Injection pump timing (Bosch / Bx)

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Gavin1
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Injection pump timing (Bosch / Bx)

Post by Gavin1 »

I'm in the process of changing the fuel pump on my Td Bx from a Lucas (it died) to a bosch (from a ZX-non keypad). I've changed the pump sprocket, timed the engine with bolts on the pump sprocket, cam wheel and fly wheel and have managed to start the engine. However the engine will only start with ether and will only run with the throttle held open - also it then pours out black smoke.
The black smoke suggests the timing is too far advanced which is strange as the timing holes all line up. Has anyone else tried putting a bosch pump on a bx engine? Any ideas what could be the problem. The engine was running fine up until the lucas pump failed.
Dave Burns
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Post by Dave Burns »

When you say you have changed the pump sprocket, you do of course mean you have used one designed for the Bosch pump, and not put the Lucas sprocket on the Bosch (if it fits), the keyway may not correspond with the timing holes.
Also the Lucas injectors have a much lower opening pressure than Bosch injectors, opening pressures play a major role in the timing of injection.
IIRC Lucas injectors open at 132 bar or lower (1914 psi), Bosch open at 175 bar (2537 psi).
When you get the correct injectors fitted you will need a static timing value for the pump, don't know if that pump was ever fitted to the BX TD so an timing value may not be available, you will then have to take a stab at one from the other XUD's, i.e 1.9TD DHZ,D8A for a value of 0.66mm and take it from there.
Dave
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Post by RichardW »

Think about the pump like a distributor - if you rotate the pump body whilst the shaft is held steady you will alter the timing. You really need a dial test indicator to check it, but you should be able to get it somewhere near by slacking the bolts off and rotating the pump a bit and see if there's any improvement. Sounds like the timing is too far advanced, which to my mind says you need to rotate the pump towards the front of the car to retard the timing.
Richard
mg46783
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Post by mg46783 »

Hiya..dont know if this will help but the last post, re; thinking of the pump like a dizzy - is spot on... I had it once where the pump had been timed up 180 degrees "out"....the engine started but puffed black smoke like a gud 'un.... took us a while but we fig'd it it in the end. 180 out! Might be worth a try. mike
Dave Burns
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Post by Dave Burns »

Are you sure Mike, 180' is a fair old error, its half a crankshaft revolution and a whacking great 90' at the pump, hehe must have sounded like a ford diesel.
Dave
Gavin1
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Post by Gavin1 »

I've changed the injectors to Bosch injectors when I fitted the new pump so there shouldn't be any problems there.
Have rotated the pump as far as it will go towards the engine and its producing less smoke and is a little less reluctant to start and run, so I'll move the sprocket one tooth on the timing belt, that should give me a little more adjustment on the pump timing.
Cheers
Edited by - Gavin1 on 23 Oct 2002 14:49:00
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