think my injector pump finally went

[os101king]

ok. been pissing a little bit of fuel from somewhere for about 6 months now, but it was a VERY small amount, would find drips under the car. about 2 days ago, when I started it up it shuddered and died once, then restarted perfectly fine. I did notice a growing fuel smell over the next day, then this afternoon getting onto a major highway (of course) the power (? in a diesel?) went away altogether and it just sort of slogged along, randomly firing on a cylinder less than normal. got it home, shut her down and looked under the hood. i'm a bit clueless as to oil-burners, but I didn't let the smoke out of anything and there was nothing twisted, charred or broken. She struggled to start about three times, but now she won't fire at all.

so I'm at a loss. sounds like the IP, right? Are these things really as expensive as I've heard? I found one link after searching 1990 300D Injector pump, but it was one of those BS auto part sites.... can't find the darn thing online at ALL.

Chances are you just need a delivery valve o-ring.

[os101king]

So that would fit the symptoms? How would I go about finding that valve, do I have to remove the pump from the engine? Is there a fuel pressure relief protocol to follow?

[barry123400]

First of all are you sure you just do not have a bad fuel filter? It might be a good ideal to have a good professional check it out. Sure fix the delivery valve seals if they are obviously bad. Just do not assume your pump needs changed out or rebuilt until absolutly sure.

[os101king]

yeah, you may well be right. i'm a bit of a shadetree with gas, but with this black stuff I don't know my ass from my elbow so to speak. worst part being you can't exactly find the manual for this thing on the shelf at Advanced, and I haven't bothered to order one. So I don't know the half of what to check. How many filters are there? I can see quite obviously one in a clear plastic housing hanging sort of mid-air right next to the stop switch... is that the only one?

Professional is the other problem. There are NO mercedes shops, and I don't have to pay capital gains tax so there's no way I could afford a dealer... I'm going to take it to an import guy near me on monday. But if you could fill me in on the first couple things to check it would be greatly appreciated...

by the way, went outside to re-check, it started a couple more times but only for matters of seconds. does that say anything about the issue?

sorry for the omission, it's a 1990 300D Turbo.

[TMAllison]

First thing to do is to clean up the engine compartment sufficiently that you can determine where the leak is comming from. Once the leak is located someone can help you.

[Diesel911]

Your experience with gassers will help you. Think about the things that would cause this type of power loss on a fuel system in a car.
It is always a bad idea to start replacing parts; especially expensive parts until you know what is wrong or have rulled out the less expensive ones.
I think what I would to do is try to arrange for someone the give me a ride back and fourth to work or see of you can barrow a vehicle for a few days. As you said you have some things to learn and weekend may not be enough time to do a good job troubleshooting.
I am also thinking that the member who suggested the fuel filter change (should be 2 of them if you follow where your fuel lines go you will find the filters) a good $20 or less way to rule out that problem.
Also make sure the fuel supply hoses are in good condition and the hose are tight to rule out air getting sucked into the fuel system.
The filter change idea sounds good because I believe that on a fair weather day you could probably start up a good running engine with 1 of the fuel injector lines disconnected. Meaning that I think it would take a considerable leak to cause the problems that you are haveing and not leave a pool of fuel on the floor. It would take a large leak or alot of air in the system to bog you down when you were already running down the road.
Before you change the fuel filters loosen all or your fuel injection lines up by the injectors and have some one floor the pedal and hold it there. Have them crank the engine and watch to see if you are getting good fuel delivery up to the injectors and it is spurting out with some fource. Ask yourself if you think that there is alot of air comming out instead of fuel (you get a strong spurt of fuel but the next time a weak spurt).
Replacing the "O" rings on the fuel injection pump is no difficult. There should be a thread on that somewhere on this site. But you may need a splined socket to remove the delivery valve caps from the pump and a torque wrench to re-install them.
Keep us posted and if you find the problem let us know.

Is there anyone else out there that has had this type of problem?

[os101king]

That was really helpful, I should have already know to start small. I shouldn't have assumed the worst. I can see the one filter as I said, I'm sure I can find the other one. Thank you so much for your tips and information, and I will keep you posted.

[Diesel911]

I forgot to ask are you using only regular diesel fuel as it comes from the pump at a service station?

