Cleaning alternator...

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Ok, narrowed it down a little. Took injector cap off (single point injector above inlet) Tried to start her and big jet of fuel comes flying out of the top of the injector - so fuel line ok.

Removed injector, load of fuel had collected in and around the injector - (is this normal???) - this trickled down into the inlet when I pulled the injector out.

Tried to start her again, fired up for a few seconds (w/big puff of smoke coming out of the hole) Assume this was just the excess drained fuel burning off, and that the smoke is nowt to worry about.

So she fires with fuel in the hole but doesn't sustain...leads me to think that injector isn't erm...injecting!

So borrowed another injector from other vehicle. Same injector, same part number......Same problem! :mad:

So initially it would appear that whatever controls the injector opening and closing is not doing it's job, however I don't know what that is :confused:

Possibly the ECU? Problem with that is that it resets itself every time you change the battery, and I keep having to switch between 2 batteries because they are wearing down v/quickly trying to start the bugger.

The little pin at the bottom of the injector depresses slighty when pushed, I assume it doesn't actually need to travel that far to do it's job?

There is a spec for testing the inj. with a multimeter, it says it should be 1.2 to 1.6 ohms, however I've no idea what the MM should be set to in order to get that reading (electric/tronics not my strong point :oops: )
 
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Logic would suggest that, as you have removed and replaced the inlet manifold intact, you haven't disturbed the fuel injection system. It worked before so it should work now. Double check all electical leads also any rubber hoses etc connected to the manifold for leaks.
Obvoius things like plug gaps. Does your model have a distributor? Does everything look ok in there? You may have a spark but it could be weak.
Does the throttle position sensor have any adjustment? If so could it have been knocked out of alignment?
The only other thing I can think of is an air leak. When you replaced the inlet manifold are you positive both the cylinder head and manifold were clean when you fitted the new gasket? Any bits of old gasket,crud would affect the new gasket and allow air to be drawn in.
Keep the faith, your almost there ;)
 
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Curiously enough, I had the very same problem on the last Polo I did......fuel system untouched, cranking away merrily etc.
This one did reluctantly start after what seemed to be an age, and seriously the only thing I could think of was the hydraulic valve lifters had to fill up with oil before anything would happen. Maybe yours is the same, or maybe I'm talking cobblers!
John :)


had a few like this, wouldnt start by cranking and had to tow them but bump started almost straight away
 
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I'm beaten :(

All (new) gaskets went onto clean faces, all hoses were left in situ when I took the head off, the plugs are the triple prong versions, no gapping required, they are as they were when I took them off apart from a quick toothbrush and clean in solvent and they are sparking. There is no throttle adjustment afaik, all controlled through the ECU. Bosch monotronic.

Is it not a dead cert that cranking the starter and pushing down on the accelerator would cause fuel to leave the injector nozzle? Well I laid a piece of paper under the nozzle and over the inlet whilst cranking, and it remained dry. I've tried 2 injectors now, both look clean.

Oh, also checked the wires from the big multiconnector, all are fine.
(didn't bother checking upstream it's all wrapped up tight in tape and they haven't been touched or moved)
 
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If you are positive that you've got the timing bang on and that it's getting a spark, (which it must be because you said it runs but won't sustain) don't mess about with half flat batteries, either get a decent battery or just tow the bl00dy thing.
 
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Defo got spark, if the timing was out it wouldn't even kick in at all would it??? Yesterday, the fuel that was drained out of the injector was enough to run it for a couple of seconds, and a few tries of that and the exhaust downpipes got ever so slightly warm, so these are good signs regarding spark and timing?

I'm worried the ECU might be bollaxed and isn't telling the injectors to open, assuming that's what the ECU actually does :?:
 
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It might run if the camshaft is out one tooth either way. I had that with an Astra about 20 years ago, it ran but not very well. Have you tried dribbling a wee thimble of fuel straight in to it?
 
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I don't wish to sound patronizing, but are you 100% sure ALL the electrical plugs are connected and in the right places?
 
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Stiv: tried that, as mentioned previously it starts but won't sustain.

Mr T: Patronise away! I'm getting way out of my depth now (in fact I was about 4 pages back but I made it this far :LOL: )

There is a single cable that runs beneath the TB somewhere, this is connected up securely to it's plug.

The throttle body has one of these on the front, one of the plugs goes onto the right hand side, is there anything inside this unit that can be checked? There seems to be a panel on the right held on tightly with clips, can't be sure.

OK, I'll confess, I'm clutching at straws now. :oops:
 
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Have had a look around t'internet. A lot of starting problems on VW single point fuel injection seem to stem from the temp sender.
Found one on DIYNOT too.
//www.diynot.com/forums/viewtopic.php?p=1321252
Different car but similar system.
It has been suggested elsewhere that disconnecting a faulty temp sensor fools the ECU into cold start mode and gives a richer mixture for starting.
 
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Good work! I'll try disconnecting it, it's the blue one above the thermostat IIRC. Although I do remember reading somewhere that this can set the ecu into limp home mode and will need to be reset :unsure:

Doh, might as well just swap one out of the other motor instead of just taking it out. I've got another Polo in the garage, for 'parts' :mrgreen:
 
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is there anything inside this unit that can be checked? There seems to be a panel on the right held on tightly with clips,

No mate, don't even think of taking it apart! and it is very unlikly to be your problem. A very common problem(as Whit has just mentioned) with a no start due to lack of fuel out of the injector is the coolant temp sensor, I would prefer to try a known good sensor rather than just unpluging, but either is worth a try.

Edit: Sorry mate your post wasn't up when I started typing, Yes it's the blue one.
 
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Not sure if there are two temp senders (one for gauge and one for ECU) but one thread I read mentioned the temp sender being under the distributor. Not sure if its the same model as yours but it was single point injection.
 
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