| Author | Message | ||
     Brad Clinch Frequent User Username: brad_clinch Post Number: 14 Registered: 11-2004 |
Hi, Does anyone know the fuel quantity sender impedance for a UK delivered SS II? Advice greatly appreciated as I am going gas (actually dual-fuel) and wish to connect the existing fuel gauge to the gas tank via a change-over relay. Thank you. Regards, Brad C | ||
| Brad Clinch Frequent User Username: brad_clinch Post Number: 16 Registered: 11-2004 |
Would anyone please advise the fuel quantity sender impedances? E-1/2-F please. | ||
| Robert Wort Grand Master Username: robert_wort Post Number: 132 Registered: 12-2004 |
Unfortunately Brad, I'm not qualified to answer your question and it seems that no-one else has noticed your thread. If you go to the contact utility and connect to Bill Coburn or Robert Chapman, Hopefully they may be able to help you. Good luck Brad. | ||
| Marek Pruszynski New User Username: marek Post Number: 5 Registered: 8-2004 |
Brad I have a new, unused RHD sender that I'll measure for you, just my meter's "kaput" at present. Bear with me until the weekend and I should have it for you then. Marek | ||
| Brad Clinch Frequent User Username: brad_clinch Post Number: 17 Registered: 11-2004 |
Thank you Robert, It seems there have been some changes to this site, which appears to have made all my shortcuts to various topics inoperative. And the forum in general seems to have gone rather quiet. The contact utilities doesn't list either Bill Coburn or Robert Chapman, and the User list shows all contacts as hidden... even my own which I allowed be available. I shall find a post with comments by both Bill Coburn and Robert Chapman to see if I can contact them that way. Alternatively I may email David Gore or dig out Robert's contact details which I should have at home. 'Bye. | ||
| Brad Clinch Frequent User Username: brad_clinch Post Number: 18 Registered: 11-2004 |
Thank you Marek, When I read Robert's posting above I found his post to be the only response visible at the time, hence not commenting in my last posting. I appreciate your offer to measure the sender and will be interested in knowing the result. Thanks again. Brad | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 613 Registered: 4-2003 |
I have just picked up that the earlier postwar cars have a sender with a range of 0-80 Ohms, roughly linear, but at half full that's 40 Ohms. Empty is = ohms, full is 80 Ohms. I'll bet yours is the same as these things don't usually change from model to model or even make to make. I need to do some maintenance work on my Turbo R over the weekend. If I have a chance I'll check the sender impedance to confirm the figure (the Fluke meter is already in the boot). RT. | ||
| Gordon Norris Frequent User Username: crewes_missile Post Number: 57 Registered: 2-2005 |
Richard, and Brad, Have my backboard out to check some wiring. Just measured my Turbo R sender in-situ(Chassis 31130)-With about a third of a tankful it is 122ohms, so continuity with the the earlier post-war car impedances looks not to be unfortunately...to be safe better wait till Marek or someone measures a Shadow sender. Kind regards, GN. | ||
| Marek Pruszynski New User Username: marek Post Number: 6 Registered: 8-2004 |
Hello Brad, Sorry about the delay: Measuring a new RH2720 (was UR19863) tank sender (marked "other than N. America" on the box), which I intended to fit on one of my ex-UK RHD SSII's (eventually), I got: Full: 40 Ohms Half (about): 150 Ohms Empty 280 Ohms Now bear in mind these are + or - a little as I made the big mistake of buying a digital multimeter...the thing varies up and down some, I'll try and borrow my friend's "normal" multimeter, and if the values are substantially different, or you find there's a problem with the values I've supplied, we can get together on that. Hope it helps. Good luck! Marek | ||
| Bill Coburn Grand Master Username: bill_coburn Post Number: 355 Registered: 4-2003 |
For Brad et al. If you want to contact any registered user, go to utilities/User List/name/profile and there is an invitation to contact anyone on the list! | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 622 Registered: 4-2003 |
