RPM meter goes up and down on idle

[netdobeiras]

My RPM meter goes up and down on idle. My galaxy doesnt shut off because of this nor is it noticeable without looking at the meter. Any ideas what can cause this? I noticed my injector pump is leaking/ wet and sometimes I find an air bubble in the clear fuel line that goes to the injector pump but i never had any problems. I have a 1996 ford galaxy with a 1.9tdi motor with 153k km.

[insanitybeard]

When you say the vehicle 'doesn't shut off' do you mean that if you turn the ignition off it carries on running? And that the engine speed is fluctuating at idle? How much fluctuation is there?

[netdobeiras]

The engine does shut off if i turn the ignition off. My idle fluctuates by about 50 rpm from time to time.

[johnnyroper]

When it carries on running take wire off the fuel shut off solenoid on pump and see if that stops engine as could be sticking plunger. Probably worth checking for power there before doing that though. Should be 0v as it is 12v to start when ignition ignition is on. If thereââ,¬â,,¢s power there then look at relay 109 and fuse box.
Another final check if above fails to find an issue is disconnect alternator

[brianh]

I think the op's wording is a bit confusing - I think his problem is the idle isn't stable on the engine and fluctuates. But hes trying to say the engind doesn't stall as a result of that, not that it doesn't switch off when the key is turned off.

Any suggestions on the air bubbles comment and leaking pump?

[insanitybeard]

Being that it's a fairly high mileage pre-PD unit with mechanical fuel pump and fully mechanical injectors, there's a possibility of an injector that's not closing off fully? I know places in the UK like Lucas (when they still existed) and Electro-Diesel can test them but as with all things it depends on how bad the issue is for you to want to try to remedy it. If the engine is surging badly and the issue is affecting drivability that's one thing, if it's a relatively minor fluctuation on an older vehicle, do you really want to delve into it?

Of course it could be something else entirely to the injectors, OP has also mentioned the mechanical fuel pump leaking- whereabouts is the leak and how bad is it? From the description it's implied it's not leaking all the time.

[johnnyroper]

Oh yeah good spot just seen he says it does shut off,forget everything I said and concentrate on the leak initially as that will need fixing regardless and itââ,¬â,,¢s quite possible itââ,¬â,,¢s drawing air in causing the slight hunting/fluctuation