Difficult cold start

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slantsixdan said:
Not a good pick; read this (about the same kit/same seller).

Then read about the HEI upgrade for a guide on how to do it better.



This one. As with all others you can buy now, it's going to be a Chinese copycat part.

Didn't sound like your starter was having problems, though; what makes you think it is?
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Thanks. I will go with hei if I am upgrading to pointless.
I am confused what causes this problem as all seems to work (ignition, carb, starter), so I am suspected for all components. I have no reason to suspect starter. Just have experience from other vehicle where new starter with "transmission" (I don't know what word in english means that starter has gears and it is not direct driving flywheel) made the difference.
Yes, there is something wrong with engine if it does not start with working original starter, but it would work as workaround maybe?
 
MV8 said:
I can't help you with not believing me, but the story seems to be changing. We can't see or hear anything you claim. All we have are your words. What was a "difficult" start at 10 Celsius is now "massive" at 30 Celsius. What was running and idling "great" warm is now suspected of having ignition and carb problems, but again, those areas can be improved by a mechanic.
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Sorry, I am not saying I don't believe in you. Just thinking that if cold intake would cause this kind of problems, why other cars doesn't suffer from it?

English is not my mother language so I don't always know how to write what I really want to say.

When I started this thread there was spring and temperatures were lower than now in summer. It seems that outside temp does not change this problem, maybe even higher temps make it worse for some reason.

Saying "massive" I mean that has happened twice that I could not start the car at all. Battery ended before it started.
Strangely after winter when I started car first time it started better than now when it has stood a week. Not good but with reasonable starting.

Why I suspect carb is that it really needs pumping gas constantly to keep it even promisising to start. Sounds not getting enough fuel to me. Can't say if there is something wrong with ignition as it is difficult to check how good spark is. I just think that if I convert to pointless it would solve ignition problems if it is the cause. And changing starter to new one would solve possibly starter problems. Those are not so expensible components that I am ready to invest to them even it would not solve problem, but after that I can be rule those out.

Forgot to say that I also tried with helper battery connected to main battery with cables. Trying to rule out voltage drop if old battery is not in good shape, but it didnot help at all. With digital multimeter it is hard to measure voltage drop when starting and I don't have analog one.

I need to do compression test at first.
Engine runs great when it is warm and it seems to have mostly horsepowers left but of cource it is possible that there is no enough compression in cold if oil has flown away from piston rings.
I don' t know how common this problem is and would it cause bad cold start?
 
Today I took off air filter and sprayed a little amount start pilot to carburetor (throttle open).
Engine started immediately.
I don't know if this proves anything but I think there could be something wrong with carb, but what it would be?
Accelerator pump gives strong squirts. But if engine should start without pumping gas, I don't know if that pump is needed to start cold engine at all, if everything is ok?
 
Could be weak spark and starting fluid helps it fire up. Have you measured volts at + side of coil while cranking?
 
MorganKane said:
I am confused what causes this problem as all seems to work (ignition, carb, starter), so I am suspected for all components.
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Don't fall into the trap of just throwing random lists of parts at the problem. That way you spend a lot of money, time, and effort, and likely don't fix the problem, likely introduce new ones, and never figure out what was causing the problem.

MorganKane said:
I have no reason to suspect starter. Just have experience from other vehicle where new starter with "transmission" (I don't know what word in english means that starter has gears and it is not direct driving flywheel) made the difference.
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Your original starter is a geared one. So is the mini starter.

MorganKane said:
Yes, there is something wrong with engine if it does not start with working original starter, but it would work as workaround maybe?
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No.
 
How about posting pictures? Perhaps a video with audio of you trying to start the engine that shows the carburetor linkage? I see many videos on youtube of people trying to start older cars. They typically just turn the key without working the throttle and it takes a long time to eventually crank. These things are obvious to us who grew up with and continue to operate carburetors.

The starting fluid you sprayed added fuel in a very easy to burn condition for the ignition system. It does not indicate exactly what the problem is.
 
I will try to take video. Difficulty is that I need to wait few days to get this problem to show up.
 
Understood. Not especially informative, but you might find this entertaining (note he chokes it with his arm). I'd love to have this combo:
 
Results of coil voltage when cranking?

Are the points in good condition and correct gap?
 
340sFastback said:
Results of coil voltage when cranking?

Are the points in good condition and correct gap?
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Today I measured coil voltage. It was 9.7 volts when cranking. I also wired temporal wire from battery to coil, but it didnot help start engine.
Battery voltage was 10.9 volts when cranking, so there is noticeable voltage drop to coil.
Without cranking, ignition on, coil voltage was 8.8 volts so coil resistor overdrive seems to be working.

