CDI Pump seals replaced, now engine cuts under full throttle

Highmileage

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270CLK 2003 249970 miles
As per the title, my 270CLK had been leaking diesel from the CDI pump, and finally wouldn't start at all. I removed the pump, stripped it and renewed all the seals using an OEM kit. The car then started well, although I notice that sometimes it runs rough for a second or two, and also takes a while to crank up (very random). The main problem however is that if I demand full power, especially up a steep hill, or pulling out smartly from a junction, it cuts out instantly; not a safe situation! Once I've turned the ignition off, selected park, it starts instantly. I'm assuming it's something to do with the resealed pump producing more pressure than before? Any ideas please, it's driving me nuts!?
 

alexanderfoti

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What codes do you have?
 

mersum1es

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Long start still indicates you have a leak somewhere. Instant start after cut out is happening because lines are already full of fuel and/or engine/injectors are warm. Either you hp pump can't get enough fuel from aux pump, it is so worn that it cannot deliver full flow under higher pressure, or it cannot deliver full flow beacuse of leaks in system. HP pump inner leaks are difficult to dig up, but injector leaks are easy to measure.
 
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Highmileage

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Long start still indicates you have a leak somewhere. Instant start after cut out is happening because lines are already full of fuel and/or engine/injectors are warm. Either you hp pump can't get enough fuel from aux pump, it is so worn that it cannot deliver full flow under higher pressure, or it cannot deliver full flow beacuse of leaks in system. HP pump inner leaks are difficult to dig up, but injector leaks are easy to measure.
Thanks for this, likewise it's -1C here with a strong wind so it'll have to wait. The car is running well enough until it's not quite arctic!
 
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Highmileage

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Been out in the car today. Worked fine, started first turn of the key through several stop/starts and ran fine.... Do you think it might have somehow bled itself or similar?
 
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