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Hello,<br> <br> I have an 81 380sl which cannot run at high speed. When the engine runs above 3500 rpm, it starts to cough, even in parking. The car runs very well in city, but sometimes I depress the gas pedal to get it go faster, it won't go since the engine cannot revolve above 3500 rpm. Did anybody experienced this kind of problem before? Please help me out! Thank you very much!<br> <br> Garry
 

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Check the rotor arm under the distributor cap and if it has a spring and a metal flap on the top. If it has, remove them both. It acts as a rev limiter and if the spring is wekened it will earth the ht contact.
 

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Problem solved

My distributor rotor doesn't have a spring or metal flap. The problem is the fuel relay. For any reason, I put a wrong fuel pump relay in when trouble shooting something else. The wrong relay is from 4 cylinder engine. The fuel pume relay acts as a rev limiter which receives signal from a pulse generator in the distributor and cut of the signal to the fuel pump at a certain frequency. When removing the distributor cap, we see pulse generator under the rotor. Because of the 4 cyl engine fuel relay in a V8 engine, it cuts of frequency by half. As a result, my car ran around 3200 rpm max, cannot go higher. Thank you Rasputin!<br> <br> Garry
 
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