Hello friends,

Long time lurker, first time poster.

I am at my wits end. I have a 95 F350. Changed my IPR valve the other day, ran great after air worked it self out. Two days later, It starts fine, drive about 10 miles and starts to run really rough. Stop for a school bus and it took pedal to the floor to get it to 45 mph on flat ground another mile and it just completely dies. It will crank and very little smoke if any and no start.
I have ForScan and a bluetooth dongle. 6 month old batteries and clean tight connectors, used big 200 amp battery charger to keep batteries up while cranking.
HPOP showing >1800 psi while ​​​​​​​ cranking. HPOP reservoir less than 1/2" from the top. If I unplug the ICP it almost coughs and rpms go up a little.

tach is moving , swapped anyways.
I have diesel in the bowl and cleaned out the filter and all connectors, heater is fine and fuse 22 good.
full tank of fuel.
oil on dipstick to full
used block heater for two hours
I have wait to start light
glow plug relay checked and voltage drops when engaged.
Glow plugs ohm out between 2 and 5 ohms each.
all 8 injectors buzz test, forscan says pass.
voltage 11.4 when cranking
unplugged exhaust back pressure sensor and tried
unplugged my tuning chip from the PCM (have had installed for 10 years)



I am at a loss, I have tried more things, but drawing a blank on what all I have done as it has been 2 days of fiddling with this truck.

Could really use a pointer. Appreciate it!

 

Have you checked the fuel pressure while cranking. Should be at least 20 psi while cranking.

 

Yeah, I used a tire pressure gauge and it goes to 35 while cranking.

 

Make sure your starter is up to the task, if it's spinning slowly it will never start.

 

It's spinning it over at 200 rpm, best to my knowledge that should be good?

 

Why dd you change your IPR and did you use genuine Ford parts?

 

I changed the ipr try and help with surging on startup. Yeah I ordered it from riff raff.

 

You have a HP oil leak . Injector O ring most likely . ICP 1800 cranking is what the PCM wants . IPR DC Is nearly wide open calling for pressure.

 

How did you determine this from the data the OP posted? It looks like his HPOP is over 1800psi while cranking. Not busting ballz, just trying to learn.

 

IPR %.....

 

Thanks for the info. I just went down a rabbit hole of info on IPR duty cycle percent, on this site. Wow the people on this site Rock…I want to learn everything I can about how these engines work, and I love how there is a mechanical side and a programmed electronic side controlling and monitoring it. Thanks again!

 

The truck is almost starting while its doing those numbers. Its like coughing and sputtering. when I crank it cold pressure goes up to 3600.

 

I finally got her to go. I had two issues going on. First was lift pump was leaking diesel into the block, weep hole was clear, low pressure side pumped good, but high pressure side would fluctuate,. I initially just used a tire gauge on my fuel bowl to test, later I went to a fuel injection gauge to see it really read only putting out around 5psi while cranking.

So I changed that pump, and my oil was pretty mixed with diesel so the oil was very aerated and the injectors were not firing very well. So after oil change and new lift pump and bleeding the system. It runs great.

 

Nice! That brought a bunch of parameters down on the readout

 

thats a fun fuel leak to figure out, thanks for posting back