diesel car brain teaser

[thanuttiscotsman]

hi folks,
some of you may remember a while back i posted up about a diesel astra i had that wouldn't start. well since then ive learned some more but have not yet fixed it.

so for all you engine heads out there that know your stuff about petrols and diesels, here's one you should be able to figure out this problem! or just confirm what i think is wrong.

well basically its an 96 astra estate 1.7 tdi. basically this car will start and run if its left lying still and no attempt to start it is made for 3 or 4 weeks. when the car starts it starts quickly with no problem and drives great. only she's fairly smokey out the back. but if i turn the engine off it will not start again no matter what. ive tried hours with jump leads etc and got nothing. but if i leave her again for 3-4 weeks charge the battery and turn the key she goes easy first time.

so what do you think it could be. i dont know very much about diesels but from basic knowledge my guess is the diesel pump has something inside that seems to block the pump when started, but not enough to stop the engine when running. but after starting the pressure in the pump im guessing increases greatly. and that pressure keeps the crap blocking it until a month later and the pressure drops again freeing up the dirt.

now i could well be completely wrong as im just guessing at what could make sense. i would appreciate the opinion of anyone and eveyone who knows about diesel engines and who may have had these problems before.

i know it aint a valver but if i can fix this car then i can sell it for about £600 which will buy my some nice rims for my valver, so its all for a good cause .

cheers rossco

[Channel Hopper]

I would suggest taking off the top of the fuel filter (near the bulkhead behind the engine ?), and run a small bottle of diesel straight into pump/injectors as a test. If the car continues to run after restarting then you have a leak somewhere in the main fuel line which is sucking in air, rather than dumping fuel on the road (as it is under vacuum) .

Check under the car for any damp (or areas of excessive road dirt) spots along the lines running back to front.

[Anonymous]

Hi,

The pumps on later GM diesels i.e./ Tdi, DTi and Di are notoriously crap. Theres a control module / solenoid built into the pump that causes these type of issues - fairly similar thing happened to both my dads and a work colleagues DTi ('02 plate).
The pumps are 'sealed for life' and contain no user servicable parts, so its a new pump job at around £1000 IIRC failing that a second hand one, but the breakers know about these issues and charge a good old price for a used one - and remember if you get a used one you'll need to get the immobiliser re-programmed since this is built into the pump module.

Both my Dad and the guy at work took the easy option and sold the car on.

Cheers

[thanuttiscotsman]

hi there,
sorry chaps i should have also said i have done this test with a gallon of diesel straight to the pump!

I would suggest taking off the top of the fuel filter (near the bulkhead behind the engine ?), and run a small bottle of diesel straight into pump/injectors as a test. Check under the car for any damp (or areas of excessive road dirt) spots along the lines running back to front.

also i have been to the scrappers and have changed the soliniod fuel switch thing and it made no difference. TONY M you are right!! the sports car breakers wants 75quid for a used pump. rediculous!!

but basically i enjoy spending long hours messing with cars. what im looking for is confidence or confirmation that the pump is buggered, so then im going for fork out and change it myself. these cars still go for around 600-800 quid and the one i have is a nice one. i got it for 150.

i didnt know these cars have immobilisers!! if mine has one maybe its at fault?! im assuming now the immobiliser would be the plastic black box on the pump with 3 or 4 wires?

anyhow anymore input ideas or suggestions are very welcome!!

cheers rossco

[Anonymous]

What year is the vehicle? since on the models I was referring to the solenoid/control module is integral to the pump and is not replacable. When you say TDi, I'm therefore presuming its simply a TD ie. 1.7 model - has it got the Isuzu donkey? If it is the later models they DO have an immobiliser built into the control module, if its an older TD then I don't think they do.

Cheers

P.S. if its the later type pump you'll be lucky to get one from the breakers at less than £250

[thanuttiscotsman]

hi tony,
my car is a p reg 96. it is badged a td and is 1.7, its the older shape one, same shape as older ones back to l reg i think. i dont think it has an immobiliser but not sure. but on the engine block for some reason it says tdi and it does appear to have an intercooler low down behind the front bumper. the scrappers already quoted me 75 quid for the pump, but im holding back till im really sure thats the prob cause i dont want to loose the money. by all means i could take the pump back say it doesnt work and get refunded but that would be a big pain.

what do you think?

rossco

[tim leech]

Ive heard the fuel pumps do give trouble myself.

[Vanny]

when you say it wont do anything when you put the key in could you be specific.

