intermitant non starting

[boyzey]

Hiyaaa guys hoping for bit a past experiance hear haha so hear goes. Every so often il drive polo out some were runs perfect no issues atal. But il tern her of and and she wont even cough or spluter just crank over and over. Now its very rare it does it and its always in the worst possible place haha. But It did do it at home other day. So I did my checks. I had spark and fuel in to the rail. So im thinking something electrical telling injectors not to fire. Does this sound like hall sensor or a ecu fault. And the best bit is if I bump start her whilst she is playing up she fires up a treat and may be fine for another month. Any one had this fault or any ideas I can try next time she decides to messaround thanx

[samg40]

How old is your coil? My last one died after not starting occasionally but running fine when it did. Worth trying another one.

[boyzey]

Its old ye buddy and its a idea pall thank you. But yesterday wen it refused to start. I dafo had spark from the plugs. And I cant understand why I can bump it off and it fires straight up. Bt cranking on starter motor it wont even cough or splutter.

[GR40]

Start simple! Check your fuses. I have seen a lot of times gremlins coming out from fuses simply not sitting properly or weird shortcuts from them.

[cheys03]

I've had similar when my first in-line high pressure fuel pump (the one under the car) was on it's way out. A tap with a foot or bit of wood got it turning again.
Easy to test if it's this, if you have someone to turn the key for you - turn the ignition on to prime the pumps while you have a hand on the pump. If you can't feel a vibration from it turning then you've found the problem (or if whacking it fixes it).
It can be deceptive as the low pressure in-tank pump can shunt enough fuel to wet the rail, but at too low pressure to be useful.
There might be enough of a kick when bumping it to get it working again.

[boyzey]

Yep checked fuses pal had little green corosion last winter but all good this time. And yes fuel pumpes were my first idea. But they do both prime when it refuses to start. And I do get a decent amount to rail so im thinking something is telling injectors not to open. I removed dizzy to test hall sensor but that was after the fault so was working fine. But im thonking it could be the hall sensor

[boyzey]

Its realy puzzeling me because it run spot on all today amd have bin out and about few times. Is the hall sensor basicaly like a cam/crank sensor does any body no. Am I right that its the hall sensor that fires the injectors when the roater arm sends the spark. Thanks for all help guys. I kinda hoping it will break down propavso I can do some propa tests haha

[G40supercharged]

The Hall sensor tells the ECU the position of the engine (just like a crank sensor except the G40 Hall sensor runs off the end of the camshaft). It is used by the ECU to time both the injector firing and the spark firing; the rotor arm just aims the spark at the correct cylinder. If you have a spark it suggests the Hall sensor is working. I had a similar problem on one of my G40s which I think was the ground connection at the coil. The mounting bolts for the coil provide an earth so check they are not corroded. It seems odd that it appears to have both spark and fuel and still doesn't run but it may be an intermittent problem caused by a bad connection somewhere.

[ereeiz]

My bet would be shit earths. They may look fine but replacing/ taking them off and cleaning them up is always a good start. If nothing else you can then definitely rule them out and know they're good going forward. Make sure the connections to the body/ battery and so on are good, clean them up and paste a bit of copper grease on everything before reassembling, helps prevent corrosion and increase conductivity.

Next up, the coil, then rotor arm/ dizzy cap, then leads. Check the lot, don't assume. It's always handy to get a multimeter (about £8) that has a continuity tester on it, it can highlight bad connections instantly.

[brownysblower]

check the relay no top of the fuse box !!

[boyzey]

Cheers for that info g40supercharged verry helpfull. That kind ov skuppers my theory haha. I defo had fuel to the injectors and a spark at plugs so yes not good maybe ecu then. Only earth I havent checked is the connector wer all the earths are connected together inside the wiring loom. Il check that at weekend thank you

[boyzey]

Cheers ereeiz as I saod above only earth I havent checked is wer they all connect together inside loom. And ye last case scenario will be firing parts at it haha. Ideal world u like to no exactly whats the problem then fix it. Its no fun crossing ur fingers every time you turn key haha

[boyzey]

And brownysblower you mean the fuse for fuel pump on top of fuse box yes checked that pal cheers

[brownysblower]

Not the fuse relay on top of it they corrode inside

[boyzey]

Have checked the ecu and fuel pump relays if thats what you mean buddy yes. Not missed a beat still used it every day since