2005 5.9 auto crank no start

[DonFitzwater]

Truck was running fine and started to miss and buck then quit. Checked lift pump-15 psi and lots of volume. Fuel filters are new, rail pressure is 5800-6200 cranking. Rpm is being indicated while cranking. Disconnected fan clutch and cranked engine, still no start, doesn’t even try. Disconnected FCA and cranked, fired after about 3 seconds and sounds good. Plug in FCA and it starts to run poorly again and quits. Thinking about throwing a new FCA pigtail harness are it. Any other recommendations?

Truck has 135k on the clock and is running a FASS and stock filter. Engine is fully stock otherwise and has never had any running problems.

 

[Ozymandias]

Jfyi, as soon as the engine runs, it doesn't need the lift pump anymore. The CP3 does that just fine.
It even pulls the fuel through my FASS unit, surprisingly.

Change the FCA first, then if problems persist change the wiring pig tail.
I'm on 200K Mike's still with OEM harness, but second FCA.

 

[cerberusiam]

Truck was running fine and started to miss and buck then quit.

Happening that quick I would suspect fuel as the issue. As a rule do not see an FCA take a dump that fast unless there outside influences. Are you seeing any smoke or weird exhaust emissions when it is running? Might try an alternate source like a fuel can to see if it makes a difference after you get the existing fuel flushed from the system. If you do not run a constant additive package a cleaning is in order before parts replacement.

Jfyi, as soon as the engine runs, it doesn't need the lift pump anymore. The CP3 does that just fine.

That is a false assumption to make, CP-3 is not made to to pull its own fuel like that on these trucks. The LP is there for a reason, suggesting otherwise is not very good advice.

Standard rule with gear rotor pumps, input pressure should be in the 25-30% range of output pressure to minimize wear and cavitation. Output is regulated at 75 psi, that gives the optimal inlet pressures.

 

[DonFitzwater]

Happening that quick I would suspect fuel as the issue. As a rule do not see an FCA take a dump that fast unless there outside influences. Are you seeing any smoke or weird exhaust emissions when it is running? Might try an alternate source like a fuel can to see if it makes a difference after you get the existing fuel flushed from the system. If you do not run a constant additive package a cleaning is in order before parts replacement.

The truck has a 60 gallon fuel tank and ran 3/4's of the tank just fine before this happened. I thought maybe it had a fuel gauge problem so added 15 gallons and still wouldn't start. The fuel is clean and so are the filters I replaced. As the story unfolds, my buddy who owns the truck said he has had several no start conditions leading up to this complete failure. The high pressure side makes 26,000 psi with the FCA unplugged and the engine runs well until I plug it back in. This truck has run very well for 135k miles so could things be dirty, you bet. The engine makes no smoke when running with FCA unplugged.

 

[Ozymandias]

Happening that quick I would suspect fuel as the issue. As a rule do not see an FCA take a dump that fast unless there outside influences. Are you seeing any smoke or weird exhaust emissions when it is running? Might try an alternate source like a fuel can to see if it makes a difference after you get the existing fuel flushed from the system. If you do not run a constant additive package a cleaning is in order before parts replacement.




That is a false assumption to make, CP-3 is not made to to pull its own fuel like that on these trucks. The LP is there for a reason, suggesting otherwise is not very good advice.

Standard rule with gear rotor pumps, input pressure should be in the 25-30% range of output pressure to minimize wear and cavitation. Output is regulated at 75 psi, that gives the optimal inlet pressures.

My point is that the engine does not shut down with a bad lift pump.
Not to run it forever without.

The OEM lift pump makes 9psi.

 

[cerberusiam]

If it is actually making 5800-6000 cranking there is a problem somewhere, that is way high for cranking at 200 rpms or so. I would verify that number as it does not sound reasonable. If it has that pressure at cranking then it isn't the FCA.

You posted 15 psi of LP pressure but where? At the pump? At the CP-3? Need to verify it has adequate pressure at the CP-3 first, then verify rail pressure. CP-3 may have given up or the COA is stuck\worn.

