Possible Fuel Problems.
Although obvious this is the most common cause for an engine failing to start. Your fuel gauge
may show there is fuel present however the mechanical measuring devises can be flimsy and prone
to wear or clogging from any contaminated fuel giving an inaccurate reading.
How to check For Fuel.
Locate the in line fuel filter and have someone turn over the engine and see if you can see
fuel passing through the filter or fuel line or,
Take off the fuel cap and place your ear close to the opening and rock the car gentle
from side to side and listen for the fuel sloshing around or,
A fool proof method, get a can of fuel and put it in the
Note: If there is fuel present but its low and your vehicle has been stood on an incline
this can cause fuel starvation. If you have a primer pump in the engine compartment squeeze it
three or four times until it stiffens up and try to start the vehicle again.
If your car has a fuel primer pump it will look
something like this. They come in a verity of colours
often quite bright if they have been replaced.
If it starts it may stop again when
what was primed has run out so get a can and fill her up.
Fuel present but wont Start
Depending on the age and type of car you may have a carburettor or a fuel injection system.
Either could be faulty or have blockages which is unlikely but never the less possible this
being the case professionals will need to take a look as taking a carburettor apart to clean
requires considerable knowledge and electronic fuel management systems can be tested quickly
and easily with specialist electronic equipment.
Diesel cars require heater plugs to warm the fuel to a temperature at which it can combust.
Each cylinder has a heater plug and they are consumable items which perish with use. They can
be checked by removing them individually and examining them visually. If they are disfigured or
black with soot the chances are they need replacing.
This shows the difference between a worn glow plug and a new one, the latter being on the bottom.
Click on the image to view a larger picture.
Any main dealer or auto parts retailer
will stock them and they vary in price depending on manufacturer. It it's always recommended to
buy genuine plugs for the make of your car as they last longer but expect to pay more.
Possible electrical problems
Modern cars have become more dependent on electronic
management systems and as a result have become very complex. There is an upside to this however
as computer diagnostic equipment can be plugged in to your car and for a cost of around £50 you
can get an analysis which could in the past have taken hours and come with a hefty bill.
Electrical problems are more likely in a petrol engine as in order to run you need fuel,
ignition and compression and a diesel needs only fuel and compression but does need electrics
to initially fire.
If there is no spark there is no fire. Remove the spark plugs
and check they are in good condition. They should be a light brown in colour, dry and
undamaged. If they are white, oily or wet with fuel you could have fuel/air mixture problems
and/or worn cylinders or piston rings and possibly leaking valve seals. This being the case a
mechanic is a good idea as cleaning the plugs will only be a very short term fix.
Check for a spark
Obtain a spare spark plug you know is working and one by one so
you don't mix up the plug leads disconnect a lead from a plug and insert the spare. Place the
spark plug metal to metal somewhere on the engine to earth it and get a friend to turn over the
engine. You should see a bright spark between the terminals at the end of the plug.
If all work then remove each spark plug one by one from the engine replacing the removed plug
with the spare so you don't have an open cylinder and repeat the exercise.
No spark from a working spark plug
This could be the plug lead or the
distributor/distributor arm. Remove the distributor cap and look to see if the the rotating arm
contact point and contact terminals are worn this will be quite apparent if they are. They may
also be corroded with a green oxide layer which can be cleaned with sand paper for a temporary
fix. If the terminals and arm are worn then they may be no contact so replace them. Same goes
for the plug leads, check for corrosion on the connections and if you have a circuit tester
make sure current can pass along the lead.
Its best to leave compression testing to the professionals as
you will need specialist equipment. And if there is a compression problem it may be a major fix
such as replacing piston rings or a head gasket.
If you have already examined the heater plugs as described
above and found them to be in good shape you can test them by removing the plug. Making sure
the plug is still attached to the connection wire place the thread used to screw in to the
cylinder head on a metal part of the engine. Keeping the element clear of anything in the
surrounding area (including your hands they get hot! Use pliers or vice grips) have a friend
turn the ignition to the on position but not all the way. You don't want the engine turning
over with an open cylinder. If the plug is working properly it will glow beginning at the tip
and moving upwards. Switch off the ignition and repeat the exercise with the remaining
Heater plugs working but not glowing
This could be a result of poor connections or
a faulty heater plug timer relay which controls how long the plugs receive current. Remove the
inline connecting wire and clean the connection points and when replacing ensure the connection
nuts are secure. Using a circuit tester on the wire will fitted will help trace the problem
back to the timer relay.
Remove the timer relay from its connection point and check the terminals are clean. Use sand
paper if they are corroded or replace it with a new one.
In the case of both diesel and petrol cars check the fuel filter and air filters are clear and
free from build up. If they are dirty or contaminated replace them. An engine starved or air
will run rich and be inefficient both in performance and economy.
All internal combustion engines require a host of events happening in the correct sequence at
the right time controlled by a timing belt or chain. If a timing belt or chain becomes loose or
worn it can slip or jump if this happens the sequence of events required for an engine to run
correctly will will be out of step. The same result will obviously occur if a belt or chain is
fitted incorrectly. Setting the timing will require a manual to find the settings and is best
left to a qualified mechanic as if it is set out of time too far you can cause engine damage
such as bent valves which can become expensive.
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mechanical assistance here.