I am rebuilding a 1951 Lister CS 5/1 fitted with a CAV I.P and a Bryce
I have bled the fuel line and I am getting squirts of diesel at the
injector end of the hp fuel line, but the injector (known to be a good
one and tested on another pump) fails to fire.
I deduce that the problem lies with the pump, either drawing air into
the line or just failing to be able to produce enough pressure to
overcome the spring pressure within the injector.
I am sure someone on the list is an expert on the CAV pump and can give
me a full description of the likely failure.
Is this something I can fix, or would I be best advised I take the pump
and injector to a diesel injection specialist, for repair and
I would be interested to learn from others that have experienced
injector pump problems, and any advice on the inner workings would be
Correction, the injector is also CAV, type BKB50S507b as fitted to
most of the smaller Lister engines.
The pump is the standard CAV BPF1B70CS6253 . (Thanks to Peter's old
engine pages for help identifying these parts).
Before you get to deep are you sure fuel in and out of the pump is totally
airtight as any leak will cause a problem. All seals should be copper
washers. When you operate the pump do you feel resistance, I assume you are
using the hand pump.
Thanks Peter and Martin,
I suspect the delivery valve, as when I bled the system, I applied a
little pressure to the fuel tank by mouth, and I saw fuel weeping from
out of the top of the injector, suggesting that the valve was not
Is this something that I can easily access and clean without risking
damaging the plunger. Are there any serviceable parts that I should
have before I begin.
Peter's article on common diesel injection systems was most
informative, but I am still not fully confident on unscrewing the
delivery pipe connection to get at the valve, without opening a can of
The hand pump on the CS is for priming the oil only - unless I am
Further advice sought please.
Something to do with Hamburglars? :-))
The delivery valve is under the top housing which should unscrew and there is a
spring, seat and valve centre inside.
If the valve is leaking or the spring is bust, then you won't maintain a decent
pressure in the system at injection time.
I think we have spare valves, haven't dug the box out for ages.
The other thing is of course the element itself, which may be U/S. Or has been
assembled back to front.
Peter & Rita Forbes
The engine is now running, albeit without a silencer!
The delivery valve had stuck in the up position and needed a little
very gentle persuasion to get it to move freely.
Using some air pre-heating with a propane torch, I managed to get the
engine to start and sustain running.
Thanks for all the advice,