More interested in the exhaust content with the FCA plugged in as that is where the issue seems to be. Still leads ot fuel being the issue with 3/4 tank running well thne it quits. That is an after market tank and no telling what the inside condition is or the fuel like or how good the source is. All the bad fuel and garbage will be on the bottom quarter of the tank, depending on how the the draw straw and return is setup it may be sucking up bad fuel that is being churned by return flow and suction point. If it isn't pulling fuel from a basket all bets are off. If it does have a fuel basket it might be partially plugged or something else with the fuel pickup.

Yes, the stock LP only make 9 psi and that is barely adequate for stock fueling and filters, not adequate for general rule of thumb to stop cavitation. The posted statement was the LP was not needed after it started, not that the LP won't interfere. Both of which are erroneous statements. LP is needed all the time and an LP can and will fail blocking the fuel flow, depends on the failure.

 

[sag2]

When the lift pump suddenly failed on my 04 or 06 the engine promptly quit and had to be towed to the dealer so they could replace it. So in my experience the CP3 will not pull fuel through the lift pump.

 

[DonFitzwater]

"More interested in the exhaust content with the FCA plugged in as that is where the issue seems to be"

With the FCA plugged in after starting the engine with it unplugged, it starts to smoke and run rough/knocking then quits within a few seconds.

"If it is actually making 5800-6000 cranking there is a problem somewhere"

My 2005 Liberty CRD with the CP3 makes the same pressure cranking so I had assumed that was a healthy cranking pressure. Any I've had with less than 4k had starting problems. All the info I could find on HPCR showed 4-7k psi rail pressure for normal starting.

 

[cerberusiam]

If it is knocking and smoking you likely have an injector stuck open or sticking badly and maybe cracked and bleeding pressure off.

The 5800-6800 psi at 750 rpms is the normal range for most CR systems depending on year and tuning, but that is not 200-250 rpms cranking with the starter. Injectors disabled and a good starter cranking around 200-220 rpms 3-4k psi is normal, it will fire on that. Minimum 3000 psi to get the injectors to fire per Bosch.

Given all things in the system operating nominally it should be at +3000 psi by the 2nd revolution when the cam and crank sensors synch up or you get a long crank until RP builds adequately. You need a scanner that can monitor cranking rpms and rail pressure to see what it is actually doing when cranking.

 

[Wayne M.]

What is the low rail pressure threshold to light off?

 

[AEdelheit]

When the lift pump suddenly failed on my 04 or 06 the engine promptly quit and had to be towed to the dealer so they could replace it. So in my experience the CP3 will not pull fuel through the lift pump.

From my experience the CP3 will pull thought a dead lift pump until it looses prime then it will not and your stuck on the side of the road.

 

[Wayne M.]

From my experience the CP3 will pull thought a dead lift pump until it looses prime then it will not and your stuck on the side of the road.

Isn’t that the Duramax dilemma?

 

[Wayne M.]

From my experience the CP3 will pull thought a dead lift pump until it looses prime then it will not and your stuck on the side of the road.

Isn’t that the Duramax dilemma?

 

[cerberusiam]

From my experience the CP3 will pull thought a dead lift pump until it looses prime then it will not and your stuck on the side of the road.

As long as the LP doesn't fail and block the inlet that can be true. An LP "failure" can take on multiple connotations and consequences, not all the same thing.

 

[DonFitzwater]

I replaced the FCA and the truck will now crank and fire but sounds terrible. I’ll be checking injectors this weekend and will hopefully figure something out by tomorrow. Have a good 4th!

 

[nibroc]

subscribed

 

[Ozymandias]

I replaced the FCA and the truck will now crank and fire but sounds terrible. I’ll be checking injectors this weekend and will hopefully figure something out by tomorrow. Have a good 4th!

Does it Sound the same "horrible" when you start the engine with the FCA disconnected?

 

[DonFitzwater]

Does it Sound the same "horrible" when you start the engine with the FCA disconnected?

The engine runs reasonably well with the FCA disconnected. I took a fuel sample from the fass filters and found lots of water. I disconnected the fuel feed line to the cp3 and jumpered the fass relay. Took a fuel sample and was surprised to find an emulsified version of diesel fuel in his tank. I took a sample from the engine mounted filter initially and it was clear like normal fuel. So far I’ve got 1.5 gallons of water out of the tank. No more mystery!

 

[DonFitzwater]

Now to drop the tank and start replacing parts.

 

[Wayne M.]

Yikes Don! I hope she recovers.