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Guest esseven

Engine Problems S2

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Guest esseven

My S2 engine has a lack of power. It starts good and is very well running to 4000 /min . Then if I give more power

the engine speed goes down to 3500/min and it is out of round.

Do you have any idea ? Carburator, Ignition , Fuel Pump ? My local dealer ( not Lotus specialised ) didn

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Can you give more details of what happens when you get to 4000 rpm? Does the engine run roughly and then slow down or does the speed just drop?. The rotor arm has a rev limiter device built into it so when the engine gets to a certain speed a part slides out under inertial force against a spring and shorts the spark out. If the spring is broken it will cut the spark at lower engine speed than it should.

I would think a bad fuel pump would mean that the engine would lose power above a certain speed and throttle when the pump could no longer keep up but once the power demand dropped to a level where the pump could cope the engine should be able to maintain that condition. When the pump was struggling to keep up the engine would run lean and lose power gradually as you tried to go faster. Does the engine spit back through the carburetors at all as if it were lean?


S4 Elan, Elan +2S, Federal-spec, World Championship Edition S2 Esprit #42, S1 Elise, Excel SE

 

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Yep - more info Mario, and a great fault for us to get our teeth into. :)

Like Trevor in a way, I am straight away suspecting the fuel system, and most likely the pump. A quick check of the filter though (replace) is a must. When the car dies, pull over and get a hand underneath and feel the SU pump for two things. 1. is it bleeding hot so much that you cuss me for suggesting it?, 2. is it 'tic tic tic' about every 20secs or so. If no tic tic - try tapping it with the blunt end of a screwdriver and listen for 'tic tic tic' in quick succession. Either of these symptoms would be indicative of a fuel pump dying. Try searching for other fuel pump topics.

Another thought - float heights / sticky float valve seats.

Iain

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Guest esseven

Thank you for your answers.

If the engine runs on idling speed and I give more power it runs well till 4000 rpm . Then it decreases to 3500 rpm

und is spitting. If I drive on the road the engine speed doesn

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Ok Mario, I am going with the fuel pump.

I (and others) have been where you are with the pump. The first attempt is to clean the contacts and it later sub-fails or degrades again. There is an upgrade to non-contacts (hall effect), but your problem could be with the electrical solenoid coil in the pump. These coils are getting hammered with collapsing EMF current and their service life is to be expected as such (10-15 years).

My coil died and Lotus no-longer warrantee coils with a 'replacement' fuel pump - read the tea leaves.

Iain

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Mario

Find a new garage, preferably one with standard diagnostic equipment - there is nothing complicated with an S2 ignition/carburation. What colour is the inside of the exaust tailpipes? (black, grey or white)? What colour are your spark plugs? Are they all the same? Are they wet are they dry? That will give a good indication if it fuel or ignition related (white-fuel, black-ignition).

I dont know what your level of experience is, but here are a few things you can try at home with a 'mechanically minded' person:

I quite like the theory about the mechanical rev limiter, I would try replacing with a standard lucas part (couple of pounds from any car shop - in england!!) - Its a direct swap..

Fuel pump? - simply disconnect the outlet pipe and see how much fuel it pumps. I would try this at the pump and then the carbs to make sure there is no filter blockage. As long as it can fil a jar in 30 seconds or so, its unlikely to be your problem.

Might be worth taking the top covers off the carbs to ensure they dont have any silt in them, also blow through the main jets while the covers are off. Can you see the 4 jets of fuel being pumped when you press the throttle? (By looking into the venturi when pressing the throttle.

Check ignition timing with a strobe, or even statically to make sure its OK.

I have had exactly this symtom before with simply 'duff' sparkplugs, consider also coil and plug leads.

NB Are you on 'points' or Luminition ignition, or something else? If points, check your gap is wide enough.

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