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Hard/No Start? Check here first.

375K views 82 replies 42 participants last post by  meador123 
#1 · (Edited)
Thought I'd post this as a sticky thread now that cold weather is on us.

How to check Glow Plug System

To check the Glow Plug Relay (GPR)
· Be sure the engine is cold, so that the PCM will tell the GPR to turn on. If the engine is hot, you won’t have as much time to check. (if oil temp is above 130F, it won't turn on at all)
· Locate the GPR – It's behind the fuel filter on top of the engine, a little bit toward the passenger side of the valley. There may be two relays there. If so, the rear one is the GPR. It will have two fairly large wires (yellow and brown) connected to the large post without the rubber boot.
157028

Another location photo here:
157025

Photo credit F350_6

With your multitmeter set to DC volts, and 15 V range (if not autoranging), clip the positive (red) lead to the output terminal (with yellow and brown wires connected), and the negative (black) lead to a good ground point (like the battery ground terminal or someplace metal directly on the engine block.)​
Turn the key to ON (do not start)​
If your GPR is good, it should click, and you’ll see 11 volts or so on your meter, then, depending on temperature, it will click off up to 2 minutes later. You should do this a couple of times to make sure it consistently makes the connection.​
If you don’t get voltage with this test, confirm by retesting as follows.​
Remove the two small wires from the smaller two of the four GPR terminals.​
With jumper wires, apply voltage from the battery across the two small terminals. If your voltmeter now reads voltage on the output terminal, your GPR is OK, and your problem is in the PCM circuit that tells the GPR to activate.​

GPR for 99 & up 7.3L
Ford F81Z-12B533-AC
NAPA GPR#109 (mounts 90 deg out of rotation from original)
Carquest #RY-175 (clone of GPR#109)
Autozone Sorensen MR-99 (also clone of GPR #109 I think)
International #1831646C1 (Identical to the one you'll get from Ford) ~$25-$30
[added on edit] A forever GPR - White Rogers/Stancor 586 902


To check Glow Plugs.
Remove the electrical connector on the inboard side of valve cover at the gasket. Press down on the top of the connector latch and pry gently with a screwdriver.​
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Disconnecting VC harness connector.
157027

Another photo of it loose.

There will be 9 pins on the valve cover gasket where you removed the connector. The two pins furthest forward and the two pins furthest back are for your glow plugs.​
With your multimeter set to resistance (ohms) and low range (single digits) if not autoranging, clip the negative (black) lead to a good ground point.​
Probe each of the 4 outer pins individually with the positive (red) lead, noting the resistance. Good glow plugs will have a resistance between 0.6 and 2 ohms. If you get infinite resistance on any glow plug, that one is either bad or the connector under the valve cover has come loose.​
 
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#53 ·
This little gem of a string saved me at least $100. My truck cranked and cranked and was real slow to start on Monday. Finialy fired and smoked out the entire neighborhood. I hopped on line and found this string and figured out that it must be the GPR. Called my local blue oval dealar for a price on the relay...$130. Ouch! Called International and they said no problem we have a bucket of them at $24.75 each. Guess which one I bought!

Pulled the old one out and it was gone for sure. The hot terminal pulled of in my hand when I started to loosen the nuts. Got it off and the new one on and problem solved. The part matched exactly down to the part number stamped in the base. I couldn't beleive how bad you know who is ripping us off.

Thanks to all who suffered in the past and wrote about it here!

Buckstopper
 
#54 ·
I second your comments about this "String", Site and most importantly the Members on this site, I am a new member, and was having the same problems, after (2) new batteries (both had less than 7amp cranking power), a GPR and an Oil change my problems went away. Thank You all for everything on here. JD
 
#56 ·
[ QUOTE ]
If International dealers have GPR for $25 does anyone have international part #?

