Hey guys,

Been having various running problems on my sisters mk4. In the cold weather we've been having its has been taking an age to start and sometimes will not start at all, regardles of how long I crank it.

I've changed the HT leads, dizzy cap and rotor arm. I also found that 2 of the spark plugs were only finger-tight. After rectifying these problems i was sure that the problem would go away but it still persists. When the engine starts it runs perfectly.

A new problem has arisen these last couple of days; the engine will start and run for a few seconds, then cut out. However this is totally intermittent as the engine started and ran fine this morning.

I'm beginning to think there could be a problem with the fuel pump and/ or relay. I've got people telling me to replace the blue temp sender but the engine runs fine when it starts (no missfiring or excessive fuel consumption).

Any other ideas? I've considered the ign. coil but i'm not convinced. When the fuel pump went on the G40 it was an instant thing, it must have shorted internally or something.

Anyway, any help is much appreciated as i'm not too familiar with MK4s, and the car is undriveable atm.

Regards

Tom

coilpack ? had a similar thing on mine brought a new coil and runs fine now

Hello Tom,

Before you go much further, it might pay to replace the petrol filter, as the problem may be caused through water/ice in the filter of pipes, this is particularly important if it hasn't been changed recently, or if you may have bought some dodgy petrol.

Regards.

Hey Tom,

From what you are describing, I'd be inclined to agree with you and target the fuel pump relay...

(It is known to fail on the 6n and we had similar symptoms when we had one. Swift change and back to normal!)

For the life of me, I cannot remember if is next to the fuse panel in the front, or under the fuel pump inspection panel under the rear seat bench...

Anyone else?

PoloD.

Edited 2 January, 201115 yr by PoloD

Thanks for the advice guys. Right i've been out to the car again tonight. The car limped into life on the first turn of the key, and idled faultless for the first 20 mins or so. When the engine almost reached full operating temp i blipped the throttle and it immediately cut out, and would not start again. I then bridged out the fuel pump relay (number 167 i believe?), and with the pump running constantly it still wouldn't start.

Even after all the cranking i'd been doing i couldn't smell any fuel.

Another thing to note is that with the engine running, occasionally the tacho goes a bit wild and fluctuates randomly. Had a very similar problem with my BMW E30, had to replace the ECU in the end!

Any more ideas guys? As mentioned I'm thinking pump and filter might be next on my hit-list!

Thanks

Tom

Thanks for the advice guys. Right i've been out to the car again tonight. The car limped into life on the first turn of the key, and idled faultless for the first 20 mins or so. When the engine almost reached full operating temp i blipped the throttle and it immediately cut out, and would not start again. I then bridged out the fuel pump relay (number 167 i believe?), and with the pump running constantly it still wouldn't start.

Even after all the cranking i'd been doing i couldn't smell any fuel.

Another thing to note is that with the engine running, occasionally the tacho goes a bit wild and fluctuates randomly. Had a very similar problem with my BMW E30, had to replace the ECU in the end!

Any more ideas guys? As mentioned I'm thinking pump and filter might be next on my hit-list!

Thanks

Tom

TTT, anyone had similar symptoms?

when my ignition coil went on my 6n it just went, was driving down the road and the car just died, no signs before it happened.

quick call to the AA and they found what the problem was, also wanted 86 quid for a new 1...i got 1 on ebay for 14 and fitted it myself lol.

when my ignition coil went on my 6n it just went, was driving down the road and the car just died, no signs before it happened.

quick call to the AA and they found what the problem was, also wanted 86 quid for a new 1...i got 1 on ebay for 14 and fitted it myself lol.

Yeah whenever i've had coils fail in the past its been an instant thing. Gonna fit the new fuel pump tonight, will update thread accordingly..

good luck mate :)

also I'm having some running problems with mine, not totaly un related tbh, I'm gonna clean out my throttle body valve in the next few days so maybe give that a go too if this dont work

Right guys, changed the fuel pump which made no difference. Thats the pump and relay ruled out.

The engine is starting reasonably well in this warmer weather. However, when the engine is almost warm an i rev the engine up to about 2500-3000 it suddenly cuts out, just like someone has turned the ingnition off. If you immediately try to restart the engine it will not start. However if you leave is for a couple of minutes it will start up again.

Gotta be electrical, i'm thinking maybe distributor/ dodgy hall sensor.

Any help?

It sounds a lot like the Hall sender as you say, but you also say that it cuts out and won't start when hot, there is a chance that the temperature sender ( in the cylinder head - drivers side - under the air cleaner - it's a blue colour), but normally when this fails, the engine will run, but it gets too much petrol, which you may smell, also black exhaust and rough running.

Regards.