Hello Tony,
Your pump act like this:
Either the pump shaft does not turn when the engine turns.
Or, the stop arm is in the stop position.
Or, the trottle arm is at the lowest idle position.
The 2 first conditions will cause the pump to pump absolutely nothing.
The 3rd condition will cause the pump to pump very very little.
The first condition can be checked with the pump in place, cranking the engine and with the little cover on the side of the pump open you can see if the shaft inside turns.
For the second and third condition you need to take the lid off.
Under the lid you will see some springs, and you must lift it up very carefully and not stretch them. Then make a drawing and point out in what holes the different springs are connected to.
So that you are able to put it back as it was.
Then, you need to find out if something is broken in the pump, that means the stop is in stop position but the arm is in the running position fooling you, or that the trottle arm is in the full position but internally it is in idle position.... for whatever reason.
Or that the pump piston is not pumping.
Before you open it, please clean it like a babybum... and disassemble it on a clean piece of paper. Cleaness with diesel systems are at outmost importance. A tiny piece of dust is enough to ruin it.
You also need to use compressed air to blow things clean, but at the same time, remember that if you blow on 2 assembled parts there is a chance you blow the dirt further into the system, rather than blow it away.
So, sometimes it is better to bring 2 connected parts apart, and then clean them and after that with some lubrication bring them together again.
Work slowly and use your brain wisely. Don't bring the last baseball game with you to the workbench, or an argument with someone.
When not worked with such a pump before, you need all your concentration. And don't let the pump irritate you. Look at it as a challenge. You are the boss, the pump is a tricky brat doing what it can to fool you. Don't let it.
That was todays psycology lesson.
Good luck, and don't be afraid to ask. I will go away for the weekend, but I will bring the puter with me, and a spare pump I have. But, it is not a pump for the engine you have, so I can only look at it for general questions.
Bill