Ran great before I parked it last weekend?

[Joe Mc]

Truck in signature.
Typical "Now WHAT?! Ran great last weekend..."
NOTES (hopefully to reduce questions):
1- Walbro fuel pump
2- Big line kit
3- Pre-pump filter/screen
4- 2 Post pump filters = Fleetguard spin-ons, water separator, and fuel (forget numbers)
5- All filters changed 2 months ago.
6- Westech 0-30 psi gauge.
Have had this set-up for well over 15 years. Replaced pump once. Problem turned out to be a piece of foil from an additive bottle restricted the pump inlet, hence the pre-pump filter/screen.

Started and ran fine last weekend. Was going to take her out yesterday but...
Turn key to on, I always observe fuel psi as I turn key to on, went to 10 and crept back as usual, wait to start goes off, crank and just cranks. Let go after 4th crank and no start. Turn key off, then on and jogged starter, no fuel psi, listening for pump, no pump running.

The norm is: turn key to on 0-10 psi, takes maybe 2-3 seconds, then drops back to 0 and after wait to start is out if fires on the 2nd turn of the engine. On the occasions where i've changed the filters (per past experience and FSM, I could be off a bit on this next statement, but not too far off) if you jog the key to "just" bump the starter and let go of the key the fuel pump runs for 30 or so seconds. "EVEN" if you turn the key to the "off" position...

This isn't happening = fuel pump runs for X amount of seconds after jogging.

I connected volt meter to the pump's + and a frame ground. Turn key to "on" position and observe 12.7 volts (or so) and 8-10 psi on gauge then 0 psi and 0 volts while wait to start goes thru process. Jog starter 0 volts/0 psi.

I swapped fuel system's relay with known good spare, no change. I checked all fuses and they're good.

Oddly, if I turn key on (after leaving it off for a minute or two) the fuel pump and psi act normally. If I turn key off for only 5 seconds or so and then turn to on (not jogging starter) no psi no volts.

I think the ECM tells pump to cycle (prime) during normal wait to start sequence as well as to run for 30 or so seconds when starter is jogged/bumped.

Thank goodness I don't have to rely on this as my daily driver but on the rare occasion she's let me down in the past I've always been able to figure out what the what was wrong and able to get her back on line.

Late Notes/Edits:
1- I disconnected both +/- on batteries before I decided I needed to walk away for today. Never know might fire right up in a day or so, the power of positive thought "sometimes" works...
2- Batteries are good, clean connections, cranking speed is as usual and cranking speed does "not" slow down.
3- If it doesn't start after cranking the usual amount of time (2-3 seconds) I know something is off.
4- I've had to crank it 20-30 seconds (give it a minute or so brake then go again) in the past but "only" when I ran out of fuel maybe 2 times over the years, or changed fuel filters forgetting to put fuel in them before installing.
Any ideas what the heck is going on now?

Thanks,

Joe Mc

 

[Joe Mc]

Just realized something that may be of importance (realized as I was scanning Mopar1973Man's site) a few weeks ago I started it up and realized the CEL was lit, I shut it down, started it up and the tach then wasn't working. Gave it another shut down/start up and all was well except the CEL was still lit. Later on that day I read codes (2), both were (forget the numbers) Crank Position Sensor. I cleared the codes and went out the next day - all was well. That was last time I drove her = last weekend...

From what I saw on Mopar1973Man's site there was mention that if the crank position sensor is failed the ECM has no signal to engage the fuel pump to run. Thinking the ECM has multiple fuel pump commands = 1- when key turned to "on" - runs for a few seconds to prime, 2- bump starter - pump runs 30 or so seconds and 3- engine running - run pump constant???

 

[Timd32]

Found this description of the modes just for reference then some info on your Code P0336 you posted eariler, which says monitored with Engine Running, so dont know if that exact code will prevent start, but could have an issue in general with that sensor.........

-------‐----------

Normal current flow to the pump is 12 amperes.

With the engine running, the pump has 2 modes of operation: Mode 1: 100 percent duty-cycle with a minimum pressure of 10 psi except when the engine is cranking. Mode 2: 25 percent duty-cycle with minimum pressure of 7 psi with the engine cranking

The 25 percent duty-cycle is used to limit injection pump inlet pressure until the engine is running.

The transfer pump is self-priming: When the key is first turned on (without cranking engine), the pump will operate for approximately 2 seconds and then shut off. The pump will also operate for up to 25 seconds after the starter is engaged, and then disengaged and the engine is not running. The pump shuts off immediately if the key is on and the engine stops running.

---------------------------

SYMPTOM
P-0336 CRANKSHAFT POSITION SENSOR SIGNAL

WHEN MONITORED
Engine running.

SET CONDITION
The crankshaft position sensor indicates no engine speed or position signal to ECM.

POSSIBLE CAUSES
- DTC not = To freeze frame DTC
- Ckp sensor ground circuit open
- Ckp wiring harness intermittent defect
- 5-volt supply circuit open
- 5-volt supply circuit shorted to ground
- Ckp sensor signal circuit open
- Ckp sensor signal circuit shorted to ground
- Crankshaft position sensor def
- Engine control module defective
- Engine control module defective

------------------------

The Crankshaft Position Sensor (CKP) is located on the lower left-rear side of the engine behind the starter motor.

Engine speed and crankshaft position are provided through the CKP. The sensor generates pulses that are the input sent to the Engine Control Module (ECM). The ECM interprets the sensor input to determine the crankshaft position. The ECM then uses this position, along with other inputs, to determine injector firing sequence and fuel timing. The sensor must be powered up by 5 volts to operate.

