Is this Fuel Distributor test accurate?

[architect1803]

ok, i took my fuel distributor from my W124 1986 300E 6.Cyl MB and disconnected the fuel lines and cranked the engine a couple of times to see if any gas would shoot from the fuel distributor. Out of the 6 holes in the distributor (one for each piston), none of them shot out any fuel what so ever. Does this mean that my fuel distributor is bad? My guess is that there needs to be fuel shooting out of the holes when the car is cranked in order for it to get through the injectors and to the pistons, right? Did I run this test right?

PEACE!

[dkveuro]

Like the car rental commercial used to say ..."Not exactly!"

When the engine is cranked, the 'cold start' injector squirts a timed amount
of fuel into the inlet tract.This causes the engine to 'catch' and air flow increases and moves the air flap down in the fuel distributor, initiating fuel injection pressure .
So, unless you have propped the air flap open slightly, no fuel will come out of the injection ports on the fuel head.

I would suggest you do NOT crank the motor with the injection lines off the fuel head. While you crank, the ignition system is making sparks. The amount of fuel issuing from the fuel head is enough to start a fire you will not be able to put out before serious damage or worse .
If you do test the fuel head this way, you need to disable the coil.

[stevebfl]

Actually unless you are below 59 deg the cold start valve doesn't work. This means that the combined enrichment of starting and starting cold allows fuel to flow at cranking speeds. The amount of fuel is that which runs the car 20 miles to the gallon or about twenty minutes to a gallon at road speed.

If you think about that, you will see that the amount of fuel used in each stroke is quite small. It won't spurt. Even if the airflow plate is held way down the flow will be small.

The mechanism I use for basic setting of mixture after the fuel distributer has been replaced is to bypass the fuel pump relay and adjut the mixture till fuel rises in the threads on a removed fuel line. Once flow is noticed the mixture is adjusted lean till it doesn't flow. Key on engine not spinning there should be no flow. Push the plate down and there should be even flow from all six chambers.

[architect1803]

steve,

im only worried about disconnecting all this stuff, then not knowing how to put them back. This is my first Mercedes Benz ever. I have worked on Chevy, Ford, and others cars before, but not something even close to a german car.

How about this. What if I pull the Fuel Distributor out, get an air blower, and blow air through the incoming fuel port of the distributor to see if fuel comes out through all six chambers? Is that a good idea? Will I be able to see if the fuel distributor is good or not?

The problem with my car, I do not know of. I cannot find the problem. The only sign I am getting that leads me to believe that the fuel distributor is bad is that a) the EGA Valve which connects to the distributor on the side is leaking gas, b)the car will not start anymore, c) there is electricity working in all spark plugs, d) the economy gauge reads all the way to the red, e) the car automatically smells like gas when cranked.

PEACE!

[dkveuro]

Originally Posted by stevebfl

...............
If you think about that, you will see that the amount of fuel used in each stroke is quite small. It won't spurt. Even if the airflow plate is held way down the flow will be small.
..................

With the greatest respect to Steve.....I take issue with the statement that there is little fuel flow even with the air flap pushed down.
With most CIS system operating with the correct pressure,
there is enough fuel coming out of the injectors to support 200 hp.to 400 hp.
Without the injector lines installed on the fuel head the amount of fuel will be more than enough to support ignition of the fuel.

Personally, I do not suggest our friend just allow raw fuel flow freely out of the fuel head without doing something about the risk of fire.
There also exists the accumulator pressure in the system. Rupture of this supply with a flame present will generate more heat
due to the fuel spraying without you being able to stop it.

Ask me how I know !

Cranking the engine and then cracking an injector line is usually enough to see if fuel pressure is present.
Pressing down on the air flap checking for resistance will also tell if pressure is being built up
I would never encourage someone to 'raw fuel flow test' a system due to the chance of fire.

But there again, I rode a motorcycle at 206 mph too....!


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[architect1803]

DKVEURO,

I forgot to mention that I had disconnected the middle wire on the distributor cap, which is the main wire for all six sparks. So there is no fire hazard now.

Aside from the fire and explosion issue, I have decided to do one of the two following things:

a) I may just buy a used (and good) complete fuel injection system with fuel distributor + air flap & air body unit + fuel regulator on eBay.

-OR-

b)take the car to a MB Technician and have them tell me specifically what it has wrong.

Which would you do? I'm just trying to find a way to save money and not have to pay a technician so much money, none the less a towing service (est. $160 from my house and back).

What if I get the fuel injector deal on eBay, and the car cranks, then take it to the MB Tech?

Do you think I should take this chance? Or do you think I should just stay on the safe side and get jipped?

PEACE

[dkveuro]

Originally Posted by architect1803

DKVEURO,

I forgot to mention that I had disconnected the middle wire on the distributor cap, which is the main wire for all six sparks. So there is no fire hazard now.