1)If you put the key in (having just started her up and turned her off on the key), and turn it to the first position, do you get any lights on the dash?,
2)second position, go the glow plugs come on?
3) If you leave it in the second position does the plug light go out followed a little while later with a clunk from the glowplug relay switching off?
4)turning the key to the start position, does the starte engage and or turn?
5)can you visually see parts of the engine moving? (if you stick it in first and flick the starter on and off does it shunt forwards (safety first, make sure you dont have anyone or anything in front of the car)
6) is there power to the stop solenoid (should have 12v on the second key switch).


I THINK the Isuzu engine has TURBO written accross the rocker cover and the injection pump down the back of the engine, but a picture would be good!

Have like a whole long list of other questions once the first ones are answered!

[thanuttiscotsman]

hi vanny,
yes after starting and turning off again the key does trun lights come on plugs heat and starter motor turns the engine over a a good speed i.e starter is great. but i can have it hooked up to the valver on jump leads and the astra engine with turn over forever on the starter motor but wont fire up. it is a gm 1.7 tubo diesel. non isuzu. and the turbo goes like fu*k when the car works. the diesel pump is on the front left of engine when looking under bonnet. the fuel stop solinoid has been changed since this pronlem started and i have also re-wired it as before i couldn't hear it open when i turned the key on. (hence thats why i changed it first before re-wiring it) but now when ign is turned on there is a healthy click you can hear with door open etc. just before this happened she had 50 litres of fresh diesel put in her which has since mostly been removed (and put into the hire van that brought my parts from lukes.) the van went fine so its not a fuel problem. oh and the glow plugs are brand new as i changed them when the problem started to occur. oh and in gear turn key car goes forward with a jump.

ok next questions , cheers rossco

[thanuttiscotsman]

hi folks,
does anyone think the problem with this car could be to do with the pump timing being wrong??? if so how does one go about adjusting it on a diesel? as a mate mentioned it could be the cause of the problem. where is alan s when you need him?

cheers rossco

[jayw]

Hi Rossco,

A friend of mine had the same problem with their diesel Cav, turned out to be the fuel temperature sensor. Not entirely sure where it's located as i can't get hold of him but the symptoms were exactly the same.

Brand new one was thirty-odd quid from Vaux.

Hope it helps.

Jay

[thanuttiscotsman]

hi there,
sounds very interesting! you have my full attention!! ive never heard of such a part!! but if you can find out what it looks like and where it is im sure i can get one from the scrappers.

cheers rossco

[jayw]

It appeared to all us lot that it was an immobiliser issue, but it was an AA man who cracked it in the end. Apparently if the diesel fuel is too hot it 'pre-ignites' so thats the reason for the sensor.

I'd hazzard a guess that it would be in the fuel line before the pump?

Don't know any more than that i'm afraid. (although this is also a common fault on BMW 2.5td, also fitted to the Omega as that sensor is attatched to the pump right next to the exhaust manifold).

Will let you know when i've spoken to him on monday.

In the meantime might be worth throwing a few randoms at the search engines and see if you get any relevent results?

Jay.

[thanuttiscotsman]

hi there,
that would be great if you could find the info for me. i have tried endlessly at searching astra td starting faults and got nowhere. if its a faulty sensor then how does this sensor go about stopping the engine from starting?? also could this be a reason for the cars emmisions being extreme?? a in when i give it one big rev it leaves a massive black powder carbon mess on the ground under the tailpipe exit!! this may be irrelevant but 2 years ago the belt snapped and fecked the head but it had a new head put on and gasket belt etc but even and ever since that happened the emmisions have been really heavy.

cheers rossco.

[thanuttiscotsman]

It appeared to all us lot that it was an immobiliser issue, but it was an AA man who cracked it in the end. Apparently if the diesel fuel is too hot it 'pre-ignites' so thats the reason for the sensor.
I'd hazzard a guess that it would be in the fuel line before the pump?
Jay.

hi there jay,
you may just be the prob cracking god of all astras!! i have just phoned vauxhall and this car does have one of these sensors!! good start !! also i noticed before where the fuel filter is just before the pump there is a sensor looking thing screwed into the filter housing plugged into brain with 2 pin plug. getting warmer! they are only 25 quid new but im going to the scrappers to get a few!! the parts guy put me through to technical and they advised me that if the sensor was faulty not broken then i could allow the car to start first time as giving ecu acceptable starting readings but then giving dodgy ones after warming up because the sensor is giving strange info so next time dont let it start up. he said the false readings could possibly be a reason why the emmisions are extreme as its overfueling (too rich mixture) then could be flooding so it cant start again after being turned off. im not sure but because diesel is basically oil i imadgine it takes a long time to evaporate. anyhow down to the crunch im off to get and fit what i think is the sensor on/in the filter and see if it solves the problem!! will do it and let you guys know what happens.

cheers rossco