Bosch primer pump

[Diesel42]

Thanks to Lostmarbles for the excellent research and writeup on the primer pump problems. Saved me a ton of research without question. I was able to source the Bosch primer pump(item#2 447 222 126) at a local diesel injection shop for $23.00. Installed quickly and easily. One question though. When you pump this pump,and you crack the bleeder at the fuel filter, should there be a great deal of pressure ro is it just enough to push the diesel out? It didn't feel like th epump had a great deal of resistance when pumping. Whether or not th ebleeder was open or closed. But as i pumped it up and down, it did push diesel out,just not at much of a pressure. All and all however, i crancked the 3B over and it without hesitation fired off and purred even after 1-1/2 years of sitting during my resto. Now that i know it will run without any problems, i removed the exhaust manifold and installed my new 13bt mani,adapter, and turbo. Pretty easy with all the room(no fenders,hood,or grill,etc.

 

[roscoFJ73]

Thanks to Lostmarbles for the excellent research and writeup on the primer pump problems. Saved me a ton of research without question. I was able to source the Bosch primer pump(item#2 447 222 126) at a local diesel injection shop for $23.00. Installed quickly and easily. One question though. When you pump this pump,and you crack the bleeder at the fuel filter, should there be a great deal of pressure ro is it just enough to push the diesel out? It didn't feel like th epump had a great deal of resistance when pumping. Whether or not th ebleeder was open or closed. But as i pumped it up and down, it did push diesel out,just not at much of a pressure. All and all however, i crancked the 3B over and it without hesitation fired off and purred even after 1-1/2 years of sitting during my resto. Now that i know it will run without any problems, i removed the exhaust manifold and installed my new 13bt mani,adapter, and turbo. Pretty easy with all the room(no fenders,hood,or grill,etc.

There shouldnt be much pressure with an open injector line.
You can definately notice the difference between the line being open and closed when you pump.

It greatly satisfying when a diesel starts for the 1st time after a long lay up

 

[Diesel42]

Will it pump at all if you haven't cracked the bleeder fitting(the one at the fuel filter)? Because this will pump although you don't fell any resistance. Once you crack the bleeder it does spit fuel but not with alot of pressure. It did get the job done though. Considering the lines and tank very completely dry i was happy not to have to crack the injectors. After a couple 4 second starts, it just purred. Just want to determine if this pump is working completely as i could returnit for a new one if it isn't.

 

[roscoFJ73]

Will it pump at all if you haven't cracked the bleeder fitting(the one at the fuel filter)? Because this will pump although you don't fell any resistance. Once you crack the bleeder it does spit fuel but not with alot of pressure. It did get the job done though. Considering the lines and tank very completely dry i was happy not to have to crack the injectors. After a couple 4 second starts, it just purred. Just want to determine if this pump is working completely as i could returnit for a new one if it isn't.

The manual says the hand pump should be able to draw fuel from the tank with empty fuel lines in 30 strokes.If it doesnt,its kaput.
It will pump with the bleeders closed until the pressure builds up and then you are straining the pump.
I can feel a definate change in mine when this happens,usually about 3 strokes

If its in doubt, disconnect a rubber fuel line somewhere and pump,you should see a solid squirt of fuel.
When they are not working well they usually leak fuel while pumping

 

[lostmarbles]

... It didn't feel like th epump had a great deal of resistance when pumping. Whether or not th ebleeder was open or closed. But as i pumped it up and down, it did push diesel out,just not at much of a pressure....

Will it pump at all if you haven't cracked the bleeder fitting(the one at the fuel filter)? Because this will pump although you don't fell any resistance. Once you crack the bleeder it does spit fuel but not with alot of pressure. ............................ Just want to determine if this pump is working completely as i could returnit for a new one if it isn't.

Hi Diesel42.

You've prompted me to go outside and check mine. (As you know, I have the same Bosch primer pump as you.)

When I push down my plunger without any bleeder open - It moves only about 5mm (say 1/4 inch) and feels a bit "springy".

However if I open a bleeder I can move it much further as diesel fuel gets forced out (via the bleeder).

If you can push yours right the way down while all your bleeders are closed (no diesel escaping) then something is wrong. - But it may not be a fault with your Bosch primer.

How is that check valve that sits beneath your primer pump? It must "seat properly" when you push down on your primer pump or else the pump will push fuel back into your fuel tank (instead of trying to push that fuel towards your injector pump - which - with the bleeders closed - is a "closed circuit").

If you removed the plastic check valve and accidentally dropped some cr#p into the hole - that would account for the problem you have now.

Here's a picture where you can see the black stem from the plastic check valve with the spring sitting on top. You have to be careful to fit that stem into the hole in the base of the primer pump before screwing it into place (with a new copper washer that is supplied with the pump):

 

[Diesel42]

I removed the old primer and saw that spring. I remembered your caution from your post about not disturbing this. So i sat the new primer over the hole and screwed it down(with the new washer). No leaks but there didn't seem to be any resistance whether or not the bleeder was open or closed. But with the bleeder open, it would push fuel out. I'll pump it tomorrow without opening bleeder to see if i can get some resistance. I assume there is a bypass to prevent over pressurizing?

