Reluctance to start in cold weather

bjmullan · Post by **bjmullan** » Mon Jan 22, 2007 3:52 pm

My car finds it very hard to start in this cold weather. I’m aware of the reason why it difficult for a car to start in the cold but my car seems to be a bit fun. I have a good battery, the engine turns pretty well and the engine will even “catch” without any joy. I have had to resort to cold start spray which seem to kelp. Once I get it started everything is OK, even if the engine immediately dies it will start again without much problem. Anyone any ideas or tips?

chris68 · Post by **chris68** » Mon Jan 22, 2007 4:14 pm

Hi,

Is the mixture too lean? Try turning each carburettor mixture screw 1/2 turn anti-clockwise to richen the mixture and see if the situation is any better.

Alternatively it could be plug fouling. Check the condition of the plugs and clean / renew if necessary. I fitted an electronic ignition (CDI) to avoid this problem.

See this link for more info on plugs. http://www.carcraft.com/techarticles/spark_plugs_tips

Cheers.
Chris

Gary71 · Post by **Gary71** » Mon Jan 22, 2007 4:29 pm

Assuming ignition is all as it should be are your accelerator pumps squirting enough?

In this weather (0 degrees overnight cold start) I have to turn on the ignition, let the float chambers fill, 5 full clean pumps on the throttle, crank then catch it, hold for a few seconds at 2500 ish and wait for it to smooth out. Then all is fine even for an immediate restart when I stall it!

If I remember correctly you are on Zeniths? So no choke or any other cold start aid other than flooding it with pumps on the throttle. Your problem sounds like the mixture is just not rich enough to start when cold, so the cold start spray is doing the job of the accelerator pumps.

Relative to the amount of fuel you pour in with the accelerator pumps the idle mixture screws will not affect the starting mixture greatly.

Good luck

Can't have that mintiest of mint T's not running!

bjmullan · Post by **bjmullan** » Sat Feb 17, 2007 4:42 pm

Finally got a chance to look at the car again and the right side accelerator pump shaft was not returning correctly so no fuel on that side. Got that fixed but on further investigation I have found that both the middle Accelerator injector are not pumping any fuel. I partly took off the accelerator shaft on one side and removed the pump diaphragm and spring. The diaphragm was clean and in good condition and there was fuel in the chamber. I tried compressed air in an attempt to clean the injector passage but no joy.

Two question....1) Will she start with only 4 accelerator injectors working and 2) can I get the injectors out without removing the carbs from the car and is it an easy job? This last question is for Gary of course!!!

As a bit of background I have found that I have had to give a good 6/7 pumps to get her started at cold (so maybe the 2 injectors have not been working for a while).

team914 · Post by **team914** » Sat Feb 17, 2007 10:56 pm

The pump jets need to work all the time otherwise will not get smooth performance during the "acceleration phase" of the throttle stroke.Also the amount that each jet discharges on each acceleration stroke should be set up and measured with a graduated minature test tube secured by a thin wire so it can be held under the pump jet while checking.
Re Zeniths,getting the pump jets out can be very difficult as the very small sealing gasket around the body of the pump jet can harden and stick to the carb body.Dont prise under the jet tube but remove by grabbing the pump jet body with an appropiate tool,being careful not to damage the brass jet body. There is a little glass ball which acts as a non return valve in the pump jet body,so you need to squirt carb cleaner backwards through the jet while keeping the glass ball lifted with a piece of wire so the cleaner can wash through the pump jet and hopefully wash out the offending blockage.Getting all the jets to spray with a clean straight jet of petrol can be a time comsuming business if they have been blocked or semi blocked.I have been experimenting with an ulrasonic cleaner recently but I fear that the utrasonics may damage the internal glass ball in the jet body. Also be careful when cleaning and removing, as there is also a little "drawing pin" shaped valve under the pump jets which can easily get lost.All the above work is easier with the carbs removed out of the car.
Hope this helps.

Gary71 · Post by **Gary71** » Sun Feb 18, 2007 3:26 pm

I'm with team914 I'm afraid Brendan, You can change them with the main body still attached to the car, but you save very little time and only the gaskets to the inlet manifolds.

Here is a little pic of how to flush the puppies out:

..and the bits...

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bjmullan · Post by **bjmullan** » Sun Feb 18, 2007 3:30 pm

What about the other question....will I get it started on just 4 pumps?

BTW Thanks for the advice guys

Gary71 · Post by **Gary71** » Sun Feb 18, 2007 3:59 pm

I'd imagine it will start, but only four out of six are getting a rich mixture so it will be harder. Also your transient acceleration performance will be flat, as it will only pick up on four.

It will keep you going for a while, but it may well be carb rebuild time...

bjmullan · Post by **bjmullan** » Tue Feb 20, 2007 3:36 pm

I replace the relative new NGK plugs with Bosch and after a lot of trying yesterday got her started. Today she starting first time and as the sun was out I when for a blast. Perfect way to spend your lunch break.

Thanks for all the advice.

Gary71 · Post by **Gary71** » Tue Feb 20, 2007 4:39 pm

I'd imagine an extra 5degC in ambient temp has made the difference

Cars are always hardest to start around 0degC.

DDK - Die Deutschen Klassiker

Reluctance to start in cold weather

Reluctance to start in cold weather

Starting in the cold