Fuel System, Fault Diagnosis

Unsatisfactory engine performance and excessive fuel consumption are not necessarily the fault of the fuel. In fact they more commonly occur as a result of ignition and timing faults. Before acting on the following it is necessary to check the ignition system first. Even though a faulty may lie in the fuel system it will be difficult to trace unless the ignition is correct. The faults below, therefore, assume that this has been checked and sorted out where necessary.

// Smell of petrol when engine is stopped.

Reasons :

A. Leaking fuel lines or unions.
> Repair or renew as necessary.

B. Leaking fuel tank.
> Fill fuel tank to capasity and examine carefully at seams, unions, andfiller pipe connection. Repair as necessary.

On emergency, a bath soap bar can be use to stop the leak. Smashed the soap with petrol and apply to the leak, let it dry for a moment. It will hold forever unless the soap get wet or being removed.

// Smell of petrol when engine is idling.

Reasons :

A. Leaking fuel line unions between pump and injector rail or carburetor ( if applicable ).
> Check line and unions and tighten or repair.

B. Overflow of fuel from float chamber due to wrong level setting, ineffective needle valve or punctured float ( in carburetor )
> Check fuel level setting and condition of float and needle valve, and renew if necessary.

C. Overflow of fuel from injector rail due to bad injector.
> Do injector cleaning and calibrating if necessary. It’s not fully close by blocking dirt or lack of power supply.

D. Broken carburetor gasket.
> Replace with new gasket.

// Excessive fuel consumption for reasons not covered by leak, float chamber faults.

Reasons :

A. Worn jets ( on carburetor ).
> Renew jets or carburetor body if not removable.

B. Over rich setting.
> Adjust jets ( on carburetor ).

C. Sticking linkage / controls.
> Check correct movement of mechanism of butterfly ( on carburetor ) or throttle body ( on injection ).

D. Bad spark plug by worn or other reasons.
> Clean or replace as necessary.

E. Wrong adjustment on mass air flow and or throttle body control flap ( on injection ).
> Check and adjust, renew if necessary.

F. One or more injectors fail to work properly.
> Do injector cleaning and calibrating. It’s not fully close by blocking dirt or lack of power supply.

// Difficult starting, uneven running, lack of power, cutting out.

Reasons :

A. One or more jets blocked or restricted ( on carburetor ).
> Dismantle and clean out float chamber and jets.

B. One or more injectors blocked or restricted ( on injection ).
> Dismantle and clean, calibrating if necessary.

C. Float chamber fuel level too low or needle valve sticking ( on carburetor ).
> Dismantle and check fuel level and needle valve.

D. Fuel pump not delivering sufficient fuel.
> Check pump and filter delivery and clean or repair as required.

E. Bad or wrong spark plug setting or type.
> Check, clean and adjust as necessary. Replace if necessary.

» Sharing Knowledge for Live and Drive Well «


2 responses »

  1. wiratmo says:

    It’s been nice to able sharing knowledge and get others knowledge to have a better live. Keep the good work of yours as well. Thank you.

  2. wiratmo says:

    Thank You for the comment and love, Yelena. Let’s keep us keep up the good works.

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