Mysterious Missing
Turbo Mini Forums

OK I am very hesitent to ask this sort of question because I know it's impossible to diagnose over the internet but...

I had my NA MG Metro engined Mini layed up for about 3 months, when I first took it out and had a fuel leak at the (mechanical) fuel pump (just a loose clip) but once that was fixed it was fine. A few months later again I took it out (after I replaced a battery and freed up a siezed alternator) and it is now missing at low revs. I went through the entire ignition and it is all dry, no bad connections, then I replaced the coil, leads and plugs and still no joy (it's an MG elcetronic dizzy so no points- cap and arm is near new). It just misses (not dropping onto 3 cylinders or anything just starts missing and goes limp) from idle up to about 3000rpm and then it cleans up. Won't pull over 50mph though as it drops onto 3 cylinders then. Any ideas? Head gasket is OK, I'm thinking about fueling next. Can't really see how that could be though, it will sit at 5000rpm no probs but just doesn't pull under 3000rpm. Any ideas?

Clean out the carb and replace ALL the fuel

piston seized or sticking in the dashpot ?

3 months isnt a really long time for it to be sitting though. I assume you do have a good supply of fuel getting to the carb ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Ive had my car sit for over 2 years with no fresh fuel, and it started and drove well enough, that I personally dont think fuel goes off in a matter of weeks/months...

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

depends, i've had fuel go well off in a matter of weeks.

we had a 1275 that wouldnt go over 60 a few years ago that had been layed up for a few months. tanked it up and it then had no problems passing 60!

maybe depends how its stored, i dont know.

Yeah i put fresh fuel in and the dashpot/piston has been out, looks clean so far but maybe there is a prob with the needle in the fuel bowl. I've had fuel starvation before with another engine but it manifested itself with the engine cutting out if reved for too long or pushed too hard. Still with the tank sitting half full for a few months maybe it rusted a bit and is it's flaking into the fuel. Is there a gauze filter on the HIF? Carb is coming off tomorrow, hate working with HIFs though, much easier with the HS. OK thanks for your help.

little gauze filter under the brass bit the needle valve goes in

Metro turbo weekend driver,Mini turbo in the making again!

OK just an update, I pulled off the carb and cleaned it out even though it was rather clean anyway. Gauze filter was fine, as was the fuel bowl, jet and needle valve. I double checked all low tention conections and they are all really good. But still no joy. When you rev it in neutral it will stagger a bit then once past 3000rpm will rev fine. It will keep going as long as you hold it but when you let it go it will stall or idle real bad for a few seconds then pick up. Fuel pump is fine as far as I can tell. I'm going to limp it to a petrol station near by and get some more petrol that I know for sure is good (it's on E now). Apart from that I am out of ideas!

have you tried other sparkplugs already?

Yes that was the first thing I did. Compression test is 150psi all round so that rules cracked valves/blown head gasket out. Mixture is spot on according to a borrowed gas analyser. I'm running out of tests to do! I literally don't know what to look at next. Maybe the module on the electric dizzy is on the way out? I have a spare somewhere but my garage is a tip right now so can't find anything. Can I use a multimeter to test something like this?

Gunsons spark testers are handy tools, and only a couple of quid.

Dodgy coils/ignition systems can be hard to trace.
Assuming the float bowl is full, there should be enough fuel to perform a full rev cleanly, even if the pump wasnt working.

No idea on testing the module....

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Hi,
You'll need some really technical gear to test the module, the best way is to try another one on it.
Cheers,
Gavin :)

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Gunsons spart tester is a great tool..... it might not test individual compenents, but it tests the end result.

very bottom of page

http://www.vehicle-wiring-products.co.uk/V...ers/meters.html

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

do a search as TD showed a way of testing the ignition module that was simple and cheap

Hmmm, did a search but the general concensis seems to be swap for another one and see. I have access to a spark tester so at least if it's spark related it should show up with this and then I can leave the fuel side of things alone. I have a whole dizzy somewhere with module attached but my garage swallows everything. OK thanks for your help so far. I missed my MOT apointment last week cause of this too!

OK so the update is.... I swopped over the ignition module for a spare and it works! It runs well now. Of course it's a pitty I didn't check this first as I spent about £30 on leads, coil etc and I had a spare module the whole time. Of course I have an air leak now and it sounds like someone has slipped in a wild cam when I wasn't looking. OK thanks for your help guys.