Little or NO power after bottoming out suspension- 1981 300SD - Page 4 - PeachParts Mercedes-Benz Forum

funola · #46 02-18-2013, 11:33 AM

Quote:

Originally Posted by ROLLGUY

The bottle was clear with the lines directly on the lift pump and return fitting on filter. I could clearly see fuel returning, and the feed line submerged in fresh fuel.

You didn't have clear lines? (easier to see bubbles in clear lines than just a clear bottle)
Does the engine start with the first crank or does it take extended cranking before starting?

I think this symptom in the first post needs to be scrutinized:

engine died a mile after the impact and will not restart.

Why?

The impact is an up down motion rather than the more common fore aft motion of most impacts. What is more likely to be damaged in an up/down impact? (other than the oil pan)

kerry · #47 02-18-2013, 12:15 PM

This is a real mystery. At this point, I'd post a video of it starting and running with the hope that additional sense data provided to the body of minds here, might produce more viable hypotheses.

Delibes · #48 02-18-2013, 12:19 PM

Quote:

Originally Posted by ROLLGUY

I have not considered the position of the throttle at which the highest RPM is attained. I am not sure if that makes a difference anyway. Every time after I do something, the engine runs exactly the same (with maybe the exception of smoother idling with the new IP). I was also told that the exhaust was much cleaner than before, after the new IP was installed

That's what I meant with the linkages, sorry! There's a few little plastic tabs and rubber pieces around the firewall that might have been damaged, affecting the response between the gas pedal and the engine. If actuating the throttle by hand (in the engine bay) can make it run and rev properly, then the problem should be isolated more and more (not the IP, not the fuel lines... and so on) down to a specific area.

On another note, depending on the location of the fuel lines, they may have been dented in the impact just enough to allow for a normal idle but not allow enough fuel to run past certain demand from the IP. It would make sense in the "limiting" aspect of the problem.

Quote:

Originally Posted by kerry

This is a real mystery. At this point, I'd post a video of it starting and running with the hope that additional sense data provided to the body of minds here, might produce more viable hypotheses.

Agreed 100% on the video!

funola · #49 02-18-2013, 12:21 PM

I think ROLLGUY already actuated the throttle at the IP and verified it has full travel motion. He replaced the IP 3 times already!

kerry · #50 02-18-2013, 12:38 PM

If the air and exhaust are confirmed clear and open, I don't see what it can be besides fuel delivery. But lots of strange things can happen, hence the need for the video I think, and lots of footage at that.
Have you checked fuel pressure and flow between the secondary filter and the IP?---the reason I ask this is that there's a bypass valve in that secondary filter assembly I think. Perhaps the shock of bottoming out made that bypass valve stick in the open position and it's not delivering enough fuel or pressure to the IP.

funola · #51 02-18-2013, 01:00 PM

Agree on the fuel delivery. