Fuelling issues

[iow_corrado_g60 0]

Afternoon all,

 

having a few issues with my golf highline.

 

Recently the car has been stuttering under very light load between 1200-1500rpm, then since then the car is still doing that but its having trouble starting, when I turn the key it seems as if the pump is not priming?

 

Could this be the case or could it be something like the fuel pressure regulator,

 

I have also changed the maf as i thought this was the cause of the original stuttering problems.

 

Any suggestions?

 

Cheers in advance Andy

[Jon_vr6 1]

Ignition switch

Fuel pump relay

Fuel pump

fuel pressure regulator

 

Possible causes

[iow_corrado_g60 0]

cheers, can I rule out the plugs and leads? as im just trying to think originally what would have started the hesitation lower in the rev range?

[Jon_vr6 1]

Worth checking plugs and leads and coil pack/dizzy for any arching. Try the cheap things first

[Dox 23]

Check for inlet air leaks including breather pipes, air entering the engine after the Maf will lead to a weaker mixture than what's required leading to hesitation, rough idle etc

[vw rule 19]

Hello there,

 

When was your Golf last serviced ??

 

I'd check dash for any orange engine warning light,

this means you have an error (ECU has stored a fault code)

So you'll need to have the ECU's chip scanned to see if it's one of the sensors.

The ECU will only store a fault code if the error it picks up is always there,

if it's an intermittent fault it may not store a fault code.

 

If the fuel pump is not priming as it should once the ignition is switched on,

then it could be one of the above as Jon_VR6 has said.

 

Ignition switch: (Switch could be warn or faulty)

Check how the key slides in and out of the barrel,

plus how the switch turns.

Check for slack movement / play in ignition switch and the barrel, that's normally a clear sign that the switch is on the way out.

If the barrel is really lose and warn and catchy to turn, then this can course the key not to always fit into the switch.

the barrel is fitted in the steering column lock casing, and the ignition switch is on the back of the barrel, normally.

 

 

Fuel pump relay (Faulty relay and or Bad connection) - (immobilizer staying on or playing up)

Check to see how the alarm / immobilizer are working, do they always arm and disarm every time.

 

Fuel pump:

This should always prime the fuel system once the ignition is turned on,

you should be able to here a slight buzz from the pump for around 6 to 8 seconds.

And once the engine catches and starts up the fuel pump should be working then full time,

until the ignition is switched off.

 

fuel pressure regulator: (But remember this is vacuum operated, normally)

The pressure regulator is normally vacuum operated so isn't electrically connected in to the ECU.

The regulator is just to maintain fuel pressure from the injector rail to tank (in the return line)

 

I think the fuel pressure regulator maintains pressure in the return fuel line back to the fuel tank,

so if it was weak the fuel pump should still prime the system once ignition is turned on via the key.

 

But if the pressure regulator has packed up completely then it may not allow the excess fuel,

to return under pressure back to the fuel tank and so coursing a back lash fuel blockage,

in other words the fuel pump may only come on just and cuts out too soon on start up,

as it's finding it difficult to pump through to injector rail,

because the fuel in the return line isn't moving through and so not allowing the car to start up.

 

Regarding your spark plugs and HT coil packs or HT leads,

these would course a misfire or lumpy running all of the time under load.

Really you would have to check your spark plugs too be sure.

 

HT coil packs these are the ones that bolt individually on to each spark plug,

normally when these are worn you can smell the carbon burnt smell from them when they're removed.

I've replaced loads of these off Renaults and Peugeots and Fords over the years.

 

HT leads these can show signs of wear i.e cracking in the outer silicone skin,

and by lifting off one lead at a time to see if it makes a difference or not to the rough running,

if it makes a difference then you know that lead and plug are working ok,

but if there is no difference and the misfire is still there then you know then that lead or plug aren't working correctly.

 

 

There are other sensors that can course similar symptoms,

but these do not course the fuel pump not to run.

The fuel pump obtains it's power from the fuse box through the fuel relay.

 

Coolant temp switch: A warn switch will course the ECU to dump in extra fuel as the ECU can no longer read the coolant temp,

the car can be a real swine to start up from cold or even when hot.

This sensor is also known as the thermal transmitter.

7/10 car won't start.

3/10 car will start but run really rough.

 

Cam shaft position sensor: These I think control the injectors (Tells them when to fire)

So if it is faulty it can course the injectors not to fire quick enough,

so at idle it may seem ok but once under load i.e at 1500 RPM or above can course running issues.

 

Fuel injectors: these are governed by the cam sensor and crank sensor,

to ensure that the injectors fire at the correct time.

These injectors can play up as they've normally got a needle valve in side them,

which operates via an electronic pulse, which makes the needle valve open and close,

the needle valves can wear uneven coursing injector spray to be too thick or thin,

or the injectors can drip fuel even though the needle valve is closed,

coursing fuel to go in to cylinder when it shouldn't be coursing black grey smoke from exhaust and rough running under load.

 

Crank sensor: This tells the spark plugs when to fire.

So this is normally working or not working.

8/10 will course the vehicle not to start.

2/10 the vehicle will start but with running issues or can start up one day then not another.

The crank sensor communicates with the knock sensor as well.

 

Knock sensor: This sensor measures the timing angle with in small tolerances.

It detects pinking and so keeps the timing on it's advanced limit for good performance.

It can course a misfire when they pack up.

 

Air flow sensor: This measures the amount of air entering in the inlet via air filter,

this communicates with both the cam sensor and crank sensor,

and so if it dies it can course the car not to start or if it does it will run rough,

as it's no longer able to measure the fuel to air ratio together.

 

Lambda sensor: This measures unburnt fuel deposits with in the exhaust fumes just before the cat,

it acts as a final check to make sure the engine is at it's top performance,

plus communicates with the cam sensor and air flow sensor.

When this sensor dies it courses the ECU to go in to limp mode and so there will be a reduction in performance.

Most of these fuel sensors get a signal from the coolant temp switch regarding rich mixture at cold and lean mixture when hot.

 

But like I say I would get it scanned first,

i.e diagnostic scanner, as this should find the error straight away if it's a sensor.

You might be able to found the fault with one of the sensors,

but unless the ECU fault recorder chip is cleared clean the engine may still run a little rough,

as it'll thick the fault is still there.

 

 

Hope this helps.

 

Si

[iow_corrado_g60 0]

Hello there,

 

When was your Golf last serviced ??

 

I'd check dash for any orange engine warning light,

this means you have an error (ECU has stored a fault code)

So you'll need to have the ECU's chip scanned to see if it's one of the sensors.

The ECU will only store a fault code if the error it picks up is always there,

if it's an intermittent fault it may not store a fault code.

 

If the fuel pump is not priming as it should once the ignition is switched on,

then it could be one of the above as Jon_VR6 has said.

 

Ignition switch: (Switch could be warn or faulty)

Check how the key slides in and out of the barrel,

plus how the switch turns.

Check for slack movement / play in ignition switch and the barrel, that's normally a clear sign that the switch is on the way out.

If the barrel is really lose and warn and catchy to turn, then this can course the key not to always fit into the switch.

the barrel is fitted in the steering column lock casing, and the ignition switch is on the back of the barrel, normally.

 

 

Fuel pump relay (Faulty relay and or Bad connection) - (immobilizer staying on or playing up)

Check to see how the alarm / immobilizer are working, do they always arm and disarm every time.

 

Fuel pump:

This should always prime the fuel system once the ignition is turned on,

you should be able to here a slight buzz from the pump for around 6 to 8 seconds.

And once the engine catches and starts up the fuel pump should be working then full time,

until the ignition is switched off.

 

fuel pressure regulator: (But remember this is vacuum operated, normally)

The pressure regulator is normally vacuum operated so isn't electrically connected in to the ECU.

The regulator is just to maintain fuel pressure from the injector rail to tank (in the return line)

 

I think the fuel pressure regulator maintains pressure in the return fuel line back to the fuel tank,

so if it was weak the fuel pump should still prime the system once ignition is turned on via the key.

 

But if the pressure regulator has packed up completely then it may not allow the excess fuel,

to return under pressure back to the fuel tank and so coursing a back lash fuel blockage,

in other words the fuel pump may only come on just and cuts out too soon on start up,

as it's finding it difficult to pump through to injector rail,

because the fuel in the return line isn't moving through and so not allowing the car to start up.

 

Regarding your spark plugs and HT coil packs or HT leads,

these would course a misfire or lumpy running all of the time under load.

Really you would have to check your spark plugs too be sure.

 

HT coil packs these are the ones that bolt individually on to each spark plug,

normally when these are worn you can smell the carbon burnt smell from them when they're removed.

I've replaced loads of these off Renaults and Peugeots and Fords over the years.

 

HT leads these can show signs of wear i.e cracking in the outer silicone skin,

and by lifting off one lead at a time to see if it makes a difference or not to the rough running,

if it makes a difference then you know that lead and plug are working ok,

but if there is no difference and the misfire is still there then you know then that lead or plug aren't working correctly.

 

 

There are other sensors that can course similar symptoms,

but these do not course the fuel pump not to run.

The fuel pump obtains it's power from the fuse box through the fuel relay.

 

Coolant temp switch: A warn switch will course the ECU to dump in extra fuel as the ECU can no longer read the coolant temp,

the car can be a real swine to start up from cold or even when hot.

This sensor is also known as the thermal transmitter.

7/10 car won't start.

3/10 car will start but run really rough.

 

Cam shaft position sensor: These I think control the injectors (Tells them when to fire)

So if it is faulty it can course the injectors not to fire quick enough,

so at idle it may seem ok but once under load i.e at 1500 RPM or above can course running issues.

 

Fuel injectors: these are governed by the cam sensor and crank sensor,

to ensure that the injectors fire at the correct time.

These injectors can play up as they've normally got a needle valve in side them,

which operates via an electronic pulse, which makes the needle valve open and close,

the needle valves can wear uneven coursing injector spray to be too thick or thin,

or the injectors can drip fuel even though the needle valve is closed,

coursing fuel to go in to cylinder when it shouldn't be coursing black grey smoke from exhaust and rough running under load.

 

Crank sensor: This tells the spark plugs when to fire.

So this is normally working or not working.

8/10 will course the vehicle not to start.

2/10 the vehicle will start but with running issues or can start up one day then not another.

The crank sensor communicates with the knock sensor as well.

 

Knock sensor: This sensor measures the timing angle with in small tolerances.

It detects pinking and so keeps the timing on it's advanced limit for good performance.

It can course a misfire when they pack up.

 

Air flow sensor: This measures the amount of air entering in the inlet via air filter,

this communicates with both the cam sensor and crank sensor,

and so if it dies it can course the car not to start or if it does it will run rough,

as it's no longer able to measure the fuel to air ratio together.

 

Lambda sensor: This measures unburnt fuel deposits with in the exhaust fumes just before the cat,

it acts as a final check to make sure the engine is at it's top performance,

plus communicates with the cam sensor and air flow sensor.

When this sensor dies it courses the ECU to go in to limp mode and so there will be a reduction in performance.

Most of these fuel sensors get a signal from the coolant temp switch regarding rich mixture at cold and lean mixture when hot.

 

But like I say I would get it scanned first,

i.e diagnostic scanner, as this should find the error straight away if it's a sensor.

You might be able to found the fault with one of the sensors,

but unless the ECU fault recorder chip is cleared clean the engine may still run a little rough,

as it'll thick the fault is still there.

 

 

Hope this helps.

 

Si

 

had a mental couple of weeks at work so this is the first time I have been back, the advice you have all offered is excellent and I want to thank you, I will from this weekend try to start fault finding and slowly cross things off the list,I'm not a newbie to the VR so hopefully I'll be able to sort it, will post back shortly. Cheers Andy