[pheru8b]

I bought one of the last Zens which had a carburetor in 2000. The car has been a reliable companion all these years, and I have done over 90k km in it. I even proposed to my wife in the car, so letting it go isn't an option!

Now 22 years old, the engine has a strange issue.

It starts immediately and idles well. But the moment I shift into 1st gear and accelerate, the engine appears to choke up and shuts down. After 3 to 4 minutes of idling the issue reduces, but doesn't go away, so while I can drive the car, every time I accelerate, it first slows down, struggles a bit like it's timing is off, then slowly, very slowly, starts to pick up speed. It works fine till the next red light, when this struggle starts all over again when I start driving from stop.

I've tried 2 mechanics, and both are nonplussed. I've changed the air filter, engine oil, spark plugs, carburetor, to no avail.

Can anyone please help me, or recommend a good engine specialist is south or Central mumbai?

[BeemerBug_06]

Originally Posted by pheru8b

I bought one of the last Zens which had a carburetor in 2000. The car has been a reliable companion all these years, and I have done over 90k km in it. I even proposed to my wife in the car, so letting it go isn't an option!

Now 22 years old, the engine has a strange issue.

It starts immediately and idles well. But the moment I shift into 1st gear and accelerate, the engine appears to choke up and shuts down. After 3 to 4 minutes of idling the issue reduces, but doesn't go away, so while I can drive the car, every time I accelerate, it first slows down, struggles a bit like it's timing is off, then slowly, very slowly, starts to pick up speed. It works fine till the next red light, when this struggle starts all over again when I start driving from stop.

I've tried 2 mechanics, and both are nonplussed. I've changed the air filter, engine oil, spark plugs, carburetor, to no avail.

Can anyone please help me, or recommend a good engine specialist is south or Central mumbai?

Hey man, first off all great to see that you've retained the car. Secondly, the problem faced by you isn't anything extraordinary. It's a common occurrence for carburetted cars. I too faced something similar in my own Zen which is a 96' carb model. As per what you've written, I think the carburettor is probably clogged with gunk and dirt accumulated over time , which is causing the "Slow Jet" to not work properly. The slow jet is a vital component necessary to keep the car running smoothly at low speeds and RPMs . If not the slow jet, then it could be an issue with the accelerator pump. I think a complete carb service, overhaul, tune-up and tappet set is in order for your car.

Also, what about the fuel filter and fuel pump assembly ?
Have you replaced them too ?

For any further queries feel free to PM me at anytime

https://www.team-bhp.com/news/regret...lessons-learnt
Here's my thread which is all about my Zen. This portion specifically focuses on a similar issue I faced with my carb.

[Jeroen]

Beemerbug has some very good points.

In addition I would check a few ignition components and settings.

Did you check the contact breaker? Is the gap set sufficiently? What is the state of the contacts? They do wear down, so do need adjusting and ultimately replacing.

I would also check the static and dynamic advance of the ignition. Recently I have had some issues with my W123 which is also a carburettor engine.

You, or your mechanic, should ideally have a timing light and or dwell meter. Although it might be possible to measure the static advance with a simple test light.

You are likely to have a vacuum and or centrifugal advance on the distributor. Make sure they work correctly. Vacuum hoses perish causes less vacuum. The mechanical centrifugal advance wears out after a while.

Good luck

Jeroen

[BeemerBug_06]

Originally Posted by Jeroen

Beemerbug has some very good points.

Did you check the contact breaker? Is the gap set sufficiently? What is the state of the contacts? They do wear down, so do need adjusting and ultimately replacing.

I would also check the static and dynamic advance of the ignition. Recently I have had some issues with my W123 which is also a carburettor engine.

You, or your mechanic, should ideally have a timing light and or dwell meter. Although it might be possible to measure the static advance with a simple test light.

You are likely to have a vacuum and or centrifugal advance on the distributor. Make sure they work correctly. Vacuum hoses perish causes less vacuum. The mechanical centrifugal advance wears out after a while.

Good luck

Jeroen

Completely agree with what you said there. However, in the case of the Maruti Zen carb, the distributor is a Direct Electronic type ignition distributor and not the Contact Point condenser type which was found in the other cars sold by Maruti at the time such as the 800, Omni etc. The points going weak or burning out is a common issue faced by several 800 owners to this day.

