Fuel Injector| Fuel Atomiser | Construction of Fuel Injector | Working of Fuel Injector | Faults , causes and remedies of Fuel Injectors |
-: Fuel Injector / Fuel Atomiser :-
Fuel injector is defined as - A device which use to inject air-fuel mixture in combustion chamber of C.I. engine is known as fuel injector . It is also known as Fuel Atomiser .
Construction and working of Fuel Injector / Fuel Atomiser :- A fuel injector consists following parts -
(i)- A needle valve
(ii)- A compression spring
(iii)- A nozzle
(iv)- An injector body
When the fuel is supplied by the injection pump it exerts sufficient force against the spring to lift the nozzle valve , fuel is sprayed into the combustion chamber in a finely atomized particles . After , fuel from the delivery pump gets exhausted , the spring pressure pushes the nozzle valve back on its seat . For proper lubrication between nozzle valve and its guide a small quantity of fuel is allowed to leak through the clearance between them and then drained back to fuel tank through leak off connection . The spring tension and hence the valve opening pressure is controlled by adjusting the screw provided at the top .
Faults , Causes and Remedies of Fuel Injector / Fuel Atomiser :-
1- Pressure too high -
Cause:-
(i)- Spring rate too high .
(ii)- Needle valve seized in almost closed position due to dirt etc.
(iii)- Carbon blocking injector holes .
Remedies:-
(i)- Adjust if possible or replace spring with one having lower spring rate , or vary the number of shims .
(ii)- Soak in fuel oil . Then try to remove needle valve . If necessary replace with new needle valve and nozzle .
(iii)- Clean with pricker . Reverse flush using syringe and paraffin .
2- Pressure too low :-
Causes :-
(i)- Spring rate too low .
(ii)- Spring broken .
(iii)- Needle valve seized in position .
Remedies:-
(i)- Adjust if possible or replace spring with one having a higher spring rate .
(ii)- Replace with correct type .
(iii)- Soak in fuel oil then try to remove the valve . If necessary replace with new needle nozzle .
3- Excessive leakage off :-
Causes:-
(i)- Too much clearance between valve and hole in nozzle .
(ii)- Nozzle cap loose .
(iii)- Injector body and nozzle separated by dirt or burns caused by lack of care in handling .
Remedies:-
(i)- Fit new nozzle and valve .
(ii)- Tighten .
(iii)- Remove nozzle and examine pressure faces . Remove dirt or burns . Do not over-tighten cap nut as a cure .
-: Fuel Injector / Fuel Atomiser :-
Fuel injector is defined as - A device which use to inject air-fuel mixture in combustion chamber of C.I. engine is known as fuel injector . It is also known as Fuel Atomiser .
Construction and working of Fuel Injector / Fuel Atomiser :- A fuel injector consists following parts -
(i)- A needle valve
(ii)- A compression spring
(iii)- A nozzle
(iv)- An injector body
When the fuel is supplied by the injection pump it exerts sufficient force against the spring to lift the nozzle valve , fuel is sprayed into the combustion chamber in a finely atomized particles . After , fuel from the delivery pump gets exhausted , the spring pressure pushes the nozzle valve back on its seat . For proper lubrication between nozzle valve and its guide a small quantity of fuel is allowed to leak through the clearance between them and then drained back to fuel tank through leak off connection . The spring tension and hence the valve opening pressure is controlled by adjusting the screw provided at the top .
Faults , Causes and Remedies of Fuel Injector / Fuel Atomiser :-
1- Pressure too high -
Cause:-
(i)- Spring rate too high .
(ii)- Needle valve seized in almost closed position due to dirt etc.
(iii)- Carbon blocking injector holes .
Remedies:-
(i)- Adjust if possible or replace spring with one having lower spring rate , or vary the number of shims .
(ii)- Soak in fuel oil . Then try to remove needle valve . If necessary replace with new needle valve and nozzle .
(iii)- Clean with pricker . Reverse flush using syringe and paraffin .
2- Pressure too low :-
Causes :-
(i)- Spring rate too low .
(ii)- Spring broken .
(iii)- Needle valve seized in position .
Remedies:-
(i)- Adjust if possible or replace spring with one having a higher spring rate .
(ii)- Replace with correct type .
(iii)- Soak in fuel oil then try to remove the valve . If necessary replace with new needle nozzle .
3- Excessive leakage off :-
Causes:-
(i)- Too much clearance between valve and hole in nozzle .
(ii)- Nozzle cap loose .
(iii)- Injector body and nozzle separated by dirt or burns caused by lack of care in handling .
Remedies:-
(i)- Fit new nozzle and valve .
(ii)- Tighten .
(iii)- Remove nozzle and examine pressure faces . Remove dirt or burns . Do not over-tighten cap nut as a cure .
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