Bosch diesel pump

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Doc
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Bosch diesel pump

Post by Doc »

On the XM 2.1 turbo diesel with Bosch mechanical diesel pump, there is a pipe attached to what looks like a regulator on the pump which then seems to be attached near the radiator and/or air to air intercooler. The Haynes manual makes no mention of this pipe. Does anyone know what it does and where it goes to?
Thanks for any advice
Doc
Simon Canfer
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Post by Simon Canfer »

This sounds like the air pressure sensor to add more fuel when the turbo is "boosting". At least that's what it was on my 1.9TD.
Simon Canfer
Edited by - Simon Canfer on 17 Jan 2003 16:20:23
Doc
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Post by Doc »

Thanks for your prompt reply. I now suspect that the pressure sensor is faulty causing a under-fuelling problem when under load and turbo is boosting.
Regards,
Doc
RichardW
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Post by RichardW »

It's very unusual to hear of problems with the Bosch injection pump, unless the engine has covered lots of miles - not to say that yours isn't faulty! You could take this pipe off and the rev the engine - you should get a nice healthy stream of warm air coming out of it - this will show that the turbo is blowing. To see if the regulator is working, you could blow into the regulator - I think the engine speed should increase as the pump will inject more fuel - you might need to do this with a tyre pump, as you will probably need 5-10 psi to see any effect.... To check if the turbo / waste gate is working properly you need to connect a pressure gauge into this pipe, and then monitor the boost pressure on a run - it should reach about 0.8barg under full load (eg hill climbing at 3500 rpm) - and not increase above this if the engine speed increases.
Mind you, I think the 2.1 has some electronics on it, so this may all be cobblers!
Richard
Doc
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Post by Doc »

Thanks for replying RichardW. Car has covered 91,000 miles and has a full service history. Spent all day (19th Jan) hunting airleaks into the fuel lines in the engine compartment. Found a small leak on filter to pump supply pipe that was weeping where pipe joins some sort of flow monitoring device. (Looks like a metal version of the old plastic inline petrol filter, and has a wire leading from it to a relay). Haynes manual doesn't mention it so I suspect it is linked to the immobiliser. (solenoid valve or fuel flow meter?)
Have re-checked filter assembly and priming pump which were all okay and airtight. Engine ran better and idled better but still not 100%
I reckon as Bosch pump should outlive the engine, there must be air entering lines between tank and filter.
Doc
Doc
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Post by Doc »

As my engine is the 2.1 Turbo diesel with the Bosch mechanical pump, it doesn't have any electronic controls. I think the EPIC system came out on the M plate 1995.
Doc
Edited by - Doc on 20 Jan 2003 22:58:13
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