om603 Fuel starvation - IP issues?

[jbrianfoto]

Hello team -

I recently replaced the head on my 300TD, got him running last weekend, barely. It will idle sort of roughly, even let me rev it up to 2K rpm, but as soon as I put it in drive and try a loop around the block, it has ZERO power and tries to die (and sometimes does).

The PO had installed an electric fuel pump in the engine compartment (he ran it on WVO all the time). It did not appear to be running, so I rerouted the hoses back to factory config (and replaced the primary plastic inline fuel filter) - but this made things worse. Now the engine is allot harder to start, and when it does, it will only run for a few seconds, then it dies. I am suspecting there is a problem with the IP - I have read about a check valve on the backside of the pump that can fail. After I would let it sit for a minute or two it would start again and then die after it runs out of fuel.

As a test today I reinstalled the electric fuel pump and started the car. It runs better, but is still totally gutless. Idles is rough, will rev up some of the time, but if I try to drive it, I can barely go along at 3 MPH. When revved up it runs smooth, but it cannot be sustained, it always dies down and then tries to stall.

Also noted is the #6 cylinder is leaking allot of fuel from around the pre-chamber - I think it is loose (tiny bubbles). Am going to have to get the proper socket to put this in tight, it came out when I removed the injector. I fabricated a socket for this, but it wasn’t a very good job and I think I didn’t get it tight enough.

Before I removed the old head this car ran like a dream. The ALDA has been removed, the EGR is still intact. I am going to check that the turbo turns freely later this morning. The secondary fuel filter is brand new, though it also appears to be leaking a little fuel (weeping is more like it).

[jbrianfoto]

Also - When I removed my ALDA (while the intake and head were off) - I simply removed it and plugged the line. No other adjustments or modifications were made. Was I supposed to do anyhting else to the IP where the ALDA was attached? I read the post about how to remove the ALDA and there were instructions on how to adjust the shims, my assumption was this only needed to be done if you were going to replace the ALDA after adjustment.

[sixto]

Some things to try:

1) Drive the car with the fuel filler cap off.

2) Rig a fuel container in the engine bay vented to atmosphere to take the fuel tank out of the picture.

3) Gently pinch the return line to the fuel tank. Don't drive for too long like this!

There might be a problem at the exhaust end. Remove the plug on the #1 exhaust runner. It'll be noisy and spew exhaust in the engine bay but it'll suggest an exhaust restriction if the engine frees up.

No IP adjustment is necessary (or possible) when you remove the ALDA.

Sixto
87 300D

[jbrianfoto]

Am ruinning downstairs now to try this. BTW - whats an exhaust runner? I have noticed where the exhaust manifold connects to the bypass tube (that replaced the old trap oxidizer) there is a thick ring of black soot. I really cleaned that part when it was off the car, so the fact that it is now dirty is noticable.

[sixto]

Look where the exhaust manifold extends from the cylinder head by the #1 cylinder. There'll be a bolt head that takes a 17- or 19mm wrench.

Sixto
87 300D

[jbrianfoto]

I installed a mason jar with about 10 oz of fuel, but it got sucked down so quick I couldn't really tell. I disconnected the electric fuel pump and tried it again, but it draind within a few seconds. SO I'm going to the gas station to refill my can and will install a bigger fuel supply (an empty, well drained antifreeze container. I also have the fuel filler cap off and the return line to the tank gently pinched.

I will also look on the exhaust mainfold for that 17/19mm bolt.

Thanks !

[sixto]

I wasn't clear. You have to do it like you're using Diesel purge. The lift pump draw line and the fuel tank return line should both go into the temporary fuel container.

Sixto
87 300D

[barry12345]

Slow down if the car was running well before you pulled the head. Your first check should be to align the timing marks with the valves on the first cylinder pointing upwards and check for the tang for being in the centre port of the injection pump. Rotate slightly to get the right degrees on the harmonic balancer first. Then check for the tang.

How was the replacement head checked out? What is the current compression with the new head? You have obviously introduced something when you changed the head.

Do the timing double check first. Or I would. I very much doubt anything you did changed a good previously working fuel supply system. Other than perhaps it's timing .

[jbrianfoto]

Originally Posted by sixto

I wasn't clear. You have to do it like you're using Diesel purge. The lift pump draw line and the fuel tank return line should both go into the temporary fuel container.

