2000 7.3 Died while driving

[FarmerBill]

Yesterday my 2000 7.3 (145k, oil changes every 3k) died while I was driving it. Got it off the road and purged the water accumulator. Still would not start. It would want to start, but couldn't stay running.

I felt certain it was the camshaft postion sensor, had it towed to the Ford dealer and they replaced the camshaft position sensor, but this did not fix it.

They recommended that they do a diagnostic to determine problem.

Have not found a cause yet, but the service advisor said they thought it was a fuel supply issue, something about sucking air with the fuel, rust in the fuel tank, needed to get a bigger lift freed up to check out tank, etc. (Isn't the fuel tank plastic?)

When the service advisor recommended the diagnostic, she said that it might be low oil pressure, I asked if she meant low fuel pressure, but she said "no, low oil pressure". The low oil pressure doesn't make any sense to me. Am I missing something?

I'm not sure that the mechanic at the dealer is all that familiar with diesels.

Advice on this issue would be greatly appreciated.

Thanks,

Bill

[partsguy84823]

Low oil pressure does make sense. The powerstroke uses a HEUI injection system, which in its simplest form means that instead of delivering high pressure fuel to the injector via an injection pump, low pressure fuel is delivered to the injector and the injector uses oil which has been pressurized to between 500 and 3200 psi to drive an intensifier piston which pressurizes and injects the fuel. I don't know the exact number, but I think the truck needs to make 500psi of High Pressure oil before the injectors will fire, so low oil pressure could cause the truck to not start.

Here is a link on how the HEUI system works. Its good reading. CLICK HERE

Oh ya, welcome to the org.

[RRSA]

Need oil pressure to fire the injectors.

[FarmerBill]

Thanks, I learned something. It sounded like they were going to check the oil pressure first.

Bill

[scagle1]

had same problem a few months back and mine was the lift pump

[partsguy84823]

No problem, thats why we're here.

When you're cranking the truck and it tries to start, are you getting any smoke out of it? If so, what color?

Have you checked your fuses? The fuel bowl heater has been known to ground out and blow the same fuse that runs the PCM and whalaa, no start.

You said you drained the fuel/water seperator? -Is it filling back up with fuel? Have you changed the fuel filter? Did you prime the fuel system after draining the fuel bowl (turn the key on untill the fuel pump stops running, three-ish times)?

Was the truck running or starting funny before it had its random death?

[FarmerBill]

I turned the ign on a couple times and waited about 30 seconds. Also told the mechanic that I had purged the water accumulator.

The fuel bowl heater had come apart the last time I changed the fuel filter. The dime sized silver discs had come loose, so I cleaned the fuel filter chamber out real good and only put the part of the heater assembly back in that the bottom of the filter has to nest into. (I ordered the aftermarket part and was going to put it in before winter.)

Doing nothing funny before it stalled.

Can't comment on the exhaust color.

Hey, just spoke with the service advisor. He mentioned yesterday something about air mixed with fuel. I just read something about a lift pump that fails will allow the engine to suck enough fuel through the lift pump for the engine to run, but that this allows air to mix with the fuel. When I asked if it could be the lift pump, he said what's that, and that the only fuel pump is on the frame rail. What am I missing?

Thanks,

Bill

[partsguy84823]

That fuel pump is what would be called a 'lift pump' by some.

Lift Pump, Fuel Pump, Frame Mounted Fuel Pump. - Six in one, half-dozen in the other. On trucks with injection pumps (IDI's, Cummins, Duramax, Common Rail Powerstroke... Etc) There were two fuel pumps, an injection pump which timed and delivered fuel to the injectors (or pressurizes a fuel rail on a common rail engine), and a 'lift pump' which 'lifted' (delivered) fuel from the tank to the injection pump. Both are fuel pumps, but both perform different tasks.

The powerstroke only has one fuel pump, the 'lift pump' because it uses high pressure oil inject fuel. So there is no real ambiguity. Its just the fuel pump.

That pump pulls instead of pushing, this can cause the fittings to draw in air. If the truck was running okay before it died out of nowhere, I would doubt that is your issue. (Not to say it isn't an issue on your truck, but its probably not the pressing issue.

[FarmerBill]

What is the PCM?

Sounds like if the fuel pump is sucking air, this is happening in a fitting between the fuel pump and the tank, right? Or maybe inside the tank? The tank is about 3/4 full right now.

[partsguy84823]

PCM = Powertrain Control Module. It is the brain of your drivetrain. It controls your whole drivetrain except the job of actually sending the current to actuate the injector. (The IDM-Injector Drive Module does that).

I would guess if the tank is over 1/2 full, the problem is outside the tank, between the tanks pick-up and the pump.