Hey all, I'm wanting to change my fuel filter as my truck has been dying on me lately. Everyone I talk to says it's fuel filter. Anyways, reading the process in my Chilton's Manual, it says I need to depressurize my fuel system. It also claims that I need a special guage in order to do so. I'm guessing it's a mandotory step, and not just a suggested one, but I'm curious about it. How much is the guage? What's the whole process for my 4.9L? Any help, comments, or suggestions are greatly appreciated!

Thanks,
-Jbotto

 

Let it sit overnight and the system will depressurize on its own. Then just get under it and change the filter. It's a super easy job that shouldn't take more than 5 minutes even if you've never been under a vehicle before. Just make REAL sure you get the hoses back on the filter all the way.

BTW I seriously doubt that it's why your truck is dying but it's never a bad idea to change the fuel filter.

 

That's one way. If you don't want to wait, get a small straight blade screwdriver and an old tupperware container or cup. Remove the shrader valve cover on the fuel rail [it's small plastic cap] and line up the screwdriver w/ the valve stem. Hold the cup or container upside down over the valve, then press on the stem w/ the screwdriver. Gas will spray out over the engine but the cup will keep it from squirting upward and into your eyes. It's not really an advisable way to do it but I've gotten away with it in an "emergency" before when I've needed to depressurize the system but didn't have time to wait.

Also I agree with andy- it's not likely the main reason your truck is dying, although it could be a contributor.

 

Here is the CORRECT way to depressurize the fuel system to remove the filter...

mounted to the firewall behind the clutch/brake pedal is the fuel pressure inertia switch. Looks like this:

-Either using a small flat blade screwdriver, pop the red button up, OR you can just unplug the harness. Either way, this will prevent your fuel pump from turning on.
-Next, try and start the truck. It will spit and sputter as it uses up the fuel in the lines, then all you will hear is cranking.
-Now your ready to remove the filter
Once you get the new filter on, either push the red button back down, or plug the harness in.
-To reprime the system, turn the key to "run" 2-3 times. Dont start it, just to the forward position.
-Now try to start it. It may crank for a bit, but it should start right up.

 

Ok that's a better way to do it.

 

Or instead of digging around under the dash, you can just pull the fuel pump relay under the hood and crank the engine.

 

Thanks Blue Rebel! That one is so easy, even I could figure it out! Thanks everyone else too!

 

+1 This is what I do too but just be careful because no matter what there's still going to be some fuel in the lines. Safety glasses and a closed mouth would be good things to remember when take that first line off.

 

I have changed the line filter, both tanks work & I can hear fuel pumps come on when I turn on ignition, I only get a TEN pound presure reading at Schrader Valve.
HELP
Is there another valve or filter I am missing?

 

Can't say without knowing more about the truck. year, model, engine, dual tank?

 

The truck is 1990 Ford F250 5.8 liter engine, I can switch from front or rear tank & hear the pump humm for about two seconds, when I turn ignition on, I replaced the line filter, with ignition on the fuel pressure gauge builds pressure to about #10 at the schrader valve.
Is there a closer place to check pressure on gas line?

 

Hello,

Just want to add some things that I found useful from this post.

The back story-
I have a 2001 F250 V10 with 234k I purchased used with no maintenance history. It began shuddering at 1000 - 2000 RPMs but would right itself and go full power past 2000RPM's.

Cleaned the Throttle Body & replaced MAF sensor and it cured the problem temporarily, maybe 500 miles. When it returned but the shuddering was 50% of what it was before and was limited to 1500-2000 RPMs

Check CP's and changed plugs, no fix.

Changed Fuel Filter and runs like a champ now. Only did 10 miles but the difference is night and day.

I found this thread useful when trying to understand depressurizing the fuel system to R&R the fuel filter. I was stuck on what method to use and could not get a clear answer if just releasing the fuel cap overnight would suffice or not. And I didn't want to be a guinea pig...

I released the cap over night and purchased the fuel pressure test gauge with release valve in the morning. I happy today that when I hooked up the gauge the pressure was 0.0 psi. So yes, releasing the cap overnight will work, or at least it did in my situation.

Before I changed the filter I did start the truck to test the pressure and it was a steady 29 PSI. This would lead most people to say the filter is fine. Since I had the filter already I went ahead and changed it wanting to eliminate everything that could be causing the issue. After changing the filter the gauge read 31 PSI. A manual test of the old fuel filter via blowing through it revealed significant restriction.

So far, 10 miles of testing and trying to recreate the issue has lead me to believe the filter was the the culprit but time and mile will tell. A true test will be this weekend pulling the 7500 travel trailer over 2 mtn passes.