Fuel Pump Check Valve..........

[Sunroof]

I replaced my failed rebuilt fuel pump on my 1973.5T/CIS with a new Pierberg unit, but was not sure about a check valve. My old pump had an internal check-valve according to the manufacturer. Do "banjo" type fittings act as some type of check-valve? Everything I have seen thus far as the actual check valve requires a "banjo" attachment. I cannot locate a direct-in-line unit unless I am looking at the wrong place.

Anyone have a photo and/or source for an in-line check-valve? What am I looking for? On the CIS pump located in the rear left wheel well, would I want the in-line check valve after the tank and before the pump or after the pump before the accumulator?

Thanks
Bob
73.5T

[ossiblue]

My 73.5T had the original pump replaced by an aftermarket brand (sorry, don't know the manufacturer) and remounted on the front crossmember. The new pump has an internal checkvalve and does not use banjo fittings--you might check with the manufacturer of your pump to see if yours has a check valve internally. As far as positioning an in-line check valve, theorically it shouldn't matter however, I believe it's typically on the outflow side of the pump.

[Sunroof]

Thanks LJ.
I bought the Pierburg from our host but unlike my prior OEM Bosch pump with the banjo fitting coming off the side of the pump, this new one has the fitting coming directly out the rear. The banjo fitting from the old pump will go on the fitting on the new pump, but the banjo is not one of those check valve types. I did some research and found part 911-608-901-00, which is a banjo fitting with a built in check valve. Now its just an issue of size, end caps (for the banjo fitting) and getting it all together to mathc the hose sizes. I really answered my own question on this............

The new pump has re-vitalized performance, however, on hot start without a check valve it takes awhile for getting the injectors going.

Bob

[Jim Sims]

Banjo type containing check valve and ending in a hose barb was used only on the 1974 models. Was used as a quick fix for CIS pumps from other years with failed internal check valves. Unfortunately NLA from Porsche. Perhaps you can locate a NOS or a used one.

[Jim Sims]

See:

Fuel Distributor - Check Valve 73.5T?

When is a "check valve" not a check valve???

If adapting to the "in-line" check valves always ensure that the portion being threaded into the pump isn't so long that it bears against the the moving parts (motor armature) inside the pump and jams them. This can be an issue with the side output pumps and jamming can cause the pump to burn out.

[Sunroof]

Thanks for chiming in Jim....

In fact I went back to your old thread and found the part no. 911-608-901-00 for the banjo fitting with the built in check valve. With a bit of searching its still available and prices run up and down on this ($25 to $53) depending where you buy it. The fittings on the Pierburg pump both flow in and flow out have to retrofitted so the existing fuel hoses fit. I am not sure though what the diameter is on that banjo fitting. I believe I need 10mm. Unlike the older OEM fuel pump with the side mounted hose fitting, the Pierburg is a very snug fit on the mount as its heavily rubber coated and both hose fittings come straight out. Mounting it in the front is a consideration. With summer coming on, I dread those hot start issues.

Bob
73.5T

[Jim Sims]

On my son's 73.5T we mounted an axial flow Walbro fuel pump (with integral check valve) at the OEM rear axle location using the OEM line Banjo output fitting without issues. We also added an inexpensive NAPA fuel prefilter on the suction side without any suction head problems. The new fuel pump transformed the car's performance. Glad to read the '74 check valves are available.

[Gunter]

Originally Posted by Sunroof

Thanks LJ.
I bought the Pierburg from our host but unlike my prior OEM Bosch pump with the banjo fitting coming off the side of the pump, this new one has the fitting coming directly out the rear. The banjo fitting from the old pump will go on the fitting on the new pump, but the banjo is not one of those check valve types. I did some research and found part 911-608-901-00, which is a banjo fitting with a built in check valve. Now its just an issue of size, end caps (for the banjo fitting) and getting it all together to mathc the hose sizes. I really answered my own question on this............

The new pump has re-vitalized performance, however, on hot start without a check valve it takes awhile for getting the injectors going.

Bob

If you know the number of the new pump, Pierburg has a table with specs showing if yours has an internal check valve.

[rching]

Jim, sent you an email msg. Digging through the old posts for info! Thanks,

[Sunroof]

Not sure if the Pierburg came with an internal check valve or not and to date I have not installed any inline. If it has an internal unit it certainly sucks! After years I am used to turning the key, let the pump hum and let the darn thing energize the injectors and then spark up that flat six! I would be curious though how the mounting in the front would make a big difference, especially with the hot start issues here.

Bob
73.5T

[rching]

I called Pelican about the Pierberg and they called their source and confirmed that there is "no" check valve in that pump. I'm hoping someone has "been there, done that", so I can follow their lead. I've gotten tons of info about everything else and sources too, but not on the check valve, yet.

Thanks,

[Sunroof]

My old Bosch fuel pumps (OEM) that were replaced over the decades had built in check valves, which was unique strictly for this first CIS model (like everything else); however, I found that I still had "hot start" issues from evaporation. I am considering an inline check valve before the real hot weather is upon us. Good luck with the installation.

Bob

[BoxsterGT]

This Banjo w the check valve inside is still available from Porsche (5 in CA and 234 in Germany) and likely from our host.

If someone can post a photo & give us some thread sizes (M10x1.5 or M12x1.5, etc) I can look for fittings to mate with it.

Shouldn't be too hard to find, as I have a pretty good selection.

Len

[mspirito]

I was wondering if anyone knew whether the walbro pump has an internal check as a matter of course or is it something special?? I have on order one of these generic pumps talked about in some older posts.

[porwolf]

Walbro pumps come both with and without internal check valve. I bought one with the interanal check valve last year and it works fine. It was a direct replacement for the original Bosch OEM one with the same specs and dimensions. Check evil-bay.

[Jim Sims]

The Walbro GSL392 has an internal check valve - I currently have one installed in my 1976 911S. In my son's 73.5 911T we installed a NAPA P60424 which may have been made by Federal Mogul at the time as I recall. The GSL392 should work in either application - just make sure you have the correct fittings; for the '76 I had to obtain and add a fuel system cap nut to utilize the existing fuel line banjo (non check valve type) fitting. There are on-line vendors that offer the various fittings one may require. Jim

[Jim Sims]

If required to use an existing fuel line banjo with a stud type banjo fitting (instead of a banjo bolt) here are the dome or cap nut Porsche part nos.:
M10 x1.25 thread: 900-070-010-02
M12 x 1.5 thread: 928-110-475-04

[rching]

Here is the check valve off the stock CIS fuel pump. I can use this on the Pierberg pump, right? I just have to have a Cap nut on the end? Now there is the Walbro option, and still, the rebuilt original pump. Hmmmmm?

[rching]

Pulled this plug thinking there was a filter here but just a drain. Only other lines are supply and return. Thinking if putting a flare on these is possible.

[rching]

Tank lines and lines entering the tunnel. I think the exit from the tunnel is really tight. Can't see how it's possible to flare while it's in the car.......