Navigator Cranks but Won't Start Without Starter Fluid

[bobfake]

Hi all,

2007 Lincoln Navigator with the 5.4L V8. For several months now, the Navigator has had to crank a while before it would finally fire. Within the last week or so (after sitting for a few weeks) it would crank just fine, but wouldn't start. I shot some starter fluid into the throttle body and it fired right up and ran smoothly. Took it out and it ran fine. Stopped and restarted it several times with no issues. Thought maybe it was a fluke.

Today, after changing the MAF (chasing a P0174 code) I went to start it and encountered the same problem. With starter fluid, it did fire up and ran fine.

Any thoughts about where I should look next to try to troubleshoot? I have fuel, spark and air since it does run once started. Anyone run across this scenario with your Navigator and determined a solution?

Thanks!!
Bob

 

[Action]

If you have fuel, it isn't enough!
Or maybe you have too much air.

The P0174 code is air/fuel mixture is too lean on bank two. (The left bank) This is being reported to the PCM by the up stream O2 sensor.
And do not assume the air/fuel mixture is too lean on that one bank. That may be the situation if there is a vacuum leak. But it may be the most lean bank of the two banks and that is what is tripping the code for now. As it is possible both banks or all cylinders are fuel starved. Which is the reason for no cold engine start.

Typical causes:
Vacuum leaks
Faulty oxygen sensor
Clogged fuel injectors
Malfunctioning mass airflow sensor
Fuel pump issues

You did not post the milage on the engine, so the above are just general items.

Initial things to do ............
Getting a vacuum reading at idle and warmed up engine would be a good (cheap and easy) diagnosis tool. Will tell you if there is a vacuum leak.
OR inspect of the vacuum system and intake manifold for leaks. Or spray around intake and listen for engine RPM changes while engine is running. Repair any leaks found.
I would rule out fuel pump issues for now as the engine runs (acceptable) based on what you wrote
If the fuel filter is replaceable and has not been replaced in a couple of years, do this first. If doing this note the old fuel in the old filter. Was it clean?
If there are over 100,000 miles on the engine, replace all of the O2 sensors. O2 sensors slow down after that kind of usage and are reporting to the PCM late data. The PCM is making fuel trim adjustments on old data.

Post back with mileage, condition of old fuel in old fuel filter if replaceable.

Action

 

[driller]

2007 Lincoln Navigator with the 5.4L V8. For several months now, the Navigator has had to crank a while before it would finally fire. Within the last week or so (after sitting for a few weeks) it would crank just fine, but wouldn't start. I shot some starter fluid into the throttle body and it fired right up and ran smoothly. Took it out and it ran fine. Stopped and restarted it several times with no issues. Thought maybe it was a fluke.

What's the mileage/age of the spark plugs?

I vaguely recall an instance years ago with such a symptom that was resolved with a fresh set of spark plugs.

 

[bobfake]

Hi all…quick update. Put a fuel pressure gauge on the fuel rail. No real pressure with key on “run” position, where I would expect the fuel system to pressurize. While cranking, the pressure slowly builds up to about 30 psi and it then starts. I’m guessing that the fuel pressure sensor is telling the PCM not to fire the injectors or in some other way prevent the starting until appropriate pressure is reached.

Once running, the pressure builds to about 45 psi (not sure if that is low or within acceptable range). After shutdown, I monitored the pressure for 40 minutes. Dropped from 45 to 40 psi over that time, which I thought was reasonable.

Therefore, I am lead to think it is either the fuel pump or the fuel pressure regulator. The owner says the pump was replaced about 10 years ago, but can still be suspect.

Question: on a 2007 Navigator with 5.4L 3 valve…what kind of fuel pressure regulator is used? External?

Thanks!
Bob

______________________________

 

[Action]

Therefore, I am lead to think it is either the fuel pump or the fuel pressure regulator. The owner says the pump was replaced about 10 years ago, but can still be suspect.

Question: on a 2007 Navigator with 5.4L 3 valve…what kind of fuel pressure regulator is used? External?

