zexel injection pump return fitting stripped threads

[John V]

Howdy, today I accidentally yoinked on the return fitting a little too hard and stripped the threads. Got the fitting off, it's m12x1.5. Anyone foresee an issue putting a helicoil in there? Figure I'll run a vacuum as I drill and tap the hole. Is it the return fitting, so hopefully if metal shavings did go inside they wouldn't be able to reach the pumps?

 

[thepumpguysc]

It’s ok.. the only problem will be getting wide enough gaskets to seal..
You’ll probably be miles ahead if u use air pressure in the inlet, blowing the aluminum back atcha.. instead of sucking them into the pump..
Use a gob of grease or Vasoline on your drill and tap.. most of the bits will stick to that..
Good luck

 

[John V]

It’s ok.. the only problem will be getting wide enough gaskets to seal..
You’ll probably be miles ahead if u use air pressure in the inlet, blowing the aluminum back atcha.. instead of sucking them into the pump..
Use a gob of grease or Vasoline on your drill and tap.. most of the bits will stick to that..
Good luck

I’m curious and not knowledgeable about the internals of these pumps.Does the inlet and return have direct flow to one another, or is there a check valve stopping the inlet fluid from going out the return? If it’s just open between the two, how do the injector return lines have enough pressure to send fluid back to the pump?

 

[thepumpguysc]

Ancient Chinese Secret..lol

Yes they’re connected.. the check valve is in the return fitting or banjo bolt..& it’s set to a specific pressure (1.5 bar)
That puts enough fuel in the fuel gallery (housing) to allow each of the pumping plungers to fill and have enough fuel to shoot to the injectors..
That’s why overflow valves play a pivotal role in a “low power” problem in an in-line pump..
On a rotary pump, they have a tiny orifice.. no spring to wear out.
I hope this helps..

 

[John V]

Ancient Chinese Secret..lol

Yes they’re connected.. the check valve is in the return fitting or banjo bolt..& it’s set to a specific pressure (1.5 bar)
That puts enough fuel in the fuel gallery (housing) to allow each of the pumping plungers to fill and have enough fuel to shoot to the injectors..
That’s why overflow valves play a pivotal role in a “low power” problem in an in-line pump..
On a rotary pump, they have a tiny orifice.. no spring to wear out.
I hope this helps..

Interesting. I'll take apart my return fitting and check that that spring is good while I have it apart.

After I stripped the threads on the return fitting, my stop solenoid/lever no longer works. I tried manually pulling on the stop lever to make sure it wasn't the actually solenoid. Is it safe to assume this is connected to the lack of pressure in the fuel gallery?

 

[thepumpguysc]

Can u snap a pic.??
If U can’t load it here, try my email.. my screen name at aoldotcom
I’ll help u out..