 

[lostmarbles]

I removed the old primer and saw that spring. I remembered your caution from your post about not disturbing this. ......

Did you see the black stem of the check valve in the centre of that spring too? (You can see it in my photo with some "shiny diesel" sitting on top of it.)

Here's another picture with an arrow pointing to the check valve I'm refering to:



If it is somehow missing that would certainly account for the problem.

Don't worry about disturbing it. (I just mentioned in that thread how "not disturbing that check valve" meant that somehow I didn't need to purge air after I swapped my primer pumps.)

 

[Tapage]

If you primer your diesel circuit at your filter bleeder, there is a positive pressure, that didn't allow you perform the complete travel on the primer ... with the circuit titaly closed. At this time if you open the filter bleeder you must have pressure of air ( air on the line ) or diesel ..

If not .. your diesel circuit have a pinhole somewhere, your primer or plunger it's faulty and you are not getting proper amount of diesel from the tank ..

 

[magnus_heydoc]

decent parts site

After reading your discussions on the primer I decided I should replace mine with a bosch. My pump would pump some but when I read the post about 30 strokes I knew mine was dead. It's 24 years old so I guess it's done it's job. Here's the site where they have the same bosch pumps for about 14 bucks:
Mercedes Parts - Mercedes Benz Parts - Discount Prices - Bosch - Mercedes Benz 300D Bosch
Aaron

 

[muskeg]

3B in a bombardier muskeg

Hello diesel42, lostmarbles and others. I am a shop teacher in northern BC new to the diesel world as well as the world of forums so please bare with me.My 3B starts fantastic thanks to new 10.5 v ngk glow plugs wired direct and runs fantastic untill it suddenly dies after several minutes with significant air accumulated in the injection pump.I know I need a new primer pump but havent been able to find one through mercedes benze parts or the bosch #'s with my local parts stores BUT I noticed an o-ring at the top of the plunger and assumed that if it was tightly threaded closed it would seal. I have been using an inline electric pump between tank and fuel pump to bypass primer pump leak problem assuming the air leak problem would go away. Even with the electric pump running during operation the engine will konk after several minutes of running with lots of frothy air built up in the injector pump. If I purge the air I am good for another too short while.I wonder if anyone has a ngk, nd or any other # that might help my local store find me a primer pump like the bosch 2 447 222 126 you guys talk about and more important Is this the cause of my air leak? With pressure from an electric pump I thought I would be avoiding all problems like primer pump and fuel return line leaks.Sorry for all the words.

 

[Tapage]

I found my bosh at eBay with the dieselcare dealer .. ( so far so good the service ). But I know that delphy also have other options that include a filter with water separator and primer all in one ..

But now you need to adress your air leak and I tent to think that it's not only your primer right now .. did you still have your factory water separator .. ?

 

[jzilla]

Fredholmesfuelinjection.com (in richmond B.C.) has the denso pumps as well as others as far as I know.
I am sure they could help you with part numbers.

 

[muskeg]

Not presently using the water separator so that shoudnt be the problem. New line tested between tank and electric pump and between electric pump and fuel pump. I saw last night that the return line from the injectors goes into the injector pump so im wondering if Im sucking air there. thanx fer the help.

 

[lostmarbles]

....I know I need a new primer pump but havent been able to find one through mercedes benze parts or the bosch #'s with my local parts stores......

Why bother with local parts stores Muskeg? As Tapage says, these Bosch primers are readily available and very cheap on the Internet. Also their size and weight are both very low so freight is not an issue and I'd be surpised if it took more than 2 weeks to arrive to your door.

....I noticed an o-ring at the top of the plunger and assumed that if it was tightly threaded closed it would seal......

Yes - Unless the body has a split in it or something like that, those "screw-down-to-stow" OEM-style pumps should be "sealed from being able to leak" when in the screwed-down position. Which makes me suspect that your air-entry point is elsewhere. (But I'd still change that primer pump - particularly if it leaks any diesel at all when you operate/pump it.)

...I have been using an inline electric pump between tank and fuel pump to bypass primer pump leak problem assuming the air leak problem would go away.....

Not something I would have done - Because I like my vehicle to be as "simple as possible" and believe that the existing fuel supply system is entirely adequate. (However I don't know anything about "alternative-fuel systems" and perhaps you installed that electric pump in conjuction with something like that.)

I generally believe that adding a component that is unnecessary - particularly into a fuel-circuit - is just providing "another potential problem source".

....Even with the electric pump running during operation the engine will konk after several minutes of running with lots of frothy air built up in the injector pump. If I purge the air I am good for another too short while..........

Classic symptoms of a leak being present somewhere in the "below atmospheric pressure" sections of your fuel lines.

(But if you get the air at your injector pump and NOT at your fuel filter as well - that would be interesting?????)

