Almost at my wits end!

[karitoki]

Sorry for starting a new post on this, but I can't think of what to do next. My 78 240D still won't start! I had troubleshot it down to what I thought was a bad fuel pump. I replaced the fuel pump, both filters, and installed parallel glow plugs. I just got back from towing the stupid thing around the neighborhood with no joy. It's a 4speed, so my buddy pulled me up to about 15mph, I turned the key to the glow plug point, waited about 5 seconds and dropped the clutch in 2nd. Sounded like it was running, blue smoke was coming out, but as soon as I pushed in the clutch; nothing. I also had the pedal to the floor while it was turning over.
I'm assuming the blue smoke was fuel, and if it wasn't a diesel I'd say something electrical was going on. I also checked each of the tips of the glow plugs with a 12v lamp and they were all bright. Help!

Thanks!

[04 Diesel]

Do you have fuel at the injector lines? You changed both fuel filters? Did you fill the big filter with fuel? It takes alot to get fuel back to the injectors after the filter change.

[jonbobshinigin]

Sounds like a fuel issue to me...confirm that you are getting fuel to the injectors and report back. You should also give us some more data on vehicle.

Miles?
History?
Last time it was running?

[karitoki]

Will do...

[karitoki]

Again, I apologize for starting this in a new post…
The car is a 1978 240D base model. No AC, crank windows, 4 speed. It had been sitting for 7 years before I bought it (running).
I just loosened the caps for the injectors and turned it over. Nothing comes out of any of them.
Disconnected the fuel pump output line that attaches to the secondary filter housing. Pumped the manual primer pump; heavy flow for each pump (just less than an ounce). When I turn the engine over not even a teaspoon of fuel squirts out. Reconnecting that line and disconnecting the connector that connects the output of the secondary fuel pump to the injector pump, same results. Big squirt when pumping the hand primer, very small squirt when I turn the car over.
At this point I’m thinking the injection pump cam that engages the roller pump inside the fuel pump has something wrong with it. Crap. Replacing that thing is beyond both my mechanical ability and my budget for this car.
What do ya’ll think about my bypassing the mechanical fuel pump and installing an electric unit? I think the injector part of the IP is still working. Don’t they use those things for bio diesels?
Again, thanks in advance for all your help everyone.

[kerry]

It's a viable option.

[barry123400]

I preffer the original type lift pumps. About the only thing that would stop a good lift pump working is the crankshaft in the injection pump not turning.

If that where the case an external pump is not going to get the car running as the crank in the injection pump has to turn to supply fuel to the injectors. Check to make sure it is turning.

Rare type of fault but not totally unknown. If that injection pump crankshaft is turning and the lift pump activation lobe is still there it sounds like there may still be issues with the lift pump.You can either deal with that or run an external fuel pump then.

Slow yourself down and go at it systematically. Whenever I felt any emotional response to working on a mechanical thing I just always took a break. Then when I returned to whatever the issue was it usually went quite fast.

Well I just re read your post and it does sound like the injection pump crank is turning as you get a lesser squirt out of the lift pump when engine is cranking.

I am starting to wonder if the return valve on the injection pump might be open all the time. Or the injection pump turn off device is always activated.

Quick test I would do. Pump the primer pump. Does resistance start to build to finger pressure? Do you hear the return valve squeel a little as much more resistance is encountered. This is the relief valve opening at pressure. Tell us what is happening and test number two can be done. The results of the finger primer pump reaction should suggest where to test next.

[Diesel911]

If the Hand Primer is working good but for some reason the Fuel Supply Pump was not working; you should be able to start if someone is pumping on the Hand Primer while you try to start. This might give you an idea if an Electric Fuel Pump would work.


Long Fuel Pressure Relief Valve/Overflow Valve Thread
Fuel pressure relief valve adjustment - PeachParts Mercedes ShopForum

Also you said the Car sat for 7 years. In the time Fuel inside of the Injector Nozzle could have solidified; not to mention rust could have formed.
It may be that the Injector Pintels inside of the Nozzle are stuck up wards.

I have also seen examples where the Plungers (part of the Elements) inside of the Fuel Injection Pump stuck in the upwards position (this is part of the high pressure Fuel Injection System; not the Fuel Supply System). If this happend they would not come down to fill up with Fuel.

Maybe the Fuel Rack inside of the Fuel Injection Pump is stuck in the idle position and will not go to full Fuel.

[WINGAS]

Put a good charge on that battery as well. It'll need all the crank speed it can muster to fire.

[karitoki]

Thanks for all your responses, and ditto Barry123400 on "breaking away". I did some more research (before I saw your post) and guess what I read about that gave me hope that I might not have a bad IP; the relief valve. Also, what do you call the device on the IP that is vacuum operated and cuts fuel flow when you turn off the key? Maybe it's that that's not working?
Diesel911, your post reminded me of something! First, this is a brand new Bosch lift pump. But when I was troubleshooting the old one, one of the things I did was pump the primer pump repeatedly while my wife turned the engine over. I did this while the injector caps were loose, and nothing came out of them. I bet the relief valve is the culprit! I'll report back tomorrow. Thanks so much for the help!
Wingas; Good idea!

[barry123400]

The proof again that the relief valve is functional enough is the finger pressure needed on the primer pump increasing and the noise of the relief valve opening.

No increase in priming effort assuming the valves in your new lift pump are good. That is a reasonable assumption for now. Then the relief valve is open or the primer pump is defective.

Or if the pressure of pumping the primer pump builds until you can no longer push it without the relief valve squeeling would indicate a totally obstructed fuel filter perhaps.

First test of the fuel shutoff on the injection pump is to remove the vacuum line from it. There was an excellent post a little while back on your thread about problems that can be encountered with an injection pump sitting a long time by diesel 911.

Since your injection pump and injectors where working well reciently even though it had sat a long time. For the time being those potential problems can be set aside in my opinion.

[jonbobshinigin]

You could also re-route both fuel lines into a bottle of diesel or diesel purge to make sure it is being drawn from the tank. I think you are on the right track with what you have said thusfar, but you may want to take this out of the equation. In my experience with these cars, it is usually more simple then it appears.

My uncle bought 1969 220D that had been in a warehouse since 1981. Pierre Hadardy, a benz guy here in Florida got the car running with little work!

[Stevo]

Did you try disconnecting the brown vacuum line that operates the shut off switch on the IP?

Also the idea of a portable container hooked up for a fuel supply would be a very good thing too try, its free and easy to do.

[whunter]

Here is a link to his other thread.

Quick 240D fuel pump question



.

[Stretch]

Clutching at straws?

IP stop lever stuck at stop?

Throttle linkage smoothly operating?