95 PSD wont start when hot

zuk-86 · Mar 10, 2012

working on my 95 psd 4x4 dually auto. so i pulled into the gas station to fill up. filled the truck up and when i went to leave it would not start. had it towed to our shop to work on it. that same day i changed the fuel filter after the fact and still wouldnt start. let it sit over night and the next morning it fired right up. got it warmed up and shut it off and wouldnt start again. ordered seals for the ipr and bought a new cps. the next morning with motor cold i put the new cps in and changed the seals on the ipr. fired it up and i took it for a spin and it died on me on the drive , it shut off while coming to a stop sign , i couldnt get it fired back up , it didnt shrug or anything it just died as if i shut the key off.i have checked all fuses and unpluged the fuel bowl heater. what else could possibly be bad on it? were do we go from here? any help would be appreciated.

Binder · Mar 10, 2012

zuk-86 said:
were do we go from here?

Check the codes.

zuk-86 · Mar 10, 2012

no codes , check engine light is not on

Binder · Mar 10, 2012

zuk-86 said:
no codes , check engine light is not on

You can have codes with no light. Did you scan it?
If no codes at all I would guess (over the internet

) a fuel delivery issue. Like maybe fuel pump?

ChopTop84 · Mar 10, 2012

You can rule out the CPS by watching the TACH bounce ever so slightly while cranking. This only works on trucks up to 2001. If the TACH bounces, then the CPS is good and is sending a signal to fire the injectors.

If the TACH does NOT bounce, then the CPS (or the wiring going to it) is suspect. You can buy a new CPS and have it be bad right out of the box. This was especially true with the new "grey" body CPS sensors that only cost like 20 or 30 bucks compared to the old international ones that cost over 100 bucks.

Look at the face of the CPS and make sure it hasnt been "hit". If the camshaft endplay is too great, it can strike the CPS and ruin it. The earlier the truck, the more likely your CPS was shimmed out to prevent a strike. Later trucks dont have the shims.

You really need a live scanner to troubleshoot this problem. With a live scanner, you can monitor your IPR duty cycle, your Injector Pressure, and your TACH signal all at once. If your IPR duty cycle is high, and your injector pressure is low, then you have a sticky IPR or weak HPOP, or leaking O-rings on the injectors.

Im leaning towards a weak High pressure oil system, based on your statement that the truck starts cold, but not hot. In those situations, the cold oil is able to build enough pressure to fire the injectors, but as the oil warms up and flows easier, the truck loses oil pressure and the engine dies at idle and wont restart.

Really need a live scanner and not just a code reader.

Binder · Mar 10, 2012

This link could help.
http://www.intellidog.com/dieselmann/tech.htm#nostart

zuk-86 · Mar 10, 2012

ChopTop84 said:
You can rule out the CPS by watching the TACH bounce ever so slightly while cranking. This only works on trucks up to 2001. If the TACH bounces, then the CPS is good and is sending a signal to fire the injectors.

If the TACH does NOT bounce, then the CPS (or the wiring going to it) is suspect. You can buy a new CPS and have it be bad right out of the box. This was especially true with the new "grey" body CPS sensors that only cost like 20 or 30 bucks compared to the old international ones that cost over 100 bucks.

Look at the face of the CPS and make sure it hasnt been "hit". If the camshaft endplay is too great, it can strike the CPS and ruin it. The earlier the truck, the more likely your CPS was shimmed out to prevent a strike. Later trucks dont have the shims.

You really need a live scanner to troubleshoot this problem. With a live scanner, you can monitor your IPR duty cycle, your Injector Pressure, and your TACH signal all at once. If your IPR duty cycle is high, and your injector pressure is low, then you have a sticky IPR or weak HPOP, or leaking O-rings on the injectors.

Im leaning towards a weak High pressure oil system, based on your statement that the truck starts cold, but not hot. In those situations, the cold oil is able to build enough pressure to fire the injectors, but as the oil warms up and flows easier, the truck loses oil pressure and the engine dies at idle and wont restart.

Really need a live scanner and not just a code reader.

the new cps i replace is grey , the tach goes to like 200 -300 rpm while ccranking does not bounce at all.

im gonna screw around with the truck some more on monday and should know more , im thinking the injector o rings are bad at least some of them.

