5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
I'm new to the forum, but have a problem if anyone can help.
I have a 1995 525tds auto which starts absolutely fine when cold, catches as soon as you turn the engine every time. However, when hot it takes a good 10 to 12 seconds of churning before it starts, again every time. Also, the engine has a habit of stalling when you engage drive or reverse, and also when changing from one to the other etc. This second problem can be averted by applying a little revs whilst engaging gears, but you shouldn't really have to do that. It idles at somewhere in the region of 600 to 650 rpms and I wonder whether this is a little slow for an auto diesel? If so, how do you speed this up, it doesn't seem to have a throttle cable as such as the car has cruise control fitted, so I am presuming it is all controlled electronically.
Back to the starting problem, one mechanic has suggested that this is a fuel pump problem, but that sounds as though it could be extremely expensive, therefor any help or advise would be greatly appreciated.
Ok, try a bottle of injector cleaner 1st before you start spending out to much,add the whole bottle to a nearly empty tank ( ignore what it says on the bottle and make sure you get the one for diesel injectors!),then fill it up, see how you go, then if that fails we will go from there.
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^ cleaner COULD help... But sounds more serious... when did you notice this happening?
When and what was the last service performed on the car. when was the last time it had a tune up?(airfilter fuel filter and such...)?
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The hot start issue is due to the lift pump not functioning when starting on a hot engine,all m51 engined cars do it,rangerover,vauxhall,bmw etc.Injector pump runs hot,over 80deg and fuel evapourates,lift pump will not run until engine starts when warm,on cold start it runs when glowplugs on,hence instant start.My tds (94) does it,but when I add 20% or more veg oil the problem goes away.The stalling and tickover problem will not be related to this.Lift pump lives in diesel tank,around £100 new,but nothing wrong with yours,if you stop car when hot it will start instantly,it's only when you leave it for more than five mins the evapouration occurs and cranking is required.
Vapor lock... you could also try wrapping the fuel lines in a heat sheild like aluminum foil or a fiberglass sheath. Also, try cycling the ignition switch on and off 3 times before attempting to start it after it has sat hot. This will cycle the fuel pump a few times and help to push the fuel back up the fuel lines to the IP. Good luck man! Wish I could get one of those babies over here!
Alas the lift pump will not run on a hot/warm engine start,so cycling it will not work.The vapour lock occurs inside the injector pump itself,there is a fix which involves a resistor or diode that can be fitted to pump relay to make pump run on warm engine although this also fires up the glowplugs as well.The lift pump only runs around 10psi ish pressure if that much,its not a high delivery system like petrol engined cars,and I believe ecu stops and starts it during engine running/fuel pressure sensor in top of filter head,although I may be wrong on that,people running vegtable oil have described signal from ecu as switching off and on when testing pump wiring,this made sense to me as pump does not have a high return flow to tank,it only needs enough fuel to run engine.
Gentlemen, many thanks for all your suggestions and comments.
Because the cars in Spain, its difficult to try these straight away, however the injector cleaner has to be worth a try, and is relatively inexpensive, so will do that next time we go in a couple of weeks.
The lift pump suggestion seems logical, but I wouldn't know how or where to fit the resistor, so I will need to find a reliable auto electrician over there, that could be a bit of a task in itself.
As for the engine surge, and stalling, I think I agree that this is a separate problem. I did find another thread on this site from someone else who had the same problems and he fitted a new injector pump which apparently cured the problem, although a trifle expensive. I think I might see how this progresses for a while, the car is only a run about, and you can compensate for these nuances with driving style, even though this is all a bit annoying.
Yes, the car does need a good service, but I don't feel this alone will cure all.
Once again, thanks for the help, and keep them coming if anyone has any further suggestions.
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