I looked up some stuff to check under the title; Loss of Engine Power:
Restricted air intake
Blocked or damaged exhaust system
Restricted fuel filter
Blocked vent in fuel cap (or on top of fuel tank)- to check this remove your fuel cap and operate engine; if your symptoms go away the fuel tank vent is blocked.
Contaminated fuel and Tank- injectiom pump fuel supply blocked- Put clean fuel in a clean bucket. Disconnect the fuel line from the inlet at the plastic fuel filter and run a fuel hose into the bucket. This bypasses the fuel tank and the hoses the come up into the engine compartment. Run vehicle and see if symptoms go away.
Fuel supply pump not working correctly- (after being sure fuel supply is not blocked from the tank). Disconnect the fuel hose from the OUTLET side of the fuel supply pump. Have some one crank the engine and see if there is a good output from the supply pump. A good volume should spurt out of the out let.
I do not know the spacific reading on your vehicle but if you put a pressure guage between the large fuel filter and the fuel injection pump fo my 84 300D I believe the pressure at idle was around 8 psi and a max of 18 psi. If you are not getting the minimum look for plugged filters or blocked/restricted fuel lines n the suction side of the fuel supply pump.
Here is a pic of the secondary filter: You have 2 filters the plastic one and the secondary one . Also note the 2 "O" rings in the picture you should have new O rings when you change the secondary filter.

[os101king]

Ok, update. I went out there yesterday before the storm started and pulled out that plastic filter. Looks GUNKY. Real ugly. Also, by the look of things there IS somewhat of a leak coming from one of the injector lines at the top of the pump. Can't get it to a powerwash to clean the block off, so I put the old filter back in (also can't get to a parts store until this morning) and did what the manual said to do to prime the system (turn wheel to right, crank for a minute with it floored). She coughed back to life, but is still running about the same way before I got her home on Saturday (idling low, very little power, super hard shifts). That's an improvement however, since before I did the priming protocol she wouldn't start at all.
I'm a little hesitant about going through all the issues of special sockets and checking the O rings on the pump, is it really relatively easy? There aren't even any dealers within 50 miles let alone indies... and you would NOT find me at a dealer regardless.


Oh, to answer a question it's 100% pump juice. Nearly always the same station as well, a rest area on the GSP. Always lots of trucks, good fuel turnover.

So, I'm going to bum a ride to go out and hunt down those filters (plastic and secondary can) and see what that does. I checked the o-rings on the filter bolt, they're in perfect shape, no distortion.

The air filter is new, and the exhaust is in decent shape (tiny leak, but not crushed anywhere). Will try the vent cap thing, and move on to checking the fuel pressure as well... anybody know the correct spec for a 1990 300D Turbo 2.5?

Thanks guys, you're freakin awesome. I will update when I know more.

[os101king]

ok. changed the filters and (sort of) located the leak. It's dripping off the bottom of the pump assembly towards the rear. Dropping it at a indy shop on wed. to get that and the bad motor mount looked at.

[Diesel911]

If your plastic filter is real gunky I think you are on to the main problem. It appears that there is nasty stuff from your fuel tank plugging the filters.
I am guessing that when you removed the plastic one and hand primed you distrubed the crap enough to let some fuel through.
Also there is a filter screen in the bottom of your fuel tank the can get plugged up.
After you change your fuel filters I hope that you see improvement. If you do see improvement you will need to search the threads on this forum and find out what type of cleaner to put into your tank. There is actually a fungus that can grow in the diesel fuel and it looks black and slimey. You will also need some more filters as when the chemical kills off and cleans it also loosens that stuff and it ends up in your filters.

[Diesel911]

I looked up this thread concerning fungus in the fuel tank.
Click on it to take you there.
Filters, Fungus, Biocide, etc.
http://www.peachparts.com/shopforum/showthread.php?p=823378

[os101king]

Ok. So here's the timeline. The problem first started last week when I noticed a stumble on startup. This happened about two days in a row, but no real trouble starting, just a fumble. A couple cold days, and I left her running outside my shop for an extended period of time (over 20 min) and I noticed a real severe fuel smell. There was always a little more than a whiff, but I also noticed fuel on the ground.

That night, on the way home, she lost power. Started shuddering and sputtering at idle and had NO power to accelerate. Also shifted VERY late and VERY hard. Got her home, she restarted once then refused the next time.

