The high pressure for proper injector pop is built up between the plunger/barrel (element) and delivery valve. The feed pump simply feeds the reservoir surrounding the elements within the IP. The pressure relief valve is on the engine side of the IP, where the return line leaves the pump on its way to the fuel filter, and on back to the tank. The banjo bolt back there needs to have a ball and spring in it, or it can't keep the IP reservoir properly primed.

What you just stated goes basically against the grain as to what whunter said, unless it takes channel lock pliers and definitely more than thumb pressure to activate the pump to keep the ten pounds consistent. What you stated about the low pressure function of the pump is what I thought. This was a known good injection pump and had worked for me prior to being installed. Do you know if you are supposed to be able to pump the auxiliary pump with your thumb? The pump mechanism just rides on the injection pump crankshaft, (correction) camshaft. Do you know how the pressure is built up in the injection pump or how the pressure relief valve (fuel line) functions? This line on the back side of the injection pump is one of the issues that I asked whunter about in my reply to him. My compression issue has nothing to do with solving this problem, in my opinion, and I will not even go there because that is not going to help me solve this fuel pressure issue BECAUSE it can easily lead back to "guessing", which I'm not going to do. I can tell you that 350 psi was the highest reading that I got. And I adhere to the philosophy that it is best to take a warm engine read to get a true picture in terms of engine compression and a cold engine numbers can be misleading. Does engine compression and fuel pump pressure work off of each other?


BenzDiesel

Never had much reason to remove a 603 feed pump before (they don't often fail), but I just went out to my shop and pulled one from a spare pump. It pushes easily with one finger.

It's really not a crankshaft in the pump that drives all the action, it's a camshaft--this pretty well explains how pressure is built up and delivered to your injection lines:

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back side of the injection pump. Thanks. I'm open to checking out ANYHTING that has a chance to help me solve this low fuel pressure issue. And I was thinking along the lines as you just stated about function of the barrels inside the injection pump producing the pressure. That is where those copper gaskets would come into play, just trying to figure out what is going on without having concrete data and information relating to the Bosch injection pump. I know that I can loosen the valve seal holders and get plenty of fuel. I just can't get it to pop pressure, where I can see the fuel being injected "outside" of the engine, which I would think should be able to be acccomplished and also know that I could be wrong. But everything I've read states that the injection pump is a mechanical pump, but then again the 603 pump has an electrical component (idle control) at the very back of the pump, which I don't know how the big red idle control, electro mechanical mechanism functions in relationship to affecting fuel pump pressure. Again, thanks and any relevant information is very well appreciated by me and will be checked out.

BenzDiesel

When I timed the pump with the the "vee", showing in the governor hole, at 15 degrees past TDC, the barrel was at the "almost" near top in it's recess hole, sort of like a piston looks in a cylinder at almost TDC. If I'm not mistaken, I think number 1 was at TDC or on the injector compression stroke when I timed the engine. I even asked myself a question? When the engine is going to TDC on the compression stroke, does the injection pump need to be timed to be injecting fuel for the INTAKE stroke that will be receiving fuel in relationship to the #1 cylinder's heading toward TDC. In other words, does #1 TDC at the engine match the #1 TDC in the injection pump or should TDC in the injection pump be matching the correlating INTAKE stroke? And thanks for correcting me and calling it a cam and not a crankshaft in the injection pump. But do you understand what I am asking? Because looking at the lifters in the cylinder head, when #1 is going up on the compression stroke in the engine, I think #3 be at the INTAKE STROKE. I will have to go back and recheck. But you can see the issues that I've seen, but have no concrete data to know what should be. And believe me, once you see a diesel in "run away" mode, you will not be hooking up or reinstalling that injection pump again, even if Bosch men came in person and told you that the injection pump was good.

BenzDiesel

benz,for your reference, just because an ip can be timed and appear to be functioning doesn't mean it will pump fuel, the pressure plunger that produces all the high pressure is shoved up by a cam shaft in side the pump but is returned by a spring. i have disassembled a lot of ip's that have all the plungers stuck up and you ain't going to get a drop of fuel till you get the plungers back down. this is why i mention inserting a straw so you can see the plunger move up and down. you get that motion with fuel available and you have to get small volume under high pressure.
larry perkins
71 old cars

With H202 diagram, I have a little more to work with. I've got to study that diagram and find out what is the "firing order" for a four cylinder engine as it relates to the diagram. This diagram is the kind of information that I have sat here ALL DAY searching for. But thanks again, and you can bet that I will be taking into account what you just said and make cetain that the barrels are doing what they should be doing. At this point, anything less than having to TAKE DOWN HEAD #11, I'm all for it, because I will do a #11, if I have to.


BenzDiesel

Can you post any instructions as to how your manual says the injector pump should be installed? Especially showing the relationship as to on which injection pump cylinder should be firing or is at start of delivery as the engine is moving toward 15 degrees After TDC on the engine's compression stroke. Any information will be appreciated. I'm inclined to believe that as the engine goes toward the #1 cylinder's compression stroke, the injection pump should be timed to the "relevant" INTAKE stroke (number three, I think) and not timed to the #1 cylinder, unless at 15 degrees past TDC on the compression stroke "IS" the beginning of the INTAKE stroke. Do you understand what I'm trying to ask? Thanks.