Aside from the fire and explosion issue, I have decided to do one of the two following things:

a) I may just buy a used (and good) complete fuel injection system with fuel distributor + air flap & air body unit + fuel regulator on eBay.

-OR-

b)take the car to a MB Technician and have them tell me specifically what it has wrong.

Which would you do? I'm just trying to find a way to save money and not have to pay a technician so much money, none the less a towing service (est. $160 from my house and back).

What if I get the fuel injector deal on eBay, and the car cranks, then take it to the MB Tech?

Do you think I should take this chance? Or do you think I should just stay on the safe side and get jipped?

PEACE

First of all, pulling the primary coil wire out of the cap will still leave you with a spark. Best is to pull cover from coil amd disconnect a low tension wire, this totally disables the coil. Second choise is to ground the coil wire leaving no spark gap.
BTW....What vehicle are we discusing here ?

On top of the fuel head there is a plug with a 12mm head...this is upper fuel pressure....need a guage to read pressure.
The leak you are seeing is usually the two green 'O' rings between the control pressure regulator and fuel head. These are renewable.

However, without a test gauge to check upper and lower chamber pressures you might just have to commit to a shop for help.

As a rule...and others may disagree....I have had very few 'Fuel control heads' fail. Usually it is bad pump, pump relay, bad wiring or no spark that results in no fuel pressure.

Would suggest you go to Alldata DIY.com and invest in a subscription to you vehicle on line for one year. $24.00 for first vehicle or invest in manufactures publications or cd which is usually higher $$$.

Your other options are as you suggested....but hit and miss.
Ever tried a salvage yard for used ?





Next would be to

[architect1803]

yea i have been to plenty of salvage yards, but the fact that I bought a fuel distributor already and my car still did not want to crank made me think that the fuel distributor i picked up at the salvage yard was bad as well. Also, I bought the green o-rings new from the internet a while back and replaced them on my original fuel head. Still, it leaks through those tiny holes on the ehg valve.

I have checked for sparks and it seems the car is doing well as far as the sparking goes. by the way, thanx for the subscription info. I will go ahead and try that thing today, prolly sign up for it.

As far as what I dod with the fuel head from the salvage, do you think that I made the right choice in returning the head? It's not like I really knew if the head was bad or not. I just got paranoid because the car still did not wanna crank. It's like the car is either 1)not getting gas, or 2)not getting fuel pressure. This issue is weird and confusing...

My car is a 1986 MB 300E 6Cyl. Gas engine

PEACE!
dj cee

[dkveuro]

Originally Posted by architect1803

I have checked for sparks and it seems the car is doing well as far as the sparking goes. by the way, thanx for the subscription info. I will go ahead and try that thing today, prolly sign up for it.

As far as what I dod with the fuel head from the salvage, do you think that I made the right choice in returning the head? It's not like I really knew if the head was bad or not. I just got paranoid because the car still did not wanna crank. It's like the car is either 1)not getting gas, or 2)not getting fuel pressure. This issue is weird and confusing...

My car is a 1986 MB 300E 6Cyl. Gas engine

PEACE!
dj cee

Don't know .....did you get another fuel control unit ?

If you put 1/4 cup of fuel down the air flap and crank the motor with the spark plug leads hooked up...does it run for a few seconds ?

The fuel pump is under the car in front of the rear axle...passenger side.
You could rig up power to it there and see if it runs. The pump is marked - and +. on the body.
Wire the pump with twin cable wire and THEN hook up to the Battery.

Let me know.

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[architect1803]

nope i have the same control unit. Infact, today I opened it apart. It doesn't seem that complicated as far as its internal parts. Everything seemed ok except for one clogged up chamber, in which I used some Berryman brake cleaner to clean away. Also the diaphragm looks ok, it's a little wrinkled up though.

I put everything back together as normal. All shaft seals and small gaskets and diaphragm. I have the feeling that the EGH valve on it is messed up. It leaks gas only seconds after I crank the engine.

I'll go ahead and try to put fuel down the air chamber. Is that any dangerous? I don't want it to backfire again in my face like it did a while back. What will the fuel do when I pour it down the chamber?

As far as the fuel pump. I think its working because I unhooked the line that comes from the Fuel Pump to the Fuel Distributor and turned the key (not cranking the engine, only turned it until I heard the fuel pump pumping fuel). It shot out fuel from that line. I guess its ok, right? Is there some other and more accurate way I can test the pump, or do you think its fine?

I don't know, but that EHG Valve is really getting to me. But then again, I dont really think that might be the problem because when I had the other used fuel head, the EHG didnt even leak at all, and still, the car would not crank unless I slightly pushed down on the air flap. And even with that, the engine would die about 7 seconds after it was running. The third time, it resulted in backfire through the air chamber...

