2004 6.0 Diesel Crank/No Start Situation

[weboughtabus]

It's been a while since we've posted on here, but we haven't been slacking off! We have started experiencing an issue, though. We parked the bus in November and when I went to start it a few weeks ago, it would crank, fire and then immediately stop.

Troubleshooting and Attempted Fixes:

I assumed it was a fuel delivery issue, so I changed out the fuel filter and the fuel pump (which was supposedly a weak point).

When that didn't do the trick, I pulled the ICP plug off and attempted to start it, base on some advice I found on a PowerStroke forum. Apparently if the ICP Sensor is bad the engine will finally start with it disconnected since the computer assumes the default values for the sensor.

That was a bust, so I changed out the seals on the IPR, since that's apparently another point of failure. Unfortunately the bus still isn't turning on. I don't have a known-good IPR to swap out and the idea of potentially dropping another couple hundred on that to *MAYBE* fix the problem isn't ideal.

What's next?

Unfortunately I don't have access to a scanner and since the bus isn't running I can't drop by my local AutoZone for a scan. Does anyone have any suggestions for how I can continue to diagnose? I'm really hoping it's not a big-ticket item like a FICM or HPOP!

For those interested, I've got a video of the attempted start here.

Thanks in advance!

[Johnny Mullet]

The only way to figure it out correctly without throwing parts at it is to get a scanner that reads the data while cranking. This will tell you if you have the proper pressures in the injection system and other data. One thing you can do is while cranking the engine, the oil pressure needs to come up on the dash gauge before the engine will start. The low pressure system works with the high pressure system.

[weboughtabus]

Thanks for your reply! I've got a ScanGauge II ordered and should be here Monday. AutoZone is doing a 20% off and 1 Day Shipping deal for a few more days, if anyone else needs any high-ticket items!

[weboughtabus]

Originally Posted by Johnny Mullet

The only way to figure it out correctly without throwing parts at it is to get a scanner that reads the data while cranking. This will tell you if you have the proper pressures in the injection system and other data. One thing you can do is while cranking the engine, the oil pressure needs to come up on the dash gauge before the engine will start. The low pressure system works with the high pressure system.

Ok, I got the ScanGauge on the bus and tried to get some data. I cranked the bus a few times. This is what I have to report:

IPR - Key On - 14.8, Cranking 14.8 with one jump to 46.8
FICM am/Crank Sync - 1 (Synced)
FICM Main Power - Key On - 47.5, Cranking went down to 47.0
ICP - 430, but it jumped to 1,280 and 1,231


P0231 - Low Voltage Fuel Pump Secondary Circuit
P0299 -Turbocharger/Supercharger A Underboost Condition
P0472 - Exhaust Pressure Sensor Low Input
P2614 - Crankshaft Position Signal Output Circuit/Open
P2617 - Crankshaft Position Signal Output Circuit/Open

If anyone has ANY suggestions what to try (especially cheap/free ones) please let me know!

[Truthseeker4449]

The first code makes me leery of your fuel lift pump, which from quick research is mounted on the frame just behind the front suspension. I am not able to readily find out however if it's suppose to run initially with key on as a gas engine does. You could get a partner to crank the engine while feeling the pump for any signs it is running.

EDIT: saw late that you said you've already changed the pump, perhaps a wiring issue?

[Johnny Mullet]

Monitor the cam and crank sensor data while cranking. The pressures seem fine.

[Jsneeb]

The first three codes would not prevent engine from running, but those last two will. The crank signal is the primary information used by the computer for RPM, fueling and timing.

Check or replace sensor.

I don't know where it is located ( don't own a 6.0 ) so take my advice with salt. But another opinion doesnt hurt.

[weboughtabus]

Originally Posted by Truthseeker4449

The first code makes me leery of your fuel lift pump, which from quick research is mounted on the frame just behind the front suspension. I am not able to readily find out however if it's suppose to run initially with key on as a gas engine does. You could get a partner to crank the engine while feeling the pump for any signs it is running.

EDIT: saw late that you said you've already changed the pump, perhaps a wiring issue?

Thank you very much for your reply. After some more research it seems like it very well could be a chafed wiring harness. Apparently it's a big problem with the 6.0.

Originally Posted by Johnny Mullet

Monitor the cam and crank sensor data while cranking. The pressures seem fine.

Thanks for your reply! I think my only way of monitoring that with my ScanGauge is the FICM Cam/Crank Sync, which does appear to be good. The Cam Position Sensor wiring can be an issue, so I may pull that for inspection.

Originally Posted by Jsneeb

The first three codes would not prevent engine from running, but those last two will. The crank signal is the primary information used by the computer for RPM, fueling and timing.

Check or replace sensor.

I don't know where it is located ( don't own a 6.0 ) so take my advice with salt. But another opinion doesnt hurt.

Thank you! Yeah, those are definitely the more concerning codes, I'd think. The bus does fire over, but immediately dies which is why I was suspecting fuel delivery.

[weboughtabus]

Interestingly enough it turned out to be a big case of nothing! A family friend who's an excellent mechanic came over and we went over everything with a fine tooth comb.

We eventually realized that the new fuel pump still wasn't pumping (what the hell was I feeling when I cycled the key and was sure I felt it working under my hand?!). So we won't about testing the fuel pump relay and fuse and everything seemed normal until we checked the voltages at the fuel pump plug.

We talk about just running a new jumper between the relay and the fuel pump, but we consulted the wiring diagram, first. Turns out between the relay and the pump is an Inertial Fuel Cutoff Switch. I look up where it's located, give the switch a press, cycle the key and we have pump! We had the filter cap off, so we watched to make sure the filter housing was filling up and it did. So we threw the cap back on, primed the system to try to make sure all the air was out, turned the key and she fired right over!

In my head I was already saying goodbye to the rest of my conversion funds and most of my travel money! Thank goodness for a free fix! So now I have fresh fuel filters, a new IPR screen and seal and a good spare fuel pump!

Thank you to everyone who chimed in and tried to get us back on the road! It was greatly appreciated!

TLDR: Check your Inertial Fuel Cutoff Switch before you start freaking out!

Originally Posted by Jsneeb

The first three codes would not prevent engine from running, but those last two will. The crank signal is the primary information used by the computer for RPM, fueling and timing.

Check or replace sensor.

I don't know where it is located ( don't own a 6.0 ) so take my advice with salt. But another opinion doesnt hurt.

Originally Posted by Johnny Mullet

Monitor the cam and crank sensor data while cranking. The pressures seem fine.

Originally Posted by Truthseeker4449

The first code makes me leery of your fuel lift pump, which from quick research is mounted on the frame just behind the front suspension. I am not able to readily find out however if it's suppose to run initially with key on as a gas engine does. You could get a partner to crank the engine while feeling the pump for any signs it is running.

EDIT: saw late that you said you've already changed the pump, perhaps a wiring issue?

[Frank.Nursery]

Glad you got this sorted, and glad I found this post. I know this is an old thread, but I am filing this bit of information away for future use.

[Retired Roughneck]

yes! thanks everybody for this useful thread of information. i have the 6.0 and like to learn all i can about it for future issues?
i love this forum!
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