[Gilo]

82 spirit
Hi folks, had my fuel pump go bye byes on me, cant afford new one so have been a bit inventive!
X2 pumps in parallel to double flow rate to 180 lph (ish) whilst keeping psi at 4-7.

Am i a fool or a genius???
Total cost £43 instead of £264 for a "facet".
Thoughts?

 

[guyslp]

If it works, and you're happy with it, then document it for others!

The Bosch originals are up over $200 on US sites, and even higher on UK sites. If it performs the needed function, and you are not someone who is a stickler for originality, then go for it.

 

[Gilo]

Fitting tomorrow, I'll post result.

 

[Gilo]

The origials pump was a "pierburg" and is no longer made.
In uk Flying spares and introcars sell a "facet" pump with the same spec.
(Fyi that is 190 Litres per hour (43 gals) and 6-8 psi)
so very high flow rate and very low pressure. This makes them a difficult/ pricey pump to replace. I had a bit of trouble finding that spec. So i hope that hrlps someone one day.

 

[Wraithman]

You will have much better output flow if you double the output size, otherwise the flow is constrictive at the neck.

 

[Gilo]

I did think that was a possibility tbh, would i have to run a whole new fatter line back to carbs?
I ndid toy with the idea of one pump feeding each carb separately but thought id just give this a whirl first. Ive seen lots of your posts and comments on various forums and totally respect your opinion though.

 

[Jim Walters]

Yes, just start typing your post in the dialogue box below the last post where it says "Write your reply" in the top left hand corner.

 

[Gilo]

Would you happen to know the colours of wires which is live and neutral at the pump by any chance?

 

[Jim Walters]

Wiring diagrams are at www.rrtechnical.info, click on "Technical Service Documents 005 Silver Spirit etc" then "05-02 Workshop manual 1980 - 86 TSD 4400" then "complete wiring diagrams in colour", then one of the blue links.

 

[Gilo]

Great, thank you very much.

 

[Gilo]

Please excuse my ignorance but i cant make head nor tail of that wiring diagram, i found the fuel pump (at 31, attached) but still have no clue as to what colour the wires are that serve the pump. Is black generally the neutral in the loom for all things?

 

[guyslp]

The origials pump was a "pierburg" and is no longer made.

I covered this, too, in the RR & Bentley Parts, Repair, Restoration & Other Resources Compilation.

Search for Substitute for Dual SU or Pierburg rotary vane fuel pump.

 

[Gilo]

Right, i think i've got it, the + & - should be embossed on the terminals and the + should be white/pink,
- should be earth braid or black as far as i can make out from the workshop manual.
Thank you so much for that link i never knew such a thing existed.
I'll update tomorrow as to if im successfully back on the road.
Cheers, G.

Amazing resource guyslp thankyou. Using the specific FACET model no. You gave me i have found one for £121 which, if my bodge is a failiure, i can purchase saving a cool £143.
I love this forum already.

 

[Michael_j_brown]

Is your carbureted? if so, the Facet pump did not work for me. Here is a link to a YouTube video I made illustrating the issue I had with that pump on on a Shadow II.

After this happened, I spoke with a 40 year Rolls master mechanic that says this is common. This is the pump that he fits to carbureted cars:

https://www.summitracing.com/parts/sum-g3136-1

I am switching out the pump today for this new one and I will report back my findings. If your car is fuel injected, this is not the correct pump.

 

[Gilo]

Hi thanks, i have twin su's normally carbed.
I fitted "Frankenpumps" car wouldnt start and pumps didnt shut off as they should when full of fuel, not sure if i have another problem too but either way the car wont start.
Look forward to hearing if your fix wotks.
Thanks G

 

[Michael_j_brown]

My Shadow II has the same twin SU carbs. That is not surprising as the car is very finicky when it comes to flow rate. I tested a variety of pumps from Facet and Holly on this car and none of them work well. Now to be clear, the FSM has specific requirements for flow and lift and all the pumps I tested met or exceeded the FSM requirements for the car yet none of them worked well when fitted to the car. I actually setup a test rig outside of the car where I tested lift and flow. The interesting thing is, this Facet Gold Flow was the worst performing pump of all the ones I tested yet is seems to be the one that's being sold as a replacement.

