Engine stalls when warm whilst coming to a halt

[moretonjr_4430]

I have Spitfire Mk3 which when gets up to temp and running for about 45 mins - 1 hour stalls when coming to a halt.  Always restarts without a problem and otherwise runs smoothly.  I try and keep the revs up whilst approaching junctions/traffic lights etc but not always successful.  Any ideas or thoughts or anything????

[Pete Lewis]

is this std or has pancakes rather than the orig air box ???

 

sound like its on the rich side of happy ,  whats your  normal idle speed when its ok. 

[JohnD]

Is this the legendary blocked fuel tank breather?

J

[rlubikey]

Whilst stationary & in neutral, does it stall when you set revs then *gently* take your foot off the throttle? Yes? Worn carb. butterfly spindles. Confirm by pushing spindles up & down and see if the revs change/stall. No? See other suggestions!

 

Cheers, Richard

[moretonjr_4430]

I omitted to mention that the engine is a 1300 Dolomite fitted by the previous owner.

 

It can smell a little rich at times but the choke appears to return properly.

 

I've looked at other Triumph forums and the blocked fuel tank breather is a contender.

 

The engine can stall when the foot is gently taken off the throttle and I will try as you suggest.

[Pete Lewis]

an odd ball thats time concious is having the HT coil polarity reversed  simple check the -neg terminal goes to the dizzy.

 

if the points have a nut  check the points post is secure ,

 

pull a fuel pipe is the pump giving a good squirt

 

what do you do to re start it  ???

[moretonjr_4430]

PL - the HT and points etc look ok.  The pump is also working ok as recently cleaned.  The car starts perfectly well with the a turn of the key but the battery sounds a little sluggish.

[mishmosh]

it could be the spring returns on the SU CARBS. mine can be a right arse ! 

[moretonjr_4430]

Thanks for all your input; plenty to consider.  Any others with ideas?

[dougbgt6]

Well, no one's said it yet, so I will! Have a look at your plugs, black and sooty would indicate running too rich. Grey white, too lean. You want a nice biscuit colour for just right.

t

[Ben Caswell]

If it stalls when you dip the clutch it could be worn crank thrust bearings.

[moretonjr_4430]

Ben - only stalls if I don't keep the revs up

[Pete Lewis]

Have you checked the idles screws are actually contacting the carb body and youre not relying on the throttle cable to controll the idle speeds,

[rlubikey]

Is it coming to a halt that stalls it or the throttle coming to the idle position after the engine's been working??

[moretonjr_4430]

rlubikey - Throttle coming to the idle position.

[rlubikey]

OK, so gently waggle the carburettor throttle shafts up & down - without turning them. You can try it both outsides but I think it's in the middle (i.e. between the carbs) that the problem happens, because that's where the return springs are - on a 1500 anyway, and I'm guessing it's the same on a Mk3. If the engine note changes then it shows there's wear on the body where the shafts run through. If not, then the problem is elsewhere, but at least we now know it's not forward motion that's the cause!

 

Cheers, Richard

[moretonjr_4430]

Hi Richard, thanks for the tips and after working through a few of the other excellent comments I am fairly certain it is the carbs.  Weekend job sorted !!  James

[Peter Truman]

Ref the stalling My Sprint recently had a similar problem, checked for air leak found the carb mounting bolts were not loose but only finger tight so tightened them car was no better, whilst checking the points happened to brush the back my hand past the coil and it felt damp, the year old Bosch 1.5Ohm coil was leaking oil and the coil overheating. Replaced the coil with the original 40yr old Lucas carried as a spare and all's sweet.

Similarly the Mk2 Spit a couple of years ago started stalling when hot, rebuilt the head cause I could and checking for airleaks, but eventually noticed the carb floats were angled back towards the exhaust manifold and it was vapour locking. I replaced the plastic insulator/locator bush that mounts the floats to the carb $20 worth and also installed a DIY heat shield which is mounted one to each carb and behind the carb to manifold flange and therefore removable without removing the carbs making work access easier. Problem fixed vapour locks are not unusual with Trumpies here in OZ.

Peter T