| Author | Message | ||
     David Howard Unregistered guest Posted From: user-514c5949.l3.c5.dsl.pol.co.uk |
Dear Sirs purchased my non running,non braking rusty Shadow 1973 SRH 14936 five years ago,now been on the road and with M.O.T.for the past 2years still lots of little jobs to do,one of those was to replace the top S.U.float chamber gaskets which were weeping slightly.Job done but now the car will only run correctly(as before)when the fuel weakner hose is disconnected from the float chamber lid connection.When it is connected after a few minutes the car starts backfiring thru the carb inlets and dies when I try to rev it.I know that the weakner device works by putting a vacumn into the float chamberI have found some sort of electrical switch in the weakner plumbing close to the bulkhead I presume it is temperature controlled to switch the system on and off.Any pointers to sort this problem gratefully received. I am assuming that replacing the gaskets returned the system to being air tight which with leaking gaskets will be the first time since I have owned the car (Message approved by david_gore) | ||
| bob uk Unregistered guest Posted From: brig-cache-4.server.ntli.net |
The fuel weakening device is AS FAR AS I AM AWARE only meant to work when the engine is turned off at the igniton to stop running on. It does not AS FAR AS I AM AWARE adjust the mixture or have anything to do with the choke and engine warm up. The idea is that the vacuum from the mainfold is applied to the top of the float bowl thus not allowing the carb to deliver fuel and stopping the engine, which you have found does work. The device should only do this when the ignition is turn off. The wires from the device should be earth and the other only live when the ignition is on. you mention MOT. This device is not an MOT requirement. ( in the UK that is ) So providing the car does not run on then the device can be left allowing the top of the float bowl exposed to atmospheric pressure all the time. My car is 1974 SRH 17768 and has no such device. Bill Coburn has kindly issued the workshop manual in PDF form in the technical section of this forum . If you refer to that it will give the low down on the device. (Message approved by david_gore) | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 725 Registered: 4-2003 |
David as Bob suggests have a look at section K4 of the Shadow 1 manual in the library of this site. I assume you are in the UK and reading the text this device (the weakening one) was fitted to your cars. But Service Bulletins also suggest it was fitted to PVI and the one in my care certainly doesn't have it. The most likely problem I have found with these systems is a leaking solenoid valve. But whether you have the two usually involved ie the weakener and the anti-run on I wouldn't know. The engine will run perfectly with it disconnected so I wouldn't worry until you have figured out what you are supposed to have and what you have got. | ||
| David Howard Unregistered guest Posted From: user-514c5949.l3.c5.dsl.pol.co.uk |
Bob and Bill Thanks for your prompt replies,infact the fuel weakner system should give a vacuumn of about 3 inches of water when switched on it is controlled by a solenoid which is triggered by the otter switch in the choke flap mounting.Tho solenoid should open at 61 fahrenheight when triggered this gives the vacuum to weaken the mixture when the engine is warm.The antirun on system is different this solenoid when activated gives full manifold vacummn to the float chambers to weaken the mixture in a massive way to stop run on just as the ignition is switched off(I dont have one of these )The above is my understanding of the two systems.Please could anybody comment! (Message approved by david_gore) |
