3B Injection Pump won't prime (1 Viewer)

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Nov 5, 2006
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Location
Port Townsend, WA
Hi.
Looking for some suggestions/advise/help; I've run out of threads to read, ideas and solutions to try.
Working on my 40 Series truck that the previous owner started a 3B swap on. (Supposedly the motor came out of a running 60 before the transplant.)
I'm struggling to prime the Injection Pump, pressurized lines and injectors.
So far I have-
-EDIC arm removed, lever in default "run" position
-clean diesel to the hand primer pump (hand pump creates and holds pressure)
-confirmed no air in lines or filter and fuel flow to the injection pump body.
-cracked 17mm nuts at injectors and cranked motor= NO FUEL
-removed glow plugs to ease spinning motor, crank, crank, crank= NO FUEL

I repeated the above steps numerous times to confirm I have fuel flow and pressure to the IP inlet.
On the Injector line closest to the firewall there is the slightest amount of fuel and maybe a hint of some air being pushed out but it's super minimal at best and inconsistent.

What could/would be stopping fuel from entering and cycling through the injection pump?
I found 1 thread that mentioned a bar/rod in the pump that can become stuck?
Any help would be great, thank you.
 
did you fill the fuel filter with diesel?
did you let the air out of the pump at the bleed screw?
were you able to get diesel out of the filter bleed screw with the hand pump?
 
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i know that there is a low oil pressure shutoff but not sure if that would cause this
 
How long has this engine been sitting.. its possible the fuel rack is stuck in the closed position. If you're definitely glowing it and it still wont start then you can check the movement of the fuel rack by removing the Governor cover.. this guide I wrote on the Leather Diaphragm repair job shows the rack.. and I'll also link a video below that that shows a stuck rack I had quite a few years ago.. I had to tap it with small hammer and work it back and forth and it came free. The guide and the video are 2H specific but the 3B inline pump is technically identical (just smaller by two delivery ports of course).


Diaphragm guide: Repair Guide.. Leather diaphragm

Stuck fuel rack: Fuel Rack video
 
did you fill the fuel filter with diesel?
did you let the air out of the pump at the bleed screw?
were you able to get diesel out of the filter bleed screw with the hand pump?
Filter and lines to the IP are filled with pressurized diesel from hand pump and free of air. I haven't found a fuel bleeder on the IP body, only the oil bleeder.
 
How long has this engine been sitting.. its possible the fuel rack is stuck in the closed position. If you're definitely glowing it and it still wont start then you can check the movement of the fuel rack by removing the Governor cover.. this guide I wrote on the Leather Diaphragm repair job shows the rack.. and I'll also link a video below that that shows a stuck rack I had quite a few years ago.. I had to tap it with small hammer and work it back and forth and it came free. The guide and the video are 2H specific but the 3B inline pump is technically identical (just smaller by two delivery ports of course).


Diaphragm guide: Repair Guide.. Leather diaphragm

Stuck fuel rack: Fuel Rack video
Thanks for the reply and the links. Truck has been sitting 4-5 yrs, fuel filter was still full of diesel and it looked super clean. I disconnected the tank from the start so only clean new diesel was introduced into the system.
I actually found your post about the stuck rack yesterday, super helpful.
Looks like access is going to be a pain with the motor in the truck but that's next on my list as I don't know what else to try.
Question 1- when the rack was stuck on yours did the run/shutoff lever still rotate/move freely and as it should? When I pulled off my EDIC control arm the lever free sprung to the default "run" position. (The lever on mine seems to operate well, I can pull it back to the "over fuel", let it go and it parks in run and push it forward to the shutoff.)
Question 2- can I inspect, confirm and mess with the position of the rack from the side of the pump? Is that a panel that comes off with 2 hex bolts? What seals that panel when reinstalling if I remove it?
THANK YOU for the information and advise.
 
Question 1- when the rack was stuck on yours did the run/shutoff lever still rotate/move freely and as it should? When I pulled off my EDIC control arm the lever free sprung to the default "run" position. (The lever on mine seems to operate well, I can pull it back to the "over fuel", let it go and it parks in run and push it forward to the shutoff.)
Question 2- can I inspect, confirm and mess with the position of the rack from the side of the pump? Is that a panel that comes off with 2 hex bolts? What seals that panel when reinstalling if I remove it?

Answer 1: The fuel control lever was definitely stiff to move on mine. if yours feels fine and springs back easily from STOP to RUN I'm less inclined to think your rack is stuck.

Answer 2: Actually yes.. I think you can observe the rack from the side inspection plate.. thats a good point. Here's a video I took showing the movement of the rack and associated hardware through the side plate.. Rack moving, observed through side plate. Video

Are you definitely glowing the engine prior to your start attempt? 12V+ direct to the rail for 5 seconds if there's any doubt about your glow setup.. Not much fuel really comes out the injector lines when you're just cranking.. its really deceptive.
 
PS.. The inspection plate has a rubber gasket and can safely be removed and reinstalled generally without fear of damaging the rubber gasket.
 
Answer 1: The fuel control lever was definitely stiff to move on mine. if yours feels fine and springs back easily from STOP to RUN I'm less inclined to think your rack is stuck.