Lemmie know what u think...

PS: Is there anyway to bypass the cold start valve? Do you think this may be a factor in why my car doesn't start?

[dkveuro]

Originally Posted by architect1803

.......................
I put everything back together as normal. All shaft seals and small gaskets and diaphragm. I have the feeling that the EGH valve on it is messed up. It leaks gas only seconds after I crank the engine.

I'll go ahead and try to put fuel down the air chamber. Is that any dangerous? I don't want it to backfire again in my face like it did a while back. What will the fuel do when I pour it down the chamber?

As far as the fuel pump. I think its working because I unhooked the line that comes from the Fuel Pump to the Fuel Distributor and turned the key (not cranking the engine, only turned it until I heard the fuel pump pumping fuel). It shot out fuel from that line. I guess its ok, right? And even with that, the engine would die about 7 seconds after it was running. The third time, it resulted in backfire through the air chamber...

Lemmie know what u think...

PS: Is there anyway to bypass the cold start valve? Do you think this may be a factor in why my car doesn't start?

If you give it a squirt of fuel and the engine back fires...you may have a chain problem....back fire is due to an inlet valve being open when the spark arrives in that hole. Pull the valve cover and check the cam timing. Small drill hole or slot should align with cam tower front cast mark. Both #1 cam lobes down.

7th injector pintal could stick open. Blue connector may stay energised..check for no voltage with KOEO...Two small socket head screws and loosen the fuel connection....lay over cloth and briefly crank motor...Should squirt if under 60degrees F...... Pump should run 1/2 second after cranking...Make sure there is a Fire Extiquisher handy...and read the instructions first !


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[architect1803]

well it back fired through the air chamber, not the muffler (tailpipe). I didnt see any fire popping out, but a sudden burst of air i think it was that popped out like a shotgun from that air chamber. This also happened when I pushed the air flap down, NOT USING FUEL. I bet if I ran the test using fuel I'd blow to pieces, along with the car. LOL..


dj cee

ps: what in the world is KOEO???

[dkveuro]

Originally Posted by architect1803

well it back fired through the air chamber, not the muffler (tailpipe). I didnt see any fire popping out, but a sudden burst of air i think it was that popped out like a shotgun from that air chamber. This also happened when I pushed the air flap down, NOT USING FUEL. I bet if I ran the test using fuel I'd blow to pieces, along with the car. LOL..


dj cee

ps: what in the world is KOEO???

Okay....Begining to sound like plug wires crossed. Back fire out of intake is, as I said before, jumped time = cam retarded...or = crossed wires.

As the ignition rotor is run by the end of ther cam, this will index incorrectly if cam retarded too.

Chain tensioner will be slack when cranking, from extended sitting time and a little chain slack will allow cam to skip position. It has a ratchet action to stop the plunger from slackening off but a back fire will sometimes push it back if it is the origonal tensioner.

The chain can be reset by slackening the tensioner on the side of the head....big socket head set screw, and if required, removing cam sprocket.

The next job is to roll in a new cam chain, if this is the case, to prevent it from slipping a lot and bending the intake valves.

Check plug wire routing from cap to spark plugs.

The KOEO is a short hand for = Key On, Engine Off.
KOER is = Key On, Engine Running.
Sorry...used to short handing to save time.

The air flap will pop up as back fire reaches it. Has built in ability to absorb this.


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[architect1803]

dkveuro,

we put another fuel distributor, the electrical unit beside the injection body, and the car cranked for a little after several tries. However, when I pressed on the gas pedal to give it some fuel, and the airflap responding as usual, you could visualize and hear air going into the engine, but with the exception that there is no fuel going in the engine. Usually, when you accelerate you have fuel and air entering the engine. But in this case, you have air, but no gas going in. The car starts, but in very low RPM's. The problem starts when you try to accelerate, and hear air, but no fuel going in the engine.

Tommorow we are going to test the fuel pressure and replace the fuel filter.

What can you tell me about what might be wrong with the car now? The sparks in the spark plug show a yellow spark going through when we tested the sparks. Is that normal? Or should it be a different color. Coil sparks look strong.

Write back asap!

PEACE!

[MattBelliveau]

Originally Posted by stevebfl

The mechanism I use for basic setting of mixture after the fuel distributer has been replaced is to bypass the fuel pump relay and adjut the mixture till fuel rises in the threads on a removed fuel line. Once flow is noticed the mixture is adjusted lean till it doesn't flow. Key on engine not spinning there should be no flow. Push the plate down and there should be even flow from all six chambers.

In regards to this post, must one deflect the air plate a bit to get fuel to rise in the threads, or should it do it without touching the air plate?