Fuel pressure is regulated by the fuel pump driver module. (FPDM) It is bolted to the inside left frame rail behind or very near the LR tire/wheel assy. These are known to have a physical issue based on corrosion at the mounting area due accumulation of road dirt. Based on location AND environment. When they go bad they usually generate a code.

The fuel pump is electronic. When it goes bad it usually generates a code.

What you have not listed in your diagnosis is the easiest, the fuel filter. When was that last changed? (see post 2)
A restricted fuel filter may act as you have described.
And a restricted fuel filter isn't healthy for the fuel pump. As the pump has to over come the restriction of the filter to get past the filter.
It is located on under the vehicle in front of the LR tire/wheel assy.

The fuel system needs at least 20psi to operate the fuel injectors. While rather low I have seen engines start on this low pressure. The fuel injectors won't open at lower pressures.
Typical operating pressure is 30psi or higher. Pump PSI limit is between 40 and 50 PSI. If you are getting 45PSI, I would say the pump is good.

Action

 

[bobfake]

Fuel pressure is regulated by the fuel pump driver module. (FPDM) It is bolted to the inside left frame rail behind or very near the LR tire/wheel assy. These are known to have a physical issue based on corrosion at the mounting area due accumulation of road dirt. Based on location AND environment. When they go bad they usually generate a code.

The fuel pump is electronic. When it goes bad it usually generates a code.

What you have not listed in your diagnosis is the easiest, the fuel filter. When was that last changed? (see post 2)
A restricted fuel filter may act as you have described.
And a restricted fuel filter isn't healthy for the fuel pump. As the pump has to over come the restriction of the filter to get past the filter.
It is located on under the vehicle in front of the LR tire/wheel assy.

The fuel system needs at least 20psi to operate the fuel injectors. While rather low I have seen engines start on this low pressure. The fuel injectors won't open at lower pressures.
Typical operating pressure is 30psi or higher. Pump PSI limit is between 40 and 50 PSI. If you are getting 45PSI, I would say the pump is good.

Action

Thanks!

 

[bobfake]

Thank you all!! When I get back, I’m going to change the filter first. If that does not resolve it, I’ll change the FPDM. I’ll post results next week.

 

[Action]

If the engine does not start after the filter change, you might take a pressure reading again.

Then remove the FPDM and look at the back side. (Shoot a picture and post)
Looking at listings, these are fairly cheap at $20 on eBay.

Action

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[bobfake]

Hi all - got the fuel filter changed (can they make the connections any harder??) It cranked for a while, but did eventually start.

The fuel pump driver module has been mentioned, but I've also read in the forum that the 2007 Navigator does not have an FPDM?? Can someone post a pic of where it is located specifically (I've looked and don't see anything obvious) and a pic of what this thing looks like?

Thanks!!
Bob

 

[Action]

My 2006 FPDM is on top of the left frame rail, behind the left rear wheel.

The 5.4l 3V engine was used in Navigator from 2005 to 2014. (Revised in 2009 with an increase in HP) I would assume fuel pump pressure was controlled with a FPDM all the way to the end. Maybe not.
I have seen that the 2008 Navigator moved the FPDM. It was mounted on the side-frame on the outside of the left frame rail, under the driver’s door. This was seen from a shop manual post.

I saw a posting of the 2007 location being under the rear seat passenger's side. And the rear seat cushion had to be removed. I have seen no data on the net to confirm this. In 2006, the rear seat folds out of the way.

The FPDM is available for 2007 & 2008 as there multiple listings for this.

I would look in the shop manual and I do not have one for a 2007. Only the 2006.

Action

 

[bobfake]

Thank you very much. I know it’s not inside the left rear wheel, as I removed it today as well as dropping the spare. You noted my cause of confusion…the FPDM is a valid part for a 2007 Navigator, but I can’t find the damn thing

Under the rear seat may be why I can’t find it. I do not have a shop manual to help me and I doubt my boss will want to buy one as he’s planning on selling it…

Thanks!!