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Title: Lack of power under acceleration Post by: Crazypierre on December 23, 2019, 02:19:40 PM Hi, I have a 1979 1300CL with a pushrod engine with twin choke carb.
Recently, it's been struggling when I put my foot down like when pulling out of a junction. The revs are not coming up and it just won't move. Or when I'm driving and floor it, it kind of doesn't rev. It's like the engine is hesitating when I accelerate. It's not miss-firing and I can hear it is running on all 4, just doesn't want to rev. Trying to work out of it's ignition or carburration. Any thoughts? Thanks PC Title: Re: Lack of power under acceleration Post by: Thotos on December 23, 2019, 06:36:32 PM I would say the problem is most likely with fueling. More fuel and a much richer mixture of fuel and air is needed when accelerating which is why carburetors such as the ones fitted to the 131 have accelerator pumps to pump extra fuel into the engine when accelerating. With the engine off and the air filter cover removed, have a look into the top of the carburetor. While depressing the throttle there should be a steady jet of fuel seen going into the top of the carburetor from the accelerator jet. If there isn't, then either the jet is blocked or the accelerator pump diaphragm is split.
Title: Re: Lack of power under acceleration Post by: Crazypierre on December 23, 2019, 07:37:43 PM Hi Theo,
Thanks for your reply. Yes, I should have said- the accelerator pump was the first thing I'd check and it was fine- it injects a nice stream of fuel into the carb. Other than the accelerator pump, are there any other jets in the carb that may be blocked? From what I describe, could it be ignition? Points? Condensor? Thanks PC Title: Re: Lack of power under acceleration Post by: Thotos on December 23, 2019, 09:43:07 PM Certainly worth checking the points gap but I doubt it would be condenser as that would cause misfiring and starting problems. Also worth checking the ignition static advance (should be 10 degrees BTDC) and also checking that the advance mechanism works. The ignition timing needs to advance as you accelerate. In the 131 that's achieved by little weights under the rotor arm which move out against springs as the revs rise. Should advance up to 25 degrees BTDC (I think.... ). Take the distributor cap off and make sure you can twist the rotor arm by hand and that it returns by spring action when you let go.
Title: Re: Lack of power under acceleration Post by: Crazypierre on December 25, 2019, 09:57:17 AM Hi thanks Theo,
Yes, I read about the centrifugal thing with the weights in the distributor. I'll check that its working OK and also the points. After that I'll check the carb but there's a big in-line filter between pump and carb so I can't see any rubbish getting through... Merry Christmas. PC Title: Re: Lack of power under acceleration Post by: Crazypierre on January 26, 2020, 08:48:25 PM Hi,
OK, I sorted the problem. It was that the points gap had closed up. So I opened them up a little and it's running much better now. Thanks for your help. Pete |