Poor starting TR3a Discuss.

[stuart]

Right here we go chaps a topic for discussion received from one of our members on the Tech email system

Poor starting on an early`ish 3a

"I hope you are able to give me some technical advice on a problem with my car - a

1958 TR3A comm.no. TS29455. After having set up the car with 2 colourtunes and a carb balancer and the car then running perfectly, after putting the car in the garage, the following day it will not start. Eventually after numerous times removing the spark plugs, cleaning then and checking and even heating them with a blowtorch, the car starts. I then double-check everything, colourtunes, etc., and the car seems to be running perfectly, I then put the car back in the garage and then next day the whole scenario happens again!

The car has reconditioned carbs, new petrol pump, new distributor, spark plugs, leads, etc..

I have taken it to 2 garages specialising in classic cars, one of which was recommended by a club member, all to no avail. I really hope you can help with this".

Stuart.

[Alec Pringle]

New distributor of what variety ?

 

Condenser springs to mind as a possible culprit ?

 

Fuel supply - as in disappearing somewhere overnight, and perhaps even air locking ?

 

Cheers

 

Alec

[Don H.]

Old fuel?

 

Damp around distributor?

 

Vacuum leaks?

[Jersey Royal]

Overfueling on choke, soaking the plugs, new plugs especially Ngk dont like being wet when new. Check the float level and put the new plugs in the oven for ten minutes or so.

Thats my opinion.

 

Guy

[Guest ntc]

Overfueling on choke, soaking the plugs, new plugs especially Ngk dont like being wet when new. Check the float level and put the new plugs in the oven for ten minutes or so.

Thats my opinion.

 

Guy

+1 it is flooding.

[graeme]

Has the cylinder compressions been checked? Low compression will cause poor starting.

 

Possibly old fuel?

 

Graeme

[Chilliman]

I'm definitely in agreement with excess fuel on initial start up - most logical answer

[Bobbie]

All of the above, + has coil been changed to eliminate any fault in that department?

Has a basic check for spark at the plugs been checked when cold?

 

Regards Bob.

[Peter Cobbold]

The engine has to be cold to show up the fault. So....plugs fouling with rich cold start mixture? Try new plugs ( have never have much joy myself trying to clean old ones.)

Edited April 10, 2015 by Peter Cobbold

[LGFromage]

Try a new set of plugs purchased from a reputable dealer. Plugs can vary in quality.

 

Tim

[BlueTR3A-5EKT]

Coil polarity to match vehicle battery connection.

Over advanced ignition static timing.

 

 

Peter W

[Richardtr3a]

I fitted a racing condenser from a mini race supplier and my starting was transformed. Well worth £32.00. It is mounted on the engine and there is a new earth lead from the coil mounting to the chassis.

 

My problem was hot starting.

 

Good luck.

Richard & H

[RogerH]

The car runs OK when warm - so that should rule out most of the above.

 

Why do the plugs get wet/foul up - are they stopping it from starting or suffering because it hasn't started.

 

There was a post on the TR6 forum the other day pointing out exactly this problem. The battery was too small (not enough adequate cranking amps) to start but was more than adequate when running

Replace battery with more CCA and bingo.

 

The cold starting process was robbing the battery of volts - possibly not helped by other things - more CCA keeps the battery volts where they belong.

 

Roger

[BrianC]

I think Roger has the answer. I had similar problems during the winter and suspected previous occasional culprits of fuel starvation or flooding due to sticky needle valves (curable by tapping float chambers with a spanner or screwdriver head) . However, using a jump pack, the car started perfectly and the battery alone was enough to restart it once warmed up a little. The real problem was simply that the elderly battery, although still good, was just not enough to turn a cold engine and fire it up. A new battery resolved the problem, even in freezing conditions.

[Lebro]

I agree to a point, but this is a 3A, not a PI job, so there is no fuel pump to worry about.

Many years ago I had a Dove '4 which used to crank over incredibly slowly in the winter - but it always started.

A good battery will certainly help, but there may be something else going on as well.

 

Bob.

[Don H.]

I'd have never guessed a battery that was good enough to turn over the engine wouldn't have enough juice to power the primary on the coil.

