School boy error!...What could cause this issue?
Turbo Mini Forums

Morning Chaps,

Ive made a stupid error and by not paying attention i accidently reversed the polarity when connecting the batery back up in the mini by dropping the batt in the wrong way round!!! Stupid and careless I know!

Anyway its a 1989 red hot but with a 1990 cooper engine fitted so is running a HIF44 carb and 65DM4 electronic dizzy.

The only damage I could find was that the two brown wires which run together to the alternator had burnt all the insulation off. These were both connected to the starter solenoid terminal on the inner wing and had been both connected to the B+ terminal on the alternator. (My alt doesnt appear to have the standard 3 pin plug) I have replaced these two wires with a single bigger cable (a pre-made battery lead).

The car starts perfect and all electrics appear to be working fine. However after anything from a few seconds to a few minutes the idle drops to the point of stalling and it just wont pick back up again. If i touch the throttle at all it stalls (if it hasnt already). It starts back up again perfectly and then the whole cycle starts again.

The only other thing which is non standard is that at sometime in its life it has had a facet electric pump fitted instead of the mechanical pump. (The previous owner ran a different engine and used it for sprints) I can hear it click clacking away all the time so i think this is working ok.

The charge light is working correctly so I dont suspect the alternator to be at fault although i could be wrong? Also the battery isnt being discharged so there doesnt appear to be any earth leakage.

So does anybody have an idea of what it could be? A completely seperate issue with fueling or spark and how is best to diagnose it? Could i have fried anything when it was connected incorrectly?

Cheers
Andy

Perhaps the electronic module on the side of the dizzy has damaged?

If something is worth doing, it's worth doing half of.

Hi John,

Was thinking the dizzy myself but wanted to be sure before i fork out for a replacment!

you not got an old a+ dizzy you can chuck in as a test?

If something is worth doing, it's worth doing half of.

unfortunatly not, the last couple have been MPI or running Emerald.

Volt meter on the wiring to the the dizzy, and a low pressure gauge in the fuel feed, one or other will drop off, if they dont you know you have fuel, and if you have volts at the dizzy then swap coil out and try again, still no joy then swap out dizzy...

Right chaps, so I've swapped the dizzy and also the coil but the problem is still there. The Alt is doing what it's supposed to and whacking out approx 14.4v when running so I'm confident it isn't a spark issue.

I think it must be either the carb or the pump. It as a. Facet pump which obviously runs when the ignition is on. Now I have found that if I turn off the ignition immediately after it stalls then when it restarts it will only run again for a few seconds. But if I leave the. Ignition on and the pump running a while then it allows it to start and run for circa 40 seconds, which tells me that the pump is struggling to get fuel in to the carb reservoir at a high enough rate while running but then slowly refills it when stalled

So before I go about buying more bits and bobs are there any easy checks I can do. Could I have done something to the pump w,hen I reversed the polarity on the battery or do you think it's just a coincidence? Or could something be sticking in the carb
It's a na Hif44 carb

Any help appreciated
Cheers
Andy

You're maybe jumping to conclusions that it's electrical.

You say it only happens when you touch the throttle ?

So if you start the engine and let it idle....will it idle forever ?

Have you checked for fuel flow the entire time it is idling until it stops ? even whack in some clear fuel line if need be, or stick a fuel pressure gauge on the line to the carb

If so, then it is mostly likely a carb setup problem.

And of course the most important aspect...did this engine run fine before you mucked up the battery ?

Edited by stevieturbo on 7th Nov, 2012.

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

Hi,
Yes it did run perfect prior to this. Yes the problem occurs when at idle also. It will rev perfectly fine but if i do rev it then it will cut out sooner, most probably as it is running the fuel out of the carb sooner/quicker.

It cuts out even if i dont touch the throttle, so it will idle for a max of 30-40 seconds. hence why i think its struggling to get enough fuel through to the carb. I think i will have to get an inline fuel gauge in and see if this sheds some light!

Can't you install one of those cheap see through fuel filters before the carb to see if it is running out of fuel?

I thought about that but wasnt sure if i would see it slow down through one of those as there should be no air which is why I thought the best option may be to stick a gauge in?

A simple pressure gauge or clear fuel filter would be fine.

Or even just hook up a pipe and gravity fed funnel feeding the carb. That should supply plenty of fuel for it to sit and idle for ages.

Or easier still...let the pump run into a bucket with the ignition on and see if it dies after a few seconds.

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

This would be my next step.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Thanks gents.....know what im doing tonight then!

And for any of the above tests...bare in mind petrol is dangerous, and fuel vapour is highly flammable/explosive.

Just in case lol

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