7.3L won't start cold - Ford Powerstroke Diesel Forum
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post #1 of 17 Old 04-02-2009, 08:24 AM Thread Starter
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7.3L won't start cold

Hey guys I am new here but I have a problem I can't figure out on a powerstroke. The truck is an 03 7.3L with 175k miles. It won't start if the block temp is cold. When the engine is warm or if the owner shoots ether to it it will fire. The high pressure oil goes to 2300 psi and the regulator goes to 40 percent, and the truck just chugs smoke but will not fire. It has a new regulator and icp sensor with no change to the problem. If I unplug the icp sensor and short the high side to the signal return the truck will start. I have a break out box on it and have checked all power and grounds to the computer and inputs and outputs from the computer. Are there any ford techs on here that can maybe provide some input here or anyone that has any info as to what might cause the computer to think it has low oil pressure causing it to go that high while cranking.
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post #2 of 17 Old 04-02-2009, 08:34 AM
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do we know that the glow plugs and relay are working

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post #3 of 17 Old 04-02-2009, 08:43 AM Thread Starter
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The glow plugs and relay are brand new and work correctly. The truck is overfueling while cranking for some reason. That is why if I short the high side and trick the computer into thinking the pressure is to high it lowers the oil pressure and the truck will fire right off. Which is why I put an icp sensor in it with no resulting change. Something is telling the computer that the pressure is low so it keeps raising the pressure to try to get it to fire which causes it to over fuel and not start. I just can't figure out what is causing that.
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post #4 of 17 Old 04-02-2009, 08:45 AM
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overfueling isnt the issue , its an oil pressure problem of some kind , i thinking ipr is stuck

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post #5 of 17 Old 04-02-2009, 09:13 AM Thread Starter
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If the ipr was stuck then the pressure wouldn't come back down when I short the icp sensor to the high side. It would just stay high.
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post #6 of 17 Old 04-02-2009, 09:54 AM Thread Starter
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I dont' mean to be short with any one i am just pretty frustrated over this truck. Our shop is also the second shop that has tried to fix this problem. There is a new ipr in the truck with no change to the problem also. We also tried another computer with no luck. It just doesn't make sense why it won't fire.
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post #7 of 17 Old 04-02-2009, 10:01 AM
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thats tuff good luck theres no wiring issues is there maybe you got a bad sensor hell if i know but heres a bump for ya
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post #8 of 17 Old 04-02-2009, 10:19 AM
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Quote:
Originally Posted by 97singlecab View Post
If the ipr was stuck then the pressure wouldn't come back down when I short the icp sensor to the high side. It would just stay high.
just throwing out something to ya , but good luck on the repair , sounds like you know more about it than i do

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post #9 of 17 Old 04-10-2009, 12:59 PM Thread Starter
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No one has any ideas? If you get the truck to warm up in the shop I can get it to fire and once there is some oil temperature it will start and run just fine until it gets cold over night again. It acts as if it doesn't have enough cylinder temperature to fire. But the glow plugs have all been replaced as well as the under valve cover wiring harness's. Compression test shows four cylinders at 340 two at 320 and two at 300. I realize these are all a little low but is it enough to make it not start?
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post #10 of 17 Old 04-14-2009, 06:28 PM
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I had a similar problem on a 99 and it was the fuel heater in the bottom of the fuel filter bowl. Also my truck does not have this but other 99's and newer do and that is an intake heater.
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