I would like to get the detailed description of how to properly "fill" the lines from the fuel pump to the fuel injectors. I replaced the fuel injectors yesterday and I pumped the hand pump quite a bit but I still had to try cranking the car about 5 or 6 times before it started. What am I doing wrong? thanks

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Jim

Pumping the hand pump will properly prime the primary side of the injection system. If it does not start right away, you can simply crack open each line at the injector while the engine is being cranked, sort of like bleeding brakes. Once fuel comes out at that particular injector, moves to the next. You will probably only have to bleed one or two injectors before it starts.

Good luck,

engatwork,

In my experience unless you have an air leak on the suction side, or a fuel leak on the discharge side of the pump, once it starts it purges the air out of the lines as it runs and you don't have to repeat the process. Give it a try and see if it starts right up. If not, you have to look for the place where air is getting in and fix that before you can expect it to start without having to prime the pump each time. Once it runs let it run for a while. The net effect is very much like changing the filters, where fuel leaks out and air is inevitably let in. Once the air is gone, the hand pump event, which can take a long time to be effective, need not be repeated. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Here is how I got it started. After putting everything back together I pumped it up with the hand pump then would try to crank it with the key for five/six revolutions or so, turn the key off, pump again and then turn it over with the key again for about the same amount. After about five or six cranks with the key it finally started. I may try loosening the lines at the fuel injectors next time. I would hate to burn up a starter trying to get one running. OT - I am seriously considering keeping one of the fuel injectors to take to my machine shop and modifying it to turn it into an "adapter" for a compression tester. What do ya'll think of this idea?

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Jim

engatwork,

I have used the hand pump as the battery is usually not good enough to sustain a long cranking effort to start when there is a lot of air in the lines. The hand pump is not much fun, and I ususally get a blister on my hand from gripping the rogh edges of the plastic "handle" and pumping. I have taken to using a rag to avoid the blisters, but the number of strokes is usually beyond something I count. The noise starts to change from a whoosh to a whoosh with a buzzing. It also gets a little harder to manipulate the pump. At this point it usually only take a few seconds of cranking to get it to start.

The idea to use the old injector body as a compression testing fitting sounds pretty good. You could make a few of them and rent them out. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

I usually loosen all the injector lines and crank until no more bubbles come out, only fuel.

It is also a good idea to bleed the IP istelf -- you can pull the overflow line off and pump until no bubbles come out, or open the bleed screw next to the oil level check on the old pumps. Don't know where it is on the new ones.

If you don't bleed the pump it takes forever to get fuel into the lines.

Takes forever to pump one up, eh? I know, I ran out of fuel (stupid, I know, was pushing it) the other week. Fortunately, the engine was still hot so I could crank if forever to get it started, I didn't have any tools with me!

There is no priming pump on the 603 and newer diesels -- you have to just crank. The bleed off faster, though so not so bad.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Jim-
Why did you replace the fuel injectors? I also have a 85 300D. It dosen't seem to have the juice it use to. Could it be the fuel injectors? How much does it cost to replace them?
Thanks,
Ed

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Ed
1985 300D w/ 196,000 miles

I replaced the fuel injectors because I thought they were leaking and I don't know if they had ever been changed. I also changed the hose between the injectors. The biggest improvement seems to be that the car starts a little quicker and it seems to have helped the fuel milage slightly. I think the Redline DFC seems to help too. The only cost was purchasing the injectors from partsshop.com - thanks Phil. You can look up the price. They are about like changing spark plugs on a lawnmower for difficulty .

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Jim

I did this myself and it works like a charm...you dont need to take to machine shop...heres what to do:

1. I don't remember exactly what i did, but you disassemble the injector and throw away the guts...I think I remember enlarging the hole in the threaded portion (opposite the spray end) with a standard drill bit. Just make sure you have an unrestricted avenue for air flow.

2. Grind off the two fuel bypass nozzles....braze or weld those two openings shut. (I did it with standard mapp gas & brazing rod from home depot). Another easier idea would be to clean with degreaser, fill bypass nozzles with epoxy, and flatten with hammer to crimp shut...should easily hold 350 psi.

Done!