Next day, changed the filters, re-primed and she started. At first sounding MUCH better than even before the problem started. Unfortunately the fuel started leaking worse. Had a new driver's side motor mount installed and the car came back leaking even worse (just a growing problem, not the shop, he couldn't get the o-rings at that time). Took it back and had to prime it to start it to get to work. Same thing on the way home.This Friday the mechanic's wife drove about an hour and a half out of her way to pick the o-rings up for me. Had to self-prime to start it to get it there. I dropped the car off and they did the replacement.

Here's where it starts to suck. Got in the car to go home, started it and.... crap. It feels like it's missing on a cylinder. Idling REALLY rough and very noticeable at below 2000 rpms. Sorta smooths out, but I don't think the missing cylinder is firing at higher rpms, it's just the vibration is at a higher frequency. The mechanic told me on the way out, you might need to do the self-priming or just clear out the engine it should smooth itself out.

Hmm. Yeah, well the guy's not a deezel expert, but he's gone out of his way more than a few times to get my car in and out within the day. So even if it's his fault, I'll trust the guy. But the missing DOESN'T and HASN'T gone away. It's not getting worse, but she smokes like a chimney on startup and never used to.

So, any suggestions? Any pitfalls that he may have fallen into when replacing the o-rings? Please tell me there isn't something he could have screwed up majorly (let's assume the guy is at the very LEAST totally competent, just ignorant of diesels) that may cause this? I just hope it's not some tiny part that you can crush while doing o-rings that requires a pump rebuild. He said one o-ring came out in pieces... could it have dropped a chunk into the pump and cause a single line injection failure? Forgive me, I'm technically ignorant on how an IP works (squeeze fuel, and squirt is about as far as I get) so I don't know what can fail. Would it be more likely that contamination in the pump would get stuck downstream in an injector?

Any ideas fellows?

[Diesel911]

Thanks for letting us know what is going on.
My guess is that it is not a serious problem. It is real easy to get some dirt of foregin stuff into the fuel system when you take it apart. The importance to keep clean is too the point that even lint from a rag can jam up you fuel system.
If the delivery valve O rings were changed probably what happend is that something foregin got into the system and worked it way up to 1 of the fuel injectors. To test for this; while the car is idleing take a wrench and loosen 1 fuel injector line nut up by the fuel injector until fuel is spurting out. If it is a good injector your engine RPM should drop (if your car has a tachometer have someone watch it) and the engine should run rougher.
If you do this to the bad injector the engine RPM will stay the same and the engine will not run worse.
Do all the injectors, loosen, listen, observe tighten up the injector nut until there are no leanks and repeat the same with each injector. When you loosen the bad one it will have no or little effect on the engine idle.
You should be able to identify what cylinder is causing the problem this way.
Let say it was #1 causing the problem (scratch a mark on that injector to identify it). But now we do not know if it is the #1 injector or the #1 element on the fuel injection pump. You remove #1 injector and pick another injector that you know is good and remove it also. you swap the #1 injector for the good one and put the good one inplace of #1. Torque them properly, tighten the fuel injectio line nuts only enough to seat them. Crank the engine; some fuel should spurt out; this helps push out any dirt out and bleeds the air from the injector fuel lines. tighten up the lines.
Start the car and let it idle. Do the loosen, listen, observe test on the 2 injectors that you swapped. If the problem dissapeared from #1 and was transfered to the other spot it is the injector that is causing the problem.
If the probllem stayed on the #1 cylinder after swapping injectors the problem is in the injection pump.

If it is the injection pump it is likley that some that something was assembled wrong or missing and the delivery valve area will need to be looked at again to make sure it was assembled correctly.

If something got into the injector the injector can be taken apart and cleaned or replaced with a rebuilt one.

A question that I have is you said his wife picked up the O rings. I believe that when you do this job there is copper washers that also should have been changed when the O rings were changed. It is possible that 1 of the copper washers is leaking now or that during the work it fell off unoticed and and never was put back in.
The good news is that you have achieved a lot of improvement and you now know that there is nothing seriously wrong with your injection pump.

On the side of your mechanic. I worked for 18 years as a diesel mechanic and you are working on a vehicle it is easy to get dirt and ect. in places where you don't want it. Even being careful I have had the vary same thing happen to me occasionally.