[/ QUOTE ]

Try this one

International #1831646C1
 
#58 ·
Can the GPR's go partially bad? As in limiting the total current available? I have new battery's, and have even had them checked.Good. I get up to 3000psi HPO when cranking. Lots of smoke. When it does start all is right with the world. I have checked all my glow plugs for power at the plug, under the valve cover, and checked out good. However I have all the same symptoms as everyone else. /ubbthreads/images/graemlins/shrug.gif
 
#59 ·
You might get one that will show some voltage, but not pass enough current to get the GP's hot, but that would show up as low voltage at the large output terminal. You could try jumpering across the GPR terminals and see if it makes a difference.

GPRs aren't that expensive. When in doubt, change it out.
 
#60 ·
[ QUOTE ]
You might get one that will show some voltage, but not pass enough current to get the GP's hot, but that would show up as low voltage at the large output terminal. You could try jumpering across the GPR terminals and see if it makes a difference.

GPRs aren't that expensive. When in doubt, change it out.

[/ QUOTE ]

And that is exactly what I did. After some more testing, I found out that with no load, the old GPR worked fine. .3 ohms resistance. However under load, It opened. Weird. Anyway, I replaced the GPR and This morning life was good again. /ubbthreads/images/graemlins/wink.gif
 
#61 ·
[ QUOTE ]
I replaced the GPR and This morning life was good again. /ubbthreads/images/graemlins/wink.gif

[/ QUOTE ]

/ubbthreads/images/graemlins/cool.gif
 
#62 ·
Hey all,

Im having similar problems to others on this thread. For the last couple of weeks the truck (2003 7.3L f250 4x4) was hard to start in the mornings. Seemed to fall on its face when you got on the gas etc. The problem kept getting worse. It would run rough for 3-5 minutes and then be ok once up to temp.

Yesterday I changed the oil, fuel filter, and air filter to knock out the basics. Then when I went to crank her up she started ok but lots of white smoke and then died. It would take 15 - 20 seconds of cranking to get it to start again. I noticed the tach would sit still for the first 10 seconds or so and then start to climb and the truck would begin to fire. It would die after about 60 seconds of running real real rough. Finnaly got it to stay running and warm up but there was more smoke than normal. I would give it the gas to about 1600-2000RPM but it would not stay there and dump smoke like a mo fo. it would slowly fall down \ blow more smoke die.

Once it got warmed up it would drive ok but ocasionaly barf out some white smoke and loose power. didnt sound quite right either.

I am pretty sure i didnt goof up and put gas in it. the station i go to did just recently change their pumps but it seems like maybe this is a glow plug problem to me.

I am running amsoil.

I took it to the shop this morning because i forgot all about this forum.

I dont want to get taken for a ride by this service center in austin so if anyone could chime in on what they think this could be that would be a great help.

Thanks in advance

TxDiver
 
#64 ·
I've got the bad glow plug symptoms. Should I replace them all while I'm at it, or just the one(s) that are bad? Just wondering what the concensus is on that.
 
#65 ·
[ QUOTE ]
Help? Can someone please tell me what I can do, I have ONLY all positives on my glow plug control! Any advice is welcome, thanks!
\
I have a 2000 F550 7.3l powerstroke.

[/ QUOTE ]

Not sure what your issue is here. You should be reading all voltages in the GPR test as positive with respect to ground. /ubbthreads/images/graemlins/shrug.gif

Welcome to TheDieselStop /ubbthreads/images/graemlins/smile.gif

suvdrivr, I'd replace them all as long as you're in there.
 
#67 ·
[ QUOTE ]
how many glow plugs can you have that are bad before it is hard to start?

[/ QUOTE ]

Not sure. I know I had one unplugged /ubbthreads/images/graemlins/blush.gif for quite a while, and had no issues except a little more smoke on startup.

I have also started my truck at 6F with no working gp's or block heat. Took 20 minutes and filled the neighborhood with smoke. /ubbthreads/images/graemlins/phoney.gif

Someone else may have some more info for you.
 
