[anjan_c2007]

I am not very sure about the common rails that I have been using since the last four years. I have never faced the problem with my Scorpio.
But all the older diesels I had used, right from the Mahindra CJ 500 D, FC 260 D, 540 DP and later the XD3P had vapour lock problems.
That is, the last five litres or so of fuel acts as reserve and topping up would be extremely essential once the fuel level came to the low point.
The vapour lock problem can get on our nerves, as the fuel pump just refuses to pump the diesel fuel to the engine owing to the fact that there is an air pocket, that affects the functioning of the fuel pump.
Hence, for all the older diesels the vapour lock has been a perennial problem and restarting the engine meant one would have to push the fuel piston in the Mico Bosch fuel pump and drive away the air pocket to release the vapour lock and ensure smooth flow of the fuel.
The Tata and Ashok Leyland trucks too suffer from vapour locks, if the fuel level in the tank is very alarmingly low.
With petrol engines, this problem is not faced and one can safely go to the last drop of fuel.

[a4anurag]

Originally Posted by anjan_c2007

The vapour lock problem can get on our nerves, as the fuel pump just refuses to pump the diesel fuel to the engine owing to the fact that there is an air pocket, that affects the functioning of the fuel pump.

Hence, for all the older diesels the vapour lock has been a perennial problem and restarting the engine meant one would have to push the fuel piston in the Mico Bosch fuel pump and drive away the air pocket to release the vapour lock and ensure smooth flow of the fuel.

With petrol engines, this problem is not faced and one can safely go to the last drop of fuel.

If this state of vapour lock appear in a diesel engine is it advisable to crank the starter motor after filling the tank to brim with diesel Or the whole lines and fuel pump have to be opened up to drive the vapour lock out?

Diesel or petrol what is the difference in the vapour lock bothering more in the diesels than in petrol?

Anurag.

[deadguy25]

My post may be off-topic, please delete if need-be.

For the verna - fluidic, I was told by the service engineer that if the diesel dries-up, the pump will get air-locked and wont start after refuelling. In such a scenario, I would have to take (tow) the car to the nearest Hyundai service centre to get the car running. He said there is no other way to get it running. Been wanting to ask this, did not know where to post this query.

[StarrySky]

I agree with the opinion that the fuel guage in the OP's car is incorrect. I have gone really low on fuel thrice in my Punto. Twice I did about 18-20km after the Range display had gone blank (displaying "---km") - with AC, music system etc turned off. The car has not stalled due to low fuel. These days, I do not go so low on fuel and go to fill the car up with a quarter tank of fuel left, or atleast as soon as the yellow warning lamp starts glowing.

[JoshMachine]

@ Samartha - typically , all engines usually need combination of these factors to run smoothly or not stall - correct air:fuel ratio, sufficient idle rpm (else the ECU will give wrong signal) and finally a good spark. Since yours is a diesel, sparking is ruled out.

Further, in case of multi-injected fuel engines (like yours for example), there could be various culprits upsetting the air:fuel mixture - like faulty fuel injectors or low fuel pressure to the injectors, which in turn could be caused by the various reasons mentioned in the thread by fellow TBHPians.
Another reason you might want to check is quality of diesel filled in the car. Obviously, you cannot check the absolute quality but atleast you may want to fill from a pump which is "known" to be reliable. Else there is a danger of moisture creeping in and affecting the mixture, specially when the levels go down in the tank.

Suggest you try the following:-

1. Fill diesel from a good pump and see if the problem recurs
2. Conduct detailed diagnostic scans from the auth. service station and determine any fuel injector problem codes

[better4worse]

Guys, I drive a 2010 punto on Delhi roads which is due for a service, the other day while returning from friends place my car wouldn't start after refuelling. I realized the needle had touched the E mark and was looking to slip below that. Given the humid weather and the AC on, I had no choice but go for Diesel at the first available outlet on my way back. it just happened to be the Bharat Petroleum (Blue yellow) Pump. Despite repeated attempts, the car just wouldn't crank to life. All electricals looked fine, but with each crank the engine just wouldnt kick in, thankfully there was a slope on the way out of the station, with a little push from a few of the support staff I managed 'dhakka start' my car by slotting it in the second gear. The car's been working fine ever since, but has spooked me enough. In hindsight, it seemed like a vapour lock problem !

