Little or NO power after bottoming out suspension- 1981 300SD - PeachParts Mercedes-Benz Forum

barry12345 · #1 02-18-2013, 12:29 PM

I asked if you were aware the linkage was responding in a linear fashion for a few reasons. Sometimes things that seem even almost irrelavent can be signifigant.

The exhaust being cleaner only would have really counted if you were still on the original injection pump and in comparison to before the bump. The fairly clean exhaust emisions do indicate some things though in themselves.

Things like the engine is getting enough air for example and the timing is not really retarded signifigantly. That gets the mechanical advance unit out of the way. Other wise I would expect more black smoke as the rpms picked up and where limited by no advance. Others with more experience will probably have more signifigant or accurate interpretations.

I assume the turbo is spinning up and the wastegate is not staying wide open. Although I do not know if that would limit the available revs under no load conditions. This is proof of my limitations on cars. Or if so perhaps how much.

I also tried to consider any effect that could really get the injectors but there where a few roadblocks there. Things like at idle there is apparently normal and with proper fuel volume and the idle is smooth and little smoke.

Plus the worse one is how in the world would hitting a bump possibly get more than one injector. Even If the bump caused a lot of junk to get out of the fuel filter and into the injectors I feel the symptoms would be differant. Again not an absolute certainty at my experience level. I also considered any effect perhaps by the fuel tank getting a severe unusual shaking up but the fuel filters should have caught that. Maybe they did as the engine died a mile or so after the bump.

At this point I have become very interested in what it may prove to be. This was to me the only really significant indicator of the original fault. Something drove the engine into a fuel starvation mode. If this was not so the engine would have still been capable of maintaining at least an idle even then as it is now in my opinion. That is where I got into suspecting you may have introduced something else. There is no certainty in that just a remote possibility.

Even at my age I still learn something every day but have no ideal of why except it has been a lifelong thing with me. Another possible bonus of this is over time having real expertise in a few fields. Unfortunatly not when it comes to cars though. That is in both Mr hunters and several other senior site members strengths..

I can do many things well in certain fields that present major difficulties to many. I will probably continue doing them until I am unable to as I have no ideal of how to stop. Or desire to.

I am accused of being a perfectionist all too often when doing things for others in areas where my knowledge is well grounded. Unfortunatly I do not have enough time left in my life to come fully grounded and up to speed on cars. You have to do a lot of hands on experience on a almost continious basis as well to get it.

For example I am just about to leave to buy materials. Waiting for the snow plough to go through one more time first.Heavy winds are causing drifting conditions here today. The tractor and blower that clean our property have come and gone.

At the same time seeming always to be dealing with design considerations and other relavent issues for a new commercial replacement building this spring or something else. Plus winding up this and that. Compound this with family involvement it is still a very full life. I even think it is keeping old age away to some extent.

Can only hope my mind lasts as long as my body. What I do in general may be helping myself and hopefully others. Anything that exercises the mind at any age was probably worth the effort over the long haul. In a case like your current one something is there to be learnt for some of us with limited knowledge like myself.

From reading this whole thread over. I can only think of one thing I would do first personally now if the car where here. Either with a pressure gauge or by some other method it would be important to me to find out if the fuel pressure in the base of the injector pump was remaining at 1800 rpms or falling off to nothing as that speed was approaching. The lack of apparent linearity from the linkage at the injection pump could be another indicator that this might be occuring. Sorry about the long post but I suspect this issue may be seriously concerning you at the moment.

Under load the car has absolutly no power is another strong indicator of this as a possibility at least to me. That lift pump might have got a load of something from the bump if pressure is not maintained. Does manually pumping the primer pump as well help increase rpms while at 1800 rpms or so? I know from your posts you know more than average but still are missing something.

ROLLGUY · #2 02-19-2013, 12:44 AM

Quote:

Originally Posted by barry12345

At this point I have become very interested in what it may prove to be. This was to me the only really significant indicator of the original fault. Something drove the engine into a fuel starvation mode. If this was not so the engine would have still been capable of maintaining at least an idle even then as it is now in my opinion. That is where I got into suspecting you may have introduced something else. There is no certainty in that just a remote possibility.

From reading this whole thread over. I can only think of one thing I would do first personally now if the car where here. Either with a pressure gauge or by some other method it would be important to me to find out if the fuel pressure in the base of the injector pump was remaining at 1800 rpms or falling off to nothing as that speed was approaching. The lack of apparent linearity from the linkage at the injection pump could be another indicator that this might be occuring. Sorry about the long post but I suspect this issue may be seriously concerning you at the moment.

Under load the car has absolutly no power is another strong indicator of this as a possibility at least to me. That lift pump might have got a load of something from the bump if pressure is not maintained. Does manually pumping the primer pump as well help increase rpms while at 1800 rpms or so? I know from your posts you know more than average but still are missing something.

Long post or not, a lot of good info here. As far as the lift pump, I used the one that came on the used IP I got from the wreckin' yard, so it has been changed as well. I can only assume that either BOTH IP's and BOTH lift pumps are bad, or both of them are good. I am sure that when the problem is solved, we will all learn something.

barry12345 · #3 02-19-2013, 10:27 AM

Quote:

Originally Posted by ROLLGUY

Long post or not, a lot of good info here. As far as the lift pump, I used the one that came on the used IP I got from the wreckin' yard, so it has been changed as well. I can only assume that either BOTH IP's and BOTH lift pumps are bad, or both of them are good. I am sure that when the problem is solved, we will all learn something.

The faults if any between different lift pumps and injection pumps would not be identical even if they existed. Certainly both could be bad in some way but it is again almost certain the faults would be different.

Since Mr hunter has seen jelly like substances hit injectors before as long as you have fuel pressure indications in the injection pump at 1800 rpms. Having the injectors checked and cleaned out if the need is indicated makes sense. I am all too familair with straight waxing of the fuel at really low temperatures so the concept is not alien to me. The rule is never buy fuel from a pump that has a heater on it in cold weather especially. Unless you have one load of fuel thinners in the trunk.

Or grab a set of injectors out of one of the engines you pulled the injection pumps from if cheap and give them a try. Turn the engine over with the starter with the injectors out as this may also clear any residual junk that may also be present in the injector lines.

Since it is now a different injection pump I assume there is no impariment of it's delivery valves with junk as might be the case with the original injection pump.Although this is not much of a consideration if any because the engine is running almost the same except a little better in some ways now.So I would still flush those injector lines as well before installing either your current injectors once dealt with or a test set from a wreck if cheap enough.

There should be a relief valve present somewhere there. I have seen it mentioned that it was further along the system on one car. Right or wrong I do not know. There was one situation where the relief valve was on the input to the pump as well I think. A misteak of installation. Either way whatever was the situation previously it did not stop normal running in your cars case. Unless when you changed pumps there was some change relating to the relief valve. Again any form of real pressure present in the base of the injector pump at 1800 rpm deals with this issue. Or during the process to correct the low pressure if present will.

I have nothing but respect for Mr.Hunters abilities and experience. It is a wise decision to converse with him. I have not had the need to yet for one of my own issues but that day will probably come. His helping people out goes way beyond the norm. Also it is not all that simple in some cases to do so. Human nature being what it is people do things like leave important information out when describing their issues.