2002 7.3.

I cannot believe I am still having this issue. Last year, I attempted to get rid of it by installing

GPR
Wiring Harnesses
Glow Plugs (motorcraft)
Fuel Injectors
Up Pipes
Turbo Rebuild
Intake
Exhaust including manifold gaskets
IPR Sensor
Fuel Filter
High Torque Starter
CAC boots
Cleaned in-tank filter screens

I also wired to GPR directly to a switch in the cab so I know when they are on. HPFP was tested at the time.

I cannot, for the life of me, figure out why I have this issue at 50 degrees. My dad has a 99 7.3 and in this same weather can just turn it on immediately without waiting. I, for example, ran the glow plugs for about 30 seconds (over multiple (10?) starting attempts) to get mine started this am.

Any ideas on this ?

 

Can't say you haven't been thorough. Have you tried running 5w-40 synthetic oil? That did more to help my cold starting performance than anything else.

But, you really should have no issue at 50F. Does it run strong and well after it starts?

 

Yes, after started it runs great, no issues. restarts just fine. on the stock programming setting, it runs 0-60 in just under 9 seconds...i dont have anything heavy to haul to judge it any other way. I believe my dads 99 does it in about 11.

I have 5w-40 synthetic with archoil mixed in (rotella t6)

i ordered a larger glow plug relay today and will be testing the GPs when i change this... I cant imagine them going bad after one season though... i mean i have a switch connected to them and I havent had to use it but for a few days.... though it's odd that i even had to use it in the 60's... about 5 seconds

 

I plugged my truck in and it started great this am, no glow plugs needed. it was about 55 deg when i left the house. its now 46 deg and the truck has been parked for 5 hours and it will not start.

I really do not understand this. It should be warm enough to start

 

You need to move this thread to the 7.3 forum - many smarter folks there.

 

Only thing I can think of is glow plugs aren't actually heating? Now this may be totally different but on my old 93 7.3 ...if one of the glow plugs was bad....the others wouldn't stay on long enough to heat up hot enough to start truck in cooler weather. I'm guessing your wait to start light still lights even with your switch mod for glow plugs? How long do plugs cycle for?
Have you tested continuity in the new plugs you installed to make sure ones not faulty?

 

Ok, It sounds like something either was bad from the start or got hooked up incorrectly. If you’re going to buy a NEW GPR definitely look at the Stancor GPR it will provide you all the current you need to the GP’s. If you don’t have one buy yourself a plug-in voltmeter and put it in the cigarette lighter for now and see what your voltage drops to when you energize your GPR. With help you could also do this with your multimeter when my GPR activates my voltage is in the high 10’s lower 11v. Since you wired in a switch you’re definitely going to have to check to make sure that was done properly. in my opinion, you’re better off hooking it up to the PCM again, but wire a small LED light into the cab that shows you when the GPR activates and for how long. If you plugged it in and it started fine it sounds like everything else is working but your GPR/GP system. In a pinch you can activate the GPR using one side of your jumper cables or just use a long screwdriver and touch both big posts with it. You’re going to want to jump The 12 V GPR power circuit to the glow plug feed circuit. The GPFC is only hot when the GPR activates.

below are some pictures to help you make sure you have everything wired correctly....

 

I have a large white rodgers relay that i will be adding. Unfortunately, either the PCM is bad or there is some bigger wiring issue. THe truck is a 2003 body with 2001 motor and has wiring just laying everywhere, nothing is mounted on brackets, wires are spliced into everywhere, and multiple connectors lay at the end of most wires that go to sensors. There is a relay jumped to under the dash that if removed, the truck wont start, and if removed during operation, the truck wont turn off. Never figured that one out. The PCM looks really nice and I cant imagine it being 'burned up' as some suggest with the GPR ground issue. I have wired around this, ground directly to where the battery grounds, and switch to the relay. I did this mainly because of how bad i was irritated when i tried to figure out what was going on the first time. Basically, the truck isnt worth a new PCM even if that would fix it :/

However, I may have solved my issue.. but I dont exactly understand why. Perhaps voltage is dropping too much.


1. press momentary switch, wait 10 seconds. Stop pressing. Try to start, nothing will ever happen until maybe im nearly out of battery and the garage is full of smoke
2. press momentary switch, wait 10 seconds, start vehicle, immediately stop pressing switch. Engine shuts off.
3. Press momentary switch, wait 10 seconds, start vehicle, wait 1 second, stop pressing button... vehicle acts as normal.

if i use option three, everything works. I guess i always got confused by option 2 and just thought i could not press this while the vehicle was starting ( which doesnt make sense as the pcm lets them run afterwards).

Is this what i should expect through normal operation, not being able to stop pressing until a second or so after start?

 

Ok, part of your problem you mentioned in your last post. The PCM operates the GPR based on oil temperature, The colder it is the longer the PCM keeps the GPR activated up to two minutes. IF everything is wired up correctly and your GPR is working properly 10 seconds is not nearly long enough to keep the GPR activated for the glow plugs with cold oil.

The next time you go to start the truck when the truck aka oil is cold, pull out your phone or something with a timer on it and hold the switch for 60 seconds…Then while still holding the button, start the truck. Let me know if that solves your problem.

 

might need to hold the switch for up to two minutes to allow for a proper running motor.

 

I had starting issues again yesterday, this time it was just dead. I had both batteries checked (one 12mo only one 2 years old) and they were both bad. I also tested the alternator and found out it was bad as well. I replaced batteries, alternator, and upgraded to the stancor relay. So far, everything is working. However, when I release my switch, the truck still freaks out and seems to momentarily lose electrical power, engine lights come on and the truck runs rough. As far as I can tell, switch is wired proper. Voltage goes down to 11 when gps engaged