DI Compressor sucks

[Boyd12]

I have a DI and I rebuilt the compressor. It really didnt need to be rebuilt but I have it apart, so I replaced the piston, rings, sleeve, connecting rod etc. Now it produces NO pressure. I can feel it sucking air into the inlet but nothing out of the top. I did nothing to the head. it is original. any thoughts? Thanks

 

[etemplet]

Never worked on one but if it is a piston their has to be valves. sounds like your valves are leaking or installed incorrectly.

 

[POPPS]

Okay, I have only rebuilt one, you may need to find the manual, it will explain the fine tolerances, there is the proper overlap, and the inch pound torquing.

 

[POPPS]

Sometimes debris gets jammed between the reeds, and therefore leak.

 

[Boyd12]

Thank you for the replies! I have the manual and it is rebuilt to SD specs. When I put my hand on top of the cylinder and crank the engine, it pulls my hand down and pushes it up on the upstroke. My conclusion is the problem is in the head, but the head is unchanged from removal and has NO moving parts! Not that I am surprised but the SD manual gives NO info on how the head works.

 

[POPPS]

When you say head, you mean the reed cage?

 

[jhjesse]

There is a hose with a protection sleeve that runs under the engine from the air intake to the side of the compressor. This hose supplies the compressor with air. Maybe blow it out and make sure it is not clogged.
The “head” reed cage sometimes gets oily gunk in it and the air passages get clogged. Maybe soak it and blow it out.

The piston assembly is pretty straight forward and hard to get wrong. You are probably good there.
On the down stroke, the piston sucks in air from the above mentioned hose. Then on the up stroke it blows this air out the top hose to the air regulator on the fuel rail. Excess air leaves out the back of the fuel rail through the return hose over to the air silencer. The reed cage makes all this happen via air passages sometimes they get clogged and need to be cleaned.