[trevor]

I have had this problem with my 4 and after fitting fuel filter realised that it was always empty when left for a while , three or four strokes of the fuel pump lever and away she goes .

Had the same problem on my Saab 96 v4 and fitting a non return valve was recommended on there forum and that is the route I' m planning to go with the 4.

Cheers, and good luck,

Trevor

[BrianC]

I'd have never guessed a battery that was good enough to turn over the engine wouldn't have enough juice to power the primary on the coil.

I'm usually reluctant to blame this sort of problem on what appears to be a good battery, but it's by no means the first time I've cured starting problems by fitting a new battery after trying everything else. Have done the same over the years and on two modern, family cars in the last 6 months. I have a small stock now of batteries suitable for test purposes or powering 12v tools in garage, workshop, etc., as I can't bear to dump them whilst they still have life in them, but no way will they go back in their respective cars.

[Don H.]

Brian, I'm sure you, like many of us of our generation, have popped the clutch on cars with batteries too weak to crank the engine in order to get them running. I've done it hundreds of times over the years. It takes almost nothing in the way of a battery for an old car to run.

 

Modern cars are a different kettle of fish indeed, with highly integrated, voltage-sensitive circuits throughout the vehicle. They're a lot fussier.

[acaie]

So find a friend with a well charged battery and a set of jump leads, and that will tell you whether more oomph in your battery will cure the problem.

 

Good luck

Al

[Andy Moltu]

Add to the above suggestions:

Are the plugs wet when you pull them out after a failed cold start?

 

Does the engine have a good earth strap?

Will it fire with a jump start battery to battery? If no have you tried linking the earth from the jump start to the engine block.

[Ian Vincent]

I have similar symptoms on my TR3a. It takes a fair bit of cranking to start, once it has started - no problem, it idles steadily at about 800/900 rpm and will restart on the button instantly. Leave it a day and it needs to be cranked again even if I prime it on the petrol pump first.

 

It's definitely not the battery because that is connected to a trickle charger usually and has plenty of juice. It needs it for the cranking.

 

There is a healthy spark and I suspect it is something to do with the fuel system but I can't find what - I have checked the float levels and they appear good but if I remove a plug after initial cranking and before it does eventually start it is usually wet. The plugs are the right colour if I take one out and check it after a run.

 

Rgds Ian

[Lebro]

Low compression ? Ignition timing out ?

 

Bob.

[Peter Cobbold]

If As the 3A does not use a ballast-resistor and coil then I can see the spark being weakened during starter motor operation. Check the spark during cranking. A work around would be to use fine wire electrode plugs which make best use of the voltage available.eg:

http://www.globaldenso.com/en/products/aftermarket/plug/power/features.html

These wire plugs ignite mixtures that are much leaner than normal, hence their use in moderns (along with fit and forget freedom from fouling.That's why they will help starting too. In a stone cold engine the mixture that the plugs has to ignite is actually very lean. The plug can only ingite petrol vapour and in a cold engine only small fraction of the petrol will evaporate to vapour.

 

Or pour a kettle of boiling water over the inlet manifold to get more petrol vapourised !

 

 

Another way to get the best cold-vapourisation is to keep the butterfly closed when cranking. The low pressure between the butterfly and inlet valve will help 'boil' more vapour off the liquid petrol seeping past the butterfly and the mixture will be richer and more combustible. It may be that the choke-cable actuated butterfly opening,intended to raise cold idle speed, is opening too much on those engines that are reluctant to fire and so not allowing enough vapour to boil off.

 

Using summer fuel for winter cold starts is also going to give problems with volatility.

 

Peter

Edited April 15, 2015 by Peter Cobbold

[rhino_mac]

I have similar symptoms on my TR3a. It takes a fair bit of cranking to start, once it has started - no problem, it idles steadily at about 800/900 rpm and will restart on the button instantly. Leave it a day and it needs to be cranked again even if I prime it on the petrol pump first.

 

 

 

Rgds Ian

 

Mine does exactly this. It's in with Stuart at the moment and this is one of the (many) things being looked at so if it gets fixed I'll try to give you a heads up where to start with it.