1983 RR Silver Spur , Crank no Start - Rolls-Royce and Bentley Forums
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post #1 of 32 (permalink) Old 05-10-2017, 05:45 PM Thread Starter
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1983 RR Silver Spur , Crank no Start

Hi forum , I am new here and this is my first post. I am a DIY Mechanic and I have a 1983 RR Silver Spur with the Twin SU HIF 7 Carbs. The car had sputtering issues when purchased 9 years ago, since then and after multiple experiences with bad mechanics and garages ,, the car has been parked and not worked on much until July 2016 , when I actually started to work on it and I managed to start it after replacing a bunch of stuff ,, ofcourse I cranked it a few times before it finally started , but when I pressed on the pedal the engine died ,,
things done after the 9 years :
-carbs rebuilt using the kits from FS,,and SU sites
-Spark plugs replaced
-spark plug wires replaced
-fuel pump replaced
so the issue I am having now is the engine cranks but it wont start ,, as if the fuel is not being sprayed out of the jets ,, when I poor some fuel into the carbs directly and then put the dash pots back , the car almost starts ,, I am confused as to what I have done wrong ,, maybe vacuum lines or something that I have missed ,, maybe something is wrong with the electric choke ,, ,, am I supposed to see fuel come out of the jets with the engine off and key on position or the fuel only sprays out of the jets with the cranking depression ,, and if so how do I check if that is even happening and I dont have a vacuum leak somewhere ,, any help would be appreciate it.
The Full VIN number is : *SCAZS0000CCX06574*

Thank you in advance.
Marc
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post #2 of 32 (permalink) Old 05-10-2017, 05:56 PM Thread Starter
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Hi Paul to answer your question , I will try tomorrow to check for the presence of fuel in the carbs with the key on and fuel pump running and someone pressing on the gas pedal.., the carbs are definitely still clean as I have rebuilt them in Jan this year ,,the fuel is is going in and back out returning to the tank in mycase I am not using the return line yet and having the fuel fill a 25 liter gallon when it comes back out from the carbs' line.. The fuel filter looked clean and its just the one that I saw which is under the car on the right side between the two doors roughly,, I tried to block the returned fuel hose with my thumb to see if fuel will come out of the jets or the breather filter next to the radiator overflow tank but nothing came out of there and no fuel in the carbs,,,
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post #3 of 32 (permalink) Old 05-10-2017, 09:31 PM
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There's a small filter at the end of the inlet pipe to each carb, there are two screws holding the lid down at the top of these filter housings. Maybe these filters are blocked but it sounds to me as though the float needles may be stuck closed so no fuel is entering the float chambers. I think that fuel is sucked out of the jets by cranking vacuum and should not come out when the engine is stopped. You could try removing the inlet pipes and spraying some carb cleaner in which might unstick the float needles but more than likely the carbs will need to be removed and the float needles inspected and possibly the float settings checked. Modern ethanol based fuels seem to gum the float needles in a matter of weeks if the engine is not run. If you have very stale fuel in the tank it would not help either.
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post #4 of 32 (permalink) Old 05-11-2017, 03:45 AM
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There should be a little petrol showing in the jets, but not flowing out.

I suspect the anti-run on valve may be faulty or disconnected / incorrectly connected.

Try tapping it.

Pull off the hose that comes out of the left hand carb towards the front and left.

Regards, Paul Yorke.
EverythingRollsRoyce.com
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post #5 of 32 (permalink) Old 05-11-2017, 09:01 AM Thread Starter
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Hi all thank you for all your replies ,, so here is what I have tried so far today and I am still at the car so any new suggestions I can try right away.,

1- I took off the dash pots and took off the fuel feed hoses from the front and the one in the back of the other carb and I blew in them and sure enough fuel fountained right out of the jets ,, I did that a few times to make sure the float pot is filling up with new fuel thus the filters are not clogged.
2- I reinstalled the dash pots and I tapped on the anti run valves and attempted to start but nothing ,,,
3- I kept the hoses that feed the fuel in the carbs out and checked to see if fuel will be spitting out of there basically to see if my needle and seat are sealing the overflow of the fuel and sure enough they are ,, now I tried something further please tell me if the results are correct ,, I blocked off the fuel return hose with my thumb and it build pressure in there but no fuel came out of the fuel overflow lines at the front and at the back of the two carbs which were still out at this point,.
4- last thing I checked was the wiring for the Anti run on valves and basically my understanding was that the valves need one black and one double white lines in each one of them ,, so i wired them and as soon as I completed the circuit connection for the one closer to the front of the car I noticed a clicking sound but when I connected the one closer to the windshield I didnt hear any clicking ,, ofcourse all this with the key on position ,, and the fuel pump running ,
5- here is where it got interresting and maybe where my problem lays ,, I connected a multimeter to the connections of the Anti run on valves and sure enough the one closer to the windshield didnt show any voltage ,, but the one that clicked before showed an 11.9 voltage,, is this normal or should I get voltage on both the Anti run on valves ? what can I check for next ?