BenzDiesel

1 revolution of the IP is all you get to fire all 6 cyls. That diagram doesn't show the 4 elements of one 4 cyl. pump, rather it shows 4 different stages of fuel delivery for a single element--any single element.

If the governor "vee" ridge is showing in the little threaded "window" the pump is somewhere around the start of delivery point for #1 cyl--i.e. it can't be for any other cyl that's 180 degrees out. Make sure both (cylinder head) cam lobes on #1 cyl are pointing up when you set the start of delivery for that cyl. I use 14 degrees ATDC for my rigs, but that's just me.

I will be doing all of the checks that have to do with that injection pump. And I really do thank you for posting that diagram. I know my pump is timed with the "vee" at 15 degrees ATDC on the compression stroke (I'm fairly certain). I will have to check to make certain that both lobes on the engine's camshaft are pointing up at 15 degrees ATDC or there somewhere near both camshaft lobes pointing up, which I think they should be, unless when the mark on the engine's camshaft and the pointer on the #1 journal camshaft holder are in alignment, it is possible to be at some place other than TDC, 180 degrees out and as the piston was moving up, it blew out my plug in the glow plug hole, but the engine was on another stroke other than the compression stroke. Is that possible to have the marks aligned and still be out 180 degrees? Again, thanks.

BenzDiesel

benz i havent had the privilege of talking to any mb engineers but i would bet a nickle against a donut hole that the eng located the port on the pump for convenience(so you could see it and be able to insert the light tester) and all that worked out to 15 deg atdc and its just a bench mark. no diesel engine could develop max power with the fuel getting to the cyl 39deg atdc (15+25)
just a experienced guess
larry perkins
71 old cars

Are you saying that the injection pump "vee" needs to be timed (inserted) so that it can be seen in the governor's hole at 24 degrees before TDC? I did notice that 15 degrees ATDC made it easier to insert the vacuum diaphram without having to use force and the slope or curve in the vacuum pump which the roller inside the vacuum pump rides on is grooved or indented at approximately 15 degrees ATDC and the vacuum pump will bolt right up with no problem. Are you saying that 15 degrees is for a purpose like that and had nothing to do with pump injection timing?

BenzDiesel

Just thought of one other thing...though it's remote.

You ARE attempting to start the engine with the engine stop lever in the up position--correct? If it's not all the way up as far as it could go, your fuel rack will not advance enough to allow the control sleeves to rotate and allow the plungers to compress fuel. It's conceivable that the engine stop mechanism has separated inside the governor, keeping the fuel rack in the "all stop" position. One way to check, would be to remove the side cover* on the IP and observe the fuel rack's movements when you move the engine stop lever and throttle arm.





*As a side note, curious diesel geeks with OM60x engines can remove the IP side cover and their ALDA units, then push down on the detent shaft (under the ALDA). Observing the relative position of the fuel rack whilst pushing on the shaft will provide a better understanding of how the ALDA functions. Pushing down limits fuel quantity (e.g. no boost is present), and releasing downward pressure advances the fuel rack (increased boost). You can push down on the detent shaft and move the throttle arm to full, then gradually release detent pressure and observe the fuel rack reach its full load position.

However, it seemed like sometimes as I was trying to start the engine, with the shut off vacuum line connected, the stop lever would seem to be pulled down slowly with vacuum, if the engine didn't start right away. That is why I tested with the shut off disconnected to prevent shuting off the fuel by accident, when my problem is I'm not getting enough pressure in the first place. But I'm not certain if that was actually happening because one day I just happened to notice that at the very moment the ignition switch is turned off, the STOP lever went all the way to the bottom and as the vacuum released, it came back up on it's own. I don't know if it was gradually going down or just went down each time I turned the ignition switch off, since I'm almost always working alone. I even thought that it was a "safety" measure that Mercedes incorporated to prevent too much fuel from being discharged into the engine cylinder in a NO START situation, which would help to eliminate the "run away" condition because of too much fuel in the cylinders, which is one hell of a scary thing! The car sounded like an AIRPLANE on take off. I just disconnected the fuel at the small fuel pump, after the shock wore off after I just stood there momentarily and looked at this monster AWAKEN and it shut off, eventually with a big CLOUD of white smoke rolling just like in the Smoky Mountains in Tennessee on a foggy, cool, winter morning. The smoke was hanging in the air as if it was alive. I didn't get scared until I went to bed that night and started thinking all of the "WHAT IFS" as I was about to try to go to sleep. And that is why I left the "electrical" control functions questions on the table to find definitive answers to.

About that Alda thing, I'm not that sophisticated, yet, but am willing to check it out, since I've been through everything else.

BenzDiesel

benz i am trying to not get you off track, from your earlier post it appears you have the thing timmed right,just double check to see if the camshaft #1 cyl has both cams in the up position(now both cly valves are closed)if you had your drip tube on it should just drip at 1 sec pace at about 24 deg btdc(remember you said you checked it)what i am saying is when the magnet is visible in the port for the light test(read)and the crank pully is on 15 deg atdc the #1 cly has already delivered,so its just a random number and the pump is timmed correctly.
if anyone knows a better explanation please step in.
you are getting close to finding your problem,like h2o2 says either the ip is not asking for fuel or the ip cant pump.
if you get to the straw test for the pressure plunger going up and down you should be able to see the plungers rotate with the stop lever up and working the throttle lever from idle to full throttle.
larry perkins
71 old cars