Air is getting in to the diesal

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Joined: 16 Feb 2001, 18:51

Air is getting in to the diesal

Post by B_Draper » 11 May 2001, 15:45

My 94 ZX TD has recently had trouble starting and I suspect I'm getting air in the fuel somewhere.
On the first startup of the day, i often have to get out and manually prime the engine. Once this is done the engine will catch. For the rest of the day the engine will start first time.
Is there a common location where this occurs or do I have to gradually replace the entire fuel system til the problem is fixed?
A friend suggested the seals on the fuel pump might have gone. Is this possible?
If possible could you include approximate prices (UK pounds pls) on fixing this problem!

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Post by Jimmydeath » 11 May 2001, 22:24

Hopefully someone will correct me if I am wrong here but a working fuel pump is not required to start the car if the fuel filter reservoir is full and there is no air in the system after that.
Given the above then it would seem that you are getting air in the system after the fuel filter, possible areas to look at are the water drain valve at the front of the fuel filter (check if it is closed off properly)and the O ring under the base of the fuel filter housing (has it deteriorated or has the bolt securing it from inside the housing worked loose.
From there check the pipe from the bottom of the fuel filter to the injector pump, check the four metal pipes from the injector pump to the injectors then check the low pressure return circuit for which you may need to remove the intercooler (2 bolts at the front and three hex bolts at the back). The low pressure return circuit are the black rubber pipes that connect from the tops of the injectors and lead to a small cylinder at the front of the engine between the injector pump and fuel filter.
If air is getting into the system then either the fuel is leaking out somewhere which should be visible or possibly an air leak is allowing the fuel to drain back into the tank via the return hose.
I suppose there is the remotest possiblity that the fuel solenoid on the injector pump is a bit sticky and pumping the circuit helps to free it but I think that we are in the clutching department of a straw factory on this one.
You didn't say whether you felt resistance when priming the circuit which would indicate that the fuel was draining away. You could always whip the top off the fuel filter one morning before starting to see if it is full.
Let me know if this helps

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Post by JohnD » 12 May 2001, 00:33

If you are parked overnight on a slope with the nose up, it will make a slight fuel line leak appear worse. Our BX has one, although it needs a week or more to become apparent.

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Post by B_Draper » 15 May 2001, 18:15

Thanks for all the suggestions. I'll be taking a closer look this weekend if the weather is dry enough!
Will keep you posted if I find the source of my troubles!

Posts: 61
Joined: 16 Feb 2001, 18:51

Post by B_Draper » 16 May 2001, 14:41

Found the problem!
On the low pressure return circuit at the No 1 injector (far left) the plastic stopper on the injector had perished which allowed pressure in the system to drop which made it difficult to start.