Engine cutting out

[CHRIST1966]

Hi everyone.

Only just joined this forum so not quite sure how it works yet.

I have a 1982 VW T25 2.0 litre Aircooled model.

It runs perfectly for between 1 and 2 hours (no set pattern) and then cuts out and wont start again.

The engine turns over but makes no effort to fire.
I have disconnected the fuel pipe from the carb when turning it over and fuel comes through as normal so I dont think its a fuel issue.

After an hour it starts again and runs perfectly.

Plugs and leads seem good.
I have changed the coil, distributor cap and rotor arm, and now the ECU.
None of this has made any difference.

Any suggestions as to what to try next?

[82JEW75]

How does it cut out?

Is it abrupt, like flicking a switch, or does it splutter and cough?

The former would suggest an electrical/ignition issue, the latter a fuel problem or overheating.

[CHRIST1966]

Hi there.

It just cuts out like a switch as you suggest.

I have been told today that it might be worth fitting an electric fuel pump as the standard mechanical one puts out low pressure when it gets hot.

[82JEW75]

Almost certainly electric/ignition.

Don't waste your money on a fuel pump, not just yet anyway.


When it cuts out, do you have a spark?

Disconnect one plug lead, connect to a spare plug, hold against the engine block with a pair of insulated pliers and get someone to crank the engine over. Spark?

Change the condensor if you haven't already, only a couple of quid and they do fail.
(Umm... assuming there is one on electronic ignition, goes to check...)
No, forget that, you haven't got one. Well, I haven't got one (1.6CT), so I assume you don't either.


Check all the earth points.

Check the battery voltage.

Check the dumb stuff that can't possibly be related.


We once had a similar issue with a Renault 21, would cut out stone dead, as if someone had pulled the plug, then restart a couple of hours later with no trouble. Took two years to find the problem, which turned out to be an undersized battery and a slightly tired electric fuel pump. The fuel pump would sometimes draw too much power, just enough to cause the battery to drop below the magic voltage required by the ECU and the whole lot would shut down.
Engine would still spin over fine, fuel was pumping, but no spark. Caused an awful lot of head-scratching.

[CHRIST1966]

I will look into the condesor first (not sure if it has one either!)

Then check if there is a spark when it cuts out.

I will hang on about the fuel pump for now.

Cheers

[Footprint]

Do you still have the idle stabiliser unit fitted? It's the square black box on the left bulkhead next to the ignition unit, the one without the finned aluminium heat sink, when they fail they do exactly what you're describing - sudden cut out, won't restart until cooled down.

If you have then you can remove the two plugs and they'll fit together taking the ISU out of circuit, (this is done when setting timing), it's nice to have one but they're not strictly necessary so you can happily dispense with it, and many people, including myself, have done so.

[CHRIST1966]

Hi

I have has a look at the idle stabiliser unit.
Which are the wires to connect together?
Would it be much trouble to take a photo and e-mail it to me?

Regards

Chris

christophertaylor1966@yahoo.co.uk

[82JEW75]

Hi

I have has a look at the idle stabiliser unit.
Which are the wires to connect together?

The idle stabiliser unit is the only black box on the left side of the engine bay that has two round plugs going into it.

Disconnect these two plugs from the box and connect them together, bypassing the box.

You can't get it wrong, there are no other plugs that will fit together.

NOTE: not WIRES, PLUGS!