Sixto
87 300D

I understand -diesel purge - will put both lines in the temp-tank and try again. Was amazed at how fast it all went away compared to my old w123 (it seemed like it would run for 60 minutes on a can of diesel purge).

[jbrianfoto]

Originally Posted by barry12345

Slow down if the car was running well before you pulled the head. Your first check should be to align the timing marks with the valves on the first cylinder pointing upwards and check for the tang for being in the centre port of the injection pump. Rotate slightly to get the right degrees on the harmonic balancer first. Then check for the tang.

How was the replacement head checked out? What is the current compression with the new head? You have obviously introduced something when you changed the head.

Do the timing double check first. Or I would. I very much doubt anything you did changed a good previously working fuel supply system. Other than perhaps it's timing .

Hi Barry -

In other posts I've already ironed out that my timing is correct (Sixto and some of the other Professors helped me out there). This car has sat for 6 months without running AND it was fed tons of WVO by the PO, so who knows what could be in the tank or fuel lines (or in the exhaust pipe - mice?).

The repalcement head was checked out by the machinist that my local Mercedes shop recommended. He certified that it was crack free and the flatness was within specs. He also replaced the valve stem seals.

We checked the IP tang alingment when I thought I had the cam out of phase - it shows up around 14 degrees ATDC. The cam was out of phase by 180 degrees, but that got fixed.

Sixto is helping me to eliminate the fuel supply and validate wether or not the IP lift pump is working properly.

Will post the results !

[jbrianfoto]

Well -

No difference when running on an aux tank (with both send and return lines inside the milk jug). Tried with the electric pump off, then on - same result both times. No improvement when the #1 exhaust bolt was removed either.

It doesn't even have enough power to pull into my garage ;-(

After it sits for about 15 minutes it seems to run better for the first 30 seconds. Subsequent starting attempts thereafter get worse and worse. Am going to read up more on the IP pressure bypass valve (I think that is what it is called).

As a good measure, I'll recheck the IP timing (probably tomorrow) - I've had it for now.

[jbrianfoto]

Could I have the wrong injectors in this engine? I took out the injectors from my #14 head and had them rebuilt (on this forum) - and installed them in my #22 head (with new crush washers). I did have a set of the correct #22 head injector lines, and they are installed. Everything lines up correctly.

[Diesel911]

Originally Posted by jbrianfoto

Well -

No difference when running on an aux tank (with both send and return lines inside the milk jug). Tried with the electric pump off, then on - same result both times. No improvement when the #1 exhaust bolt was removed either.

It doesn't even have enough power to pull into my garage ;-(

After it sits for about 15 minutes it seems to run better for the first 30 seconds. Subsequent starting attempts thereafter get worse and worse. Am going to read up more on the IP pressure bypass valve (I think that is what it is called).

As a good measure, I'll recheck the IP timing (probably tomorrow) - I've had it for now.

I am not sure on yours but some of the newer Engines have a Fue Pressure Relief/Bypass Valve on the Fuel Injection Pump that has some Plastic Piece in it that warps are falls apart.

There is also 2 threads on rebuilding the Fuel Supply/Lift Pump.

[jbrianfoto]

Hi Diesel911 -

This is the original engine in my 87 300TD. Will go look for those lift pump rebuild threads right now. Thanks !

Am also trying to find the correct socket used for tighening the retaining ring that the injector threads into - can't seem to nail the correct name for it. I built one out of a big socket, but it doesn't fit well enough to do a good job.

[sixto]

Yes, about the injector. Are you saying the prechamber backed out when you removed the injector? That's strange. The prechamber is pressed into the head and held in place with a threaded lock ring, not to mentione keyed from turning by the glow plug. To my knowledge the injector screws in to the prechamber, not the lock ring. How then could removing an injector loosen the lock ring? That the lock ring is loose is a possibility, but I think independent of what you did with the injector.

[correction] I assumed splined lock rings for inclined injection in which the injectors thread into the prechamber. In vertical injection the injector threads into the lock ring so it's possible to back out a lock ring when extracting the injector. IIRC the tightening torque for vertical injection lock rings is 100Nm. The injector spec is 70-80Nm.

Sixto
87 300D