CAV DPA injector pump - no fuel to injectors after bleeding

[mungus]

The # is 3342F150

Thanks for the offer. Apart from the FIAT shop manual's bench test data and picture of the governor plate (for pin position), I haven't been able to find any data for my pump. Almost like CAV tried to keep it all secret!

I can see what you mean about the slot now. Found a cutaway drawing that shows it just acts as a fuel duct.

Still, it's strange given that when this fault first appeared all I had done was replace the cover gasket and shaft O rings. I can't remember changing the spring position. Perhaps age is getting the better of my short term memory again...

 

[thepumpguysc]

The spring hooks up in the TOP hole on the gov.. & the back hole on the throttle..

 

[thepumpguysc]

When you took the gov plate off to pull the mv out.. how did you do that?? did you disassemble the gov rod?? or just remove the 2 big studs & the small screw in the middle of the plate & removed it as an assembly..
IF you removed the 2 SMALL NUTS from the rod, that's a problem.. there is a very precise measurement for those nuts..
THATS WHY CAV doesn't have info posted freely.. they don't want you messin w/ their product..
We have to pay thousands of dollars every year to keep their name on our building & have to go to training school EVERY 2 years for A WEEK.. at a cost of thousands of dollars..

 

[mungus]

No I didn't touch the rod nuts, I was well aware of that measurement from reading the FIAT manual. I did check it BTW, 54mm, (just within spec).
I removed the 2 little studs instead, seemed the obvious way to do it anyway.

So my spring settings were correct: top hole of the governor plate and back hole of the throttle lever (the one closest to the lever). Thus it appears I am back to square 1. I was hoping I was wrong and you had the silver bullet... Thanks for confirming the settings anyway.

Any other clues? Remembering back to the beginning of this story. At the time I discovered it wasn't getting fuel to the injectors, all (and I mean all) I had done was remove and replace the cover to fit a new gasket and O rings to the 2 shafts... :-(

I guess it could all be coincidence, and something else has failed at the exact same time. However when I stripped the pump for the re-seal kit a few days later, there was no evidence of damage that I could see. No debris, shaft turning smoothly, vanes OK, no thread damage etc. Weird! Working well before, then sudden death for no logical reason. I guess a bench test would reveal all. Perhaps a bit of muck has found its way into the orifices leading from the MV?

So I guess I'll have to pull it off again and investigate. At least this time its all clean and I've been there before.
All I did today was clean up the injector lines and check they were clear with some filtered compressed air.
At least its still winter here so I have a little time to sort this out.

 

[thepumpguysc]

Did you say you changed the filters??
I'm not certain about your tractor model but on the Fords/Perkins/Massy Ferg.. they have a 3pc filter assembly.. a filter head, then the filter & then a bottom bowl..
all held together by a long screw thru the center.. IF this is your assembly.. the oring that goes ON top of the filter.. MUST GO IN the filter head.. NOT ON the filter, but UP IN the filter head.. I hope this helps..
IF you were closer, I'd say send it to me & I'll run it across the stand..

 

[mungus]

Thanks for the suggestion, yes my FIAT has those filters, and I did fit the seal as you said. Bit of a pain keeping up there while I fitted the element, but I could see it was the only way to position its mating face properly.
Both the filters bled out nicely, no air, no leaks and nice clean diesel pouring out the top using the hand lever on the lift pump. And as I mentioned the upper and lower bleed screws on the pump itself also bled out very well. Strong streams with no air. So everything up to the head of the pump seems good.

???

Yes it would be nice if there was a test bench handy! Unfortunately like much of the western civilised nations, our rural services have withered away. The nearest good diesel shops are in our state's capital of Melbourne. Anyway pump coming off again as we speak. That fault must be in there somewhere...

I'm thinking of making a crude test bench up in my workshop. Just enough to fill and bleed the pump and spin the shaft, just to see in there is anything obvious going on. Anyway onward we plod...

 

[mungus]

UPDATE:

Well the pump is out again, and on my bench in bits. Once more I can't see anything obvious. The shaft turns freely, the weights swing out as they should. It meshs with the heads spline easily. The metering valve orifice is clear, I blew that out with filtered compressed air. The cam housing looks OK too.

I'll have a look through the two PDF manuals I have and see if there are any clues. Otherwise I guess I'll have to accept defeat and hand it over to a shop. A bit depressing as they seem to charge $800-1200 no matter what's wrong or the condition in which it's presented. Funnily enough one tractor mechanic I know thinks the diesel pump rebuild industry is a bit of a cartel!

Regardless I need to get it working somehow.

 

[thepumpguysc]

Why don't you try to get an exchange pump off the web.. probably 100.00 cheaper than a rebuild..
Just type in your pump # in your search engine.. google has been good to me..
I get pumps in all the time that have smashed lobes on the cam ring.. they're around 200.00..+ tax & shipping.
BUT when you add THAT to a 400.00 rebuild.. you can buy a NEW aftermarket pump for 600.-650.00 w/ free shipping.
& THATS what I tell my customers & they usually go that route..
Just a thought.. Good luck.. TPG

 

[mungus]

Thanks for that. I have seen some aftermarket pumps on the web. One was "STAR".
But didn't know if they would be OK as is AND ALSO would they just be a generic and so need to be completely set up (timed etc) from scratch for my application anyway?
Also didn't know if they were junk or good. Likewise was wondering about the rebuilt ones. If from a big shop of good repute then great. If from some no-name then god knows what I'm buying. I'll have a look but after the weekend may ask around too. At least if I find a reputable shop here I know what I am getting...
As my pump worked well before it shouldn't be completely buggered inside. So I guess the key is finding a decent guy who charges what it costs, not what he think he can BS you into accepting.

Anyway appreciate all the hints thus far.

Regs,

Hugh (mungus)

 

[thepumpguysc]

Star is a reputable company..
Your drive shaft is keyed & there is a timing line on the mounting flange that you should have noted where it was when removed..
The rebuilt pump will have the same.. keyed drive & timing line in the correct position on the housing..