Points seem to be good condition and correct gap.

My compression tester was malfunctioning so I could not measure compression reliably so far. I will buy new tester tomorrow.
 
I made compression test. But I wanted to do it with cold engine at first.
So I got 100-110 PSI readings what is quite low result I think.
But at least readings are quite even between cylinders.

I had no time to put spark plugs back and warm engine to take another test with warm engine as manual states.
I think that readings should be better with warm engine?
Service manual says that readings between 110-140 are ok.
Also, regarding manual, crank speed should be at least 130rpm but I have no rpm gauge and for me it seems that crankshaft maybe does not rotate over two rounds per second, but it is of cource difficult to estimate. I am little worried about starter motor as it seems to crank engine quite peacefully even there is no spark plugs in place and I had helper battery connected also.

What do you guys think, is it likely that those compression values are cause to hard cold starting?
 
No, those cold-compression numbers are plenty good enough for fast cold starts, once you will do the appropriate diagnosis and fix the likely fuel-related issue.
 
Any ideas how I can check/improve fuel system? Carburetor has no noticeable play in main axle.

This is my plan what I will try after driving season:

1. New spark plugs, wires, points and timing check + valve adjust

2. Add relay to coil power feed to provide better voltage to coil. Another relay for resistor override.

3. New "mini starter" and battery

4. disassembly carb, give it ultrasonic clean and put repair kit to it.

5. ? No idea if those won't work.
 
Plugs-wires-points, valve adjustment, timing check: all good ideas. Tune-up parts and technique suggestions in this post. Carb overhaul: another good idea. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

Your points 2 and 3 amount to throwing parts at the problem, which will probably not solve it or help anything, and will just eat up time, effort, and money. The ballast resistor is already bypassed during cranking; you don't have to put in a relay for that.

What is needed is basic diagnosis. Are the carburetor and the fuel line from fuel pump to carb emptying overnight so you have to crank the engine long enough to suck fuel from the tank and fill the line and carb back up with fuel before the engine will start?

Go to the car first thing in the morning, remove the air cleaner, hold the choke open, and operate the throttle. If you do not see a strong, steady shot of gasoline in the carburetor throat each time you open the throttle, the carburetor doesn't have fuel in it (or not much). A carb overhaul and new fuel pump will help, but it has grown difficult to get good-quality new Slant-6 fuel pumps—get an AC 6972, see advice here (and up-to-date eBay page here). If you are tempted to install an electric fuel pump, read this.

Or the fuel pump and carburetor might be fine, but the carburetor is boiling like a teapot after engine shutdown (heat rises), emptying it out overnight. This can be addressed by using the thick (9.5mm) carburetor mounting gasket, making certain your manifold heat control valve is operating correctly and not stuck, and doing the Fuel line mod.

Or the fuel pump and carburetor might be fine and there is enough fuel in the carburetor for a fast morning start, but the choke is not operating correctly. It has to close all the way (even with the air cleaner installed, so one morning go remove the air cleaner lid, press down on the base of the cleaner with your hand, and then open the throttle and look at the choke plate; is it all the way closed?).
 
Thanks slantsixdan.

I have tested carburetor and it makes strong shot of gas even after a week so I think there is enough fuel in bowl.
There is also thick gasket between carb and intake. But I think heat control valve is stuck, I haven't have time to check it yet, as I thought that it dose not affect this problem.

I have also checked choke. But it starts better without it (warm climates now), so I have disabled it temporarily now.

With choke on, car might not start at all, I assume that it gets too much fuel and wets spark plugs.
With choke, it does not even promise to start. If I pump pedal, it looks that it wets spark plugs.
Without choke, it starts "promising" to start when I pump pedal, but it still takes long time cranking and pumping until engine stays running after I release starting.

I try to take video next time.

Why I want to add relays to coil circuit is that my opinion is that under 10v when cranking is too little. I think that volts are lost in ignition switch circuit and wires so wiring relay direct from battery would help voltage not dropping so much. I am electronics engineer so electrical circuits are not problem.

This thread is also my checklist for things I need to do next winter.
 
MorganKane said:
Why I want to add relays to coil circuit is that my opinion is that under 10v when cranking is too little.
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It's not. The starter motor's load drags line voltage down significantly—on every car, not just yours—and they start up just fine, even in the cold when line voltage during cranking can be in the neighbourhood of 10v.

