half-dead injection pump?

[waqas]

Joe, thanks again for your kind hospitality during in Blacklick. It was great to meet you and Mary. I can't thank you enough for patiently going through a host of useful information, and for putting up with some of us all the way to Monday!

I'm already looking forward to the next one.
Best regards,

Waqas ('Wa-kaas') in Austin, Texas

[ja17]

Hello Waqas,

Yes, it was great fun for all of us and our pleasure also! Good to meet you and I am sure we will keep in touch before 2009. Thanks for making the journey waqas!



Joe Alexander
Blacklick, Ohio

[RCS Coupe]

I had an R20 injection pump on my workbench. While I was removing the check valves for cleaning, one of the plunger barrels lifted and rotated. I put the barrel back in place (aligning the hole and slot to the front) but its plunger then jammed slightly which in turn inhibited the free movement of the rack. After some effort, I got the plunger to go up and down without binding but the rack is still somewhat tight. Before the barrel lifted, the rack was smooth gliding with an easy self-returning action and all six plungers moved up and down smoothly.

What happened? What caused that plunger to bind and how can I fix it?

Ray
(268)Green 250 Coupe

[ja17]

Hello Ray,

Clearances in these parts are in millionths of an inch. Chances are you may have "nicked" a part or had a particle get lodged.  Use some penetrant to flush the plunger in question. Exercise the rack through the access hole in the front by moving it back and fourth its full travel. This will most likely polish the imperfection out. Rotate the pump occasionally also.  The unit rack should return on its own.

Joe Alexander
Blacklick, Ohio

[Ron]

This thread helped me a huge amount and thanks to all who gave instructions and hints.  I would have never been brave enough to tackle my "half-dead injection pump" without the reading of the advice given.  This should be in the "technical manual" to help all who have had a pump with dried gas cause the rack/pistons to stick.

No telling how long my pump has been sitting, and the injection pipes were off, with outlets from the pump open to all that dropped in.  Pistons 2, 5, and 6 were stuck causing the rack to be stuck.  As per the suggestions, I opened the side cover, and the pipe fittings/cone valves on those pistons, and doused them with all sorts of stuff: WD-40, carb cleaner, lacquer thinner, 2-cycle boat motor carbon remover gas treatment, injector cleaner, and after a week of soaking was able to get all but 5 to move with the golf tees.

I broke about 20 golf tees trying to get 5 to move, but it would not budge, and neither would the rack.  So, I figured after a week, I'd do one last thing before sending the pump off to a shop.  I took a small plastic tube, like a thick walled straw that is used in a hand lotion bottle pump, and inserted a small drift into it.  My hopes are the plastic would not scratch the side walls of the cylinder.  The drift has a flat tip, about twice the diameter of the little hole in the piston.  The the tube OD was smaller than the bore of the piston.  Placing the drift carefully down the bore, so I wouldn't touch it as much as possible, I set it on the piston, and gave it some hits with a hammer.  The piston finally moved down, about 1/4 the way.  I removed the drift, and cranked the pump, but the cylinder came up, so I had to reinstall the pipe fitting.  With the cylinder back down, and the pipe fitting off again, it took a couple of good hits to get the get the piston most of the way down.  Back on with the pipe fitting, and crank.  Off with the fitting and now a golf tee worked, all the while keeping the 2-cycle decarbon stuff in it.  A few times more and the rack freed up and moves like it should!  The piston does not appear to have any imprint of the drift on its top, so if the plastic tube didn't scratch the cylinder walls, this could work.

The now pump is on the engine, timed, and I'm feel that's a major step to getting the engine back in the car and it all running.

Thanks again all,  Ron

[ja17]

Good for for you Ron,

Sounds like your well on your way.  One thing I found over the years, is that plain old denatured alcohol dissolves dried fuel and varnish better than anything else.  I have tried lacquer thinner, paint thinner, carb cleaner, starting fluid, etc and nothing worked  as well.  I tried alcohol on a varnish plugged fuel tank drain screen and it dissolved the mess quickly and completely after I had tried everything else.