'87 3CX Perking 4.236 Injector Pump Problem

[Slooby]

Thanks Jeremy, fingers crossed that all that chud was the problem, probably more red diesel dye congealing in the system causing really tiny particles that got past the filter to clag together. Ideally I should get another filter in before I try to prime and start the JCB but as it's in the way I might not get the chance... I'd also like to blow through all the fuel lines too

[Slooby]

Didn't get to blow through the fuel lines, but I did get a new filter (actually a pair of Indian made 'Zip' filters) which I fitted this evening. The old filter was full of crap, after less than a year of being on there, and probably little more than a couple of hundred hours if that.

The new filters came with seals that were all the right size, and the system bled really easily too. The engine also feels like it has a bit more power now, and I've been back at moving soil about with it again.

Thanks again for pointing me to the regulator filter Jeremy, the fix, for once, has been surprisingly painless and inexpensive (ignoring the fact that I bought an ultrasonic cleaning bath for another job of course!)

[Jeremy Rowland]

Glad you got it sorted Tim it's always a great feeling when a problem has been more easily solved.

Jeremy

[Slooby]

Resurrecting this thread as once again I ran out of fuel, and am having a hell of a job to get tge JCB running again...properly, and by that I mean I can get the engine running, but only for about 3 or 4 minutes before a couple of stutters and dying.

I've been through the normal bleeding process, I've had the regulator filter on tge end of tge injector pump out for a look see and all seems well there.

However, something I have now observed and am slightly concerned about is that as I have been repeatedly been bleeding the fuel system the second bleed point on the injector pump (the upper one of the two on the side) has gone from passing some fuel progressively less and less ultimately being bone dry with the bleed screw removed completely. So, does anyone know these Lucas CAV pumps well and could offer me a clue as to what could be going on?

[essexpete]

I am no expert but have you got good flow to the injector pump?

[Slooby]

Seem to Pete, have fixed an air leak on the lifter pump around the cap screw, replaced the fuel filter as I had a spare (the one I took out was pretty clean), priming the system to the first bleed point on the injector pump was pretty easy from the mechanical pump.

With the engine being turned over there's plenty of fuel coming out of the bottom bleed screw on the injector pump, and initially the same could be said of the top one. Then after each stall I found less fuel coming out of the top bleed screw. I checked the regulator 'last chance' filter after one of the stalls and it was clean.

I should add that I have been cracking the unions on the fuel injectors in turn as part of thebleeding process, but since flow has ceased at the second stage on the injector pump I've stopped to scratch my head

[dixie-normous]

CAV pumps seem to be developing more problems with modern low sulphur diesel, it doesn't have the lubrication properties to keep the pumps free and gums up the internals. No fuel to the injectors can be several things from a stuck metering valve to the plungers sticking in their bores in the pump or a blockage in one of the passageways. The metering valves tend to stick when the engine stop is left pulled out and it is parked up for a while but as you had it running for a few minutes it doesn't sound like that is the problem, but it is possible that it could be the pump plungers. There are several videos on youtube about rebuilding the CAV pump but they are a bit hit and miss and plenty of people have tried to follow them and ended up in a world of hurt! If you have a good flow of fuel from the tank (mine looked fine but started to slow after a while and turned out to be the tap filter) and the lift pump diaphram is good, then you may need to look at getting your pump serviced. It's not cheap but compared to a JCB that won't run or lots of bits of pump all over the workbench it's money well spent!
John

[Slooby]

Hum, that's an interesting series of points to ponder there John

The JCB had been parked up for a few months and when I went to start it I realised that the stop pull was up because the lever on the pump needs to be pushed back by hand as the spring is too weak to return it.

With the lever reset it fired up first turn, and I picked up the buckets and moved it round to where we were going to use it, for it to cut out on me just as I got there. Assuming it had run out of fuel (can't remember the last time I put any in) I went out and got 40 litres of fresh diesel and started the priming dance to get to where we are today

[Slooby]

Forgot to add i chuck in a bit of two stroke oil in when I fuel it up having heard about the lack of lube in modern diesels

[dixie-normous]

Ahh, could be the metering valve sticking. Sometimes giving the side of the pump a tap (not hard enough to break anything) will free it off. You can free a stuck metering valve by lifting the top cover up just enough to get a small screwdriver under it to flick the top of the lever back, but there is a governor spring inside and there are 3 holes that the end can go in, if it comes out it is very important that it goes back in the hole it came from. Also if you tear the gasket it will need replacing as diesel will p*ss out when it is running

https://m.youtube.com/watch?time_contin ... =emb_title