Truck won't start in cold weather
 

I have a 80' pickup with a 20r in it, the problem I have is starting it in the cold weather. Usually in the morning when it's anywhere from 39-50 degrees out my truck just cranks and cranks with no sign of starting up and at first when I would jump start it it would start crank right up. Yesterday I took the battery out and went to have it tested and everything was fine with it, so when I got home I loosened all the grounds and cleaned them along with the surrounding area. This morning when I went to start it, same thing happened but this time jumping it didn't make a difference. I know when I bought this truck somebody had converted it with a GM alternator and I'm assuming its a GM ignition module but either was it will not start in cold weather it seems, however, yesterday around noon I turned off the truck to check the mail and no start again, had to jump it to start. I have searched for this similar problem online with no luck. I am stumped at what it could be, any help would be great. Thanks.

I'm far from an expert, but it may be a choke issue with your carb. I would give that a look.

If you turned it off long enough to check the mail and then got right back in it would still be hot...no need for the choke on a hot start.

You mentioned the only way to get it started again was to jump it. Is the engine turning over and just not firing or is it not doing anything like a dead battery?

Well it depends, sometimes (like today) I hook the battery cables right up and it fires right up and other times nothing does the trick. This morning I started my truck right up with no issues...mainly because it was in the garage. I left my truck outside (temperature was 38-40 degrees) all day at work and when I went to leave today nothing just cranked and cranked, my buddy said it sounded slow so we hooked the jumper cables up to it and it started right up, then once I got home and parked it in the garage I turned it off and tried to start it again and it wouldnt start again. Heres everything I've done to this truck thus far:

-Cleaned and replaced both the positive and negative battery cables.
-Had the battery checked and cleaned the battery posts.
-Cleaned the Weber air filter.
-Cleaned the fuel tank.
-Replaced all the rubber fuel lines and fuel filter.
-Changed Spark plugs and Spark plug wires.
-Ran a can of Sea Foam through the fuel system.

Do a voltage test on the battery while it's sitting and while is running. You should have 12 volts just sitting there and around 14-16 while the truck is running. Your battery can test good and still be bad. It's also a good indication of a bad battery when you can jump it and it starts every time. Try a new battery or borrow one from a friend if you can and see if that fixes it.

Because theres mixed results on the electrical stuff and the fact that its always cranking over just fine id say its not that.

It is a possibility that your accelerator pump is bad,, and your carb is leaking fuel into the intake overnight.

22r carbs can leak fuel if they are in need of a rebuild, and accelerator pumps in the carb can cause hard starts.


you dont have to, but this is what I would do.

One of these times when it wont start. Try dumping a tiny bit of fuel directly into the carb and try again. Just to see.

Oh thats right theres more to that.


The fuel that leaks into the intake slowly is what helps it start after its been sitting. You also had a dead battery in the morning so it wouldnt turn over, but when you jumped it,, it started because of the fuel in the intake.

After sitting warmed up for only a few minutes or hours it didnt want to start because the accelerator pump wasnt squirting any fuel in there, and your carb needs a rebuild so the venturi's arent going to start squirting any fuel until the motors got some actual vacuum going on there.

Or something like that :think:

After I wrote the reply earlier I went out and took the air filter off the carb and pulled the throttle cable, I could see fuel being shot into the carb as I pulled the cable. Wouldnt you know the truck started just fine after it had sat there for 30-40 minutes but wouldnt start as soon as i got home and shut it off and attempted to start. its like the carb is starved of fuel after being ran a good amount of time and then when some time has passed it starts just fine....as long as its not in the cold. Tested my battery also, 12.3 off and 14.5 started. Why is this cold weather affecting my truck?

Ya its not battery related, still goes along with what I was saying.


But im not sure excactly whats going on there.

I guess maybe those temperatures are cold to you but they are not really cold.When things are good these engines fire right up down below freezing with no problem.

Wonky Carbs can cause some strange starting issues.You did not mention changing a fuel filter was that just a oversight or did you not change it.

If the fuel is leaking into the engine are you checking your oil level is it rising??

Perhaps when it cranks but does not start you might also want to check for spark. Good spark plug wires plugs gaped correct??

Once the engine is running it runs like it should no other issues ??

You said you "cleaned the webber air filter" Do you have a webber carb or toyota carb?

I changed the fuel filter and replaced all the spark plugs and wires with NGK and checked the gap before installing. It's a Weber Carb.

I don't know webers that well, but as it has already been stated it sounds like the accelerator pump is gone in yours, causing the carb to drain. That would explain the hard starting, because each time you try to start the carb has to be primed.
According to the info given here: http://www.jtoutfitters.com/pages.php?pID=36 most Weber Carbs in the US have an electric choke.. some have a thermal choke much like the 60-80 GM's. Either type can be a royal PIA! They are great if they work right, but they seldom do. My advice would be:- determine which type of weber you have put a rebuild kit in it (not rocket science) and install a manual choke conversion kit. Once you do that I think you will solve your starting problems.