I have a 2000 F350. I can pull my horse trailer (3 horse gooseneck) with no problem to the trailhead at about 7900'. When I try to start it a day or two later it just cranks and won't quite catch. After trying to start it a couple of times I give it a little throttle and it starts, in a huge puff of smoke. I never have this problem at lower elevations. Any ideas?

 

What elevation is your home at?

 

how cold was it?what color smoke?

 

I bet it's more temperature related than altitude. I had the same thing happen last summer when the GPR went out. I could start up at my house fine, because temps were warmer. In the mountains the summer morning temps were much lower, and it was very difficult to get my truck to start. Replaced the GPR and no problems since.

GPR is where you should start first. If that checks out fine, then start ohm'ing out glow plugs.

 

had same cold start problem and was ICPS but was only at 2600 elevation

 

I agree, unless kc60426 lives at high elevation too. I would bet GPR offhand, but it might also be related to the barometric sensor...that is why I asked the home elevation question.

 

Check my post here https://www.ford-trucks.com/forums/610288-analysis-of-compression-test-results.html and remember that at 8K altitude the standard atmospheric pressure is down to about 10.7 psi vs 14.7 psi at sea level! You can repeat the calculation shown there but using 10 psi instead of 14 psi. The 0.7 psi accounts for the pressure drop across the air inlet path for filling the cylinders. The link I gave shows how both ambient pressure and temp effect the ability to achieve a cranking temp in the cylinders for auto-ignition temperature for #2 diesel which requires 558 K.

Does your starting problem also occur at sea level at colder ambient temps? If I had the time, I'd run the calculations for you to show the dramatic effect of operating at altitude. There's a big myth about turbo charged diesels not being effected by altitude, but when you do the analysis, and tow a 21K GCW over Monarch Pass on US 50 which is over 10K altitude, you easily discover that on a percentage comparison basis, diesels are effected by altitude just as much as gassers are.

 

To answer your questions: I live at sea level. I was trying to start it at about 2pm when the temp was about 80. I haven't had any trouble starting it in the winter when it's in the 30s and 40s. I don't have any trouble with it when I'm only at 5500 elevation. Thanx for any help you can give me.

 

I'd see if someone around in your area had as Autenginuity scanner and look at the readings from the barometric sensor. Here is the link to the scanner website:

http://www.autoenginuity.com/

What I find confusing is the part where you said that you "After trying to start it a couple of times I give it a little throttle and it starts, in a huge puff of smoke." The puff of smoke is unburned fuel and the throttle position, at start up is, I believe, irrelevant. The sensors tell the truck the conditions at startup (temp, oil temp, barometric pressure, etc) and determine injector pulse width and glow plug activity (duration). Now I could be wrong about this, but that is my understanding...fuel pedal position is irrelevant at start up. So, in my mind, some sensor is telling your truck to give it a huge shot of fuel at cold start (engine at air temperature) only at high elevation (above 7000' or so). The baro sensor, when if faults, sends an out-of-range default signal to the PCM and the PCM uses 14.5 psi (sea level atmospheric pressure) by default. The PCM then sets glow plug and injection timing based on that reading (14.5 psi pressure) rather than the actual atmospheric pressure of somewhere around 11 psi at 8000'. I believe on your truck the baro sensor is part of the PCM, where on the earlier trucks it was a seperate stand-alone sensor.

So, I keep coming back to the baro sensor being bad...it wouldn't have any effect on your truck at sea level and would only show up at high elevations...someone smarter than me will come along with a better idea, I am sure. But until then, that's my story and I'm stickin' with it .

 

When my first GPR went bad, it would intermittently work/not work. I found the same thing, give it a little throttle and it would start with a puff of grey smoke. I think GPR as well, the altitude thing is temperature or just coincidence.

 

So throttle pedal position is actually used by the truck at startup? It matters where the throttle pedal is located...that info is shared with the PCM at startup?

 

I don't know, and it may be that was just coincidence as well.

 

OK, I give! What exactly, is a GPR???

Thanks,

Richard

 

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