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Cold Start thoughts

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tweety

tweety

Jedi Trainee
Offline
'79 Midget, CA car

I have a heck of a time getting the car started when cold (this is San Diego, so cold is relative.) If the car has been sitting for a couple of days, it just does not want to start. When it does, it's missing/misfiring. After it runs for anywhere from 20 seconds to 1 minute it comes to life and runs like a top. The longer the car sits, the worse the problems. For example, if it sits a day, it's not too bad. If it's several days, it's a mess.


My mechanic took a look and found that it's the #4 cylinder that's not firing. He adjusted the timing etc, and otherwise the car runs fine. In fact, once it gets past this initial missing, it runs better than it ever has in the 3+ years I've owned it.

The mechanic thinks it's a problem with the LED ignition system as the plugs/wires all look good. He suggested replacing with a Petronix.

I'm wondering if it might be something else since the car is running so well otherwise.

Just for yucks I'm going to replace the plugs/wires, any other ideas?
 
Re: Cold Start thoughs

First thoughts... it seems unlikely that the LED ignition system would cause a miss in #4 specifically. Light leaking into your dizzy cap can mess up your LED system and cause your car to misfire and run poorly. But that would be messed up throughout your operating range, not just at start up. Other than that, the LED systems are an all or nothing scenario. Either they work or they don't.

I would check the contacts on the inside of the dizzy cap. These can get kinda junked up and cause grief.

But my spidey sense tells me it's something to do with your float and and fuel supply.
 
Re: Cold Start thoughs

I would also guess that it is a sticking float.
 
Re: Cold Start thoughs

I would put in new spark plugs one size hotter. Sometimes that makes an amazing difference and its a pretty cheap thing to try at first. I don't know much about the spit engine or what kind of carb or fule pump you have, but if its an electric fuel pump, you might try putting in a manual switch to kill the pump and run the carb slap out of gas before you park it for a while, you might have gas leaking down into one or two of the cylinders and wetting the plugs. Next I would check the valve lash, but I am thinking its not a compression problem with rings or anything. I have seen valves adjusted too tight and they stay cracked open when cold and then as the engine warms they start seating and the problem goes away. I found this problem on a friends motorcycle one time. The previous owner had never had the break in valve adjustment and the valves had worn down in the seat about .003 and mechanic at the dealer told him the engine was trash and out of the goodness of their heart they were offering to sell him a new motor :wink: It ran way to good when it ran for there to be anything seriously wrong with the engine. Your mechanic should be able to tell if its a problem with the spark or not. If he can't tell you that then you need to take it elsewhere. You can get one of those things from Harbor freight that goes inline with the plug wire and flashes with the spark. Put that on there when its acting up and see if the spark is cutting out or not. If it is, it might be the electronic ignition, if its not then you just ruled that out.
 
Re: Cold Start thoughs

I would say fuel too. Possible a leaking float bowl. Rodchesters had a problem with that. Changing plugs and wires isn't a bad idea, but I wouldn't go a heat range hotter though. These motors run on the warm side to begin with, and IMO, the last thing they need is a hotter combustion chamber.

Is the exhast sooty once it fires off for a while??
 
Re: Cold Start thoughs

So I changed out the plugs.... At the parts counter, I asked for some NGK's that I've used in the past with great success. Just for yucks I also asked for some Autolites,the same plugs that were in the car, only a temp range hotter.

Parts guy brings my NGK's and "63" Autolites. I was expecting "64" Autolites because the "65" was the correct temp range for the car. According to the parts guy's computer, the car should have "64's." At this point I'm totally confused, so I decide to go with the NGK's and see what happens.

I go install the NGK's, and low and behold, the Autolites in the car are "63's" As far as I'm concerned, these are two temps hotter than spec. Me thinks this is the problem....

Low and behold, the car starts right up with the NGK's.... Let's see how she does in the log run.

Thanks all for the advise. The info I glean from this site is invaluable to keeping the Midget on the road. Regularman's suggestion of the hotter plugs got me reading about temp specs on plugs and seems to have sent me down the right path for repair.
 
Re: Cold Start thoughs

On my 75 I run hotter plugs but still had difficulties starting when really cold. If you run into this try getting a reduction starter. Really made a big difference in cold weather starting.
 
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