Jump to content

6.0 fuel pressure at the secondary filter hsg.

Rate this topic

Fordtechnician
 Share

Recommended Posts

Fordtechnician

Fordtechnician

Posted
Posted

I guess my biggest concern is to determine if my gauge is defective. This 2004 Excursion runs perfect on the level. When it comes to a mountain it will not go over 30 mph. Boost psi is up, just will not go faster like it is governed. I suspected fuel psi so I hooked up my gauge bar kit (issued with the 6.9). I always have to adapt it because I don't have the modern one listed in the manual. Anyway I had exactly 45 psi at idle in the shop. When I drive it and floor it it drops to less then 10 psi. Would this thing even run at all with that low of fuel psi??? Or is my gauge shot???

Link to comment
Share on other sites
OHNO60

OHNO60

Posted
Posted

WELL IF MY MEMORY SERVES ME 45 IS BARE MINIMUM.HOOK UP AND GET A INLET RESTRICTION RAEDING BEFORE THE PUMP.SHOULD BE 6" MAX.JUDGING BY YOUR READINGS BETTER OFF JUST PULLING THE TANK.I REMEMBER RUNNING THE FUEL PRESSURE DOWN TO 2 PSI ON A FEW.ONE ACTUALLY WENT TO NEGATIVE NUMBERS AND WAS STILL RUNNING! NEVER ACTUALLY UNDERSTOOD WHY IT WAS RUNNING. IT ACTUALLY RAN FOR ABOUT 15 MINUTES OR SO.PULLED THE TANK AND FOUND MASS DESTRUCTION.

Link to comment
Share on other sites
Keith Browning

Keith Browning

Posted
Posted

Your gage is fine, I use the same set though I admit to verifying its accuracy. What you are up against has to be one of the more common problems we see as far as driveability and fuel system related damage. These trucks have problems with the fuel tanks in that the ones with the laminated coating are known to be susceptible to peeling caused by the use of bio-fuels and who knows what else. More commonly, the use of the vehicle can play a big part in fuel system cleanliness and filter life. We are seeing more and more trucks that get more dirt in the tank in fewer miles than ever before. I am seeing trucks with less than 15K clogging filters, most of these are stake and dump bodies used by landscapers, masons and contractors.

 

Possibly the two most crucial tests we need to perform are the electric fuel pump pressure test and filter inlet restriction test. Simply checking for fuel pressure in the service bay is only sufficient for determining that you actually have fuel pressure and is only reliable for crank/no start conditions. If you have ANY driveability concerns including damaged injectors you MUST perform both of these tests at full load/full throttle to properly test the fuel system. I'll bet you dollars to donuts that you will find more fuel problems by performing these tests... properly. You will likely find that you wont get far from the parking lot before a pressure drop becomes evident if one exists. I personally encourage you to take the extra minute it takes to install the inlet test adapter that came with the 6.0L service tools and connect it to the gage and run both tests at the same time!!! Knowing the results of both readings will allow you to make an immediate and accurate diagnosis. Don't be too quick to disconnect the test gages either, a quick road test to verify your repair can save you time if you missed something or made any mistakes. Hey, it happens to all of us!

 

 

Posted Image

 

 

Be prepared to sell more fuel filters. Knowing the vehicles service history is also important. Why? If restricted filters are the root cause of any vehicle concern you need to determine if the vehicle is neglected or IF THE SERVICE INTERVAL NEEDS TO BE ADJUSTED FOR THAT CUSTOMER OR VEHICLE. I believe there was a SSM released recommending this.

Link to comment
Share on other sites
Mekanik

Mekanik

Posted
Posted

I totally agree with Kieth, but I wanted to add that if you don't have at least 2in-hg, you are sucking in air.

The most common culprit is clogged filters, and I have seen a ton of trucks mostly aft. axle tanks that are filled with rust, peeled tank liner, ect...

Link to comment
Share on other sites
G. Bedford

G. Bedford

Posted
Posted

According to the recommended procedure test 10a: Road test the vehicle with the engine at full load condition. If you look at the recommended procedure for test 10b it states: Measure restriction at WOT maximum engine speed OUT OF GEAR(emphasis added) with the brake set and the wheels blocked. Watching restriction on the road test while under full load you may see a false failure and have you going in circles. Got this info out of the 2007 PCED in Performance Diagnostic Procedures if you would like to check it yourselves.

Link to comment
Share on other sites
Keith Browning

Keith Browning

Posted
Posted

Good point on the 10b recommended procedure but I wonder why that is not expressly written on the chart? I have mixed feelings about this.

 

It is important to verify a concern AND know the conditions when a driveability concern exists or a code is set. Say you are diagnosing a low power concern while pulling hills only. Your diagnostics show that fuel pressure is dropping below 30PSI and only while pulling hills. Fuel pressure remains in spec during the rest of the road test and in the shop. Is performing test 10b in the shop at full throttle in park going to show a developing restriction? No. It wont. Suppose there is debris in the tank that stirs up and clogs the pick up screen only after driving? See where I am going with this? I want to see if pump inlet restriction is rising WHILE fuel pressure is dropping. I don't see how this could be any different that having to test fuel pressure under a load.

 

I am not arguing the recommended test procedure but this is where we as technicians have to question what we are being asked to test and why. Test 10b is fine, but I want to know more. I know that fuel demand will increase with engine speed AND LOAD therefore I will perform the test but I am going to "kick it up a notch" and also perform the test under the conditions when it really counts.

 

Personally, I'll check fuel pressure and inlet restriction before opening the shop door because many times something is so obvious I don't even need to perform road test. Hmmm, could this be because many drivers will push the truck until it wont go? You bet and I just finished replacing an entire set of injectors because of a clogged fuel filter just under 14,000 miles. The customer paid for it but somehow got Ford to contribute $1000 to the repair. I don't understand how but at least he didn't take the truck, replace the filters and go to a different dealer. There are some honest people out there!?!?! /forums/images/%%GRAEMLIN_URL%%/surprise.gif

 

Mental note: Ask a HotLine engineer about this the next time I am on the line with one...

Link to comment
Share on other sites
eastendpowerstroke

eastendpowerstroke

Posted
Posted

Just to add one more thing to the mix I've seen the "relief" valve at the secondary housing cause similar problems where it would make enough pressure to look only slightly low in the bay but wouldn't / couldn't keep up on the road..

I'm quite sure that Bruce or Keith have pictures of the valve I'm talking about /forums/images/%%GRAEMLIN_URL%%/smile.gif

Link to comment
Share on other sites
Fordtechnician

Fordtechnician

Posted
  • Author
Posted

Does anyone have the old gauge set issued with the 6.9 in 1983 and also have the 014-00761 gauge set? Is the 014-00761 really worth buying if I have the 6.9 set.

 

I haven't had my Excursion back yet to do the restriction ttest yet, but am pretty sure there is probably nothing wrong with my gauges.

Link to comment
Share on other sites
Keith Browning

Keith Browning

Posted
Posted

Mental note: Ask a HotLine engineer about this the next time I am on the line with one...

Had that opportunity today I did! He said he didn't know why it's recommended that inlet restriction be tested unloaded and couldn't think of a good reason either. He basically agreed about looking at data when the condition occurs. I think I'll keep asking others as I speak to them and see If I get different answers.

Link to comment
Share on other sites
  • 4 weeks later...
LARRY BRUDZYNSKI

LARRY BRUDZYNSKI

Posted
Posted

If there is a question about the injectors I can test them. Please guy's give me a call I'll help however possible and probably save you guy's some bucks. I am the OEM repair center and can save you guy's money or make you more, depends on the situation.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing
×
×
  • Create New...