Topic: 22R cold starting.

[Lewis Hein]

Hi all,

I have a recently acquired stock '85  pickup with a 22R motor. It seems to run great, except that cold starts are a PAIN. If the temperature is below about 50 F, I have to pump the gas pedal twice before cranking and it will probably run. If the temperature is below about 35, the procedure is more like:

1) pump the gas pedal twice.
2) Crank the engine. It fires and dies.
3) Pump the gas pedal a few more times.
4) Crank the engine again. It fires, and usually runs if I give it gas. But sometimes the gas pedal seems to do nothing at all at this stage, and the engine dies.
5) If the engine didn't start at step 4, keep on cranking and giving it gas when it fires until it decides to run. Usually, I don't have to repeat this more than once or twice.

I have checked and adjusted timing and fast idle speed. I have checked the plugs and distributor; the plugs are new and well adjusted and the distributor is clean. I've sealed lots of vacuum leaks but there could still be one or two hanging around.

I am at 5500 feet elevation, running 85 octane gas, and no HAC (the original one was broken and I can't find a replacement). Also worth mentioning: I am told that this truck was used for towing behind a motor-home for years and years. Thus, I assume it had ample opportunity for the carb to get gummed up.

So -- What is my problem? Is this normal starting behavior for a 22R? Do I need to rebuild the carb? Try to repair my HAC?

Thanks,

Lewis.

P.S. I can't speak for how it starts when the temperature is above 50F -- That will have to wait for spring!

[H8PVMNT]

I have been trying to tune for the cold start for a while.  I live in MT and we have had a lot of sub zero temps this winter. 

Your cold start sounds pretty typical for the stock 22R carb. As much as I like the Aisan carbs I will admit that these things are cold blooded. Mine is freshly rebuilt, fairly clean and all the cold start features are working. I usually have to let mine fire once, sometimes twice before it will keep running below freezing.  It will keep idling kind of low at this point and in about a minute or two I can drive away.

Usually I pump the pedal twice, then it fires and dies.  The second time, I pump twice and it fires and may or may not run that time.  The third time I usually always get it going, however, if I push the gas pedal it at all for the first 30 seconds or so it will die.

The HAC probably won't help with the cold start but it would be worth running if you can find one just for dealing with the altitude.

I would start by setting your idle mixture per the manual.  Turn your mixture screw all the way in to the shut position then back it out like 2 1/2 turns.  It's OK to adjust your idle speed screw to crack the butterfly just a bit to get the cold start.  This sometimes helps and basically gives you a slightly open primary.  You don't want too much, just a bit.  In winter tune mode I like my warmed up idle at about 1,200 rpm. This will be a balancing act between idle mixture, idle speed and ignition timing.  This position seems to like to start better.

You should probably check to see if the choke is doing what it is supposed to.  This is the plate on the carb located on the drivers side on top of the secondary. It should be closed on startup then slowly open as the engine warms up.

I have also had good success advancing the ignition timing a bit for winter.  This might make it so you can't run on 85 octane any more but it helped me get the cold start.

It never hurts to rebuild your unknown, old carb.  I would do it when you get the time.

On other thing I have learned is that it seems to help the cold start if you run a little bigger main jet.  I started with a 112, then swapped to a 119, now I run a 116 main jet.  The fatter (richer) main jets seem to cold start a bit better.  If you don't have any carb laying around to scavenge jets you can use Hitachi main jets.  They are the same size and have the same number system as out Aisan carb main jets.

I ordered a 116 from these guys a while back...

http://www.jetsrus.com/a_jets_by_carburetor_type/jets_hitachi_main_4H7.html


One more thing.  I have had good success running thinner oil in the winter. I was running 5W30 and that was better in the cold than 10W30, but I recently switched to Mobile 1 0W40 and it made a large, noticeable difference in the cold start.  I got it on the second bump this morning at 18 degrees.  At 10 below F it will still start after a couple bumps of the starter. At 20 below it will still do it with some effort but the block heater is really nice .

[Lewis Hein [OP]]

Thanks for the suggestions. I will have to look into those jets. I already tried adjusting the idle mixture screw, but it won't turn, and if I remember right, the slot is the worse for at least one attempt prior to mine.

I am in central WY, and got the truck just before a spate of sub-0 temperatures. When this hit, it would not start because the hoses to the HAC valve were all disconnected and hanging loose. I plugged those leaks and it started, but not willingly. Now, after setting the timing, slow idle, and fast idle, it runs and idles a lot better but the starting hasn't improved greatly.

I love block heaters. But this is a field truck that needs to start in all weather, even if I don't have an outlet nearby.

[Gnarly4X]

H8PVMNT obviously knows his poop.

He has provided some really good information!

My 85 22R was at high elevation 9,500 feet and below, and sub 32d F temps many times.

At your elevation it's not uncommon for a 22R to act up at cold starts.  The oil viscosity is a really noticeable issue at really cold temps... especially at very cold starts.

The only comment I can add at this point is a possible failed AAP diagphram.  If it has a hole in it, it may not pump enough fuel into venturi to cold start the engine, and after it starts, it may cause hesitation at the throttle, or blubbering like the choke is on.

The spark is really critical to fire a rich mixture, so make sure the disty cap, rotor, spark plugs, and plug wires are fresh!

Gnarls.

[Lewis Hein [OP]]

The fellow I bought it from had put in new plugs and HT wires. I checked these and they seem good. I have no idea of the age of the distributor cap, but it shows no signs of moisture or cracking.

I will have to look at the choke and the AAP diaphragm. And maybe replace a few more hoses. I would also like to rebuild that carb -- just so I know it's in top running order.

Thanks, everyone for all the useful info.

Lewis

[H8PVMNT]

I hate to say it because I love carb, but if you really need a no drama cold start just swap some 22re EFI stuff in there.  You can get it cheap off somebody doing a 3RZ swap.  You need the harness, ECU all efi stuff including the 02 sensor and the fuel pump, but it will all go on in that '85 no problem.

My kid has a '92 22re and it starts no matter what.

[Gnarly4X]

....
 I have no idea of the age of the distributor cap, but it shows no signs of moisture or cracking.....

Hi Lewis Hein,

If you haven't already, look at the contacts in the distributor cap and rotor tip carefully.  There will usually be some rough looking corrosion on the contacts.  You can take a little flat head screw driver and gently scrape it off, don't remove any metal.  Look at the edge of the contact on rotor for the same build up.  It's carbon arc blow caused by the arcing when it's firing each cylinder.  If the cap and rotor develop too much carbon on the contacts, the stand off voltage will be too low to provide adequate spark to the plugs.

If the contacts are pitted badly, you should replace the cap and rotor.... really cheap but very important parts!!  I prefer the cap and rotors with copper contacts, not aluminum alloy.  Copper is a better conductor than aluminum.  I believe Echlin (NAPA) still uses copper.

Gnarls.