Engine suddenly 'racing' all on its own!

[Dave.Sellers]

My Traveller has a 1275 with a HIF44. I have noticed recently that it was ticking over abnormally high and just made a mental note to adjust it next time I had the bonnet open.

Driving home yesterday, when I dipped the clutch to change gear the engine was racing as though I'd left my foot on the gas.
Stopped the car and restarted: racing away at, I estimate 2000rpm
Switched off and took a look, throttle mechanism on carb seemed to be working ok but noticed the cable didn't slide back inside its cover. After a good bit of wiggling stuff around and a couple of restarts and it was still revving high but not alarmingly and I managed to nurse it the few hundred yards home by driving on 'tickover'.
On investigation I found that the throttle cable was all a bit knackered where it passed through the bulkhead and just not moving smoothly so I figured this was my problem and, this morning, I fitted a new cable thinking that would be the end of it but no, the cable was knackered but seemingly not the cause of my woes!

When I start the engine now it races, if I blip the throttle it stays at the higher revs etc...

I've just had the air filter off and manually lifted the big 'slidie up and down thing' and seems to slide smoothly up and then drop down happily enough so, what on earth is going on?
Seems to me it must be something gone awry with the carb but what would cause it to race and what can I do about it?

Any suggestions gratefully received..

Cheers
Dave

[Biggles1957]

Is your throttle return spring OK?

[amgrave]

You have probably attached the new cable with not enough slack. Check where the cable inner exits the outer under the bonnet to make sure you have a small amount of play with the throttle at rest, you should be able to lift it up and down a 1/4" or a bit less without the engine speeding up. If when doing this check the engine does speed up then slacken the cable off at the clamp on the throttle arm.

[bmcecosse]

As above - cable too tight - or too short -always fit a 'long' cable with a nice smooth curve. Maybe not fitted right through the bulkhead. carpets snagging the pedal?? Disconnect the cable from the carb - does it idle ok now ? If not -look for air leak....

[simmitc]

First thought was the throttle return spring, but then 2000 rpm is not really racing - when the spring goes the engine can hit 4K easily. Almost certainly the suggestions above will sort you out, but also check idle speed adjustment screw. It should be held in place by a spring keeping the threads pushed together, but if the problem has become gradually worse then it is possible that the throttle stop screw has wound down too far.

[Dave.Sellers]

Thanks all.

The spring seems OK, i.e. if I blip the throttle manually with my finger at the carb, it springs back.

Cable too tight sounds favourite, when the rain thunder and lightning stops I'll go and take look. If it is that, what a proper Charlie I will feel

Watch this space...

[amgrave]

No need to feel a Charlie, we all make mistakes . Lets just hope that is all it is

[firehor5e]

If still no joy,disconnect the cable and see what happens,if it still races,the prob is prob with the carb.

[bmcecosse]

Is there an echo on the forum?

[amgrave]

Yeah. A few people don't bother to read through the thread properly before offering a solution I think

[bmcecosse]

[firehor5e]

Oh yeh,derr ..am i back on the naughty step?lol

[johngrigg]

Recently had he same engine racing problem and after a new inner cable and endless adjustments noticed that I had left the end of the inner too long so it was bearing on the exhaust manifold. This was just enough to prevent the throttle closing completely. Snipped off the end and problem solved Hope this helps John G

[Dave.Sellers]

Well, loosened the cable right off and manually checked that the throttle 'lever' was sprung back as far as it would go. Started the engine and it's still racing.
I don't want to wake the whole street later so will wait a while before digging deeper. Somebody suggested an air leak might where would I look for that?

[Dave.Sellers]

I took the top off the carb, checked the needle wasn't bent, took it out cleaned and replaced it. Cleaned everything else and put it back together. Backed off tick over adjustment as far as it would go and all now seems well.

Disappointing to not really find a concrete cause but seems fine.

Thanks again for all suggestions.

[amgrave]

Thanks for letting us know and bringing this post and your problem to a satisfactory conclusion some don't unfortunately

[bmcecosse]

Well done !