Engine/Transmission (1998.5 - 2002) Fuel filter change intervals NOT set in stone

[LSMITH]

Just a heads up to the guys that have not read my sermon on fuel filter changes. THEY ARE NOT SET BY TIME OR MILEAGE.



Today was the third time I went out and checked my fuel pressure, pre and post filter with a temporary gauge I use, and found a drastic change in pressures from the last check. Normally I check it every 2500-3500 miles. Prefilter was 12PSI at idle just like it was 3000 miles ago, but post filter was down from 10 to ZERO. Anything above an idle was pulling a vacuum!! The filter had a little over 20K miles on it, but only 3000 miles ago was only showing 2PSI of restriction, meaning that it had CLOGGED in 3K miles. This is the third time I have seen the filter clog in a short period.



Get a temporary gauge at least and USE IT, check pre and post filter pressures every couple thousand miles. The good filters you don't throw in the garbage because it "was time" to change them will pay for a pressure gauge in no time at all. The best way would be to have pre and post gauges mounted and monitored all the time, and even that setup could be payed for by not throwing out good filters in less than 100K miles. I have gone a little over 30K miles on ONE filter, and as little as 4500 miles. Without a gauge I would not have known either way. Changing them for any other reason but restriction is a guess and lots of times is a waste.

 

[Steve Campbell]

Greg.....good point....

I agree with... .



"The good filters you don't throw in the garbage because it "was time" to change them will pay for a pressure gauge in no time at all. "



I have had similar mileage resuls as you except I could not get to 30,000mi before too much pressure drop. Another reason (IMO) to have the post filter number "available" is to take note of "gelling" fuel on those really crisp mornings when first starting out.

 

[illflem]

As long as your lift pump is good and you have a handle on your normal clean filter pressures all you need is a post filter gauge to check for filter plugging. I change my filter once a year or about 20k miles.

 

[pwr2tow]

That's the main reason I run two sending units with one gauge and a toggle switch in between. It is tied for first place along with monitoring the junk lift pumps. Secondary use is for pressures when adding power upgrades.



Ron

 

[RBSOB]

Agreed

Have to agree with LSMITH and illflem. I have a FP gauge, post filter. Last 2 changes were done because it was "time", no pressure drop. I saved the last used filter in a sealed container for possible "emergency" use in the future, it was that clean. I always carry a new spare in case of bad fuel and from now on will monitor for any pressure drop before next "routine" change. Good points guys . Jim G.

 

[Dane]

I change mine every 10,000 whether it needs it or not.

 

[tarussell]

Dane - I use to do the same thing. I changed mine every other oil change and thought I was doing great by a really good maintenance schedule -- WRONG !



I asked LSMITH in another post about low power and he responded with check the fuel filter first. In further reply's the discussion came up about my filter change frequency and he explained that there was no need.



My initial thoughts were that I change the filter so often that it does not matter, but that is wrong. If you change your filter and the very next tank is full of junk than you will go a long time on a clogged filter. By monitoring the fuel pressure drop you can tell imediatley when the clogging starts.



I got a second gauge to go pre filter and I am really on top of good maintenance now . LSMITH has a damn good point; Ya'll listen up - it's all about catching the dirty filter as soon as it is needed and not throwing out a perfectly good filter.



Thomas

 

[RO'neal]

THIS is why I love the TDR!

Had I already installed a second gauge this could have very well answered my questions to my current FP problems. GOOD INFO!

 

[illflem]

Possibly the record

One member reported 63k on a filter before it clogged.

It all depends on where you get your fuel.

 

[RustyJC]

I run a Westach 2DC3-201 dual combo fuel pressure gauge. It looks just like their dual combo EGT/boost gauge and allows me to monitor pre-filter and post-filter fuel pressure continuously.



Rusty

 

[Gary - K7GLD]

"Today was the third time I went out and checked my fuel pressure, pre and post filter with a temporary gauge I use, and found a drastic change in pressures from the last check. Normally I check it every 2500-3500 miles. "



Just a personal viewpoint and observation - but one that's pretty well substantiated by the rest of the above post, and others in this thread:



Relying only upon an EXTERNAL fuel pressure guage, used infrequently and kept in some distant storage location, is much like keep a gun for home protection locked down in the basement - or keeping a spare tire out in a shed in the backyard - NEITHER of them are likely to be of much real use or value when they're REALLY needed!

 

[John Berger]

The only downside to this otherwise great thread is dealers and warranty issues. I wouldn't want to go to a dealer with a VP44 on the fritz and tell them that I change the fuel filter every 25 or 30 thousand miles. I'm in agreement with this thread. I monitor pre and post filter pressure and I've went as high as 18K on a filter with no restriction. I never thought to go further with that filter.



FWIW

 

[LSMITH]

Gary, I would assume that you are picking on a gauge and not pump as you typed. A full time gauge is the best option, obviously. No one will argue that, and it was included in the original post. The point was fuel filter change intervals are not set by time or mileage, and the post was intended to illustrate why.





Also the first post should have read that it was the third check on that particular filter, not the third time fuel pressure had been checked. I think most guys knew that... ...

 

[Gary - K7GLD]

Thanks for catching that Greg - dancing fingers and crawling mind...



I primarily wanted to make that point for a few guys who either NEVER check fuel pressure - or rely on infrequent checks with outboard guages, assuming that is all the "protection" they really need. Those of us who have been around a bit longer, and are more respectful of the VP-44's weakne$$es already know better!

 

[Bob Wagner]

when

did howard (Lsmith) change his name to greg

 

[plongson]

Which is which???

On a '99, can you get "Pre" and "Post" from the top of the filter canister (the 1/8" NPT ports)? I am getting good FP from one but have not tried the other. If "Pre" and "POST" ARE possible, which is which, looking down from the top???

 

[jwinnie]

Does this mean I should change my Oil Filter the same way If I had gauges for pre/post OIL pressure?

 

[Gary - K7GLD]

"Does this mean I should change my Oil Filter the same way If I had gauges for pre/post OIL pressure?"









There's grounds for lengthy discussion on THAT issue!:-{}



Personally, *I* prefer monitoring fuel pressure right at the VP-44 - after all, THAT'S the critical area... Once "normal" system system psi has been determined under varous conditions, continued monitoring will pretty much reveal any deviations from those normal operating conditions. If fuel pressure is seen to drop, either slowly over time, or suddenly, it becomes pretty obvious SOMETHING in the system is developing or has developed a problem, and proper checks can be performed to determine what's happening. Sure, multiple test points are nice, and iceing on the cake - but the VP-44 remains the critical point in the fuel system as far as PSI is concerned...

 

[LSMITH]

Re: Which is which???

Originally posted by plongson

On a '99, can you get "Pre" and "Post" from the top of the filter canister (the 1/8" NPT ports)? I am getting good FP from one but have not tried the other. If "Pre" and "POST" ARE possible, which is which, looking down from the top???

The one closest to the center is post filter.

 

[johnrv4]

Name change?

did howard (Lsmith) change his name to greg

I want to know when he changed it from Lamar to Howard:-laf :-laf :-laf