Rebuilt injectors not firing once installed? OM617
 

Hey guys...


Just rebuilt the injectors in my '83 300sd. It ran (very poorly) prior to doing this. The injectors got new nozzles and were balanced to 2000psi. Injectors function well on the test stand with a good spray pattern.


Installed them and have since ran 3 batteries dead trying to get it to fire.


I get a trickle of fuel out of the injector nuts when loose... but not the spray I was getting before. It's as if the injection pump is not building pressure.


It had the lines off for several days but stayed covered up.


I'm considering pulling the hard lines and elements out of the pump to see f they are sticking or something but I'm at a loss.


I know for a fact that it's got weak compression but I had it on the block heater for a few hours... engine warm... and it has fresh glow plugs. Its producing ZERO smoke from the tail pipe. It's as if it isn't getting any fuel at all to the cylinders.


Thoughts?

Did you manually prime your injectors?

Update... so I'm not getting squat out of the injection pump now.

I had the stop lever tied off for several days. Could something internal to the pump be stuck in the stop position?

With the lines off the pump and cranking.. just a slight trickle out of the fittings on the pump.

For giggles, I pinched the return and cranked the engine. Within a few rotations, it build enough pressure to blow the return cap off of the #5 injector. I'd say the lift pump is producing decent enough pressure.

I pulled the #1 delivery valve. It was pretty nasty. Even with the delivery valve completely removed (not the holder, just the valve and spring)... just a trickle from the pump.

Soo... I'm at a loss. Ideas?

The injectors were pop tested and installed. Cracked the lines and cranked and cranked... nothing. No pressure from the feed lines... just a slow trickle.

You can take out the Delivery Valve but don't remove the 2 each `13mm nuts on each side of the delivery valve to pull out the elements. Turning the element changes the calibrated fuel setting and changing the number of shims under it changes the timing.

Try disconnecting the vacuum line from the Shutoff on the Fuel Injection Pump. The main color or the line is brown or brown with a blue strip; cant remember exactly which one.

When you us the manual shutoff it compresses a spring loaded plunger which telescopes up inside of they. They have been know to get rusty inside and the plunger stick up wards. Make sure the plunger comes all the way out.

Where is that plunger located? That's the only thing that makes sense.

It is called a primer i think. I'd look for something very simple like a plugged filter or as 911 says a stuck primer.

In the attached picture the hard to see yellow arrow points to the spring loaded plunger that is telescopes inside of the Idle Adjustment Screw.

I'll check the little pin. I'm pretty sure it wasn't stuck but I'll look again.


I've also heard that the rack could be stuck in the closed position.


I've got some digging to do.

Tap the side of the pump with a rubber or dead-blow mallet.

I checked the pin and it is moving as it is supposed to. I'm leaning towards the rack being stuck.

I wont have time to mess with it until Saturday at this point. Who knows... maybe sitting for a few days with the stop lever in the resting position will let it free up since being in the stop position for a few days is what caused it.

IDK at this point.

You can access the Rack by removing the ADLA with the whole rectangular plate that it is attached to. Never done that but there is threads somewhere on that.

The other way to go is to remove the Vacuum Shutoff because it hooks onto the Rack. However, putting the Vacuum Shutoff in place wrong results in a runaway engine. So if you choose that route do some research on it.

I think you said the delivery valve was cruddy. What do you think was in it?

I am asking that because if the rack is sticking whatever crud is inside of the pump can be the rack is sticking.

If the rack is not sticking crud could be restricting the fuel Feed Holes in the Element Barrels. Or the Plunger could have gone up and the crud is holding them up and the springs are not bringing them back down.

Looked to be old veggie. Just a brownish gunk. The pump was working fine and now all 5 ports are dead so I doubt its a blockage. Not impossible but unlikely.


I'll probably pull all of the delivery valves and clean them up a bit.



I'll look into pulling the ADLA and taking a peak inside this weekend.

If the Delivery Valves are full of crap then the inside of the Pump must also have solidified crap in it or had water in it and rusted.

I am assuming thins is an MW Fuel Injection Pump. If it is an MW with the Delivery Valves out (the 2 pieces of the delivery valve are mated and to one side of the Delivery Valve Body keep them in order and separated from the other delivery valve). Rotate the Engine and see if the plungers down inside of the Element are moving up and down.

Attached picture: View of Rack on MW Fuel Injection Pump with ALDA Removed

You started a second post where some members might not know of your first three page post.

At a minumin this pump would need a serious solvent soak.Acetone or laquar thinner. Other members have reported what comes out with the relief valve removed after the soaks. Sometimes is far from pretty. Think blobs of stuff.

In days gone by if the car had ran WVO before their purchase. You also do not want to put some of what might be in there through a set of new rebuilt injectors.

A few cans of a cleaner are nothing in my opinion as it takes some time to break down the accumulated junk deposits. I suspect they originate from animal fats in the WVO.

Boy am I negative tonite. Still there is also a reality. Most of us run from a WVO car. Usually the first job would be to totally clean out the fuel system. At least it sounds like the valves in the lift pump are not crudded up.

You may prevail and I hope you do. I just do not think it will be easy.Again I can be wrong. On a time basis I would clean out the fuel system. Then change that injection pump.If he system did not come back on line. I am also a guy that does not suggest changing out an injection pump easily.

You just pump the solvent in with the primer pump and let it sit. There is nothing in there the solvents can damage it seems. As nobody mentioned a leakage after the soaks. Sometimes it take a few soaks until what comes out of the relief valve port to look decent.

Your atf and diesel may have removed varnish from the elements as well. These are just guesses of course. Your earlier post indicates there may be an issue in the govenor section of the injection pump as well. That section is lubricated by engine oil. He could have been running polyermized oil. Far too many WVO users did no maintenance at all as it was not "free".

i wouldn't do anything until I verified that the fuel rack is moving freely.