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Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

I have been working on the fuel system and suspect a faulty fuel pump check valve. The external pump is a bosch 0580254984. Here is what is between the pump and the hose.

Is this where the check valve is suppose to go? I was very careful taking it apart as I thought there would be a spring and ball inside but nothing. Is the check valve down in the long hex part of the pump? Am I looking in the wrong place for the check valve?

I bet smoothie would have a photo of it but his photos have migrated to some new server and I could not access.

Shawn
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1980 931
That's thirty minutes away. I'll be there in ten.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Sounds like your check valve is built into the pump. Don't know if it is rebuildable or not, but gives you a good excuse to dump the Boswch unit for Pierburg.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

I think this explains it.
http://www.connactivity.com/~kgross/FAQ/tb/tb.20.8002.html

If I understand this correctly, the original pump had an internal check valve. Replace the fitting like I have with a check valve without having to replace the pump.

Shawn
_________________
1980 931
That's thirty minutes away. I'll be there in ten.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Cool, let us know how it works out.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

I got a check valve, Bosch 1587010004 and it fits perfect. Still have issues but it does replace the original fitting.
Shawn
_________________
1980 931
That's thirty minutes away. I'll be there in ten.

johnathan1 · Joined: 08 Oct 2007 Posts: 308 Location: Downey, Ca

Can I install an external check valve on my 77 NA? Or does mine have a different type of pump?

_________________
-1977 924, 4-Spd...Gone
-1987 Toyota Supra Turbo, Pearl White, BPU, 300RWHP @ 10psi.
-1989 Mercedes-Benz 300SEL

WARNING: MAY CONTAIN TRACES OF AUDI OR VW!

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

I cant say for sure but I think it is the same. Autohauz az shows the same part number for the 78. Does the 78 have female threads on the pump or a banjo fitting?
My problem ended up being elsewhere. You should replace the pressure regulator o ring the Ozzie mentioned in the other post. I think thats where my problem was. I did the warm up regulator at the same time, could have been there.

Shawn
_________________
1980 931
That's thirty minutes away. I'll be there in ten.

johnathan1 · Joined: 08 Oct 2007 Posts: 308 Location: Downey, Ca

Ok thanks. Do you have a part number for that o-ring, or know what size it is? Is there any special material it should be made out of?

And do you mean you replaced the warm up regulator completely?
_________________
-1977 924, 4-Spd...Gone
-1987 Toyota Supra Turbo, Pearl White, BPU, 300RWHP @ 10psi.
-1989 Mercedes-Benz 300SEL

WARNING: MAY CONTAIN TRACES OF AUDI OR VW!

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

I dont have a number for your oring, mine is a little different setup and I dont know if the early NA is the same. Mine used an industry number 008 and 011.
A Buna-nitrile oring will stand up to fuel. I used a Duro 70 (hardness) and it seems to be holding up fine.
I did replace my WUR as it had a broken spring inside. As I was waiting for my WUR, I replaced the orings in the pressure regulator. Not sure which fixed it but it's fixed.

Shawn
_________________
1980 931
That's thirty minutes away. I'll be there in ten.