Khyber problem on petrol

[cracked]

hi...hope ya'all r fine.
ive problem with my khyber tht on petrol,its iodle is not stable and also it gives out black smoke..ive tried to eliminate black smoke by adjusting mixture screw but no avail..
real problem is wen i put cng-petrol button to neutral,car RPM increases n black smoke vanishes...black smoke is there till button is on petrol,but on neutral,black smoke vanishes with rpm increase ..
i have not cleaned the petrol tank but petrol is clean as i asked mechanic to check n he sucked some petrol n it was clear!
ive used hi octane but problem is still there!
any help or suggestions?
car runs perfect on cng!
i dont want car to b equally good on both fuels but atleast black smoke shudnt b there!
may it b petrol filter???
help plz!

[roms]

hi...hope ya'all r fine.
ive problem with my khyber tht on petrol,its iodle is not stable and also it gives out black smoke..ive tried to eliminate black smoke by adjusting mixture screw but no avail..
real problem is wen i put cng-petrol button to neutral,car RPM increases n black smoke vanishes...black smoke is there till button is on petrol,but on neutral,black smoke vanishes with rpm increase ..
i have not cleaned the petrol tank but petrol is clean as i asked mechanic to check n he sucked some petrol n it was clear!
ive used hi octane but problem is still there!
any help or suggestions?
car runs perfect on cng!
i dont want car to b equally good on both fuels but atleast black smoke shudnt b there!
may it b petrol filter???
help plz!

Black smoke is caused by excess fuel that has not been burned completely. The burning of excess fuel is what we call running rich. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor but black smoke is not alarming.

Excess fuel can leak into the cylinder if the carburetor is out of adjustment. A faulty fuel pump, a leaky fuel injector, or a failing engine computer or computer sensor can be other reasons for fuel entering the cylinder.

What you shud do,

Check the engine oil to make sure excess fuel has not contaminated it.

Look at the engine oil dipstick, or look at the under side of the engine oil filler cap. If the oil is contaminated, it will have the appearance of a chocolate milkshake.

Check your choke may be it is struck.

Clean the carburetor with Carburetor Cleaner like NASA.

Also check your plugs and fuel filters

[cracked]

like i said,i didnt let car run for long,just 5 minutes or so....
have tried nasa and kangaroo carb cleaner,prob is still there!
choke is not stuck for sure!
khyber is carb based engine,it didnt have no computer at-all!
any other ideas??/
how to knw if fuel pump is faulty

[cracked]

also if some one could suggest me carb specialist!

[fas133]

It is possible that when u switched to petrol then ur Gas is not shut off completely by ur CNG Kit and is being sucked in with petrol and so result in rich fuel.
So try to completely shut off cng by closing the valve at CNG Cylinder and then check for black smoke.
Secondly It could also be the fault of float in the carb.

[cracked]

thnx fas
ill chk with cylinder valve closed tomorrow..
BTW if its float problem,how will it be rectified???

[fas133]

Float Valve is adjustable but u have to open up the carb. and adjust this according to the specs.

[cracked]

float valve is on back side of carb???
or inside carb?

[fas133]

Just open the carb upper cover and it is attached with it.In the attached image item no.38 is the float assembly.

[cracked]

fas bhai i just strted the car,shut off the valve on cylinder,car went off,then strted car on petrol..black smoke was there as it is...then wen i put cng petrol button to neutral,gradually rpm increased n black smoke vanishes..
so this eliminates the thing tht button is the culprit...
now shud i just get float checked??if float is dead,is it available new or wud i need to find kabli one???any price idea???

[ahsanonline]

it is definitely overfilling of carb with petrol.

if i were you, i would remove the air cleaner till i could see the throat of the carb, start the car and get it to run on petrol till it smokes. then i would watch at the throat of the carb to see if petrol is spilling over into the throat from one of the pipes coming up top inside the carb.

that happens if the float valve inside the carb is faulty, if the float lever is adjusted too straight, or if the float itself has a leak such that it leaches petrol and ceases to function as a float.

the fact that switching the cng switch to middle removes the symptoms is pointing to the fact that the problem is somewhat solved when petrol supply is severed.

[Sharo53]

are you using electronic fuel pump? or the original mechanical one?
check the fuel return line may b its clogged resulting over fueling...

[cracked]

i guess it original pump is there...
ill go to mechanic to first check the pump n related lines...then will check for float!
thnx for the input guys

ahsan,yup,the symptoms vanish wen button is on neutral..so wat cud b prob?cud it b like sharo said,petrol return line??maybe its comin in good but not returnin back good!

[bkmkw]

U mainly run ur car on cng. Ur car has been optimized for use of cng. As we all know cng is a much weaker fuel than petrol, therefore while using cng, the timing of the car is adjusted for the use of cng and not petrol. This is why when u switch over to petrol, it does not burn fully and black smoke is created. If u adjust ur car for petrol, the balck smoke will vanish but then u will face problems with cng. It is not a matter of concern at all.

[cracked]

black smoke is a different thing...timing advancement will cause anything else but black smoke!

[ahsanonline]

i guess it original pump is there...
ill go to mechanic to first check the pump n related lines...then will check for float!
thnx for the input guys

ahsan,yup,the symptoms vanish wen button is on neutral..so wat cud b prob?cud it b like sharo said,petrol return line??maybe its comin in good but not returnin back good!

yea it could be return line as well, but question is, why the float itself doesn't shut off fuel supply to carb once it reaches a certain level? even with return line blocked, a good float system should keep too much petrol from flowing in.

besides, once you cut the fuel supply to the carb, and if the return line is indeed blocked, then the pump should've given up and become faulty from trying to pump fuel unsuccessfully down the return line.

check it anyways, but i'l bet my marbles on the float.

[fas133]

It does not seems to be a return line problem because u r using mechanical fuel pump and it pumps fuel even when u r using CNG and so in this situation all the petrol that is sucked from the tank,goes back to the tank using the return line and if it is clogged then it would surely result in a leakage some where.
Check float valve pin,it is adjustable so no need to change.

[cracked]

yup...fas bhai wen on cng,petrol is seen as petrol line is transparent in my car...
petrol comes n goes back...means petrol line is fine..ill get my float checked inshallah on monday..
if float is faulty,is it available in market??how will it b set back to normal?

[Sharo53]

yup...fas bhai wen on cng,petrol is seen as petrol line is transparent in my car...
petrol comes n goes back...means petrol line is fine..ill get my float checked inshallah on monday..
if float is faulty,is it available in market??how will it b set back to normal?

can you plz upload some pics of engine bay showing pipes of petrol?

that float has a metal strip...mechanic will adjust it and it'll be all gud...

[cracked]

problem is almost solved..i changed the plunger n now smoke is not there..but prob on petrol is the rpm is too much,like around 1500 so wen i turn off car on petrol,it take jerks n then goes off..n if i disturb the mixture,rpm goes down but black smoke comes back again,very slightly but still visible!
any help??
on cng its still perfectly fine!