found one online for $100

Is there a way for the stealer to test the pcm and idm before replacement? Or is it better to just replace them? And obviously the injectors
 
#8 ·
Also I started using archoil fuel and oil additive as I had read it helped with this issue but no change happened

Not sure how many miles the injectors have. I'm the second owner and it has 293,xxx miles the previous owner took good care of the truck and I have all his records for the past 2 years but that's it. They might be original but I'm not sure
 
#9 ·
Just trying to get it figured out for winter I'm tired of plugging it in lol I'm in Colorado so the weather is getting very cold here lol

Again thanks for all the help I will be re doing the buzz test tonight and checking a few things out. I could have sworn last time I did the buzz test it sounded fine
 
#10 ·
Where are you at in Colorado? I'm over in Grand Junction.

At that mileage I would say it's new injector time.
 
#11 ·
I'm up in Greeley, I would say the same about them as well just don't wanna dump the money for them and it not be the problem so I wanna check everything out first. When the truck starts it runs like a champ that's for sure. Doesn't stutter never misses a beat when it's warm. When it starts when it's colder it has no power until it warms up so I don't really think it's the idm probly just injectors just want to make sure and since you are all the experts I ask for advice lol
 
#12 ·
If anyone has a California emissions 7.3 could you do me a favor and check the voltage going to your uvch connector for you glow plugs and let me know what you get with the key off and engine off please even tho that is not my priority at this point it is still very interesting. By theory it shouldn't be getting any voltage with they key off or for that matter still in your pocket lol. But if it was a relay they shouldn't have any voltage so please cali emission peeps let me know please!
 
#13 ·
With the key off. There should be no voltage.

Just to make sure we are talking about the right connector. It's the main engine that plug into the uvch? Which pins are you checking? You need to check the two outside pins on both sides.
 
#15 ·
Of course it would be pretty unusual to have a BAD, Gpcm, IDM, PCM, and Injectors ~ hehehe :wink[3]:

So yea, let's figure-out what you really need...

UNfortunately, when it comes to the PCM & IDM, I'm not aware of any "tests" other than to swap it out with a know good one (what the dealerships do). If you know anybody with a 7.3, any yr, the IDMs are interchangeable, easy to swap and with little risk of damaging the borrowed one.

The PCM, I doubt is the No Start cause. You have a WTS, it reports rpm, gives codes and communicates with the IDM for the Buzz. I would put that aside for now too.

The low voltage you see puzzles me, this IS with the KEY OFF? I can't image why it isn't battery voltage unless the plugs are on and that just can't be...

Again, put that one aside for now, it too isn't the No Start.

With almost 300K on the clock, the injectors are the most likely culprit. Any way to contact the PO and ask if he ever changed them? If they're the original, changing them now, with your symptoms, would be the least chance of wasting your money on repairs.

AFTER you do a Buzz Test, the IDM should have created further codes (if the 4 were quite). See if there are more codes it recognized as a problem there.

As you're trying to start, what do you see for ICP pressure & IPR % with the Torque App?
 
#16 ·
The only reason I ask about the pcm is my tuner issue, and the gpcm for the voltage. Chances are I will replace the injectors after Christmas as I don't use my truck daily.

Yes the 10.2 volts is with the key off and not even in the truck. when I turn key on it goes to 12v like it should. Just concerned about this one for the sake of my expensive battery's I replaced recently.

I no longer have a way to contact the previous owner but I could try and contact the shop he used to bring it to. Has lots of new parts in the records he gave me so he might have done them but I'm not positive. So I will have to check on that one.

As for buzz test giving codes I do not remember any but I will be checking again tonight so I will let you know. I can only get injection pressure on my torque app that I have found but not sure what pressure that is for. But I will give you those readings tonight when I get home and hopefully get some more answers

Sadly I don't have any friends that have a 7.3 or diesel for that matter to borrow the idm unless there is a 7.3 owner on here near my area the only way to test is to buy one lol
 
#17 ·
I say the gpcm is bad. There should be no voltage going to the glow plugs when the key is off.

When my injectors where acting up I had a dead miss when cold. Then you drive it and get up to about 2k rpm and boom it would come alive. Tons of white smoke whole cranking. I would plug it in for 3-4 hours and it would start right up.
 
#18 ·
That's how mine is when it starts on a 60's day lol no power for a little bit and sounds like it has a massive cam in it and once it starts moving it's very sluggish until it warms up more or hits a little above 2k rpm and then it's got power again

I am thinking it's bad also so chances are I will be replacing it since I found a brand new one for $100 online
 
#20 ·
#22 ·
Okay so as I said my battery's are dead so my numbers might be a little bit off but I definitely need to get this constant power problem fixed asap.

I put on a used glow plug control module because mine was trash thankfully I got it for 10 dollars but now I know why t was only 10 dollars.

So the rough numbers with dying battery's are while cranking

Rpm: 201
Fuel pump duty cycle: 101.6%
Glow plug duty coil: 98.2%
Injection pressure: 3445.98 psi
Injection pressure duty: 52.3%

And I got a few codes when I first plugged in my scanner and these are what they where:

P1280
Injection control pressure out of range low

P0198
Engine oil temperature sensor high

And all of my all of my glow plug codes where not there, that one is hit and miss but last night they where present and where as follows:

Po672
P0674
P0676
P0678
And one other that I don't remember off hand but it was a glow plug problem.

And when I found the constant voltage problem i only checked one side never checked the other side so the side with readings where found on the driver side which is the same side as the codes present I will be checking the other side in a little bit just need to eat dinner
 
#23 ·
Your glow plugs might not be coming on because your oil temp isn't reading correctly.

Compare your engine oil temp to the outside temp first thing before you start it. You need to have 10.5 volts to start so check your voltage while cranking.

Icp and Ipr look good.
 
#24 · (Edited)
I gotta tell ya,,, none of that looks good to ME! :wink[3]:

First thing is, 3500psi on the Starter? How does that happen? And the IPR % is way to high, especially with that ICP reading. Why would the PCM be commanding the IPR to be so closed with the pressure going through-the-roof like that?

Something's wrong with those results,,, get it charged back up, clear codes, and try again, I can't see them being correct.

But what's with the dead batteries? Battery power is Very important to starting and should always be fully charged when trying to diagnose problems. The PCM needs to see <100 rpm while cranking so don't even bother trying to start when they're low. Voltage too is important but, in an '02 much less so than earlier trucks. My '02 would still start with voltage dropped as low as 9v (maybe even high 8's as I recall when my batteries crapped-out).


Hey, I just had a thought that might account for your readings... Is it possible that the ICP pressure was actually 344psi???.
 
#25 ·
Well that app might be off but went out today I left my control module unplugged and charged the battery's while I was at work I have it sitting in my garage which doesn't get very warm.

Went out side to test a few things and try to figure out why I have constant voltage which I got know where with. Then I put everything back together and gave her a crank. To my surprise she started amazingly so I am going to leave the gpcm unplugged for the night and try to crank on it again in the morning.

But if it does start I need to figure out what is draining my battery's. that started since I rebuilt my harness and switched out my glow plug control module so I might have to tear open my harness again and figure it all out
 
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