Stuck R175 injection pump

[mobile_bob]

finally got to the point of starting the 175 changfa project only to find a no fuel condition

tried to remove the injection pump and found it would not come out!

removed the front cover and found the fuel rack stuck in the max fuel position which makes it impossible to get the pump out, as the rack is extended past the body and the pin that fits the governor fork has to fit out the slot, and both can't be in that position to clear the case... so here we go

i removed the front gear cover
i then tapped the rack over to near center with the butt end of a plastic handle screw driver, that took a bit of doing but it moved ever so slowly.

after removing the pump, it was apparent the roller body was fully inserted into the pump body and appeared stuck

then i removed the wire retainer ring and retrieved the pin, then removed the roller body from the pump body

i then removed the delivery port parts,

then did some research and found that George B. got Quinn's pump apart by banging it smartly on the end grain of a piece  of hardwood.... so i did the same

the result was the cup, spring and washer broke loose and came out, but in the process it sheared an edge off the pump element

what i did next was what i should have done first, i drove the pump element out of the pump body... (the plunger out of the body)

it would appear that the body and plunger come out the roller end of the pump casting but this is not the case, the plunger goes out the roller end with the gear body, spring seat, spring, and cap as an assembly. the plunger body then comes out the delivery side of the pump... the changfa manual shows the parts but not the assembly directions.

so bottom line is this,

"DO NOT"  bang the pump casting on the end in an effort to free the spring/plunger assembly from the casting... while it might work on some minor stuck pumps it will result in a broken plunger end on those pumps that are really stuck tight.

drive the plunger and out of the delivery side of the plunger body by means of the delivery port after having removed all of the delivery port parts, use a soft end punch like a soft machine screw/bolt... i used a #10 machine screw about 3 inches long, because i had it handy and used a very small hammer to slowly drive it out.

what i found to be the cause of the seizure was a yellow varnish, from the chinese fuel maybe? who knows what it was, but lacquer thinner removes it right now.

luckily for me i was able to reuse the plunger because it only had one side of the retaining groove lip broken off,  it would still work but was much more difficult to reassemble because of this defect.  

should i have reason to remove the pump again, i will take disassemble/assembly pictures and post them here for the record.

anyway, i got it back together again, and installed... the engine starts just fine and runs as it should.

bob g

[veggie]

Good tips Bob,
Thanks.

So, when you got it running, how did it behave at 1400 rpm ?

veggie

[Henry W]

This is good info Bob.

I Feel this needs to be Stickied so it will be easy to find.

Henry

[mobile_bob]

didn't run it long enough to tell much about low rpm operation, lacking intake and exhaust parts and coolant means the run time was kept very short.

more to come...

bob g

[scumbum]

 I had a similar problem with my R175 as well.. I bought the engine in June 2010 and while going thru it, I found the fuel lever would not move, so a quick inspection showed the sliding fuel rack on the inj pump to be siezed. It was hell taking it apart .. and like you, I dunno what kind of assembly lube was used at the factory, but that rotating barrel/piston that is geared to the rack was just about glued in there with what looked like polymerized WVO Took some time to gently remove and clean that piece and reassembled with ATF. The rack then slid back and forth with ease.

[glort]

I did mine a few weeks back and it was stuck with Polyed WVO.
I just kept spraying it with pressure pack degreaser and working the ting back and forth and it came out soon enough without fuss.
Wiped it all off, put it back together, bled everything out till I got the clink on the injector and she started first wind up.

The one on my 165 is a bit different to the one pictured but obviously same deal.

I run mine at a bit over half speed and it's fine.  I was thinking of giving it a loaded run tomorrow then pulling the injector to see what it looks like after running on straight WVO.

[quinnf]

Geez, I don't feel so bad now.  Thought I was the only one who experienced that. 

Quinn

[Tom Reed]

Same here in a NM195. Similar results too.

[bryanb]

I too, have had the same problem.  I have disassembled and cleaned mine but am having trouble with the reassembly.  Can someone help me with the alignment marks?  The rack has a line in the center position and the gear that mates with it has a notch on one side and a flattened tooth.  I aligned the flattened tooth with the rack line.  The plunger has a dimple on one side which I aligned with the notch on the gear.  Doesn't pump.  Any ideas?

Thanks guys!
Bryan