Cutting Out

[gruffalo]

Got an interesting one that I could do with some help with if possible.

Car starts fine and drives fine for a few miles then gets a little wheezy, recovers and then cuts out very cleanly as if I had hit the off button. If I hit the starter it spins but does not fire, If I turn her off then try again all is well, she starts up and runs fine.

After cutting out the tacho reads zero even if coasting in gear as if the ignition has been turned off.

Any ideas from the informed on here?

[jamieduff1981]

Does the tachometer on these use ignition pulses to work out RPM or use some other sensor?

[aide]

Any faults logged in the ecu?

[Supateg]

"If I turn her off then try again all is well, she starts up and runs fine."

That's the clue...

Immobiliser or relay?
The rev counter suggest complete power loss,
I would check/ run the voltage diagnostic logging see if any more clues arise.

[Andy_mr2sc]

I had a similar thing with my Tuscan. It turned out to be the fuel pump relay. All sorts of error messages were thrown up including 0 volts, no dash signal etc. for £5 on eBay all was well again.

[ukkid35]

My money is also on the fuel pump relay. My Capris used to go through them frequently, they would get so hot they desoldered themselves. The other possibility is the fuel pump itself overheating, although that must be quite unlikely at this time of year.

[morebeanz]

Cerbs do funny things if the big fuse is on the way out. It might be worth double checking that it isn't fracturing...

[gruffalo]

Supateg said:

"If I turn her off then try again all is well, she starts up and runs fine."

That's the clue...

Immobiliser or relay?
The rev counter suggest complete power loss,
I would check/ run the voltage diagnostic logging see if any more clues arise.

Thank you for the suggestion, I agree, however all I have to do is to hit the red button followed by the black and all is well I do not have to touch the immobiliser.

It could of course be the relay in side the immobiliser, I am still on the original.

[gruffalo]

morebeanz said:

Cerbs do funny things if the big fuse is on the way out. It might be worth double checking that it isn't fracturing...

Big fuse is in top nick and the other normal big fuse symptoms are not there.

[gruffalo]

ukkid35 said:

My money is also on the fuel pump relay. My Capris used to go through them frequently, they would get so hot they desoldered themselves. The other possibility is the fuel pump itself overheating, although that must be quite unlikely at this time of year.

Interesting as it has only just started happening after a period of layup.

Would the fuel pump relay cause the tacho to read zero, last time she cut out was on the M25 which was moving at around 70 so even left in gear so engine spinning and ignition turned on still zero reading on the tacho?

Any idea of a part number for the fuel pump relay, no harm in having a spare if it is not that?

[Tanguero]

If you are on the original 3 circuit immobiliser - it could be the immobiliser cutting the ignition circuit rather than a fuel pump issue.
When it cuts out what lights do you have on the dash?

As far as I can tell from the wiring diagrams the tacho drive signal comes from the ECU (pin33) via pin 14 on the engine harness so I guess the tacho is driven by the ECU in response to a signal from the crank sensor. In which case I wouldn't expect a reading unless the engine is actually running.

[gruffalo]

Tanguero said:

If you are on the original 3 circuit immobiliser - it could be the immobiliser cutting the ignition circuit rather than a fuel pump issue.
When it cuts out what lights do you have on the dash?

As far as I can tell from the wiring diagrams the tacho drive signal comes from the ECU (pin33) via pin 14 on the engine harness so I guess the tacho is driven by the ECU in response to a signal from the crank sensor. In which case I wouldn't expect a reading unless the engine is actually running.

I don't think there are any lights on, just goes dead.

Interesting I went out this morning big bump and the MIL light came on but the car ran fine.

I think it is time to wiggle some wires round the ECU area.

[Tanguero]

Lack of any dash lights at all sounds like the ignition circuit may be cutting out.

It might be informative to connect up the diagnostics and check what if any faults are logged with the ECU now that the MIL has come on. it might give you a pointer as to which harness to wiggle.

[mk1fan]

Are you sure it's not flooding damage following the TVR punting meet on Tuesday?

[gruffalo]

mk1fan said:

Are you sure it's not flooding damage following the TVR punting meet on Tuesday?

That was wet, I had forgotten how cold the wind is a Brands.

[gruffalo]

Tanguero said:

Lack of any dash lights at all sounds like the ignition circuit may be cutting out.

It might be informative to connect up the diagnostics and check what if any faults are logged with the ECU now that the MIL has come on. it might give you a pointer as to which harness to wiggle.

Yep, a job for the morning I think.

Thanks for your help.

[ukkid35]

gruffalo said:

Would the fuel pump relay cause the tacho to read zero, last time she cut out was on the M25 which was moving at around 70 so even left in gear so engine spinning and ignition turned on still zero reading on the tacho?

Any idea of a part number for the fuel pump relay, no harm in having a spare if it is not that?

Good point, I missed that. Another spare to carry is a Crank Position Sensor, not impossible to change at the side of the road as long as you can get underneath.

[gruffalo]

Morning, just tried to look at the fault logs and I can't find them, software all connected up and reading real time data but I could not find the fault logs.

Probably, well certainly, me being dumb but how do I get to the fault logs?

[aide]

To see the faults logged on the original ecu software just hit PgDn.
I can't remember if it's on the 2nd or 3rd page.

[gruffalo]

Cheers, knew I was just being stupid!