ChopTop84 · Mar 11, 2012

zuk-86 said:
the new cps i replace is grey , the tach goes to like 200 -300 rpm while ccranking does not bounce at all.

im gonna screw around with the truck some more on monday and should know more , im thinking the injector o rings are bad at least some of them.

OK, you can rule out the CPS. If your tach moves at all (or goes up to a steady RPM) then the CPS is working, and your problem more than likely is in the High Pressure Oil system.

Just for shits and giggles, check the wiring going to your ICP sensor. It should be on the drivers side head, toward the front. That sensor works in tandem with your IPR to regulate the high pressure oil. Unplug it, look over the wiring, look inside the sensor and make sure there is no oil coming up thru the sensor. Maybe give the little connectors inside a squeeze with needlenose plyers and then plug it back in. Ive seen that connector cause weird shutdowns in the past.

But my guy feeling is either your IPR is sticking/dirty or your O-rings are gone. Either way, your not making the oil pressure needed to run the truck.

I dont think its a fuel pressure issue, as these things will run on like 1psi of pressure, but wont make any power. But to rule out fuel pressure issues, open the drain valve on the fuel bowl (lever on the side of it) while someone cranks the key. You should get a high pressure blast of fuel from under the truck. If you put a piece of rubber hose on the drain line, you can catch the fuel in a can instead of spraying the ground. The drain should be a metal tube on the passenger side of the block, somewhere close to your ICP sensor.

t1h5ta3 · Mar 11, 2012

if it runs good, then just shuts off, i doubt its orings. fuel/oil leaks dont just start/stop

ChopTop84 · Mar 11, 2012

t1h5ta3 said:
if it runs good, then just shuts off, i doubt its orings. fuel/oil leaks dont just start/stop

Nah, his description is very consistent with oil pressure issues. Runs when cold, Dies Hot, and wont start hot. The "dies when coming to a stop like it just shut off" is the engine RPM dropping to below the speed needed to keep the high pressure oil pump spinning fast enough to maintain oil pressure in the heads.

If he had a live scanner and monitored his IPR duty cycle and his High Pressure Oil pressure, he would see the duty cycle start climbing and oil pressure dropping as the truck warmed up.

It could even be his high pressure oil pump itself dying. His year truck is a 15* rotary swash plate and they do wear out. In 2000, they went to a 17* pump that moves a little more oil for the larger injectors the 2000 and up trucks got.

If you want to totally rule out the o-rings, you can build a home made injector O-ring tester out of a high pressure grease gun, a o-5000psi oil gauge, and a high pressure oil line with the correct head fitting. You unplug one head at a time and hook the home made grease gun setup into it, pump it up to around 3,000psi and if it holds that pressure for 30 seconds before dropping off, then your o-rings are good. If you pump and pump and pump and cant build pressure, your o-rings are no good.

Make sure you keep a battery charger on your truck while all this is going on. Powerstrokes are hell on batteries when they dont start right away, and you actually end up melting the insides of your starter from low voltage/high current.

Binder · Mar 11, 2012

Anal Goop said:
I am dipshit

Finally something we all can agree on!
Go away Frank!

Binder · Mar 11, 2012

I don't think it's high pressure oil because if the pressure fell low enough to kill the engine there should be error codes.
The oil gun test is fairly easy to do but in this case it would be even easier to install an inline high pressure gage into one of the oil lines and see what the pressure is doing when trying to start it.

ChopTop84 · Mar 11, 2012

Binder said:
The oil gun test is fairly easy to do but in this case it would be even easier to install an inline high pressure gage into one of the oil lines and see what the pressure is doing when trying to start it.

If he has an autometer 100psi, electric fuel or oil pressure gauge (such as the cobalt series as an example) laying around, they use the same sensor connector as the Injector pressure sensor on the engine.

You can disconnect the ICP plug (which puts the truck in a form of limp mode and SHOULD set the check engine light, but truck will start and run) and plug your gauge plug into the sensor in the head. You then multiply the gauge reading by 40 to get your actual pressure. 10psi on the gauge = 400psi in the head, 100psi = 4000psi. I used to have one of these gauges with a set of gator clips on the power leads so I could jump from truck to truck with it for doing under the hood troubleshooting.

I actually bought a SECOND ICP sensor and a 100psi oil gauge and mounted it permanently so I can monitor my HPOP at all times while driving, and how things like 10k mods or chip programming affect my oil pressure. Works awesome. Installed it next to my fuel pressure gauge in a pod over the rear view mirror.