Engine misfire

[mk1coopers]

I've had an intermittent fault on the 1071 that's got a lot worse after it had a rotor arm failure last week, symptoms are that it looses power and drops onto 3 if you rev it hard accellerating up a motorway slip road, it used to be above 65mph, but didn't do it every time (90% of the time it was OK). Now it can happen at any speed, but it is always after higher RPM (which is no problem in the 1st two gears normally), once you slow down to 30 and accellerate again its back on all 4 until the fault starts again. Components / work done so far - good quality points / rotor / condensor , new plugs, swapping known good coil / leads / cap, checking float chambers and dash pot pistons, its not using water (thought it may have had a headgasket starting to go / fouling a plug with coolant), any thoughts or ideas would be appreciated, I'm going back into the garage to scratch my head some more !!

[guru_1071]

its not running out of fuel in one float chamber is it?, the high revs will slurp it all, then the slower revs will allow it to fill up again and hide the problem?

in the odd time i ran out of petrol in my 1071 it would run at low revs fine, but once there was demand only the left hand 'bank' would deliver as that was the only float to have any fuel in.

it could drive for quite a distance like this

[mk1coopers]

Thanks for that Rich, spent the day looking at it, had the carbs off, cleaned everything, rechecked the dash pots and floats, put all the electrics off another car on it (including dizzy), compressions were even, it did run better for a couple of runs, but then fell back to what it was doing before (but slightly better), going to recheck the tappets once its cold, it can run fine if the RPMs are kept low, its a pain because I am using it on Friday for a trip, and its got to be fixed for then

[guru_1071]

it might be worth checking the flow of fuel,

the problem that my sprint has is that bits of the tank sealer stuff clog the pump pre filter, which allow it to run fine on short journeys, or below 3000 rpm

however once the filter is blocked it wont drive above 3000 (then 2500, then 2000 etc etc) or dies if it comes to a hill, or what not - it only really manifests its self after ten miles or so, when the 'suck' of the pump has managed to slup enough of the flakes up against the filter.

it really shows its self up on my wide band lambda though, as it will suddenly run lean, then creap back up if i back off, then steadly get worse and worse (and slower and slower)

hope you fix it, a 1071 that cannot clear its throat must be a sad beast indeed!

[mk1coopers]

Thanks Rich, I had the inlet pipe off the pump and it was running free, I'll keep at it tomorrow,

[IAIN]

As Rich pointed out.I had the same problem of the tank filter getting blocked with fluf in the tank.
It, like you, had me going round in circles.
If it's possable, try blowing back up the fuel pipe into the tank, then see if it's any better.

[mk1coopers]

Thanks Iain, I will look at that, its back together with the tappets done now (slightly tight) I'll have another go tomorrow night when I get in from work, any other ideas will be appreciated