Carburetor engine difficult cold starting

[RigerZ]

I have a 1981 Datsun 120Y which very often has trouble starting in cold weather, especially after overnight rain. Even using the choke doesnt seem to work. I'm pretty sure the problem lies somewhere in the carburetor, but my dad suspects the ignition coil isnt making enough voltage for the spark plugs.

But then again I do notice my battery is significantly weaker in colder weather and the cranking isnt as strong. When I give it a jump start the engine would start almost all the time. I seem to understand that the weaker battery would cause the following (please correct me if mistaken):

- Slower cranking leading to weaker compression in the cylinders; air/fuel mixture doesnt burn properly

- Less voltage going to the ignition coil and finally to the spark plug; weaker spark doesnt ignite the air/fuel mixture

Anyone knows any other possible causes of this problem?

 

[vr2turbo]

Why not just change the battery and try. If okay, problem solved.....

 

[Supra_Fanatics]

I have a 1981 Datsun 120Y which very often has trouble starting in cold weather, especially after overnight rain. Even using the choke doesnt seem to work. I'm pretty sure the problem lies somewhere in the carburetor, but my dad suspects the ignition coil isnt making enough voltage for the spark plugs.

But then again I do notice my battery is significantly weaker in colder weather and the cranking isnt as strong. When I give it a jump start the engine would start almost all the time. I seem to understand that the weaker battery would cause the following (please correct me if mistaken):

- Slower cranking leading to weaker compression in the cylinders; air/fuel mixture doesnt burn properly

- Less voltage going to the ignition coil and finally to the spark plug; weaker spark doesnt ignite the air/fuel mixture

Anyone knows any other possible causes of this problem?

I was thinking the same whether my carb kancil is also because of this problem. Actually happens after replacing the spark plugs and the plug cables to borsch ones. :hmmmm:

 

[vr2turbo]

I was thinking the same whether my carb kancil is also because of this problem. Actually happens after replacing the spark plugs and the plug cables to borsch ones. :hmmmm:

Yours is still the old battery?

 

[DanzEterna]

I have a 1981 Datsun 120Y which very often has trouble starting in cold weather, especially after overnight rain. Even using the choke doesnt seem to work. I'm pretty sure the problem lies somewhere in the carburetor, but my dad suspects the ignition coil isnt making enough voltage for the spark plugs.

But then again I do notice my battery is significantly weaker in colder weather and the cranking isnt as strong. When I give it a jump start the engine would start almost all the time. I seem to understand that the weaker battery would cause the following (please correct me if mistaken):

- Slower cranking leading to weaker compression in the cylinders; air/fuel mixture doesnt burn properly

- Less voltage going to the ignition coil and finally to the spark plug; weaker spark doesnt ignite the air/fuel mixture

Anyone knows any other possible causes of this problem?

i tot all old cars has problem during cold start, had a Toyota LE before gotta pump the accelerator when turning the ignition

 

[Supra_Fanatics]

Yours is still the old battery?

New bro. Changed to NMF battery. Just recall after changing the plug cables and spark plugs and also did the air valve on the same day. Only got such problem after that. Before that it was okay.

So not sure if the spark plugs is the wrong one given. Plug Cables are borsch.

 

[vr2turbo]

New bro. Changed to NMF battery. Just recall after changing the plug cables and spark plugs and also did the air valve on the same day. Only got such problem after that. Before that it was okay.

So not sure if the spark plugs is the wrong one given. Plug Cables are borsch.

Then is new battery mah! Not battery issue dy......

 

[RigerZ]

i tot all old cars has problem during cold start, had a Toyota LE before gotta pump the accelerator when turning the ignition

Thats what the choke should be for, but on my car the choke doesnt help :(

 

[Supra_Fanatics]

Then is new battery mah! Not battery issue dy......

Could it be plug cables or spark plug problem? Cold start only problem. Always have to step on gas a bit to prevent it from dying off. Another way is crank until start. If die off, start again 2nd time then it will be okay. 2 way. But step on gas vibration not that bad.

 

[vr2turbo]

Thats what the choke should be for, but on my car the choke doesnt help :(

Have you ever had the carb serviced? Could be dirty and choke not working?

---------- Post added at 07:49 AM ---------- 6 hour anti-bump limit - Previous post was at 07:46 AM ----------

Could it be plug cables or spark plug problem? Cold start only problem. Always have to step on gas a bit to prevent it from dying off. Another way is crank until start. If die off, start again 2nd time then it will be okay. 2 way. But step on gas vibration not that bad.

Sound like fuel ratio is lean for cold start. Try the choke or like you say just step a bit on accelerator until stable. No two cars start the same way. Even my VR sometimes stable, sometimes chokes and cough, step of accelerator a while and then stable...hahahaha

 

[kazukimy]

Change battery, if it is done, check your carb, try to service it, den tune it...used to do tat to my tiara, running on carb...

 

[Supra_Fanatics]

Have you ever had the carb serviced? Could be dirty and choke not working?

---------- Post added at 07:49 AM ---------- 6 hour anti-bump limit - Previous post was at 07:46 AM ----------



Sound like fuel ratio is lean for cold start. Try the choke or like you say just step a bit on accelerator until stable. No two cars start the same way. Even my VR sometimes stable, sometimes chokes and cough, step of accelerator a while and then stable...hahahaha

Yup doing that every morning Step on gas a bit and let it run gradually awhile. Then only jalan. After that the rest of the day should be fine unless I leave it till night time then got slight cold start problem. But is bearable.

Change battery, if it is done, check your carb, try to service it, den tune it...used to do tat to my tiara, running on carb...

How to tune? U mean adjust the choke?

 

[vr2turbo]

Yup doing that every morning Step on gas a bit and let it run gradually awhile. Then only jalan. After that the rest of the day should be fine unless I leave it till night time then got slight cold start problem. But is bearable.