Sure, there are chances of the Zen' distributor not working right too after all these many years. So good that you mentioned it here

Again a good point about the vacuum advance. The Zen indeed has a vacuum line going from the carb to the distributor and as said, the problem could be something as simple as a leak in one of the lines !

Off topic : But do share some more info on your W123. Would love to know more about it. Never really had the chance to learn and experience a Petrol W123 till now. Have only been around the diesels.

[Jeroen]

Originally Posted by BeemerBug_06

Completely agree with what you said there. However, in the case of the Maruti Zen carb, the distributor is a Direct Electronic type ignition distributor and not the Contact Point condenser type which was found in the other cars sold by Maruti at the time such as the 800, Omni etc. The points going weak or burning out is a common issue faced by several 800 owners to this day.

Thanks, I was not aware. It has the same set up as my Mercedes W123. Although rare, but you might have a problem with the electronics. I checked and double checked all of mine on the W123, see below

You still need to check the static advance and the vacuum advance.

Originally Posted by BeemerBug_06

Off topic : But do share some more info on your W123. Would love to know more about it. Never really had the chance to learn and experience a Petrol W123 till now. Have only been around the diesels.

I maintain a dedicated thread to fiddling with all of my cars. It is more or less a chronological story of what I do, so you might have to scroll through a few post dealing with some other cars and or topics.

But a few pointers.

checking the ignition and checking for possible vacuum leaks on the carburettor, checking coils etc.

https://www.team-bhp.com/forum/diy-d...ml#post5449738


Taking the ignition electronics apart for checking and desoldering:

https://www.team-bhp.com/forum/diy-d...ml#post5449738

Overhauling the W123 Stromberg 175CDT Carburettor.

https://www.team-bhp.com/forum/diy-d...ml#post5449738

Putting it all back together:

https://www.team-bhp.com/forum/diy-d...ml#post5474711

Checking ignition advance

https://www.team-bhp.com/forum/diy-d...ml#post5474711

You can also just start with the first link I provided and keep scrolling through. There are some other W123 bits in various other posts.

This Thursday I am working on my friend’s Peter 50 year old Jaguar XJ. It won’t start at all, so we will be working on the ignition and carburettors. If we get it to run, we are replacing the older breaker points for a modern electronic ignition too.

I will post all the details of that job afterwards.

Jeroen

[prasad666]

Originally Posted by pheru8b

I bought one of the last Zens which had a carburetor in 2000. The car has been a reliable companion all these years, and I have done over 90k km in it. I even proposed to my wife in the car, so letting it go isn't an option!

Now 22 years old, the engine has a strange issue.

It starts immediately and idles well. But the moment I shift into 1st gear and accelerate, the engine appears to choke up and shuts down. After 3 to 4 minutes of idling the issue reduces, but doesn't go away, so while I can drive the car, every time I accelerate, it first slows down, struggles a bit like it's timing is off, then slowly, very slowly, starts to pick up speed. It works fine till the next red light, when this struggle starts all over again when I start driving from stop.

I've tried 2 mechanics, and both are nonplussed. I've changed the air filter, engine oil, spark plugs, carburetor, to no avail.

Can anyone please help me, or recommend a good engine specialist is south or Central mumbai?

Please get the fuel pump checked. I too faced similar issue in my 1994 zen and the issue was resolved after replacing the fuel pump motor.

[bikertillidie]

Pheru8b,
Please check the fuel system starting with the fuel pump, strainer, fuel filter, fuel lines. Hope there isn't any clogging nor leakage.
Next, check the ignition system - ignition coil, HT leads, spark plugs, distributor cap and rotor. Clean up everything as necessary.
Service the carburettor, pay attention to the jets, dashpots, vacuum lines, fuel enrichment device(aka accelerator pump), butterfly valves (both primary and secondary), replace all gaskets/seals during the process.
Run a compression test on all cylinders, adjust tappets per specification.
Last, check and adjust ignition timing as needed, tune up the carburettor.

P. S. Do check the timing belt as well. 22 years is a long time. The tensioner can become weak, and I have seen belts slip a tooth or two.

Please PM me in case of any doubts.

[suryaj1990]

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