Page 1 of 3 123 LastLast
Results 1 to 10 of 22

Thread: Hard to Start: 7.3L Diesel

  1. #1
    Full Member Nugget Hunter's Avatar
    Join Date
    Jun 2008
    Posts
    13

    Unhappy Hard to Start: 7.3L Diesel

    I have a 2002 F350 that is hard to start with the first start in the morning. It will start then it will die. I will do this about three times and then it will run fine and start fine the rest of the day. Is this a glow plug problem?

  2. #2
    Senior Member mrjohnwayne's Avatar
    Join Date
    Apr 2005
    Location
    Texas
    Posts
    4,054
    Sounds like it is a glow plug problem. What are the ambient temps in the morning and throughout the day. Are they close to the same? How long after the first start/drive will it sit before restarting?

    How many miles are on the truck. could just be the relay and not the actual glow plugs.

    You can test the relay to see if it is dropping to much voltage.



    it is on top of the motor behind the ac compressor. there are 2 relays. The first is for the AIH system. The second (furthest from the front) is the glow plug relay

    the wire with the boot is the feed wire (bat). The wire "circled" is the feed to the glow plugs.

    hope it helps
    John Wayne

    2000 F-350 7.3L Powerstroke 4x4

  3. #3
    Full Member Nugget Hunter's Avatar
    Join Date
    Jun 2008
    Posts
    13

    Thanks

    It looks like you have got me going on the right steps. Let me try to answer some of your questions.

    The mornings are cool for Oregon summers: 45-50 but afternoon's are 70-85.

    Once it starts in the morning it seems to start well for the rest of the day.

    I think what you are saying is put a volt meeter on the power in and also on the power out to the glow plugs. Should they be the same???? 182,000 miles

    Also thinks for the picture; it's better than words.

    Jerry

  4. #4
    Senior Member mrjohnwayne's Avatar
    Join Date
    Apr 2005
    Location
    Texas
    Posts
    4,054
    yeah if it is that cool in the mornings and warms up to the 70's-or 80's during the day to me it seems like the glow plugs aren't warming the air in the combustion chamber enought to promote combustion.

    Yes if you test those 2 poles they should be identical or a small variance in voltage with the key on. Key off there should be no reading on the glow plug side. also with the key off check the resistance between the too to see if there is any. With the key off there should be none.
    John Wayne

    2000 F-350 7.3L Powerstroke 4x4

  5. #5
    Junior Member
    Join Date
    Jan 2010
    Location
    Albuquerque NM
    Posts
    1

    Hard Cold Starting 7.3l deisel

    I’m posting this in hopes that this will assist someone in their quest to fix the 7.3l cold start issue. This is one persons resolved issue, in hope that it might add to helping you fix your cold start engine issues. Let me start by saying, I fix all my vehicles. Period, I do not take my vehicles in to any shop. Anything man builds will break, any man with the right information can fix it. And getting that information is sometimes like pulling chicken teeth. After a bit of reading and the right information can lead you down the right track. I got both time and I am patient when it comes to working on and trouble shooting mechanical/electrical issues. My 2001 Ford F-350 4x4 Power Stroke 7.3L diesel. This engine began to start hard last winter, whenever the mercury dipped below 50 degrees. It just simply would not start. It would billow out white smoke from the tail pipe. If I plugged in the block heater over night, it would start on the 2nd or 3rd try. In my quest for information, I spoke to a master automotive tech, he told me, he had read in a Ford 7.3 l technical bulletin, the glow plug system on the 7.3L’s turns on when the temperature drops below 55 degrees. This was Vital information for my issue because it lined up correctly with the issues my 7.3L was having. After gaining this bit of technical information. I concentrated on the GPS (Glow Plug System). (Hind sight is 20/20.) The first place to start was with the GPR(Glow Plug Relay). The GPR is located on top of the engine behind and off a little to the left of the Fuel Water separator, fuel filter drain valve. There are two solenoids located behind it. The solenoid we are looking at is the one located closest to the fire wall. Upon visual of my GPR, I knew, right away, It was bad. My relay did engage, but would not transfer voltage across the two big posts. The large post on my relay from the battery side was blackened and burnt. Obvious to me it was toast. Trouble shooting the relay. The 7.3l GPR has 4 posts, two small and two large. The small posts are the control posts, basically on/off. The two large post deliver the 100+amp current to the Golw plugs. Start with the small posts. Testing the control voltage on the GPR. With the key turned to the Run position and the wait to start engine light comes on, do not try to start the engine. Leave the key in the start position. The Engine Control module should be sending voltage to the GPR for 2 to 3 minutes. With a DC Volt meter, Test your battery voltage across the posts. Then to chasse ground they should be very close to the same. Now where ever you see the 11.5+V substitute the 11.5+V with your battery reading. Remember if the voltage drops. Check your battery to ground in case the load changes during the following testing. (BAD BATTERY?) Test each of the 2 small posts first, for voltage to engine ground. If your battery(s) (this should be the same for 1 or 2 battery start systems) are charged you should read 11.5+ volts DC on both poles. If you read 11.5+V on one and not the other, This indicates the internal coil of the GPR is bad and it will need to be replaced. (If no voltage on either post would indicate other power delivery issues and will not likely be the GPR, start trouble shooting power at FUSES and BUSSES, Remember you only have 2 to 3 min to do this test before the voltage drops off, this is normal, you will have to turn the key off and then back on again.) If you have 11.5+V across both the two small poles, the GPR internal coil is getting power. Now turn the key to off and On to the wait to start light position again. Check the 2 large poles one side from the battery side and one to the GPS. Again you should read 11.5+ volts DC on both poles. If the current is not the same it could indicate bad contacts in the GPR. Or if you have 11.5+V on one side and 0V, Like in my case, I disassembled my relay. If you do this, it is not intended to be ressasembled. Inside the relay I found the internal contact on the battery post eroded from 8 years 100+amp on and offs normal wear and tear I’d say. My engine starting issues were corrected with an $18.49 dollar Non OEM Relay from NAPA. The Relays recommended will work on 1999 – 2002 7.3 systems and a few others. I bought an inexpensive 4 pole relay that was not exact replacement for the engine the poles are 90 out of position but it installed and functioned correctly. I don’t work for NAPA, I’m just a customer. I bought NAPA Part MPE GPR109SB for $18.49. the link: http://www.napaonline.com/Search/Detail.aspx?R=MPEGPR109SB_0213383005.
    I hate throwing money away. So, I bought the cheap relay to test the system. Reason? If by chance there were another issue causing the relay to fail. I would not be throwing away 65 or 85 bucks when the relay blew. If the Glow Plug System Wiring Harness had a intermittent short and grounded. It would most likely blow out the GPR instantly and or a master buss fuse. I can’t stand throwing money away, so I bought the cheap one in case my system had another issue. So far it has given me 1 month of trouble free COLD starts on the first time even. Low temp's this month have been from 12F to 19F this morning. If it eventually goes out I’m only out $18.49. I didn’t expect 8 years of service from it. I’ll let it be till it goes out again. I’ll be purchasing the one of the following OEM relays with NAPA part ECH GPR110 sold for $82.99, or ECH GPR111 sold for 64.49. this one has a small wire harness that can be removed as it will not be used. Links to both parts. http://www.napaonline.com/Search/Detail.aspx?R=ECHGPR110_0222197439. http://www.napaonline.com/Search/Detail.aspx?R=ECHGPR111_0193342876#
    I have read al lot of folks with the Hard Cold start but none with a real problem found or solution. I have read others opting to use Non OEM Relays that are heavy duty. But if the relay is to large you could do more damage to your system. I think I would rather blow a relay than fry my whole Glow Plug Wiring harness. There are other heavy duty Glow Plug Relay Ideas on the Net, I think I’ll stick to the stock part. Less their arises another issue what caused the relay to go in the first place? I hope this information helps you find the root to you Hard Cold Start issues.
    Yeah, I'm long winded, but it was intended to be informational.

