Engine runs erraticaly then dies

PostPost by: elanner » Fri Aug 11, 2017 5:06 pm

This is not an area where I would claim any skill but it seems to me that you still have to identify whether you have an ignition problem or a carburation problem.

So, when you next reproduce the problem why not simply remove a single spark plug HT lead (as the engine is running - wear some thick rubber gloves) and see what impact it has on the running? Do each HT lead, one after the other. The running should get worse as the engine runs on three cylinders. If the running does not get worse with every HT lead being removed in sequence then it would seem that you have an ignition problem. Right? Would that be a simple diagnostic approach?

Nick
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PostPost by: RichC » Fri Aug 11, 2017 5:25 pm

Hey William 2 ,
I had exactly the same problem after i fitted electronic ignition and it drove me crackers and cost a lot of money with recoveries...the electronic ignition was overheating and it was to do with the resistance in the system ... The conclusion we made was that there was a ballast resistor in the system somewhere ( although there shouldn'thave been and I still do not know where it is... ) so i had to change the coil to a ballasted type, if my memory serves me right, and that sorted all the issues out ....
does that make sense folks ? or am I gettin confused? I tried to find the old thread but dinner's on the table....
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PostPost by: William2 » Sat Aug 12, 2017 4:16 pm

I have made some progress! About an hour or so after I had returned I removed both carb float chamber covers and low and behold they were both virtually empty!! That means I can rule out any ignition problem. I checked the fuel pump bowl and that seemed to be full of petrol. I find it hard to believe that the float needles would have both stuck in the closed position. I wonder if either the pump has an internal problem or if the length of fuel pipe running from the pump to the first carb is getting too warm. I could route it a bit further away from the block. My alloy fuel tank is new and therefore unlikely to be the cause of any blockage. I have fitted a rubber primer bulb near the tank like other Elan owners have done and an in-line small glass filter. I can't see how either of these should cause the same problem to occur after approx. 25 miles. The only other thing I can think of is that both times it has happened the amount of fuel in the tank has been about 1 3/4" when I dipped it but yet there was fuel in the glass pump bowl suggesting that fuel supply wasn't a problem.
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PostPost by: ericbushby » Sat Aug 12, 2017 5:13 pm

Well done William. I think you are nearly there, but I must refer you to my first post.
In my case it was an intermittent mechanical fuel pump. It started to misfire then gradually died.
I found the fuel level to be very low. It had fooled me for a long time by then.
When cranked it soon started up and ran normally.
I removed the pump and tested it manually. It would pump water up the side of my house up a clear plastic pipe. I could not make it fail.
A new one was fitted and it has been fine ever since.
Eric in Burnley
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