When using this as an adapter, install one of those heat shield/washer things for it to seal against when screwed in.
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Now you need a connector to connect the threaded portion of the injector/adapter to the compression tester. This is tough as this is not a standard metric thread (I dont think). What I did was go to a junk yard and cut off the tip of a metal fuel injection line with the threaded connector..... to connect to the injector. Luckily, standard 1/4" brass compression fitting (suagelock) worked perfectly as a connection onto the cut end of the injection line. From this I used a bunch of swagelock fittings and a standard 500 psi pressure guage to make a compression tester.

If you want to make a compression tester, you need to install a one-way checkvalve and a bleed valve in the setup, because when you check compression, you need to crank the engine 5 to 7 times in order to build up pressure in the tester. If you dont have a check valve that "saves" the pressure from each piston stroke, the pressure guage will simply go up and down with each piston stroke, and never reach the maximum pressure which gives you the compression reading. Once you take a reading, you need to bleed off pressure by opening the relief valve, then close the valve in prep. for next test.

I bought the pressure guage from Grainger, and all of the
other fittings (brass) including check valve and bleed valve, from local Swagelock distributor, over the counter.

Note about that check valve....they come in various specs. and sizes. Obviously, you need to size threads to fit the rest of your setup. The important thing is the pressure ratings....they have a "breaking" pressure, the amount of pressure it takes to break the valve open and allow air through. This you want to be low (1 psi) in order to allow unrestricted flow from cylinder into the tester. Then there is the "holding" pressure..how much the valve will hold...you want this to be above compression pressures (500 or more psi). I dont remember the exact pressure ratings of the one I got, but I belive the breaking/holding pressures were 1psi/1000 psi, or something similar.

I will post pic if anyone wants.

The whole setup cost about $60, fun to make, works like a charm, better/cheaper than those on the market.

Good Luck

Hello, I am a new member in this forum. Ihave a mercedes 300 E.My problem is that,my injector pumps too much fuel into the chanber,(upto two liters in a short period of cracking the engine. What is wrong and what do i do?
faminuelliot.

This has somewhat been covered already.
There is actually 2 sections of the Fuel Injection System that may need to be cleared of air; depending on what type of work you did.

To clear/bleed the air out of the Fuel Supply system you use the Hand Primer (if you have one). This bleeds/clears the air out of the Low Pressure Fuel Supply part of the system where all the rubber and plastic hoses are connected to to include the IP housing and 2 Filters. (typically needs to be done after changing Fuel Filters or Fuel Supply Hoses.)

If you have Run Out Of Fuel, or have not bleed the air out of the Low Pressure system well before cranking the engine or have Removed your Injectors you need to also bleed/clear the air out of the High Pressure part of the Fuel Injection System which is from the IP Delivery Valve Holders through the Injector Hard Lines and up to the Injectors. Air trapped in the Injector Hard lines will compress and very little fuel will move in them witout an extreme amount of cranking the Engine.

This is done as previously stated by leaving the Injector Hard Line Nuts up where they thread onto the Injectors threaded on but loose and crank the Enignie until you see fuel comming out of all of them and tightening them afterwards and starting.

The newer model Mercedes Diesels have no Hand Primer to bleed the air out of the Fuel Supply System, it is supposed to be self bleeding. All you can do is crank the Engine and hope your Starting System is up to it.
However, if you Ran Out of Fuel or have worked on your Injectors you still may need to bleed/clear the air out of the High Pressure part of the system.

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84 300D, 82 Volvo 244Gl Diesel

Welcome new member.

I would go back to the beginning of the "Diesel Decussion Forum" and start a your own new Thread on the question.
However, we will need some more information such as the year and model.
It would also be helpful to know some history of your car as to what type of problems were you having before and if the problem started after you did some work on the car.

Also when I read your post I am not sure what is happening. You say the injector pumps too much fuel into the chamber.

It would be nice to know what chamber you are speaking of. Is the chamber the Crankcase where the Engine Oil goes or is the Chamber the Pre-combustion Chamber where the Fuel is burned?

If this is a car with a Diesel Engine and the Fuel Injection Pump is pumping 2 liters of fuel into the Engine I would say you have an extremely unusual problem. While I believe what you say I used to work in a Diesel Fuel Injection Shop back in the old days and am finding it hard to believe that this could happen.

If this is a gasoline Engine car or a Diesel Mercedes New enough that it has the "Common Rail" Fuel Injection system I can see how it might be possible. However, this is why we need more information on your Car.

Best Wishes

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84 300D, 82 Volvo 244Gl Diesel