The sensor is a hall effect device combined with an internal magnet. It is also sensitive to steel within a certain distance from it.

 

[Joe Mc]

Timd32,

Thanks for the info.

Some years ago (probably around 10?) I replaced the CKP. Since there was a recent situation and CEL with the code CKP I ordered one a few moments ago. Read a bit on them and it appears they're not as robust as we'd hope they would be. Hot/Cold cycles weaken them, magnet gets weak over time. Just a bit of a PIA to change as the starter needs to be removed and have to be careful not to bust the old one in the hole during removal.

Keep the ideas coming guys and I'll keep posted when I change CKP - next weekend if the weather isn't too terrible.

 

[jfmaz]

Pretty sure if you hook up your obd2 scanner and you have no engine rpm input (0 rpm) while cranking that is a sign the ckp isn't reporting, for a few possible reasons. At least thats how it works on gassers (and on gasser if you have no spark advance the cam position sensor isn't reporting - doesn't apply to our ctd's) Just had the cam position sensor problem on my Silverado. Ended up being a broken wire in the main loom between the ecm and sensor. Too much fun.
Just a thought

 

[Joe Mc]

jfmaz,
Thanks for your reply. Unfortunately my "toy" code reader only reads & clears, no other potential readings. I'm certain I replaced the ckp about 10+ years back due to same issues. So when it arrives and weather permitting I get installed I'll say a few prayers, connect batteries, give her a go and report back.

Until then keep the thoughts coming.

Thanks again

 

[Joe Mc]

Update. Just want to say I forgot what a RPIA job this little sensor is to get out. Extreemly fiddly. Starter wires (2), bolts (3), which accept a 10mm "12pt only" socket or wrench (which I don't have, only the wrench, thankfully), up top then down several times - getting old sucks - not to mention the differential center section is smack dab right where you need to be = joy = not one bit. Anyhow, getting the starter out was...the easy part... Then came the dipstick tube with that stupid constant pressure wire clamp, which probably hasn't placed any pressure on the tube since well before the last time I did this job. Was lucky enough, after 5 tries, to grab it with angle head pliers and pull it down below the bottom of the tube, then back up top "again" to unbolt the clamp from the intake horn and yank it out. Then I was able to unbolt the sensor bracket and disconnect the wire plug, actually without breaking the plastic clip - YEA!!! Grab the base of the sensor "gently" with a pair of needle nose vice grips, pull, turn a little, pull, repeat and it came out - YEA again!!!

At least the old one is out, "but" I tried to put the new one in, I cleared the residue from the hole with my fingers, and was able to twist and push it in "only" about 1/4", then it basically told me "keep going bonehead and I'll screw you over but good". Since the sun was almost down it was getting colder and I could feel that if I kept at it I'd get what was previously stated by the new one. I stopped for the day in hopes of getting new one in tomorrow - "after" sharing a few thoughts and hoping someone either concurs with my thoughts or shares a tried and true method to ease installation (outside of whacking new sensor with a hammer to get it in all the way).

It appears that the new CKP (Mfg. by Walker, Geno's had Cummins units, but listed them as backordered till late this month) might be a very small amount larger in diameter than the old one? With the old unit (Cummins part) once I got beyond the o-ring tension it seemed a little snug but came out with no real fight.

Thoughts: Keep in mind I'm working on a gravel driveway and tomorrow appears to be the the last day I'll have weather warm enough to do this.
1- Try cleaning hole with Scotch-bright, wipe inside with a WD-40 dampened shop towel, then WD-40 the new unit?
2- I shudder at this next thought... Sandpaper coiled around new unit and give a few turns, try and repeat (including steps in #1) until it goes in? It is only plastic...
3- Port of Power and letter rip?

Thanks for reading and thanks in advance for your thoughts & suggestions.

I'm hopeful the above will stir the thoughts of those who have done this job before and at least gets a laugh or two. It wasn't this difficult when I did this 10+ years back, of course 10 years back I was on concrete, in the summer sun, but I know the new CKP didn't give me problems going in. Perhaps I should heat the block with my heatgun and expand the hole as I freeze the new CKP - kidding.

Oh, last thing - I ohmed out the new unit, lets say pins 1, 2 & 3 - from 1-3 994 ohms, 1-2 0 ohms, 2-3 0 ohms. Old unit same except 1-3 997 ohms. I'm guessing this means absolutely nothing as it is sort of a magnetic (I guessing again) switch? Figured I share the last thoughts of a madman for now anyway.

 

[BigPapa]

As much trouble as it is to replace, I’d find or hold out for the Cummins sensor. I haven’t looked at the part number for yours, but Cummins has started putting a core on the 6.7 crank and intake temp/pressure sensors.

 

[Joe Mc]

BigPapa,
I would prefer Cummins parts but, note I'm working outside, in gravel, it ain't getting any warmer and I ain't getting any younger. Can't afford to have truck down till spring.

Any thoughts?

I'm going to give a last ditch effort to see if I can find a Cummins one this morning...

 

[BigPapa]

Cummins part number 5491995. Other places have it. Raney's Truck Parts was the first one that popped up in a Google search, $58.95. My vendor has three on the shelf.

 

[Joe Mc]

Got a Cummins one near Scranton. Went in without a hitch = slid right in until o-ring, little push and it was home. Back on line, fired right up first try, cranked once and lit right up.

Now the fun part, trying to return the Walker unit. Let the games begin.