    Dave
    Last edited by dave_hunting; 01-01-2010 at 09:41 AM.

  6. #6
    Full Member
    Join Date
    Mar 2010
    Location
    Eastern Connecticut
    Posts
    14
    I had the same problem with my 2000. I was stupid and payed $70 for the relay. My old relay cracked apart and wasn't connecting to charge to plugs. I found if its below 30 turn the key on for 1 min and turn off and turn back on and let the light turn off and crank it over. 9 out of 10 times it would start. Pop corn maker then smooths out after 30 sec. or so

  7. #7
    Junior Member
    Join Date
    Sep 2011
    Posts
    2

    same problem

    Got a 99 F250 SD 116k miles and had this problem would not start once it was below 50 degrees or so replaced the battery's the next morning the same thing,3 years old.rrr Then put in a new fuel filter, over due. No help. So I looked and found John Wayne's story & photo, went and got a relay today $80 and will put it in the morning. Hope it works and thanks so much for your info John. The photo was the best. awesome.
    You saved me a trip to the dealer probably $300-400 soaking. hope my problem is gone. Hi 5
    Arizona going to Texas in a few days

  8. #8
    Junior Member
    Join Date
    Sep 2011
    Posts
    2
    thank you for this posting John

  9. #9
    Junior Member
    Join Date
    Feb 2012
    Posts
    3

    7.3 glow plug solenoid issue

    I tested the glow plug solenoid and one post was jumping from zero volts to 37 volts with the other big terminal showing zero volts when the key was one. Does this mean the solenoid is bad?

  10. #10
    Senior Moderator chevychase's Avatar
    Join Date
    Oct 2010
    Location
    truck forum .org
    Posts
    17,011
    Blog Entries
    2
    Did you read write up...did you have meter set at dc volts.... i read it... do not see how you could get 37 volts.
    Should be getting 11.5 volts on both larger terminal.and small terminals. If no voltage on any have power issues to solenoid.
    If no voltage on one and not other..solenoid bad.

    Gitter done have fun. Running on empty...running blind...running behind.....
    IF I CAN GET YOU TO SMILE BEFORE I LEAVE.

Page 1 of 3 123 LastLast

Similar Threads

  1. Hard Start
    By sixmilman in forum Chevy Truck Forum
    Replies: 3
    Last Post: 05-22-2008, 11:43 PM
  2. Diesel Hard Start Update
    By njk53 in forum Chevy Truck Forum
    Replies: 2
    Last Post: 03-20-2008, 12:15 AM
  3. hard start when warm
    By ike77 in forum Chevy Truck Forum
    Replies: 4
    Last Post: 12-08-2007, 11:46 AM
  4. 95 Dodge Diesel 12 valve Hard Start
    By uscgret93 in forum Dodge Truck Forum
    Replies: 5
    Last Post: 09-21-2007, 02:36 PM
  5. 7.3L hard start when cold
    By wmiller in forum Ford Truck Forum
    Replies: 9
    Last Post: 06-02-2007, 06:31 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •