Advice needed 1980 380E

[Bellow]

I have to admit the filter has not been changed but there is lots of high pressure fuel reaching the unit.

Check what was previously considered as a last chance filter. So far you have fuel at pressure up to the metering unit - but no evidence of it entering the metering unit.
I'm with carat 3.6 here - check everything before digging into the metering unit.

 

[Kerabo]

Check what was previously considered as a last chance filter. So far you have fuel at pressure up to the metering unit - but no evidence of it entering the metering unit.
I'm with carat 3.6 here - check everything before digging into the metering unit.

It won’t let me show my video clip but with the injector pipes off and cranking there is fuel and bubbles just dribbling from the metering head. No pulses but not sure how much should eject ?,
Thanks

 

[Bellow]

It won’t let me show my video clip but with the injector pipes off and cranking there is fuel and bubbles just dribbling from the metering head. No pulses but not sure how much should eject ?,
Thanks

Just pull that bolt and check if there's a filter in there.
A missed fuel filter once cost me an engine when it ran the motor lean and burned a piston.

 

[Kerabo]

I have to admit the filter has not been changed but there is lots of high pressure fuel reaching the unit. The cars owner has changed a fuel pump but there are defiantly 2 ?
I don’t know the EHA valve but will look it up and check it.

Looked up the EHA valve but don’t recall seeing anything electrical on the unit.

Do you mean a boot that joins to I think the manifold ?
Thank you

Is rubber hose you talk of number 16 in the diagram and is the valve 26—32 the EHA valve?
I thought it was an electrical valve but have not seen any electrical components attached to the Distributor.
I read that these are different country to Country for safety and emission features.

Thank you

 

[carat 3.6]

Is rubber hose you talk of number 16 in the diagram and is the valve 26—32 the EHA valve?
I thought it was an electrical valve but have not seen any electrical components attached to the Distributor.
I read that these are different country to Country for safety and emission features.

Thank you

Yes 16 on the diagram is the rubber boot. This type of injection system relies on the engine vacuum sucking down the plate in the air flow meter, as the plate moves down it opens a valve in the metering head to increase fuel flow. If you have a large vacuum leak like that boot has perished the system wont deliver much fuel.

Looking at the picture you posted earlier there isnt an EHA valve on this version, so forget about that one.

Fuel pressure and fuel flow are two different things, so 1st thing to do is get the filter changed. As Bellow has said there may be a gauze filter in the pipe union at the metering head, that also needs to be checked.

 

[Pontoneer]

Appoligies as I have asked about this before but now have seen it and know a little more.

This beautiful old car that belongs to a mate will not start.
It ran 18 months ago. All it will do is fire and run for a few seconds each time you turn the key to start it. When I looked at it today it would not start at all.
It has a fuel injection system that is completely new to me.
The thing that seems strange to me is when cranking it supplies fuel but not when the key is in and not cranking ?
Also he says it’s an electric pump but it pulses like there is a lift pump on the engine.
He has fitted a new electric pump in the tank but he is not a mechanic so is it a pump or for a gauge?,
If he tips a small amount of fuel into the intake it will fire and run on it and then stop.

So on this mechanical injection is there anywhere to bleed the system or what checks can I do please ?
There is fuel up to the large pipe towards the rear but nothing at the forward large pipe? Is this a return ?

Any help or ideas please

Those pictures are of an M110 , so it is a 280E ; the 380 was a V-8

 

[Pontoneer]

Still trying to make this run.
I have the diagram but have problems knowing where the items to test are.
The only relay I can find under the bonnet don’t appear to be connected to the injection system.
So every time you turn the key to start it runs but only a few seconds.
I understand that whilst cranking it overrides all safety circuits to run and then when the engine starts the oil pressure switch makes it complete its circuit snd run?
The thing is where are these items.
I have underlined most of the Circuit but can anyone give pictures or info as to where these are.
Our local specialist won’t collect the car and we can’t drive it.
Any ideas please

it is normal for the pump to run for a few seconds when you switch on . I'd suggest draining the tank and removing the strainer from the bottom - it may be blocked . There is also a fuel filter under the car next to the fuel pump - these should be changed periodically and anything with an M110 is going to be 30+ years old , so well overdue for a new filter if not touched recently . BEWARE - those little pipes around the fuel pump package , with the filter and accumulator , with the banjo nuts , are VERY EXPENSIVE ! So try not to break them .

 

[Bellow]

I keep downloading it but can’t find the download afterwards on my ipad

Have you found it? If not, would it be easier found if e-mailed to you? If so, DM me an e-mail address.

 

[Pontoneer]

I would start with a new set of spark plugs ....but it looks like fuel related to me .

The other M110 failing is the routing of the ignition leads over the inlet side of the cambox and down into the well ; the leads run very close to the cam cover and the little clips get very brittle with age , resulting in burning of the leads and shorting to ground , also happens as the leads run up the well between the camshafts , where the plugs are located . Won't cause the symptoms here since it starts when fuel is poured into the distributor , but it is another M110 achilles heel , and I've had just about every model that used that engine : W114 280E , W123 280E/CE/TE , W116 280SE , W126 280SE , R107 280SL ; I just never got around to the 280GE ...

 

[Pontoneer]

This is a picture on the one I am looking at

That is a W123

 

[Pontoneer]

Not sure about twin pumps ? You mean the supply pump from the tank?
The wiring diagram only shows one but these seem to differ country to country.

It does run on all cylinders but only for a few seconds. That’s why I was thinking the cold start could be supplying it’s only fuel. I think I will carry on and remove all the injectors and fit new rubber seals as they are starting to perish even though I don’t think this is the problem

Thanks Ken

Some of them had series pumps , one right under the tank , which then fed into a second one just below the rear right footwell , above a plastic cover ( follow the fuel pipes ) .

 

[Pontoneer]

Yes the supply from the tank. Kjet needs high fuel pressure so it is common on Mercedes to have twin pumps, they are normally in series so if one pump isnt working you will only have half the fuel pressure.

In this form the engine will try to start, but as soon as it fires and demands more fuel the pressure drops off and it stalls.

Or it will start and run up to moderate speeds , but then suffers from fuel starvation when accelerating hard or trying to go at higher speeds

 

[Pontoneer]

I have been viewing these on YouTube. It’s all very precise and compares with the insides of a Diesel injection pump.
I removed the injectors and blow them through and all are clear. A little better than before I blow them through.
Before I connect the injector pipes I am going to fit 6 plastic pipes to the end and see if and when it pumps as it flows through the pipes.

What I don’t understand yet is what powers the pump to injection pump. Does something rotate or pulse?

My thoughts are that when it fires it’s firing on the cold start boost fuel and not injecting but we will see.

Thanks Ken

Putting some Redex in the fuel tank might help , but only if you have drained the tank , cleaned the strainer ( in the bottom of the tank , out of which the outlet pipe comes - a thick rubber pipe ) , changed the fuel filter , and got rid of stale fuel before putting fresh fuel in , modern fuels , especially E5 and E10 variants have a very short shelf life and turn to something resembling varnish , which can gum everything up .

 

[Kerabo]

Yes 16 on the diagram is the rubber boot. This type of injection system relies on the engine vacuum sucking down the plate in the air flow meter, as the plate moves down it opens a valve in the metering head to increase fuel flow. If you have a large vacuum leak like that boot has perished the system wont deliver much fuel.

Looking at the picture you posted earlier there isnt an EHA valve on this version, so forget about that one.

Fuel pressure and fuel flow are two different things, so 1st thing to do is get the filter changed. As Bellow has said there may be a gauze filter in the pipe union at the metering head, that also needs to be checked.

Thanks I will report back when I next get to look at it

 

[Pontoneer]

I think the unit has to come apart and as skilled as I think I am this looks too technical unless you really know what your doing. Even if I managed to fit new seals and O rings it looks like even a small alteration of any settings is critical.,
I had been trying to work out where the up to 5 Bar pressure comes from but I think if I understand it correctly its from the fuel pump pumping fuel from the tank and then the unit controls it from there onwards.

So does anyone know of any specialists to talk to?

Thanks Ken

Yes , speak to Stefano Mazzoni ( Stef ) at Merparts , Port Glasgow

Merparts Ltd Independent Mercedes Benz Specialist

Independent Mercedes Benz and SMART Specialist located in Port Glasgow, Scotland

www.merparts.com

 

[Pontoneer]

I think your jumping the gun a bit here, a rebuild on these is often not needed. The 6.5bar of fuel pressure does indeed come from the fuel pumps at the rear, the metering head on the engine just sends it where it needs to be.

You still need to confirm some of the basics:

1. has the fuel filter been changed?

2. if it has two pumps and both are working?

3. on the side of the metering unit is the EHA valve, check the o rings inside are not split.

4. under the metering head is a rubber boot, check it for splits causing a giant vacuum leak.

Some of these engines , from memory , also had a crankcase breather hose on the underside of the inlet chamber which was prone to splitting or coming off , which also killed vacuum . The test for vacuum leaks is , with the air filter removed , to look for the plate in the throttle body sinking down as the engine is cranked : if there is a vacuum leak , the plate will not sink and the engine will not start ; if the plate sinks , it means you have inlet vacuum , and that is not your problem .

 

[Pontoneer]

It won’t let me show my video clip but with the injector pipes off and cranking there is fuel and bubbles just dribbling from the metering head. No pulses but not sure how much should eject ?,
Thanks

You should get a definite squirt from each pipe ; a dribble and bubbles suggests an air leak somewhere in the fuel system .

Is there a smell of petrol anywhere when you are cranking ?

 

[Kerabo]

Putting some Redex in the fuel tank might help , but only if you have drained the tank , cleaned the strainer ( in the bottom of the tank , out of which the outlet pipe comes - a thick rubber pipe ) , changed the fuel filter , and got rid of stale fuel before putting fresh fuel in , modern fuels , especially E5 and E10 variants have a very short shelf life and turn to something resembling varnish , which can gum everything up .

Well he syphoned the tank himself but I have put 2 cans of carb cleaner in with the 1/4 tank of fuel
Thanks

 

[Kerabo]

You should get a definite squirt from each pipe ; a dribble and bubbles suggests an air leak somewhere in the fuel system .

Is there a smell of petrol anywhere when you are cranking ?

No smell of fuel really apart from what I have spilt.

 

[Kerabo]

Yes , speak to Stefano Mazzoni ( Stef ) at Merparts , Port Glasgow

Merparts Ltd Independent Mercedes Benz Specialist

Independent Mercedes Benz and SMART Specialist located in Port Glasgow, Scotland

www.merparts.com

Thank you