Taking the loads off the ignition switch contacts and firewall pass-through connectors isn't a bad idea and won't hurt, but the car's lack of such a relay now is pretty much certainly not causing your hard starting.

Videos are a good idea.
 
At last I had a chance to take video. In that case car has stood four days alone. Thoughts?

 
Sounds a lot like it's not getting fuel because the choke isn't closing all the way, but also looks like you're not using correct starting procedure. That is: kick the accelerator to the floor once (twice if it's really cold or the car's been sitting a long time), then take and keep your foot away from the pedal, then crank the engine. If you've got your foot on the pedal while cranking, the choke will want to flop open. If you're sitting there pumping the accelerator, the odds are you're going to go from too lean to too rich by flooding the engine.

And for the love of Odin and Thor, once the engine starts, do not go revving it unless you like grinding parts to pieces while they're waiting for oil.
 
Trust me, I have tried all possible methods.
If I use method you (and manual) suhgest, it will not start ever.

Also, revving is only way to keep it running (or it revs because gas pedal is pressed to the bottom). I am aware that it is not good for the engine.

Only way to get it running is to keep pedal pressed. Also with warm engime, it will not start until I press pedal to the floor what is also odd.

I also think that this is fuel related problem, but like I said, it squirts strongly when pressing pedal before start.

Is it possible that there is fuel in accelerator pump but not in bowl? Are they related? I don't know how this carb works, it there is separate "fuel storage" for accelerator pump or not.
 
MorganKane, I have exactly the same problem with my /6. Hard cold starts, even in warm weather.
Spraying Start pilot into the air filter helps a lot

I think that the problem comes from the fuel pump (in my case, it's the original one and it is 53 y.o.). It works to feed the carb, but I think that it doesn't prevent fuel to come back to the fuel tank when the engine isn't started for a long time.
So, the lines are empty, the fuel pump has to suck fuel from the tank and it takes time

IMO, the best solution : you (and I) have to change the fuel pump.

François
 
Morgan, the request was for a video of the carb during cold cranking, however the video you posted does not show any pumping of the throttle before engaging the starter. You could have a suzuki motor under the hood for all that we can see. You've been given much good advice but seem to debate instead of follow, even though you are the one who is confused. Pics and video, not assertion.

I expect Finland has only high ethanol content fuel which leans the mixture if not adjusted for it. Few carbed vehicles are so finely setup that no throttle pumps are needed prior to cold start after a few days.

If you won't change anything else, then change your starting technique.
 
French demon said:
MorganKane, I have exactly the same problem with my /6. Hard cold starts, even in warm weather.
Spraying Start pilot into the air filter helps a lot

I think that the problem comes from the fuel pump (in my case, it's the original one and it is 53 y.o.). It works to feed the carb, but I think that it doesn't prevent fuel to come back to the fuel tank when the engine isn't started for a long time.
So, the lines are empty, the fuel pump has to suck fuel from the tank and it takes time

IMO, the best solution : you (and I) have to change the fuel pump.

François
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François,
I have added one-way valve after fuel filter. It didnot help at all. So I don't believe it is fuel pump issue.
Also carb accelerator pump gives strong squirt of fuel even cold so there is fuel in carb.
Albeit symptoms are same as yours. Please tell me if you find a solution.. :)

MV8 said:
Morgan, the request was for a video of the carb during cold cranking, however the video you posted does not show any pumping of the throttle before engaging the starter. You could have a suzuki motor under the hood for all that we can see. You've been given much good advice but seem to debate instead of follow, even though you are the one who is confused. Pics and video, not assertion.

I expect Finland has only high ethanol content fuel which leans the mixture if not adjusted for it. Few carbed vehicles are so finely setup that no throttle pumps are needed prior to cold start after a few days.

If you won't change anything else, then change your starting technique.
Click to expand...

What advice should I follow? I have tested compression, fuel squirt, coil voltage, ballast resistor, battery voltage
Manual says that DO NOT press gas pedal before cold start. However, I have tried all methods:
- Not touch gas pedal at all
- Give it light press to engage choke
- Pump it few times before start

Not any of those methods work. Choke closes fully and also high idle cam seems to work.
Giving a little pilot spray and engine starts right away, so my main suspect goes to carb, but all I can consider is give it ultrasound wash and put repair set to it or replace whole carb. But there seems not to be direct swap carbs available so it is a project also.

It is difficult to take video from engine/carb and start car same time. I mostly start it alone so there is no help available.
It also takes two days or more to this problem arise again so not much possibilities to diagnose or take videos.
 
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