The Holly pumps worked well at low loads but fail at about 50MPH under load. Rolls-Royce changed the placement and style of the pumps in 77 it appears (at least for American market cars)

 

[Gilo]

Very interesting.
Shame we cant get the correct pierburg pumps anymore.

 

[guyslp]

You need to realize that, depending on delivery market, the SY2 series cars had either the classic SU pump or the Pierburg Rotary Vane pump.

The whole system is different for the Pierburg setup because the Pierburg never turns off like the SU pump does once there is back pressure. In the fuel system that uses the Pierburg, there is a direct return to the fuel tank so that when the floats close off the carbs, the fuel just diverts straight back to whence it came.

In the SU based systems, once the floats close the fuel flow to the carbs, back pressure builds and once it's sufficient, the SU pump "pauses" until the valves open again and the inflow of the existing pressurized fuel reduces the back pressure enough for them to begin pumping again. Lather, rinse, repeat.

You cannot use continuous flow pumps in anything but the Pierburg equipped cars unless you were to modify the system to have a direct return to the fuel tank.

I hadn't thought of that when this topic started and presumed that the car being discussed started out with a Pierburg pump. If you put any sort of a continuous flow pump in a classic SU pump configured system the outcome will not be good.

I have one car, SRH33576, that's a European spec classic SU fuel system and another, LRK37110, a US spec Pierburg rotary vane system with direct return to the fuel tank.

 

[Michael_j_brown]

You need to realize that, depending on delivery market, the SY2 series cars had either the classic SU pump or the Pierburg Rotary Vane pump.

The whole system is different for the Pierburg setup because the Pierburg never turns off like the SU pump does once there is back pressure. In the fuel system that uses the Pierburg, there is a direct return to the fuel tank so that when the floats close off the carbs, the fuel just diverts straight back to whence it came.

In the SU based systems, once the floats close the fuel flow to the carbs, back pressure builds and once it's sufficient, the SU pump "pauses" until the valves open again and the inflow of the existing pressurized fuel reduces the back pressure enough for them to begin pumping again. Lather, rinse, repeat.

You cannot use continuous flow pumps in anything but the Pierburg equipped cars unless you were to modify the system to have a direct return to the fuel tank.

I hadn't thought of that when this topic started and presumed that the car being discussed started out with a Pierburg pump. If you put any sort of a continuous flow pump in a classic SU pump configured system the outcome will not be good.

I have one car, SRH33576, that's a European spec classic SU fuel system and another, LRK37110, a US spec Pierburg rotary vane system with direct return to the fuel tank.

This is the case with my car which started out with the Pierburg pump.


Moderator note: Michael, please take a few minutes to read through "Instructions for navigating the site" and "How to reply to a discussion thread"in the FAQ section, link here:FAQ There are other topics there that you may find informative. Please note also that it is not necessary to quote a previous post in your reply if you are following the train of thought in the thread, it just clutters up the thread unnecessarily. Simply start typing your reply in the dialogue box below the last post where it says "write your reply" , do not click on "reply" (which adds the previous post as a quote) unless it is absolutely necessary to maintain continuity in the thread. Thanks, Jim.

 

[guyslp]

This is the case with my car which started out with the Pierburg pump.

I'm not quite sure what you mean by "this is the case." But all of the cars that began life with a Pierburg rotary vane pump had a fuel system set up with a direct return when the carbs cut off fuel because they had to.

My question about that Summit Racing pump is whether it's one that will "pause" in response to back pressure, in which case it could be used in either an SU pump or Pierburg pump system, or if it is continuous pumping only, in which case it's only suitable for a system that originally used a Pierburg pump (unless you want to engineer a return loop, which most people probably wouldn't).