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Help - Rover Mini Cooper Intermittently Over-Revving Then Cutting Out.


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#1 Henry's Dad

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Posted 09 May 2018 - 09:32 AM

Hi there. I've just joined to post this and I hope someone out there has the answer...

I have a 1991 1275 Rover Mini Cooper, just over 127K on the clock and no engine mods. Generally he runs extremely well, but over the past 18 months there have been 3 occasions when, whilst driving, the engine has suddenly surged to c3,000 revs, then nearly cut out, revved and nearly cut out again several times then died. After a bit of fiddling about - checking HT leads, looking at plugs, that sort of thing, he re-starts and runs fine. The details of each occasion are:

1. Aug 2017. Towards the end of a 20-mile trip, hot sunny weather, doing 30mph in 4th. Engine surged and dropped several times before cutting out completely just short of home. Changed the plugs (couldn't think of anything else to do) and he started first time. He then ran with no trouble for 16 months, until...

2. Jan 2018. Towards the end of a 25-mile trip in heavy rain. Driving in 4th at 2,000 revs. Engine surged and dropped several times. Made it home (just), but drained battery next day trying to start him. Recharged battery, changed a split elbow connector on the vacuum advance pipe and he started first time.

3. April 2018. Sitting in traffic jam after driving for 10 mins in light rain. The usual surge/drop/surge/drop etc then engine died at traffic lights. Checked HT leads and removed a couple of plugs, looked at them, replaced them and he fired up with no problems. Been running fine since...

I've read my Haynes manual from cover to cover, had a chat with my local garage and searched various internet forums with no success. I'm stumped. Has anyone got any ideas about what the cause could be, 'because these days I'm getting a bit nervous every time I go out in case he cuts out and doesn't re-start.

Thanks in advance.



#2 cal844

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Posted 09 May 2018 - 10:10 AM

What colour are the plugs? Is it points or electronic dizzy?

#3 ukcooper

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Posted 09 May 2018 - 10:22 AM

'because these days I'm getting a bit nervous every time I go out in case he cuts out and doesn't re-start."

Get a rac card just in case and off you go , load of parts in ya boot and a coke of pop as a thank you ...

1991 1275 is hif44 carb is it not ??think they changed to injection in 93 , I had a 93 injection that did the same thing last thing I replaced was the cat - never solved as the bloke who bought it of me rolled it and killed it ....

#4 gazza82

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Posted 09 May 2018 - 10:52 AM

The two in rain sounds like you may be getting problems with damp in the HT leads. When you move them, you remove the damp and then it stops tracking back ..



#5 andyapanel

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Posted 09 May 2018 - 11:41 AM

It sounds like an air leak. Could the anti run on valve be faulty?

Keep us posted and good luck.



#6 Henry's Dad

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Posted 15 May 2018 - 12:46 PM

Hi all, and thanks for the responses so far. In no particular order:

Yes, he's normally aspirated. One of the last before the 1.3i was introduced. He originally had a cat fitted but the previous owner had it (legally) removed a couple of years before I bought him, and I've had him for 20 years this year.

I did wonder if it was damp getting in somewhere, but the fact that he first did it on a hot sunny day doesn't stack up. Then again, that might have been caused by a completely different problem but with the same effect...

Anti run on valve? Hmmm...I'll have a look. Well, I'll look in the manual then take him to the garage more likely. I am, unfortunately, rubbish at anything mechanical.

It's an electronic distributor. Three plugs are fine - as expected - but I do have a leaky valve-stem seal on No2 and the plug does get black. I check them regularly and he runs ok most of the time though.

Last bit of update: I did an 80+ mile round-trip last Thursday (carrying a tool kit, spare plugs, pliers, jump leads and head-torch in case I needed it) and he ran like a dream. No problems at all. And that's the frustrating bit about all this - I won't know if anything has solved the problem unless it recurs. I just don't know if or when it's going to happen again. I'll post any further info as and when, but meantime thank you all. I appreciate the suggestions.



#7 CityEPete

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Posted 15 May 2018 - 04:38 PM

How old are the HT leads?

#8 CityEPete

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Posted 15 May 2018 - 04:39 PM

I wonder if the carb is ready for a strip down and clean and a new online fuel filter putting in, could be occasionally sucking some dirt in, linkages a bit stiff etc.

#9 absx2

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Posted 15 May 2018 - 05:37 PM

Good point with the anti run on valve as it would draw in enough air to raise the revs before bogging the engine down.

 

Its attached to the servo bracket with a pipe leading to a Y piece from the servo to the inlet manifold.

There should be a definite click from the valve as you switch the ignition on and off. Check the earths and connections and the condition of the pipes as I once had one that had rubbed through on the servo bracket.

As for wet weather issues, leads dizzy cap and rotor arm. genuine or distributor doctor parts as cheap parts particularly the rotor arms will let you down.

 

Clean and I mean clean all the wires into the fuse box including removing each fuse as this ( the top fuse i think ) feeds the ignition and the anti run on valve.

You need electrical cleaning spray and a brass wire brush to do the job properly, if you don`t you will have more electrical issues than you started with :()

 

The ignition modules are pretty good and rarely give any trouble but if they do its normally due to excessive heat.

 

The carb will be a little worn by now on the spindle but they are sealed well being an HIF44 and the main jet if original will be very worn. The HIF carbs use a bi-metallic jet holder that rarely gives any trouble but again excessive heat build up in the float bowl that has been cooked by the exhaust in traffic can weaken the mixture enough to make the car cough and splutter until it gets some cool fuel back into the bowl.

 

There will be loads I have missed but its a start, oh and make sure you have enough oil in the dash pot SAE 20 :) 



#10 mikal

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Posted 16 May 2018 - 07:46 AM

How do you know it's a "he"?! I did read on the net recently a naked "disturbed" man was arrested for sticking his whatsit up a cars exhaust pipe. Guess that car was a "she", in his mind anyway?!



#11 Henry's Dad

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Posted 16 May 2018 - 08:48 AM

Continued thanks for the responses, people. To respond to the recent ones:

CityEPete: How old are the HT leads? I have absolutely no idea so yes, I should fit some new ones. Likewise yes, I guess the carb is probably due for a stripdown and I'll put that on my 'to-do' list. Well, my 'to-get-done-by-somebody-else' list at any rate...

absx2: Many thanks for taking the the time to write all that. As above, I will put all that on the 'things-to-get-done' list.

mikal: His name's Henry: Henry Cooper. He's a he. If he was a she he'd be called Alice... :)

 

So obviously lots to check and get done (well, he is a Mini ...) and as I wrote previously I will only know if the root cause has been resolved if it doesn't happen again, but I guess that's the nature of intermittent problems. Thanks again for all suggestions, and I'll post an update as and when I have one.



#12 CityEPete

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Posted 16 May 2018 - 04:31 PM

You could certainly have a HT lead breaking down if they are old and some crud in the carb, neither are a bad idea or expensive so I'd start there, good luck.




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