[adi_sun]

A friend's Verna CRDI had similar issue, in addition are you facing any issues like engine stalling after heavy acceleration and suddenly letting go of the throttle ?
It took Hyundai 7 days to diagnose that there is a small leak in the fuel line that was picking up air. Low fuel level and heavy acceleration increase the pressure in the line and sucks up air if there is a leakage.

[better4worse]

Originally Posted by adi_sun

A friend's Verna CRDI had similar issue, in addition are you facing any issues like engine stalling after heavy acceleration and suddenly letting go of the throttle ?
It took Hyundai 7 days to diagnose that there is a small leak in the fuel line that was picking up air. Low fuel level and heavy acceleration increase the pressure in the line and sucks up air if there is a leakage.

Not really, my sweetheart has been running fine ever since, touch wood. She does'nt have acceleration problems in low fuel, doesn't stall unnecessarily in any condition. Doesn't have starting problems, usually half a crank does the trick. Though I'd like to mention, it suffered from a mysterious missing problem
during the rainy season in the 1st year ownership, the car just wouldn't crank at all, I assumed it was starter motor or solenoid issues, but the issues came and went on its owns, the dealership couldnt recreate or solve the problem while it existed for a span of 5 odd days.

On the whole, its been business as usual, and this disruption at the fuel station could be because of the following reasons i.e apart from Vapor lock, or maybe its all rolled in together.

1. Fuel Filter problem - The car is in its 4 th year and due for a service, I haven't done the requisite kms but its close to a year since the last service. I don't suspect a fuel line problem, but thanks for highlighting I'll get the dealership to check for it as well.

2. Fuel Quality - I usually prefer Indian oil pumps that too known ones, out of choice I avoid BP, HP and IBP pumps, somehow I don't seem to get the same mileage for the money spent from these pumps. In this case, as my car dry to the bone, the quality of the fuel entered coupled with moisture and other factors could have led to this problem.

[Horizon81]

Originally Posted by better4worse

thankfully there was a slope on the way out of the station, with a little push from a few of the support staff I managed 'dhakka start' my car by slotting it in the second gear. The car's been working fine ever since, but has spooked me enough. In hindsight, it seemed like a vapour lock problem !

Good to know that your car has been running fine after this.

I was researching vapour lock and came across this thread. Doesn't a rolling start mess up your timing belt? I have read in my car's manual (i10 Magna) never, ever to try a rolling start. This goes in line with the advice that deadguy25 got to tow the vehicle to the service centre.

[modisan]

Yesterday, for the first time in my driving, ownership etc, my 4-wheeler ran out of fuel (my bike would do so almost every week, when in college). Absolutely my fault for not taking care of it while my wife was running the car whole of last week. She'd dropped me at the metro station and before I could cross 2 stations, she called me to tell that car had stopped near her office. I had noticed previous evening the low fuel warning and told her to get a fuelling next day so I could see that IT HAD HAPPENED.

Immediately went to TBHP App and searched for possible damages but it would not open, perhaps slow network in metro. Came out at 5th station which was near her office, reached her office, took keys, took an empty can of 5 ltrs from her office and arranged for diesel. Ran google and chanced on this thread and opened via chrome this time. Having gone thought most posts, found it comforting that Puntos stop with some fuel remaining to prevent damage to car.

Tried to pour the diesel from the can but could send only about half of it. Tried to crank-up 5-6 times but it won't start. The auto driver had stopped back on account of Rs 10 paid extra, helped to try and jump-start the car but didn't work. I then tried to put more diesel and was able to push through another litre and half. Another 4-5 cranks. Still unable to start. Cursed my luck and thought of calling a helpline/RSA. Just then found a 1 litre empty bottle at a nearby under-construction house and with it, poured the remaining diesel too. Another 4 cranks, no start.

the next one did it. Car started. Immediately took to fuel station and tanked-up!

