More 7.3 OBS troubles.

[m67tang]

I know I keep asking about the same truck and it’s troubles. But here it is again:
1997 7.3 OBS.
Has code for CPS. Been replaced twice! New, motor craft CPS!
I’ve traced the CPS plug and wires and find no fault.
Truck sometimes barely starts. Then idles ok for a little while. Then starts idling rough and stalling, but immediately restarts. The wait to start light come on, lets me know the engine died.
Since it’s not fixed with new CPS. What to do???
I’m remembering I haven’t drained the fuel bowl recently. Could water do this??
I’m totally lost.
What would you do next???
Thanks for ANY help.

 

[lotzagoodstuff]

Silly question: you did reset the codes after you installed the crank position sensors? It's possible that you could have an old stored code from a single CPS event that occurred a while back that simple wasn't erased.

Assuming that your not seeing an old stored CPS code, I'd unplug your ICP and see if there's any sign of oil in the connector, and see if it starts with the ICP unplugged.

After that I'd think about trying to verify fuel pressure and see if it isn't something choking off fuel supply (showerhead piece sucked up and stuck somewhere maybe?). After that I'd try to monitor the sensors with something like Forscan and post what you see.

 

[m67tang]

Silly question: you did reset the codes after you installed the crank position sensors? It's possible that you could have an old stored code from a single CPS event that occurred a while back that simple wasn't erased.

Assuming that your not seeing an old stored CPS code, I'd unplug your ICP and see if there's any sign of oil in the connector, and see if it starts with the ICP unplugged.

After that I'd think about trying to verify fuel pressure and see if it isn't something choking off fuel supply (showerhead piece sucked up and stuck somewhere maybe?). After that I'd try to monitor the sensors with something like Forscan and post what you see.

Ok, the code is cleared. Made no difference. I unplugged the ICP, and the truck started. But still stalled. There’s no oil in the ICP plug. ICP looks original too, it’s the old type with the nut at the base. I don’t have a fuel pressure gauge yet. Guess that’s next.

 

[m67tang]

Now I have NO START. I’ve unplugged the ICP and still nothing. Could this be IPR failure .

 

[m67tang]

Since the truck won’t start, if it’s an electrical problem only, Will a manual pressure gauge read while turning the key??

 

[greenskeeper]

I know I keep asking about the same truck and it’s troubles. But here it is again:
1997 7.3 OBS.
Has code for CPS. Been replaced twice! New, motor craft CPS!
I’ve traced the CPS plug and wires and find no fault.
Truck sometimes barely starts. Then idles ok for a little while. Then starts idling rough and stalling, but immediately restarts. The wait to start light come on, lets me know the engine died.
Since it’s not fixed with new CPS. What to do???
I’m remembering I haven’t drained the fuel bowl recently. Could water do this??
I’m totally lost.
What would you do next???
Thanks for ANY help.

If you have a new motorcraft CPS and still have the code I'd look at the contacts on the pigtail as well as the pigtail itself. They sell a kit that allows you to splice a new pigtail in place.

The barely starts, idles, then rough and stalling isn't the CPS...that's a run/not run failure. Sounds like a fuel or oil issue. When it stalls is there oil no less than 1 inch from the HPOP inspection port? IPR nut tight....IPR ever been replaced?

 

[greenskeeper]

Now I have NO START. I’ve unplugged the ICP and still nothing. Could this be IPR failure .

Is there oil in the HPOP reservoir? Remove the inspection port and there should be oil no less than 1" from the top.

 

[greenskeeper]

Since the truck won’t start, if it’s an electrical problem only, Will a manual pressure gauge read while turning the key??

pressure gauge for what?

 

[79jasper]

pressure gauge for what?

I think for icp.

What's icp and ipr duty cycle while cranking?

Sent from my SM-N960U using Tapatalk

 

[m67tang]

I’m gonna need to check to oil level in HPOP.
The ICP looks like a 1997 original! But unplugging it didn’t help it start.
1- I plan to check fuel bowl
2- HPOP oil level
Both tomorrow morning and report back.
Thanks for the new ideas.

 

[m67tang]

Upon further inspection,
The HPOP is full of oil, about an 3/4” from the top.
The fuel bowl has plenty of fuel too. Still no start?

 

[greenskeeper]

Upon further inspection,
The HPOP is full of oil, about an 3/4” from the top.
The fuel bowl has plenty of fuel too. Still no start?

Can you link a video of the start and stall condition you are experiencing?

I just noticed that you stated the WTS light comes on when the engine stalls....that to me indicates an electrical problem related to the "ignition" system. Any other issue (including electrical sensors) wouldn't show the WTS when stalling. The WTS light in my opinion means the PCM is losing power and then powering up again when the stall occurs.

A common area for wiring issues is the large harness that goes over the drivers valve cover....check for chafing and poor connections. Also look at all battery cable connections positive and negative chassis.

The CPS code could be caused by low voltage at the PCM or reference (5v) circuit

 

[u2slow]

I remember it being recommended to use the T444E CPS from International. I've never had a dud so I can't really comment beyond that.

If it keeps restarting, the HPOP res level is not being depleted. The Lube-oil pump keeps it topped-up when running.

The fact its starting means the HPOP is able to make sufficient pressure. However, that pressure can fall off as oil circulates and gets warmer. (i.e. failing o-rings, seals, etc.) Does it start/run better or worse when you've had it plugged in for a while?

Check the fuel pressure. Hi side and low side. Maybe you have a failing pump or a partial blockage.

IPR is a possibility. I had no-start issues. Never quit while running though. After swapping in a used hpop and brand new IPR, it behaved. Seems unlikely a bad hpop could keep the engine running fine, so I suspect the IPR was the issue.

 

[m67tang]

Right now the truck is totally DEAD, cranks but no start. In the morning I’ll pursue looking at all fuses and fuel bowl heat element being burned out. With the WTS light coming on as it was stalling out, the power supply to pcm stopping makes sense.
I did inspect the wire harness over the valve cover on drivers side. Looks just fine.
I’ll report back tomorrow with more.
Thanks for the ideas. It’s helping me.

 

[u2slow]

Fuel heater element was shot in my F350 when I re & re'ed the fuel pump; didn't replace. My E350's fuel heater got tossed out with the fuel bowl when I was done with my my repairs. No impediment to the engine running in either case.

The WTS is probably coming on because the computer is cycling the GPs again... since the ignition is on, and not running.

ECM needs 10 volts to run. Hungry GPs and long crank times chisel away at your 12 volts fast.

Few things that made my troubleshooting easier:
- 3500psi hydraulic pressure gauge to check hpop pressure at the oil rail
- mechanical oil pressure gauge (lpop pressure)
- porta-power hand pump (press up each head to check for pressure loss)
- beefy battery charger with a manual 'starting' mode that DOESN'T quit/reset from GP cycling