Thank you all for your help ,,
Marc

Last edited by marcsaab; 05-11-2017 at 09:04 AM.
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post #6 of 32 (permalink) Old 05-11-2017, 09:43 AM Thread Starter
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also can anyone suggest a cheaper alternative fuel filter ,, the one that goes under the car either inline or inside the original container ,, I saw it online and I think it was in the 35$ for the crosland 444 ,, any other brand that fits like a GM model fuel filter?
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post #7 of 32 (permalink) Old 05-11-2017, 05:50 PM
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Can't help at the moment regarding the anti run on valves because I don't know the answer but I'll look it up. I fitted an ordinary plastic in-line fuel filter on the flexi fuel hose in the engine bay, it cost about €3 and does the job, another advantage is that I can see it when I open the hood and see the fuel pulsating through it. I simply cut the hose and inserted the filter with jubilee clips on the hose at each end.
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post #8 of 32 (permalink) Old 05-11-2017, 06:23 PM
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I looked it up and one solenoid is anti run-on while the other is the weakening device cut off solenoid. There's a whole lot of information in the "Rolls Royce and Bentley Technical Library" kindly provided by the Australian RR Enthusiasts Club. You can download it for free and save it to your computer. You'll find it on google search engine. Chapter K deals with the H1F7 carbs and is a mine of information on fault diagnosis in easy steps. There's a diagram of where all the pipes and wires lead to and from the various components. You'll get to the bottom of this problem eventually. I wonder if the pistons are sticking in your dash pots, the dash pot covers are specifically made for each carb and matched to their relevant pistons and interchanging them can cause problems. You say that you have tried pouring petrol into the dash pots but only dashpot oil should go in there, maybe you meant that you poured petrol into the air intake.
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post #9 of 32 (permalink) Old 05-11-2017, 08:38 PM Thread Starter
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Hi Shadow , yes I meant I poured the fuel right over the jets hole after I removed the dash pot covers ,, I am sort of familiar with the technical library ,, Thank you for pointing out the chapter where I can find the info on the two valves,, I am not sure if the following would answer the pistons sticking in the dash pot covers but when I removed the dash pots and flip them upside down the pistons bounce freely due to the spring of course ..I wonder which one is the weakening device cut off solenoid and what its job is and which one is the anti run on valve and if both or just one should get the 12 V battery voltage when the key is in the on position... I will search the technical library for an answer ,, meanwhile I will try and post some pics here of what I am looking at and I also took a short video of me trying to crank and start it ,, hopefully they upload with no issues,, and thanks for the advice on the fuel filter , I guess that is a good aproach ,, I will have to eliminate the one under the car though ,, which is easy to do just leave it empty ,, my biggest hurtle right now is to get the engine started again,,
Attached Images
File Type: jpg 3_valve_with_voltage.jpg (252.5 KB, 10 views)
File Type: jpg 2_valve_with_no_voltage.jpg (211.8 KB, 8 views)
File Type: jpg 1.jpg (163.5 KB, 13 views)

Last edited by marcsaab; 05-11-2017 at 08:40 PM.
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post #10 of 32 (permalink) Old 05-12-2017, 08:26 AM Thread Starter
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So after reading section K5-11 and K5-12 about the Weakening solenoid switch and the weakening solenoid and the weakening mixter device ,, I have a few questions that aren't answered in the manual and maybe someone can explain it to me ,, they mention that the weakening switch will illuminate the test lamp when the engine is cold and the intake air temp is below 14 c.. and the lamp should extinguish if the temperature is above 14 c ,, does the ambient temperature matter at all ,, so if its 35C should I expect the test light to be extinguished?
My second question is ,, should I service and check the weakening mixture device is this something that can be causing a restriction in the vacuum and the fuel/air delivery in the intake?
when I started the car back in July I had the original Weakening switch with the air intake elbow installed on the car ,, but the switch's cap was broken off and the terminals were visible making the plug fall off,, so I decided to buy a used switch which came with the elbow and it was a model that cannot be removed i.e. didn't have the three screws and I plugged that one in . I am wondering now if the switch is malfunctioning and if so would that cause the weakening solenoid not to get power and in turn not causing a vacuum or something of that sort making the engine not start,, I am sorry just thinking out loud here ,,

p.s. I couldn't upload the video of the car's attempt to start yesterday,, is there a different way to upload video's on this forum or just pics are allowed?

Thanks
Marc
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