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Old 01-17-2025, 09:31 PM   #1
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What is the name of the fuel filter inlet fitting?

What is the name of the fitting used on the inlet of the Workhorse fuel filter?


For an external fuel pump, it is necessary to use the fitting at the fuel filter inlet on a 2004 workhorse W22.
The story:
I just replaced an operating but externally leaking fuel pump on my own. By inspecting the original fuel pump, it was observed that the pressure regulator is actually a pressure relief valve at the end of the fuel return piping in the base of the fuel pump enclosure. This explained the squirting through a pin-hole leak on the return line fitting. Furthermore, it is possible to install a secondary fuel pump in front of the fuel filter inlet and take advantage of the pressure relief valve to regulate the fuel pressure just like always. This secondary fuel pump can be wired in parallel with the existing one and activated with a switch whenever the original pump in the tank supplies insufficient pressure. I have done this on a prior 2003 P32 model (180,000mi & still OK), that has the pressure regulator modulated by the intake manifold vacuum at the fuel rails on the engine, and it saved me from lowering the tank a second time.
I had to lower the tank on the present 2003 W22 for an external leak at the fuel pump. It developed a pinhole leak on the plastic return fitting on top of the pump. A very sharp turn over a dirt embankment caused the dirt to scrape and push against the bottom of the tank, that temporarily deformed the bottom and pushed the fuel pump upwards. The sudden stresses on the plastic fittings caused the center return plastic piping to crack and resulted in a pinhole leak.
The name or type of fitting at the fuel filter inlet is of interest to me.
Thanks
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Old 01-18-2025, 11:23 AM   #2
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I'm a little confused , as I thought the " T " fitting on the furl filter was on the outlet ( engine side ) .

First picture is the OEM ( obsolete ) filter with " T " as part of the assembly .

Second picture is the replacement filter with " T " separate.
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Old 01-18-2025, 11:29 AM   #3
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Is your current leak on top of the tank ?

Are you sure it's the fuel line fitting that's leaking and not the elbows on the pump itself ?

EDIT : Picture of a bare chassis fuel tank shows ; fuel pressure and return are metal fitting and the emission evap line as a plastic fitting
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Old 01-19-2025, 09:46 AM   #4
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Quote:
Originally Posted by Skip426 View Post
I'm a little confused , as I thought the " T " fitting on the furl filter was on the outlet ( engine side ) .

First picture is the OEM ( obsolete ) filter with " T " as part of the assembly .

Second picture is the replacement filter with " T " separate.

Hi Skip426
Thanks for your reply.
The separate T fitting has already been installed by the prior owner. On the outlet, one line goes to the engine, the other to the pressure relief regulator in the bottom of the fuel pump assembly.
My intention is to install a secondary in-line fuel pump between the inlet to the filter and the inlet line and let the existing pressure relief regulator regulate the pressure as is done normally. In order to do so, it is necessary to identify by name the fitting used between the line and the filter. This will allow for proper plumbing. It looks like nothing I have seen in prior non-fuel fittings.
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Old 01-19-2025, 09:59 AM   #5
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Quote:
Originally Posted by Skip426 View Post
Is your current leak on top of the tank ?

Are you sure it's the fuel line fitting that's leaking and not the elbows on the pump itself ?

EDIT : Picture of a bare chassis fuel tank shows ; fuel pressure and return are metal fitting and the emission evap line as a plastic fitting

Hi again, Skip426.
Thanks for the excellent pictures.

The leak has been repaired by replacing the entire fuel pump. It was brought on by a slow driving mishap. The bottom of the fuel tank was pushed up by a dirt mound that I failed to avoid. I could feel it, and only inertia got the RV over it. It was bad and stupid of me to even try it. Since the fuel pump comes to rests on the bottom of the tank, by pushing up, the top of it was also disturbed. This caused a micro-crack in the plastic fitting of the fuel
pump. Since the return line is under full manifold delivery pressure, a very tiny leak developed. It could not be seen anywhere until the tank was lowered. It resulted in a hideous-gasoline smell in the bedroom above.


This is a background story. What I really need is to identify the name of the fitting used on the filter inlet.
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Old 01-19-2025, 01:23 PM   #6
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They are called an inverted flare.
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Old 01-20-2025, 09:13 AM   #7
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Hi David 70
Thanks for your insight. I would have never figured it out without your help.
I have made similar joints using copper tubing for propane distribution in my house.
Now I must search for the proper tooling and coupling pieces. Any suggestions are welcomed.

Thanks again for your help.
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Old 01-20-2025, 10:08 AM   #8
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You'll just have to get the correct size inverted flare nuts. Cut the tubing with a tubing cutter, slide the nuts on and use your flaring tool to make the flared ends.

If you Google Omie's Workhorse DIY pages, he did a good job of showing how to do just what you are thinking of.
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Old 01-20-2025, 10:19 AM   #9
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There's also a YouTube video by Kevin Caudill doing this.


Search Electric fuel pump bypass kit W20 W22 W24
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Old 01-20-2025, 07:02 PM   #10
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Quote:
Originally Posted by David 70 View Post
They are called an inverted flare.

Hi David 70
I visually reexamined the fuel filter fittings and could not discern a 45-degree surface as required by the inverted V type fittings.

Unexpectably, I just received an explanation of the fitting from the person that runs Workhorseparts.com .

The fuel filter female fittings are not inverted flares, which is of course the accepted coupling for fuel lines, but a GM designed O ring fitting requiring a male mate as depicted below along with an end view of the fuel filter.



So what I need now is a male and female of this special O ring based variation that I can attach to the tube. Close examination of the drawing may show a slight inverted flare to retain the O ring fitting.
Thanks again.

Any help is appreciated.
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Old 01-20-2025, 07:32 PM   #11
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Do you still have the original Workhorse fuel filter? Or do you have the replacement fitting from Ultra RV? I have the replacement parts, but I have not used them yet, so I don't know what they have for fittings. I have seen the O-ring type of fittings before. I believe they use them in those high pressure lines in order to get a tighter seal.
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Old 01-21-2025, 03:23 AM   #12
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Hi David 70

My Chassis already has the replacement that you have. It looks great and fits like a glove.


My quest is to obtain the proper fittings for installing an auxiliary, or stand-by, fuel pump between the filter inlet and the supply tubing.


I had done this on my prior 2003 p32 chassis, but it was a batched up installation hurriedly done as a result of low pressure from the in-tank fuel pump. I had to use another filter along with the existing one to get fitting continuity. Nevertheless, it took me to 180,000 miles and beyond when I sold it. The whining of the fuel pump was always audible when standing outside.


This time I am trying to do a neat installation.
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Old 01-21-2025, 08:35 AM   #13
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I looked on the internet some and I haven't been able to find those kinds of fittings. That's probably because they are not a DIY type of thing. You may have to cut into the line and use the push-to-connect fittings. If you look in McMaster Carr, they have several different types of them. At just 60 lbs. of pressure, I don't see why they wouldn't work as long as you make sure they are connected all the way. Those push type fittings are used on the air lines on trucks and they run 125+ lbs. Just get ones for steel lines.
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Old 01-22-2025, 10:00 AM   #14
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Hi David 70
Thanks for your continued interest.
I found a local independent (old fashion) automotive parts store that has been in business over 50 years. They had a store section on fuel lines. I found a match. It turns out that DORMAN makes fittings that have an exact fit and a spare O ring:
DORMAN 800-233.
800-240
800-157
800-160
Available from AMAZON.

The Quest is over. I can now do the fuel line plumbing.
Thanks for all responses. This will conclude my inquiry.

Bye
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