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Cold Starting issue -- STILL...ideas?

2K views 11 replies 5 participants last post by  1970something 
#1 ·
I'll try to be brief but have a lot of info I'm trying to sort thru with this issue: The truck won't start when overnight temps get below about 45 F. I can hear it "winding up" as if it's about to catch in the first couple seconds of cranking, and then it makes a stumbling kind of noise and all i hear is the starter spinning it. Sometimes cycling the GPs a few extra minutes will work, but normally it has to be plugged in to start in cool weather. Fires up great then.

I have done the following work since first noticing the problem, some in an attempt to fix it, others for their own reasons:
- New ICP sensor (Motorcraft) -- was legitimately bad, with oil in it.
- New CPS sensor (Motorcraft/International "purple oring") -- not sure it was actually bad, but tried anyway.
- Mitsubishi Denso high-speed starter
- The PO put in a GT38 turbo, which appears to be making 11-14 psi boost according to AutoEnginuity MAP sensor reading (no boost gauge installed).
- Compression is 330-350psi cold, 340-350psi "warm"
- New OEM-type GP relay
- New (reman) injectors (LL in #8) along with new UVCH and fresh Beru/Motorcraft GPs
- Buzz test is fine.
- Cylinder contribution test is a pass.
- PERDELS after new injectors are: 2.3, 1.7, 1.1, 0.2, 0.0, 0.0, 0.0, 2.7

Fuel economy had been dropping off and I was losing power under heavy load, prompting me to finally replace the original injectors with remans from Full Force a few weeks ago. MPG has recovered, and I had hoped this cold-start problem would be solved too, but now that temps are dropping again it's back same as before.

I do still have a tiny bit of power loss, causing the truck to shudder when towing long interstate hills; i have to back out of the throttle and just go slower to stop that. I've also noticed a small puff of black smoke any time i put my foot in it, which it didn't used to do. I did the Swamps Diesel "road test" for injection pressure a while back, and remember it being okay, but have lost where i wrote down the actual numbers (I plan to repeat it next chance i get). Does this sound like a bad HPOP? What else should I be looking at?

I really appreciate any ideas or feedback. Thanks!
 
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#2 ·
What does it do if you plug it in for a few hours?

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#3 ·
It'll fire right up if plugged in.
In 45 degree weather I can plug it for about 20 min and it starts.
Last winter overnight temps were single digits and I had it on a timer to heat for 4 hours before i had to leave for work, and it fired right up.
 
#4 ·
To me I would be suspecting an issue with the glowplug system. I know you said they are new. But I would ohm them out and see what they read. Also consider the stancor relay. Another thought because it is easy to do but is it possible you didnt seat the wire down on the plug all the way?

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#9 ·
Stancor arrived yesterday and I put it in right away. Then it didn't get cold last night, ugh! Soon as we get a freezing night I'll know if this fixes it...

Have you verified how many volts are going into and out of the GP relay?

Have you load tested the batteries?
Batteries test good. I checked voltage drop across the original GPR before getting the "new OEM type" replacement, but haven't actually tested the replacement. I really should have, but it seemed like i was going to be buying the Stancor whether or not the OEM relay tested good or bad, because either it was "good" and it sucked, or it was "bad" and i didn't want another bum part straight out of the box : )
 
#6 ·
95% chance its the glow plug system. Either the relay, glow plugs them selves or the wiring between them.

I would start with the relay first. Turn the key on, and check for voltage across between both big terminals, there should be very little voltage drop between the two, and they should both be close to battery voltage as well.

Then check the wiring. OHM each glow plug inside the UVCH to the center pin, they should all be around 2 ohms IIRC. A quick search will yield more info on this.

Report back after!
 
#7 ·
I'll try to be brief but have a lot of info I'm trying to sort thru with this issue: The truck won't start when overnight temps get below about 45 F. I can hear it "winding up" as if it's about to catch in the first couple seconds of cranking, and then it makes a stumbling kind of noise and all i hear is the starter spinning it. Sometimes cycling the GPs a few extra minutes will work, but normally it has to be plugged in to start in cool weather. Fires up great then.

I have done the following work since first noticing the problem, some in an attempt to fix it, others for their own reasons:
- New ICP sensor (Motorcraft) -- was legitimately bad, with oil in it.
- New CPS sensor (Motorcraft/International "purple oring") -- not sure it was actually bad, but tried anyway.
- Mitsubishi Denso high-speed starter
- The PO put in a GT38 turbo, which appears to be making 11-14 psi boost according to AutoEnginuity MAP sensor reading (no boost gauge installed).
- Compression is 330-350psi cold, 340-350psi "warm"
- New OEM-type GP relay
- New (reman) injectors (LL in #8) along with new UVCH and fresh Beru/Motorcraft GPs
- Buzz test is fine.
- Cylinder contribution test is a pass.
- PERDELS after new injectors are: 2.3, 1.7, 1.1, 0.2, 0.0, 0.0, 0.0, 2.7

Fuel economy had been dropping off and I was losing power under heavy load, prompting me to finally replace the original injectors with remans from Full Force a few weeks ago. MPG has recovered, and I had hoped this cold-start problem would be solved too, but now that temps are dropping again it's back same as before.

I do still have a tiny bit of power loss, causing the truck to shudder when towing long interstate hills; i have to back out of the throttle and just go slower to stop that. I've also noticed a small puff of black smoke any time i put my foot in it, which it didn't used to do. I did the Swamps Diesel "road test" for injection pressure a while back, and remember it being okay, but have lost where i wrote down the actual numbers (I plan to repeat it next chance i get). Does this sound like a bad HPOP? What else should I be looking at?

I really appreciate any ideas or feedback. Thanks!
my money is that the "new oem type gpr" is bad. i have seen 5 in a row bad rite out of the box.
i only use the stancor relay now.
 
#8 ·
my money is that the "new oem type gpr" is bad. i have seen 5 in a row bad rite out of the box.

i only use the stancor relay now.
Same. OP I would pick that up first and go from there.

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#10 ·
Okay, 28 degrees F when I got up this morning -- finally a cold night -- and no driving all day yesterday so for sure the block was at least down to freezing. And she fired up as soon as the WTS light went out! I haven't done any other work that could have impacted starting, so it was definitely solely the GPR that was causing this.

!!

!!!!!!

Stancor FTW; those OEM glow plug relays should be illegal to sell. :bsflag:

Thanks again, as usual, to this group for awesome patience, help, and advice...even if I didn't listen the first time :wink:
 
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