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completely full HPOP reservoir

11K views 13 replies 5 participants last post by  Blue-Truck-Nut97 
#1 ·
While trying to figure our a slow to start issue, I checked for oil in HPOP reservoir and it's completely full. In reading, looks like it should be 3/4" from top.

1995 F350

Only related info I could find online was this from DeadHeadDiesel:

"You can also remove the HPOP Reservoir inspection plug/fill port (scroll down to step #9 on that article) and check the oil level. If the oil is close to the top, the problem could be a bad or failing 7.3 IPR." (in the IPR test section: [deadheaddiesel.com/7.3-ipr-injection-pressure-regulator/)

But ins't there an over-fill drain in the IPR reservoir? So why would oil level get close to the top w/ bad IPR as deadheaddiesel claims? Seams like only reason would be clogged drain line.
 
#2 ·
Every time I pull the inspection plug on mine it's to the top as well, not 3/4" like some people have. Maybe some are just different? Dont forget that reservoir gets pressurized to 3000 psi, so a drain tube would be pointless. The IPR is the only way for that oil to get out of the reservoir. That, and going through the iniectors.

I would still think a sticking IPR.
 
#3 ·
Lt.Dan,

I believe that the HPOP reservoir only sees LPOP pressures. The heads see the high pressure output of the HPOP. You don't want any air in the lines and galleys downstream of the HPOP.

Cj
 
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#4 ·
So, still unsure what a full HPOP reservoir means if anything?

Still a bit tough to start. Just finished: Rebuilt injectors (some did have bad o-rings), new glow plugs, valve cover wiring stuff. Tried un-plugging ICP sensor, no change in startup.

I guess I'll just start throwing money at it here and there. Next up: IPR.

Another symptom is that it will run on 7-cylinders for 5-10 minutes, then go on 8. Which is why I started with injectors thinking one was bad. So when oil gets hot and thins out, it would flow better allowing 8-cylinders to run. Maybe it is the IPR indeed. It always starts running on 8 during acceleration after that amount of time.

Any suggestions would be helpful, but I'll try to keep the thread up to date until problem is solved. I hate those threads where you read a little and they're having the exact problem you are, but then they never posted what the solution was.
 
#8 ·
ok. Long drive helps start quicker. Not necessarily asking for help, but here's an update after a strange day:

Injector #2 not ever firing. No oil coming out of #2 injector like others (pulled valve cover). When #2 is disconnected, no change in engine sound like other injectors. So #2 definitely not firing.

You'd think bad wiring. ~53vdc signal is getting to the injector. Pic shows signal measured at injector #2 (not working) and injector #4 injector(working)



So I swapped cylinder #2 injector with #4 injector. Cylinder #4 continues to fire, #2 still no fire. I know injector is good. Which isn't a surprise since they're freshly rebuilt.

I popped out injector #2 and cranked a few times to see oil flow. Some oil flows into hole, not a ton. Maybe I'll pull #4 and compare oil flow.

Measuring voltage on ICP, it measures .9vdc at idle (600psi). When I rev and watch voltage on ICP, it's at 1.25vdc at 1,500 rpm. Highest spike when getting on it (not moving, just parked in garage w/o load) got to about 2.1vdc (1600psi) very briefly. Voltage to psi conversion: thedieselgarage.com/forums/19-2003-2007-6-0l-power-stroke/129265-icp-pressure-voltage-correlation.html

According to deadhead, those pressures are right in line with what they should be. //deadheaddiesel.com/icp-sensor-7-3-injection-control-pressure-sensor/

I'm a little stumped at this point.
 
#11 ·
I used cheap Chinese valve cover wiring harness from ebay :frown: I did replace the connectors plugging into the valve gasket harness as well. (w/ cheap ones)

After some hair pulling days I feel like I'm getting closer, but still a bit baffled.

All wiring in and around injectors is good. Triple checked. So, while I won't buy cheap valve cover harness' again, these are working for now.

I measured the resistance from the IDM/PCM connector through each injector. Resistance on inj #2 was double the rest at about 6.2 ohms where it should have been around 3.2 like the rest. Each injector bank has a common power line (center pin on the valve cover connector.) So I checked continuity between the center pin on the valve cover harness connector and IDM connector. NOT connected, from the #2,4 injector connector. So how was #4 still firing?

Once I found it wasn't connected, I pealed back the outer jacket on the wire bundle going from IDM to valve cover harness. No visible damage. There is a connector mounted next to the large fuses on the drivers side. I have good continuity from valve cover to there. But not from wheel well harness connector to IDM connector approx 1' away. It's difficult to inspect wires in that short run because they run under that fuse box.

I tried a jumper wire from that connector on the wheel well to IDM connector. With that jumper connected, cylinder #2 started firing :laugh: hooray I thought. However, upon closer inspection #4 was not firing (#2 and #4 share that common power wire, which at some point is connected to #6,8 inj.). Disconnect my jumper and #4 fires #2 doesn't. Connect the jumper #2 fires and #4 doesn't.

Next step, to somehow inspect the wires between IDM and wheel well mounted wire bundle connector. Is there anything going on between that connector and IDM? Some resistor or electrical component of some kind? Maybe its shorting, although the ohm meter doesn't think so.
 
#13 ·
Yesir! I had to take a long lunch break to go see cause what you said made a whole lot of sense. Sure enough, crossed #4 with power-in line. Man I felt so good and so stupid at the same time! This thing is purring like a kitten, all up and runnin'! Thanks all.:smile:
 
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