Thanks a lot for this discussion. Had it not been for it, I'd have given up much early and wold have ended up spending lot of time and money on calling RSA though I believe they would have helped me by doing what I did!

Any follow-up precautions?

[Rahul Bhalgat]

Originally Posted by modisan

Yesterday, for the first time in my driving, ownership etc, my 4-wheeler ran out of fuel .........

I then tried to put more diesel and was able to push through another litre and half. Another 4-5 cranks. Still unable to start. ...........

the next one did it. Car started. Immediately took to fuel station and tanked-up!

Any follow-up precautions?

Good to know that the car finally started. No special follow-up precaution IMO; just remember not to let the fuel level get too low again.

[tsk1979]

Do this
When your fuel level goes low again, leading to stalling, full up the tank to full. If the tank takes in 40+ liters, it means that your fuel guage is faulty. If the tank takes up 30-32 liters, it means tank is faulty, or the fuel pipe is dislodged and at a higher level.

[a4anurag]

Originally Posted by modisan

Yesterday, for the first time in my driving, ownership etc, my 4-wheeler ran out of fuel.

Ran google and chanced on this thread and opened via chrome this time. Having gone thought most posts, found it comforting that Puntos stop with some fuel remaining to prevent damage to car

Any follow-up precautions?

Beware and always remember that diesel engine do NOT like it when run at low fuel and NEVER drive with almost dry fuel tank. It will be an herculean task to get the car back to normalcy as the there will be an air lock and to get the air out of the system would cost you a bomb.

Always re-fill when the needle crosses the 1/4th mark to be on the safer side.

[modisan]

Originally Posted by Rahul Bhalgat

No special follow-up precaution IMO; just remember not to let the fuel level get too low again.

Originally Posted by tsk1979

Do this
When your fuel level goes low again, leading to stalling, full up the tank to full. If the tank takes in 40+ liters, it means that your fuel guage is faulty. If the tank takes up 30-32 liters, it means tank is faulty, or the fuel pipe is dislodged and at a higher level.

Originally Posted by a4anurag

Beware and always remember that diesel engine do NOT like it when run at low fuel and NEVER drive with almost dry fuel tank. It will be an herculean task to get the car back to normalcy as the there will be an air lock and to get the air out of the system would cost you a bomb.

Always re-fill when the needle crosses the 1/4th mark to be on the safer side.

Thanks for the advise tsk1979, a4anurag and Rahul, its just that in between 30 km of my home and office, pumps are not located at very convenient locations or maybe its just an excuse to hide my lethargy when there are about 3.

My tank took about 5 ltrs from the can and another 38 soon after implying almost 42.5 litres. What would be the capacity - 45? I hope there was 2-3 litres at the bottom which would have saved it.

I heard a glug glug voice during the 3 km drive to pump for top-up which went off soon after the top-up. However, it returned during my evening ride back home. Could there be damage to fuel pump? Will get it checked at Kashyap Fiat next week (They ran out of clutch master cylinder when checked on phone so will visit them once they have that too)

On other things (should this be on Fiat thread where this was being discussed on last pages, can I copy it there too?):
Kashyap Fiat's labour for the master cylinder is 800/-. torque asked for about 2k. Tuli Fiat said they closed Fiat on 30th June and have shifted to Tata but charged about 1000-1500. Same labour rate confusion/varying charges prevail. Is Fiat totally oblivious to it?

[tsk1979]

Originally Posted by modisan

My tank took about 5 ltrs from the can and another 38 soon after implying almost 42.5 litres. What would be the capacity - 45? I hope there was 2-3 litres at the bottom which would have saved it.

So your fuel gauge was showing 1/4 and you could still fill in 42.5 liters? It means your fuel gauge is faulty. Get the float checked.