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MG MGB GT V8 Factory Originals Technical - Fuel Pump
|I noticed a thread in the MGB Technical BBS about the the 'fuel pump tick' titled 'Fuel Overflowing' that has slightly worried me. I have a 1973 Factory GT V8 that was been re-built in 1999, I bought it earlier this year but I haven't driven it much due to working away. Please bear with me as I am still learing much about this car and the rover V8.|
Anyway when I put the key in position II to start the car there is an audible tick that I believe is the fuel pump, I usually leave the key in position II for a few seconds (as I was told by the dealer) to pump some fuel??. I then move the key to position III to engage the starter motor (choke is normally out when starting from cold and I return it gradually to 'off' as the engine warms up). The fuel pump tick continues and never ceases, it is barely audible once the engine has started though. Is this correct or should the tick stop after the engine has started?
|The ticking should slow and finally stop as pressure builds in the fuel system. A continuously ticking pump may mean that it has bad one way valves inside.|
|That is for the standard SU pump. All bets are off when it comes to replacement and aftermarket pumps.|
Thanks for the reply. I had it in a local old-school mechanics about 6-weeks ago for a check over. Not knowing much about the car I didn't ask him to check whether the pump noise was right, but he had it for a few hours and drove it and said most things were in reasonable order. He tightened a few things, fixed the speedo, cleaned-up the SU carburetters etc.
I am supposed to be driving to Birmingham in it tomorrow (only 100 or so miles) but I am a little worried, although I have AA cover.....
Just so you are clear about the fuel pump. It works on the back pressure created when the carbs are full. So when you switch on the key it ticks away until the carbs are full, when the back pressure causes it to stop. Actually, it will probably tick once in a while in that condition as it keeps the fuel pressure up. Once the engine starts and is using fuel it will tick regularly to keep the carbs topped up. Hope that is clear.
Time to worry is when you do not hear a tick, then out with the blunt instrument unless of course its electronic, which still tick but cannot be persuaded to work with a blunt instrument.
|...Or like my points-type did recently, which was exactly one tick for every application of said blunt instrument, even when off the car and on the bench...|
|Andy, I hope you made it to Birmingham and back last week OK. To bottom this one you will have to find out what sort of pump it is. If it is in the original location by the rear offside wheel well this is a fun task. I went through the same exercise when I got my car 3 years ago. Knowing that SU pumps ticked 'till the carbs are full and then stopped if all is well (around one tick every 5-10 secs. is normal with the engine off) I was concerned by having continual ticking. When I got the pump on the bench it turned out to be a replacement pump from a japanese manufacturer which works on a completely different principle from the SU one. Just to be sure I stripped it and apart from a little wear it seemed sound and ticks away merrily to this day.|
Thanks for that. It is in the original location I know that for sure but the car was rebuilt in 1999 and I think it isn't the original...... I will take another look and see if there are any manufacurer part no.s etc on it.
|Book says 'not more than once every 30 secs', ignition on engine off, obviously.|
This thread was discussed between 08/09/2003 and 18/09/2003
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