...With pressure from an electric pump I thought I would be avoiding all problems like primer pump and fuel return line leaks.Sorry for all the words.

Depends where you put your electric pump I guess.

If you placed it "below the fuel level" inside your fuel tank then I guess you would be right. (Is it a pump that is submerged inside your tank?) Otherwise the line between the pump and the tank would still be a source for possible "air-entry".

But even with a submersible pump, you still have to consider what happens when your vehicle is sitting without the fuelpump running. At this time, a vacuum will still be created in your fuel line upstream (tank-side) of where-ever your first non-return valve is located in your fuel circuit (as fuel lines tend to drain by gravity back into your tank at this time).

Cheers
Tom

PS. Here is the fuel circuit on my BJ40 with the part highlighted in red being the part that is at "below atmospheric pressure" all the time (for me). And the place that is particularly prone to leaking-in air (for me) is that bit of hose that is arrowed:



But I think the fuel circuit on a 3B could be slightly different to mine (shown above). I think with yours, that line from the "arrowed point" returns to your fuel tank (instead of simply "going back into the fuel pump inlet"). Can you confirm this?

PPS. I took so long to write this that a few posts appeared meanwhile. I now realise that your electric pump is in your fuel line (outside of your tank) and that you're sure you have no leaks on the upstream section (pump to tank). Also I now realise that your fuel circuit - apart from the addition of your electric pump - is indeed the same as in the diagram I've posted for my BJ40.

 

[BinaryDude]

is this also the pump on the H Diesel?

 

[FrankJames]

Works on my 2H

 

[muskeg]

Wow I'v never been on a forum before, lotsa support. Nothing about this application is origional. I have mated the 3b with th350 automatic transmission from an 87 blazer and mated that transmission to np435 grannylow 4 spd. and they are powering a tracked vehical made by bombardier called a muskeg. I will try to attach a photo. The primer couldnt leak any worse and I am definately going to replace it but in the meantime me and my seniour boys auto class are a little impatient so are using the in line electric so we could (intended to) keep the primer closed and sealed. I had a small leak in a tank fitting that was causing "carbonated diesel" but have solved that and can, with the electric pump, provide air free diesel to the intake of the fuel pump. Aftre that I dont know how the air is getting into BOTH the fuel filter and then(i think in that order) the injector pump.The return from the injectors travels to the rear of the injector pump and an online manual has confirmed that it returns to the fuel pump inlet. I now think I have to look closer at the return line,fuel pump and primer pump as my leak seems to have to be in one or more of those locations. It runs so well when it's running that i really want to figure this out. Patience would say wait till I replace the primer and eliminate that.Thanx again

 

[lostmarbles]

...Nothing about this application is origional. I have mated the 3b with th350 automatic transmission from an 87 blazer and mated that transmission to np435 grannylow 4 spd. and they are powering a tracked vehical made by bombardier called a muskeg. I will try to attach a photo. .....

That would be great. ALL of us here LOVE photos!

.....The primer couldnt leak any worse and I am definately going to replace it .......

I recommend getting the cheap Bosch replacement. (You can use the MUD "search" function to find all the info you need about doing this.)

.....The return from the injectors travels to the rear of the injector pump.....

Are you sure? Normally that "leakage line" goes either "all the way back to the tank" or "into the fuel pump inlet" (as shown in the diagram I posted).

But the fuel pump is mounted on the side of the injector pump and driven off a cam inside it. - So that might be where you're getting confused.

... It runs so well when it's running that i really want to figure this out. Patience would say wait till I replace the primer and eliminate that.Thanx again

Well it sounds to me like you've got the "knowhow" to get to the bottom of this Muskeg.

If there is no non-return/check valve incorporated into that electric fuel pump then all that "red-highlighted" part of your fuel circuit (including your electric pump) will still be under vacuum when your vehicle is sitting idle/not-running. So in that case, air could still enter anywhere there (when your vehicle is left sitting)to form "a slug of air inside your fuel lines" (as fuel drains back into your tank from that section of fuel line). And if that happens, the next time you restart your engine, it will run fine for some seconds (perhaps even minutes) until that "slug of air" hits the injector pump. At this time your engine will "stumble and then die".

And such a leak won't normally drip fuel because that red-highted leak-area is at "below atmospheric" pressure. - However I accept that if you've fitted an electric pump upstream, part of this area (downstream of your fuel pump) will then be pressurised. However, even so, air can enter a tiny pinhole far faster than fuel can exit it (due to their vastly different densities). So what I'm trying to say here is that -- even with your electric fuel pump situated upstream - a pinhole leak could still be downstream of this pump and may not reveal itself by dripping diesel on the ground.

Cheers
Tom

 

[Diesel42]

Muskeg- Welcome aboard!

 

[bj74redrider]

Will this pump work in the 13bt as well? When I pump mine, with little effort, with the filter bleeder closed it squirts fuel all over my hand. Time for the Bosch replacement? Also I couldn't find lostmarbles write up on the primer, could someone point me in the right direction?