Bosch fuel pumps

[speedo]

I have a noisy fuel pump (getting noisier) in my 74 911. I have a few Bosch pumps in my box that look to be CIS pumps. I am curious if these will be adequate for a 74, but also interested in a (link for) Bosch spreadsheet for fuel pump applications. These are the operational pumps I have.
580 254 992
580 254 991
580 254 984
580 464 021
Thanks for your help and stay healthy.

[dap930]

The 984 pump was used on 911's up through 1980. It has a check valve built into the nose of the pump. It requires a 10mm banjo bolt, seal washers and a 10mm banjo hose fitting. The stock 1974 pump had a 10mm (I think) side discharge banjo fitting(that has a ball check inside) on the side of the pump body. If you still have this, I am not sure how much adaptation will be needed to fit the newer pump. The '74 pump had an electrical plug connector that plugged into the pump. The newer pumps have separate electrical ring terminals that bolt to the pump.

[dap930]

One correction, the 984 pump does not need a banjo bolt, it needs a 10mm cap that screws onto the nose of the pump to seal the banjo fitting to the pump.

[bkreigsr]

Just out of curiosity, do these pumps work by themselves, or do you need an additional pressure pump in the rear location like my 77 Turbo?

Bill K

[spuggy]

Originally Posted by bkreigsr

Just out of curiosity, do these pumps work by themselves, or do you need an additional pressure pump in the rear location like my 77 Turbo?

Bill K

You don't actually need a rear pump for a turbo; stock 911S pump made enough pressure/flow for CIS 78 930 transplant.

Upgraded to an 044 because I thought 230K original was noisy and wanted more headroom for bigger turbo etc - 044 just as noisy, made no difference...

[speedo]

So the noisy pump in the car is a 580 254 985. It is this type...top inlet side outlet.

This is the 984 it was suggested I use. There is no direction arrow to suggest inlet vs outlet. I am assuming fuel flow is from the left (top) to the right (bottom).

Probably won't work well sucking fuel out of the engine and returning it to the tank..
Can someone please confirm?

I also see that the chassis has the fuel pump "cradle" that is part of the left side rear sway bar mount. Should my 74 CIS be a "pusher" or a "puller". Any advantage to moving the fuel pump aft?
And is everyone in agreement that the 984 pump is "the most" correct?

[red77911s]

Fuel flow is from the right to the left

[speedo]

Oh dear...the opposite direction?

[3rd_gear_Ted]

The fuel flows through the stator, rotor and brushes into the impeller back side

[speedo]

Just found this ...
https://jenniskens.livedsl.nl/Technical/Tips/Files/Bosch%20Fuel%20pump%20crossref.pdf
And see that actually the 991 pump I have (same top entry and side exit configuration) is the pump that replaces the 985...second page, top left, down nine lines.
So rather than reconfigure the plumbing with a different version of the pump...I should just swap out the similar pump?
Question remains...should the pump be behind the tank and pushing, or up by the engine and pulling?

[BoxsterGT]

Correct me if I am wrong, but since the pressure regulation is in the Fuel Distributor, almost any CIS pump will work. For the later "Flow through" design pumps, the check valve can be swapped (10mm vs 12mm) to accommodate fitment.

They are also much lower in cost as so many of this design are made & used worldwide.

Here is a later pump in place on a 74 911.....



Speedo - No matter what pump you use, for safety reasons I hope you have done something about the White Nylon Supply and Return lines that run through the tunnel in your 74 911.

The originals do not last, they turn Brown and become hard & brittle and will often crack or split if or when disturbed. They are a huge Fire risk.

Lots of info on this 74 model here on Pelican and online.

Len

[BoxsterGT]

speedo- one more thing.... the early Flow thru pumps, like yours in 2nd photo have an extended nose. This one does not have a check valve, just a hose fitting. You will need a check valve as below.

All later ones have a short nose to accommodate a check valve. Here are the two sizes used in the 911.....



and available through our host at a reasonable cost.

Len

[speedo]

Originally Posted by BoxsterGT

Correct me if I am wrong, but since the pressure regulation is in the Fuel Distributor, almost any CIS pump will work. For the later "Flow through" design pumps, the check valve can be swapped (10mm vs 12mm) to accommodate fitment.

They are also much lower in cost as so many of this design are made & used worldwide.

Here is a later pump in place on a 74 911.....



Speedo - No matter what pump you use, for safety reasons I hope you have done something about the White Nylon Supply and Return lines that run through the tunnel in your 74 911.

The originals do not last, they turn Brown and become hard & brittle and will often crack or split if or when disturbed. They are a huge Fire risk.

Lots of info on this 74 model here on Pelican and online.

Len

Good points Len. I am going to replace the 985 pump with the 991 as it appears to be a direct replacement, so I don't need to worry about a check valve. Replacing the plastic fuel lines in my son's 914 currently...and yes the lines in the engine compartment were brittle. The lines in my 74 are still stout (I do check them) probably because they stop short of the engine compartment (heat).

I am to understand that for 74 the front pump location is correct so it will stay there, all my plumbing will work, and I won't need to fuss with running any wiring.

[BoxsterGT]

My previous photo does not show the location well, but the original for the Pump on a 74 is at the rear torsion bar tube on the drivers side.

Here is another showing the rear pump location....



Locating the pump up front is best, since pumps are better pushers than pullers.

Len

[speedo]

Originally Posted by BoxsterGT

Locating the pump up front is best, since pumps are better pushers that pullers.

Len

Thanks Len,
I like the front location...so it stays : )

BTW, the pump in the picture doesn't look like my CIS pump. It has three nipples which mean it has a return line and that would make it an MFI or carbed pump?

[BoxsterGT]

Yes, this is a 72 with MFI, but it shows clearly where the rear pump is located.

If you actually have a front pump, then your fuel system has been upgraded sometime during its lifetime, and that is very desirable.

I would love to see your front system layout once back together.

Len

[al lkosmal]

Hmmmm......Doesn't look like these match your pump numbers, but maybe the reference info will be helpful, if you can find the specs for your pumps.


regards,
al

[nomore]

My 74 also has a pretty noisy pump as well. Have you checked your fuel flow
output yet? I am going to do this to get a baseline. I think a pierberg 006 is a suitable substitute also. And further, most pumps on other cars seem to be fairly quiet, my 911 pump has never been quiet. good luck, John.

[speedo]

Len,
So what does the hose fitting look like that goes over the check valve. I can't find it on the PP site.
I have pumps with the check valve but no fittings?

[BoxsterGT]

The fitting is a Banjo, and it comes with a Cap Nut and (2) Copper Crush Rings....






This one is used on the 74 w "Flow-Thru" Rear Pump in photo of my post #11 above.....


Len