Maybe stupid questions but........?

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Posts: 108
Joined: 30 Jan 2001, 18:19

Maybe stupid questions but........?

Unread post by Gaskin »

As the colder days are upon us my ZX TD is getting more reluctant to start so its time to look at all the usual suspects as per numerous threads before. But one of the suggestions is to replace the leak off pipes from the injectors. So the stupid questions are (a) what are the leak off pipes for (leaking off perhaps?) and (b) why would perished ones cause starting problems?
Thanks in advance

Dave Burns
Posts: 1916
Joined: 14 May 2001, 05:30
x 2

Unread post by Dave Burns »

Most of the fuel that passes through the injection pump per delivery stroke is returned to the tank, only a small amount makes it through to the actual injector nozzle, so the rubber pipes are there to return the leaked off fuel.
The pump its self also returns a high proportion of the fuel that it sucks up from the tank, this is to ensure constant purging of any air that gets in, it is also a method of keeping the pump cool as the returned fuel takes heat away with it.
The pump return pipe and the injector return pipes are connected, thats how air can get into the pump so easily causing all the grieff.
The inlet and outlet of the Bosch pump are not restricted by the stop solenoid, so a leak anywhere near the pump allows fuel to drain/syphon back to the tank from the injection pump, as the pump is drained the fuel volume is replaced by air, diesels wont run on air[:D]
This is seldom a problem with a Lucas pump, the stop solenoid on those acts on the incoming supply, the pump actualy sucks the solenoids plunger hard down over the inlet port when the engine is switched off, if you were to switch the ignition off and on momentarily while driving with a Lucas pump, you should find that the engine will not restart until it has come to a complete stop, the Bosch on the other hand will restart instantly.
If you get air affecting starting with a Lucas then you have a leaky stop solenoid, not a problem in its self as long as the engine will stop when the ignition is switched off, but there is a leak present somewhere in the system that needs sorting.

Posts: 263
Joined: 22 Apr 2001, 03:02

Unread post by pwatson »

How's your battery?

Posts: 108
Joined: 30 Jan 2001, 18:19

Unread post by Gaskin »

The battery is fine, about 1 year old. I'm doing the glowplugs as well now (see 'Now what.....' post.)

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Joined: 20 Oct 2002, 16:00

Unread post by jeremy »

Is the battery the correct size?

Jiff Lemon
Posts: 15
Joined: 06 Jul 2004, 21:48

Unread post by Jiff Lemon »

Quick test for glowplugs is to to give them a second turn of the key.
Earth strap good,clean and tight?
Fuel filter changed recebtly? Water trap drained?