Answer 2: Actually yes.. I think you can observe the rack from the side inspection plate.. thats a good point. Here's a video I took showing the movement of the rack and associated hardware through the side plate.. Rack moving, observed through side plate. Video

Are you definitely glowing the engine prior to your start attempt? 12V+ direct to the rail for 5 seconds if there's any doubt about your glow setup.. Not much fuel really comes out the injector lines when you're just cranking.. its really deceptive.
I'm not getting fuel, let alone pressurized fuel in the lines leaving the IP. Lots of pressurized fuel at the IP inlet, really feels like the IP is stuck in the "stop" position.
I was afraid that the smooth and free movement of that stop/run/rich lever might lean against the stuck rack theory but as that's all I have to work with at the moment I will chase that down.
I'll start with the side over and see if that offers any clues.
It would make sense that the rack could be stuck as it sat for yrs in that "off" position.
Question- Is the stop/run/rich lever mechanically attached to the rack or does it just push it into the stop position and the fuel pressure pushes it open when released?
 
I'm not getting fuel, let alone pressurized fuel in the lines leaving the IP. Lots of pressurized fuel at the IP inlet, really feels like the IP is stuck in the "stop" position.
I was afraid that the smooth and free movement of that stop/run/rich lever might lean against the stuck rack theory but as that's all I have to work with at the moment I will chase that down.
I'll start with the side over and see if that offers any clues.
It would make sense that the rack could be stuck as it sat for yrs in that "off" position.
Question- Is the stop/run/rich lever mechanically attached to the rack or does it just push it into the stop position and the fuel pressure pushes it open when released?

The Fuel Control Lever (FCL) can push the fuel rack to the closed position but for RUN and OVERFUEL positions the FCL is really just moved out of the way so that the diaphragm and spring can act on the rack.. This image may help..

1671739800916.png
 
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If the rack is stuck it will depend on whether the EDIC Arm was attached as to where it stuck.. my rack was stuck in the RUN position because the EDIC arm was off and the pump defaulted to RUN and was left sitting for about 10 years. If the EDIC arm had been attached it would have stuck in the STOP position.
 
That shorty is spectacular. So nice.
I see you're in Pt Townsend - one of my really favorite YouTube channels is there (Sampson Boat Co.).. the place looks spectacular.
 
If the rack is stuck it will depend on whether the EDIC Arm was attached as to where it stuck.. my rack was stuck in the RUN position because the EDIC arm was off and the pump defaulted to RUN and was left sitting for about 10 years. If the EDIC arm had been attached it would have stuck in the STOP position.
EDIC arm was attached so IF the rack is stuck it would be in the off position.
If I'm understanding the way this works then it seems there might still be hope. If the rack is stuck in the closed position then the FCL would still be able to move freely?
 
EDIC arm was attached so IF the rack is stuck it would be in the off position.
If I'm understanding the way this works then it seems there might still be hope. If the rack is stuck in the closed position then the FCL would still be able to move freely?

Yes this seems plausible.

Also.. I'd just like to highlight again that you really dont see much fuel at all coming out injector lines whilst cranking.. it certainly doesnt squirt or spray out..its a tiny amount.


If you wanted another test to do.. check out this video of a Mercedes Inline pump being cranked with the injector lines removed.. I've never done this on a 2H but the tech is identical. I aim to do this video soon.. but I suspect it will be the same.. maybe its something else you can try. even with just 1-2 lines removed and the engine cranked with a healthy battery (glowplugs removed if you're comfortable they've been out recently and wont cause issues on removal)..

 
Filter and lines to the IP are filled with pressurized diesel from hand pump and free of air. I haven't found a fuel bleeder on the IP body, only the oil bleeder.

Here's the bleed screw on a 2H.. Has your 3B got one in this position?


1671740439352.png
 
Thanks for the above photo. I didn't know that was an injector pump bleed screw, I'll give that a shot first.
High tempts today here are well below freezing so will probably wait until tomorrow to get back after this.
I really appreciate the information and support.
 
you could 'easily' take off the diaphragm cover and mess wiht things as per duncanrm's picture, just pull the diaphragm back and grab the rack rod with some thin pliers and try to move it, its not a fun job but doable
just be prepared to replace a bad diaphragm once you have a look at it
 
if you do decide to take the diaphragm cover off just undo the edic 'motor' , 3 10mm bolts (easily accessible), and push it to the side to get access to the flathead scews on the cover
 
Well, despite @duncanrm sounding like a real expert in the field, and my lack of familiarity with your injection pump, I was about to chime in and ask if you checked the fuel cut-off solenoid. Then I found a post of his from 2015, explaining the EDIC system and was glad I searched before I commented!! EDIC = fuel cut solenoid.

The only thing I have to add to this thread, is that I expect the Mercedes are a Bosch VE pump, and so the fuel coming out of the pump would be at something like 1500 PSI, right? I know it can be lethal if your flesh gets hit with an injector pumping diesel, but should we be similarly worried about the pressure out of the pump (because it's not atomized like it is out of the injector nozzle)? Just for my own knowledge.
 

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