Any AD21 experts? Help needed.

[realslimshady]

I've had a few fuel contamination issues over my five years with my boat, so I'm fairly adept at cleaning, clearing and bleeding the system, and have always been successful. One thing I have noticed though, is that the rear outlet from the injector pump would bleed through with the throttle at idle, while to get fuel out of the forward one I needed to open the throttle. After that with the injector pipes full, the engine always started.
However, after the latest 'event', with the engine dying as it was being fed what looked like latte, I could not get fuel to emerge from the front injector outlet. I removed the top 'block' which holds the pump shafts, springs etc in place and mucked about with WD40 and two stroke oil and eventually got liquid to squirt out as it should.
So, today put it all back together and sure enough, no fuel out of the front pipe. To cut a long story short, with the throttle full open and the cold start button pressed, fuel came through, bled the pipe, the engine started and ran. However, as soon as the revs dropped below about 1000 it died, and wouldn't start again unless the cold start button was pressed again.
So. My diagnosis is. (I'm making the assumption that in the top of the pump outlet/pipe connector there is a sprung non-return valve) and said non-return valve has gone from being dodgy to being very dodgy, and only opening under very high pressure/flow, hence the engine dying as the throttle is closed.
What all this spiel is leading to is-
1. Does anyone know if it is possible to remove the cap/pipe union from the top of the pump block and service the non-return valve?
Or, failing that
2. Does anyone know where someone might have secondhand parts for the AD21 as otherwise I guess I'm looking at a complete injector pump...
3. Any other suggestions (apart from KEEP THE FUEL CLEAN, YOU IDIOT)

[Tree]

Martin, are you still down at Quay Lane? I’m just about to have my fuel pump overhauled as it’s now getting on for 2500 hours with no record of it being touched. I’ve got a great company in Pompey that will be doing it. I’ll be down that way tomorrow to get breakfast for the team at work so can meet up and share details if that’s any help?

[realslimshady]

IMG_20220825_163030.jpg

Hello Mate! No, I'm in central Portugal, trailered Lydia out here last September, she sits on the lake here for picnics, swimming and exploring...

when the engine's working....

[dkirsop]

I am in the process of reconditioning my spare AD21. I started with the injection pump replacing all the seals. While it was disassembled I noticed one of the cam lifters was sticking. A small amount of corrosion on the side of lifter was the problem. It was easily removed with carb cleaner and a cloth. My guess is that a small amount of water entered the engine oil which also lubricates the cam shaft and lifters in the injection pump. Your description of having significant water in your engine oil has likely resulted in a similar problem with your injection pump.

You have some disassembly and cleaning in your future.

[realslimshady]

i have found some guys here who will sort the pump, but i have to remove it completely.
any tips or things i need to look out for?
I know that keeping the timing is crucial- are there marks/stamps on the pump drive? info like that appreciated.

[dkirsop]

I have attached the two pages from the workshop manual that describe the methods for keeping the timing gears aligned. You can use a marker pen as they describe or you can manually rotate the crank until the timing marks on the pump and idler gears align (stamped 1&1)on each gear face.

AD-2 Workshop Manual.pdf

[realslimshady]

cheers dkirsop

[realslimshady]

dkirsop, I have a couple more questions, if that's ok?
In fig 5 of the manual it shows a puller being used, bolted to the gear and pushing against the keyed shaft.
This is where I'm at now, it's all loose apart from getting the gear off the shaft (I'll have to try and make a puller).
My question is- what holds the gear in place on the shaft? If it's just an interference fit (as it appears to be) then how does one get the gear back onto the shaft on reassembly?
TIA

[dkirsop]

The attached photo shows an injector pump currently on my work bench. There are three studs that hold the pump in place on the back of the gear housing. The nuts are on the stern side of the pump. This is to allow final positioning of the pump. The large nut, which holds the gear in place, is behind the drive plate for the water pump.

Two 5/16" bolts hold the drive plate to the gear. I have removed the drive plate and loosely screwed the bolts into the drive gear. My puller is visible at the front of my work bench.

injectorpump.jpg

Once you have removed the gear you can then loosen the nuts holding the injection pump to the studs. Make sure you note the correct alignment of the gear teeth first.

On the side of the injection pump flange you should see an 'X' and a line stamped into the edge of the flange. This must align with a line scribed into the edge of the plate that the pump is mounted to. First, align the timing marks on the drive gears with the pump loosely mounted, then rotate the pump to align the X with its matching mark on the mounting plate before tightening the attachment nuts on the studs.

[realslimshady]

Yep, that's all fine. I have to make a puller as you have - don't suppose you could give me the measurements between hole centres could you, save me making two trips.
Sorry, was asking a very silly question - the big nut in the middle holds it all together, der....

[dkirsop]

The bar is 1/4" x 3/4" x 3.75". A 3/8" thick bar would be better. I sourced my metal from the local recycle centre so it is what it is.
The outer holes are 66mm centre to centre and 11/32" diameter. The centre hole is drilled and tapped for a 1/2" bolt.

The mixed units are consistent with Canada where sea conditions are often reported as 3m swells with a 2ft chop. You get the idea.

[realslimshady]

no worries! Having worked on aircraft all my life I am familiar with a/f and metric, and swap between the two myself
Interestingly, my pump is not timed to the '1' but to a pop on the drive gear which lines up with two on the idler gear- at which position the woodruff key is in the 12 o'clock position.

[dkirsop]

At a guess, I suspect the marks were made some time when the pump was removed by a previous owner to keep the relative position of the gears aligned. Provided the pump has worked well up to now then there should be no problem using the marks. There is a procedure for checking the timing but it requires that your pump be operational. The only other option is to remove the gear cover to reveal all the other marks which would take you down a long and winding road of discovery.

He probably wanted the key upright to make fitting the gear easier.

[dkirsop]

Just recalled a couple of points while thinking things over. Make sure to place a cloth under the gear to catch the woodruff key should it fall when removing and installing the gear. If the key falls into the cavity below you are into a world of grief.

Second, when I had to remove my pump with the engine in the boat I could not get a wrench to fit onto the lower stud nut on the back of the mounting flange. The configuration of the underside of the pump and the closeness of the engine stringer made it too awkward. I tried a variety of wrenches and socket systems to no avail. Perhaps a specialty "cranked" wrench might work. Finally I rigged a hoist to lift the engine for access and it worked like a charm. The photo below shows the hoist.

A Tough Nut to Crack.jpeg

[realslimshady]

I remember your previous post saying in the end it was easier to remove the engine than undo that nut, but I didn't have a problem- 13mm (probably should have been half inch but don't have one here!) socket, 9" of extensions and it came off no problem.
I made my puller out of an old tyre lever (tire iron I believe you colonials call it ) and it was bending as I wound tension on to it, so I sat back thinking I was going to have to make another stronger tool when there was a twang and the gear landed in my lap
So pump is removed and off to the shop - fingers crossed it returns in a serviceable condition.