Won't Start Like It's Flooded

[shane r]

Every so often, our van ('90 2.1i) shudders and then quits. Then it simply will not start. New starter motor, plugs and leads etc. It normally starts on the button and runs smooth but, when this happens it won't start for love nor money. It's like it's been flooded-if we leave it for say 30 mins, it's starts up smooth as can be again.

Sometimes, when it won't start, it will let out a huge backfire.

Our startup method never changes, don't touch the gas and just turn the key.

What's up? It's now caught us out about 5 times.

[Aidan]

fuel pump ?
when it won't start does the pump run when you turn the ignition on ? You will need to check the pump while someone else turns the ignition switch to on (not start) and pump should run for 5 secs.
If not then maybe the relay that provides the juice or the pump itself.

[shane r]

Fuel pump, you may be on to something there...

So I should be able to hear it buzzing?

And which relay, where?

[scoobydrew]

Does it do it when cold only or when slightly warm?
If warm could be the temp sensor that controls the amount of fuel, as in a choke.
Had this problem with ours but new sensor cured it.
Basically it was flooding the engine.
If you need to replace it though only use a VW one, aftermarket lasted about 3 months.

[Aidan]

there are two relays in the blackbox ontop of the coil, both 53, one is power supply to the ecu and to the fuel pump relay, the other supplies the pump, I think the pump one is the one on the left looking forward but it may be t'other one,obviously both have to work as without the first one the ecu doesn't know the ignition is on and the fuel pump relay has no supply to switch,
regards
Aidan
yes the pump buzzes a little, but the idle stab unit can buzz louder, use touch not sound perhaps to diagnose.
53 is a very very common relay so easy to obtain from just about any vwaudi from 80's and 90s if you are looking for one to swap for diagnosis purposes

[big red bus]

Have you checked coolant temp sensor? cheap and easy to replace, may be worth changing made a big difference on my 2.1. good luck.

[SuszyQ]

Not wanting to hijack this topic, but our T25 Petrol 2.1i has been doing the same. We have been told it may be the Idle stabilisation valve, but where can we get one??

SuszyQ