Diesel starting problem.

I wonder if someone can help me with a strange starting problem concerning a bog-standard (none turbo) clockwork 1.7 GM Astra diesel.

When it's been standing overnight and I then try to start it, all the while I keep turning the engine over it won't fire, that is until I release the key, then it will usually fire immediately.

I could understand this happening on a petrol engine, where the ignition system is being starved due to the drain of the starter motor, but why should this happen on a diesel engine that uses absolutely no electronics whatsoever?

Reply to
ivan
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*Vague memory of something read somewhere follows...*

Is there a stepper motor connected to the injection pump? ISTR something about 3 settings: 1 for off, 1 for starting, 1 for running. It might not move to the "starting" position when you're trying to start it but then does move to "running" when you release the key......? Something like that.

Warning: I may be talking bollox.

Si

Reply to
Mungo "three sheds" Toadfoot

Thanks, but browsing through the Haynes manual I can't find any mention of a stepper motor, it just appears to use a bog standard Bosch fuel pump.

Reply to
ivan

Ok, are you able to check that power's getting to the fuel pump while you're turning it over? I'm assuming it's electric - I haven't played much with diesels.

Si

Reply to
Mungo "three sheds" Toadfoot

It's driven by the cambelt, that's why I'm puzzled, as I would have thought that the engine would be much more likely to fire when it's being turned over.

Reply to
ivan

Yes, you said it was clockwork...

Fuctifino then, sorry. SWKWBAS

Si

Reply to
Mungo "three sheds" Toadfoot

Well you may have a very small air leak or more likely the transfer pump from the tank is taking a little while to come up to pressure. You could try hot wiring it to eliminate that from the equation.

Reply to
DuncanWood

There's still an electrically operated solinoid on the pump to switch off the fuel supply. There could be a fault in the ignition switch. You'll need to check the connection on the solinoid while someone turns over the engine.

John

Reply to
John Egan

Again another item I can't find any mention of in the Haynes manual.

If you remember Duncan this was the engine where I couldn't quite align the timing marks on the fuel pump when I changed the cambelt, due to a very powerful internal spring pulling the pump forward every time the marks came into close alignment, so I eventually left it in its original position of about one notch before the marks were aligned.

Although the actual running and performance appear fine, however do you think that this could be connected to the problem?

Reply to
ivan

MIght be but you'd probably notice the power drop if it was a tooth out. The transfer pump should be on the Haynes diagram, IIRC it's in the fuel tank

Reply to
DuncanWood

Could the stop solenoid be a bit sticky, so that it needs the full voltage to operate, which it won't get while the starter motor is churning?

You could try taking the solenoid plunger out. Establish beforehand how to stop the engine with the plunger absent - some injection pumps have a lever for the purpose.

Peter

Reply to
Peter Brumby

Checking through the Haynes manual for this engine, as far as I can gather what they refer to as a 'lift pump' isn't fitted to my particular vehicle (H reg Astra estate).

Reply to
ivan

I'm fairly certain it had one. I'd still bet on the air leak first though. Snag is it could be all sorts of shit, the other notoriuos failure modes where the electric relays & the valve clearance.

Reply to
DuncanWood

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