1hd overflow screw fuel leakage (1 Viewer)

[Rubtsov]

Hey there,
frequently scanning this website, i'm at first time posting here. i have a question about 1hd fuel pump leakage. there is a overflow screw under the diaphragm cover. The screw has a rubber cup with a short hose. it looks like some fuel may comes out from the hose occasionaly. in my case there is an intense leakage but not a permanent one. time to time it's more or less. i have no chance to inspect it constantly under the hood. the fuel pump is always wet and some fuel drops i can inspect on a front axle below. the engine runs good and a fuel consumption per 100km is about 14l in town and 10-12l on a hwy.

Alex

 

[mudgudgeon]

the only way for fuel to get into that part of the pump housing is for fuel to push past the connecting pin in the diagram.
there's no seal on the pin, but its a small pin inside a finely ground steel bush (not shown on that diagram)

any leakage should be very minimal.

how many kilometres does the pump have on it?

 

[Rubtsov]

at first i thought about fuel outlet pipe leakage. there are 2 gaskets which I've changed twice. there was also leakage detected but now it's gone for sure. The other way for fuel is the overflow screw. It's from above of the outlet pipe and a bit difficult to inspect what is leaking exactly. the pump has been overhauled by Bosh Service but i don't know when it took place and which parts were changed. I bought the complete engine and in my opinion it has 300000 or more km on it.

 

[mudgudgeon]

View attachment 1447973

Diagram attached in the quote above is from another thread.

The connecting pin (labeled "4") is the only pathway for fuel to get through to the top part of the pump housing, the pin is not sealed, nor is the overflow screw, so it must have no pressure in that part of the pump
The boost compensator mechanism is lubricated by the small amount of fuel that does get up to that area.
If you've got more than a little fuel coming out of the overflow screw, then I think where the connecting pin is must be worn

Maybe try and set up a tube on the overflow screw tube and collect what is leaking, just so you can get some idea of how much is actually leaking

 

[Rubtsov]

I've disassembled the overflow screw yesterday evening. The diaphragm governor is full of fuel. So the only way for fuel to comes in is the way through the pin gasket. That is what I want to replace at first.

 

[mudgudgeon]

Yes, I think start with that. To remove that pin, the top cover needs to come off the pump housing.
Similar deal to this thread, but different issue.

ROTARY INJECTION PUMP RE-TIMING QUESTION