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Discussion Starter #1
I have a 1994 F350 with the powerstroke and 203k miles on it.

I have been working on this truck a fair amount trying to get through a very rough cold start and miss. The truck will crank and crank with plenty of white smoke and finally start after about a minute of cranking. When it does fire it has a very pronounced miss for a while, but not at idle. It generally comes back at high RPM's and under acceleration.

I pulled the valve covers off and replaced all injector O rings and checked all the glow plugs and they all tested OK. I did some repairs to the UVCH harness and put it all back together. A few of the pins were broken. I also had to change the GPR. The truck passes the buzz test, although one or two sound a bit "weak." My HPOP reservoir does not seem to be leaking down overnight.


After all this I still have symptoms. Any ideas?

My WTS light is only on for about ten seconds. It has new oil. It has enough oil. CPS is new. IPR and HPOP were done about two years ago. Cranking RPM is about 200-250 and seems to be adequate. Batteries were new last year. Starter is two years old.


The wierdest thing is that when it does start, it will only start right after engaging the starter. If it doesn't I can crank all day and it won't do anything, but as soon as I cycle the key again it will fire right up. It will ONLY fire up RIGHT after engaging the starter. I originally thought it was the glow plugs that were needing to be recycled, but the glow plugs were not functioning at all and it still did this.
 

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Demon Dually
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How many times do you have to cycle the ingition switch for it to start right up? If it is intermittent then I would say possibly ignition switch on the column under the day otherwise I am not sure off hand.
 

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Discussion Starter #3
How many times do you have to cycle the ingition switch for it to start right up? If it is intermittent then I would say possibly ignition switch on the column under the day otherwise I am not sure off hand.
It's not intermittent - and it cranks just fine - just no firing.

Just now it was about fifteen or so. Some days it will fire right up - but the ignition switch can't be it.
 

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My 94.5 will start quickly and perfect 50 times, then on 51 it will just crank. It builds ICP like normal and it doesn't matter if hot, cold or whatever. I'll cycle the key and it lights right off. I've often wondered about the ign switch (or if its a relay that operates the IDM, PCM, etc). Haven't been too worried about until it starts doing it more often. Sounds like you're there...:confused:
 

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JFURNER77
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I have a 1994 F350 with the powerstroke and 203k miles on it.
When it does fire it has a very pronounced miss for a while, but not at idle. It generally comes back at high RPM's and under acceleration.

I did some repairs to the UVCH harness and put it all back together. A few of the pins were broken. The truck passes the buzz test, although one or two sound a bit "weak"

IPR and HPOP were done about two years ago.

The wierdest thing is that when it does start, it will only start right after engaging the starter. If it doesn't I can crank all day and it won't do anything, but as soon as I cycle the key again it will fire right up. It will ONLY fire up RIGHT after engaging the starter. I originally thought it was the glow plugs that were needing to be recycled, but the glow plugs were not functioning at all and it still did this.
- A couple bad injectors, or anything wrong w/ the injection system will cause a definite "miss". Make sure you have purged all the air out of system after o-ring replacement.

-Did you replace w/ new VC gaskets & UVCH??

-You need to see HPOP system pressure while starting,idling,wot

-What about your fuel pressure??

-A consistent high/low amp. draw on a good starter might suggest low compression on 2 or more cylinders.
 

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- A couple bad injectors, or anything wrong w/ the injection system will cause a definite "miss". Make sure you have purged all the air out of system after o-ring replacement.

It's got quite a few miles out of it - I would think this is done.

-Did you replace w/ new VC gaskets & UVCH??


No - everything was checked but determined to be in serviceable condition.


-You need to see HPOP system pressure while starting,idling,wot

I guess I'll get to work making a gauge.

-What about your fuel pressure??

Unknown - I did just change out the FPR to one from a 96. I have not checked it since I put it all back together. I'll do this also.

-A consistent high/low amp. draw on a good starter might suggest low compression on 2 or more cylinders.
What should I be looking for? Low compression is a possibility - it's got enough miles for it.
 

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JFURNER77
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Unplug main harness at each VC location and inspect for breaks,burns, and there should be no oil on outside of VC connections. Clean and dry. Check under the VC's for gasket or UVCH burns. Anything burnt or broken needs replaced w/ new parts.

HPOP system at start up(500-800 psi.)
at wot (1500 -2500 psi.) depending whether warm or cold

Fuel pressure w/ stock pump (40-50 psi.) Check fuel filter and FPR screen.

All cylinders should be within 20% of highest compression reading. Two or more out of spec, will cause baseline problems.
 
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