It seems that I was completely wrong about the sensor: sorry !! They clearly changed to an ISO system for the silver Shadow, but forgot to change the schematics from the Silver Cloud. Below is attached the schematic for a Silver Shadow and Silver Spirit. It clearly shows the minimum impedance when empty. Note that the low fuel terminal is at the minimum impedance end of the sensor winding in the schematic. I assumed that the schematic was correct and the system identical to the ones on earlier cars. Marek’s figures do not comply with the schematics, but I am sure that the schematics are wrong. If you remove the sender wire, the gauge reads zero. If you earth the wire it goes off scale. This confirms the error to me. The apparent schematic error was carried over from the Silver Shadow right through to the end of the SZ series ! The components of all these cars are the same system. The gauge is a VDO. VDO supply two ISO systems, and they are used on many makes of car, Rolls-Royce included. The first must be the type Marek measured: 33 Ohms when full, 240 ohms when empty. This is the most common characteristic used on passenger cars. 2 1/16" Type 301-505, 240-33 Ohms. 12V, with ISO symbol. This lines up well with Marek's measurements, so I suggest that they are correct as I have stated above (240-33 Ohms). This does not line up with the vehicle schematics, which show the minimum impedance is when empty. The second type has 0 Ohms when full, and 90 Ohms when empty: 2 1/16" Type: 301-509, 90-0 Ohms. 12V. One curious thing: I measured the oil sender on my car just then. With the oil maybe ½ Litre from full, the impedance is 12 Ohms. Curious. That sounds more like the latter type of characteristic. I can’t confirm the fuel sender type for sure until I measure it for fun when the weather improves. Marek, what is the part number of your sender, and is it definitely for a Rolls-Royce ? RT.  | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 623 Registered: 4-2003 |
Below are some standard fuel level sender characteristics. The first number is ohms at empty. Note that R-R switched from the GM 0-90 system apparently to the ISO 240-33 for the Silver Shadow. 0 - 30 Ohms, Early GM 0 - 90 Ohms, GM 10 - 180 Ohm VDO 240 - 33 Ohm VDO ISO, 75 - 10 Ohms, Late Ford 90-0 Ohm Tube Type Senders for Adjustable Gauges - VDO 240 - 33 Ohm Tube Type Senders - ISSPRO VW Beetle (except 1300 and Super Beetle) | ||
| Marek Pruszynski New User Username: marek Post Number: 7 Registered: 8-2004 |
Hello Richard, I listed the part number(s) in the posting, RH2720 (was previously UR19863), according to the RR box. I had purchased it to cure a "sticky" sender, but had not got round to it yet. I will remove the old (original) sender one day early this week from SRH30726 and measure that, comparing the figures to the identical looking new one and post the results for you. Marek | ||
| Brad Clinch Frequent User Username: brad_clinch Post Number: 20 Registered: 11-2004 |
Hi everyone, Thanks for all the input. It is most appreciated. It seems that everyone generally agrees that the sender is 240 to 33 ohms (E to F). Unfortunately I don't currently have access to a 'decade box' for instrument calibration so wasn't able to test for the values myself. Nor do I have the time to build one. I was intending prior to last weekend to improvise (but other commitments took precedence), by buying 1 x 100 + 1 x 200 ohm potentiometers (dual-gang if available - with 2 mechanically linked, but electrically separated / insulated windings) which would give a range of 0 - 300 ohms (x 2) by wiring one winding from the 100 ohm pot in series with one winding of the 200 ohm pot, and the other winding from 100 ohm pot in series with the other winding of the 200 ohm pot (as I said, that's if dual gang pots are available in this resistance range). The advantage in using 1 x 100 + 1 x 200 ohm pots I thought would enable a range to 300 ohms, but have a combined adjustable arc of about 540 degrees (the 100 ohms being over 270 degrees for even better sensitivity), compared to 270 degrees of a single 500 ohm pot, making the resulting testing method far less sensitive. I think the next commonly size up from 200 ohms is 500 ohms, which I anticipate would be somewhat overly sensitive. I considered that an advantage could also be gained in using dual-gang pots, as (after checking that both windings read the same values over the range) I could then substitute the fuel sender across one 'set' of pots, and connect a multimeter across the other. (I too would use a Fluke... pretty old now, but still an excellent meter) Therefore, while adjusting for any reading on the fuel gauge, I could simultaneously take the resistance measurement. But it seems that I will not now need do this. I have now sent an enquiry to APA Industries to see if they can supply a sender to suit. And I shall make a note of my findings on this forum thread for the future benefit of all. Regards, Brad C | ||
| Brad Clinch Frequent User Username: brad_clinch Post Number: 21 Registered: 11-2004 |
Just got the response from APA: "The closest we have is 282 - 40 ( empty - full ) This would give you inaccurate readings at empty. These can be suppplied by Mega gas. Regards Steve c/o APA" |