#68 ·
I talked with my couzin who is a mechanic, and he said sometimes they can be difficult to start with one or two bad, I currently have 3 that I believe are bad and I used a Fluke meter so I am pretty sure my readings are accurate, if I have run it every day it starts ok, but if it sets for a couple of days in the cold it doesn't want to start, if I plug it in it starts fine. I have just under 160K on it and I think I am going to replace all the glow plugs anyway, I just put a GPR on it last week, and the other morning when I was trying to get it to start, I jumped the terminals on the old GPR to make sure that it was getting juice, but it did not help. I am sure that 3 are bad, and I question 2 of the others, I only had 2 that had what I would call perfect readings.
Thanks for your help
 
#70 ·
[ QUOTE ]
What is the part located next to the GPR which looks like it?

[/ QUOTE ]

That would be the Intake Air Heater Relay. Controls the IAH to reduce smoke on extended cold temperature idle.
 
#71 ·
I have a "California" 1999 F-350 with 196,600 miles. I changed injector #3 and installed new Bosch glow plugs on that side while I was there. Following that the SES light came on and I pulled code po1395. I then changed the glow plug controller (Napa GPR 110) (cleaned and lubed all connections), check all wiring and connectors. The SES light and po1395 came up following each time I erased the code.

Yesterday, I pulled the valve cover and checked the ressitance of each of the four glow plugs, valve cover wiring harness, wiring from valve cover harness to controller, and the controller itself. All were within the specs that I found on this site. The SES light came on again with code po1395.

I parked the truck outside and it fired right up this morning (23 degrees F) with no difficulty or smoke.

I must be missing something simple. Thanks in advance for any help you might have.
 
#72 ·
[ QUOTE ]
I have a "California" 1999 F-350 with 196,600 miles. I changed injector #3 and installed new Bosch glow plugs on that side while I was there. Following that the SES light came on and I pulled code po1395. I then changed the glow plug controller (Napa GPR 110) (cleaned and lubed all connections), check all wiring and connectors. The SES light and po1395 came up following each time I erased the code.

Yesterday, I pulled the valve cover and checked the ressitance of each of the four glow plugs, valve cover wiring harness, wiring from valve cover harness to controller, and the controller itself. All were within the specs that I found on this site. The SES light came on again with code po1395.

I parked the truck outside and it fired right up this morning (23 degrees F) with no difficulty or smoke.

I must be missing something simple. Thanks in advance for any help you might have.

[/ QUOTE ]

Alpine, our "CA" trucks DO have a Glow Plug Controller, but not the Glow Plug Relay...The Controller looks like a small box with heat fins on top and 2 plugs that plug into it. Its located behind the first relay that you replaced. I'm trying to find a way to test the GPC as well...
 
#74 ·
[ QUOTE ]
Do the glow plugs only function when the motor is being started, or do they play a part on how the motor runs long after its running?

[/ QUOTE ]
They are only a starting aid. Depending on temperatures, they may stay on for up to 2 minutes.
 
#75 ·
IM HAVING THE GPR PROBLEM AND WAS WONDERING IF ANYONE CAN VERIFY WHAT THE STEALERSHIP JUST TOLD ME WAS ACCURATE....HE SAID MY TRUCK TAKES THE MORE EXPENSIVE SOLID STATE UNIT (03/2000 BUILD DATE) OR IF THE NAPA GPR 110 WILL WORK FOR ME...THANX IN ADVANCE /ubbthreads/images/graemlins/shrug.gif
 
#76 ·
[ QUOTE ]
IM HAVING THE GPR PROBLEM AND WAS WONDERING IF ANYONE CAN VERIFY WHAT THE STEALERSHIP JUST TOLD ME WAS ACCURATE....HE SAID MY TRUCK TAKES THE MORE EXPENSIVE SOLID STATE UNIT (03/2000 BUILD DATE) OR IF THE NAPA GPR 110 WILL WORK FOR ME...THANX IN ADVANCE /ubbthreads/images/graemlins/shrug.gif

[/ QUOTE ]

If you have 2 relays behind the fuel filter, then the GPR 110 or GPR 109 (much cheaper will work).

If you have only 1 relay and an aluminum box with cooling fins on it, then you have a Glow Plug Controller and will need to buy that, if it's truly the controller gone bad.

I think that the Excursions had the GP Controller instead of a GPR.
 
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