Denso clone of a Bosch VE diesel injection pump

[FlossyThePig]

A colleague at work has asked me to raise this query

MD email1 said:

I have a technical question about the internal workings of a Denso clone of a Bosch VE diesel injection pump that I have just dismantled. Does Pistonheads have a suitable forum where you could raise the question for me please, or do you know of any other more technical diesel based forum that may be better?

MD email2 said:

The pump was working fine, but leaking diesel from several places. I have never dismantled one before, but using a guide from the internet I successfully replaced all the leaking seals and reassembled and refitted the pump. It now works fine when the engine is cold, but once the engine has warmed up, the revs take 15 or 20 seconds to return to idle when the throttle is closed from 2000 rpm. Once the engine has cooled again, it all works fine again. It is not the external linkage that is causing the problem, the lever on the pump closes hard against the idle stop immediately the throttle is released, but the revs still stay high when the engine is warm and not when it is cold. The engine sounds like it is running fine, the turbo works and it accelerates as well as it ever did and with no excessive exhaust smoke. Any suggestions please on what I may have done wrong would be very helpful. Thank you.

Edited by FlossyThePig on Monday 5th March 13:55

[HowlerMonkey]

Is this a toyota or nissan?

[GarryA]

Sounds like you have an leak somewhere.

:-)

Edited by GarryA on Sunday 11th March 19:45

[anonymous-user]

Nope, it's a diesel!

(they run lean with excess air and without a throttle, so an air leak is immaterial)


Sounds like your pump is metering in too much fuel when warm, as more fuel = more speed (engine friction increases with rpm, torque increases directly with injection quantity, so more fuel = more speed).

Can't remember exactly how the mech pumps do any necessary warm up correction, i seem to remember they don't, they just rely on the speed governer to add extra fuel as required to maintain idle rpm.

You pump must be adding excess fuel at low throttle openings, and maybe some crucial leak path/oriffice in the pump is opening with the expanding pump body (as engine temp increases)

[HowlerMonkey]

A couple of links to threads discussing Bosch VE clones.

If you have a leak at the shaft seal, you might want to replace it with a viton seal.

http://www.dieselbombers.com/1st-generation-dodge-...

http://www.physicsforums.com/showthread.php?p=3754...

[FlossyThePig]

In my role as go between.

MD email3 said:

To answer the question, it is a Toyota Estima with a 3-CT engine.

I have dismantled it again now, and Ill have another go at reassembling it paying close attention to the bit that controls the amount of fuel to see if there are any cracks etc.