How to tune? U mean adjust the choke?

Fong should have tuned it already, right?

 

[Supra_Fanatics]

Fong should have tuned it already, right?

Yup, but still have cold start issues Cuz by the time i reach there no more cold start issues.

 

[kazukimy]

Nope, adjust choke just merely open up throttle, use screwdriver and adjust the fuel ratio to the carburetor.

How to Adjust a Carburetor: 10 Steps (with Pictures) - wikiHow

 

[Supra_Fanatics]

Nope, adjust choke just merely open up throttle, use screwdriver and adjust the fuel ratio to the carburetor.

How to Adjust a Carburetor: 10 Steps (with Pictures) - wikiHow

maybe shud use tb cleaner to wash the throttle and see how. I saw a bit oily inside.

Meaning to say according to the article, car running too lean also not good it seems. Will try to adjust again

 

[twistedichc]

didn't know adjusting the throttle (accelerator) cable can adjust idling, for my AT deer, adjusting it oni sets the gear changing mechanism to faster @ slower response.

 

[vr2turbo]

Yup, but still have cold start issues Cuz by the time i reach there no more cold start issues.

Tuning the carb is not for cold start issue. Is For normal driving.

Choke is for cold start but your very minimal so don't bother, just step a bit on accelerator....

---------- Post added at 09:17 PM ---------- 6 hour anti-bump limit - Previous post was at 09:14 PM ----------

maybe shud use tb cleaner to wash the throttle and see how. I saw a bit oily inside.

Meaning to say according to the article, car running too lean also not good it seems. Will try to adjust again

Worse case, open up and service the carb. Since most of the other parts have already been done, like your brake fluid nipple also jammed up already....

---------- Post added at 09:19 PM ---------- 6 hour anti-bump limit - Previous post was at 09:17 PM ----------

didn't know adjusting the throttle (accelerator) cable can adjust idling, for my AT deer, adjusting it oni sets the gear changing mechanism to faster @ slower response.

That one is when no adjustment screw. By pulling the cable tight already open up slightly the fuel feed to increase the idling....

 

[Supra_Fanatics]

Tuning the carb is not for cold start issue. Is For normal driving.

Choke is for cold start but your very minimal so don't bother, just step a bit on accelerator....

Worse case, open up and service the carb. Since most of the other parts have already been done, like your brake fluid nipple also jammed up already....
That one is when no adjustment screw. By pulling the cable tight already open up slightly the fuel feed to increase the idling....

Open up and clean? Can get your guidance ar? I only so far see the carb area that looks like throttle body flap. That part that I posted in whatsapp today. Izso said use carb cleaner to clean that part.

Ya so far only cold start vibrating. Other than that when driving, engine is consider smooth. Maybe can adjust to the best that can save more fuel? LOL!

Last time when it was vibrating more when driving, it saves more fuel. Now adjusted not much vibration but seems I can no longer hit 260km, now only 220-230km full tank LOL! Maybe max 240KM

 

[twistedichc]

Open up and clean? Can get your guidance ar? I only so far see the carb area that looks like throttle body flap. That part that I posted in whatsapp today. Izso said use carb cleaner to clean that part.

Ya so far only cold start vibrating. Other than that when driving, engine is consider smooth. Maybe can adjust to the best that can save more fuel? LOL!

Last time when it was vibrating more when driving, it saves more fuel. Now adjusted not much vibration but seems I can no longer hit 260km, now only 220-230km full tank LOL! Maybe max 240KM

in u'r case, the oni thing I can think of is, when idling u'r rpm is higher coz want to reduce the mounting vibration, when gear engage its rpm is lower but less engine vibration, so the more u'r car idles, the more fuel consumption. I know this coz the same wit my dear + my tachometer reading is like that when idle & engage gear

 

[Supra_Fanatics]

in u'r case, the oni thing I can think of is, when idling u'r rpm is higher coz want to reduce the mounting vibration, when gear engage its rpm is lower but less engine vibration, so the more u'r car idles, the more fuel consumption. I know this coz the same wit my dear + my tachometer reading is like that when idle & engage gear

Ya my mech did tell me that but I didnt know will drop that much LOL!
short of 20-30KM. He afraid he adjusted already no vibration but FC affected slightly.

So might try to adjust DIY and see to a level that I like. See the difference.

 

[vr2turbo]

Open up and clean? Can get your guidance ar? I only so far see the carb area that looks like throttle body flap. That part that I posted in whatsapp today. Izso said use carb cleaner to clean that part.

Ya so far only cold start vibrating. Other than that when driving, engine is consider smooth. Maybe can adjust to the best that can save more fuel? LOL!

Last time when it was vibrating more when driving, it saves more fuel. Now adjusted not much vibration but seems I can no longer hit 260km, now only 220-230km full tank LOL! Maybe max 240KM

Open and clean need mechanic to do. Will take apart and clean the internal so will need carb kit also.
But since it is idling at start only, might as well forget it first until some major stuffs....hahaha

 

[Supra_Fanatics]

Open and clean need mechanic to do. Will take apart and clean the internal so will need carb kit also.
But since it is idling at start only, might as well forget it first until some major stuffs....hahaha

Major stuffs? Gonna let it be until it crashes Well must be right timing at as when I have the budget

 

[vr2turbo]

Major stuffs? Gonna let it be until it crashes Well must be right timing at as when I have the budget

Your budget must be huge. Repairs, Mira transplant, Jetta BOT, Mini suspension....

 

[Supra_Fanatics]

Your budget must be huge. Repairs, Mira transplant, Jetta BOT, Mini suspension....

That's the problem. I can't seems to focus on one. All also want to touch. Realised that I have to focus on one 1st.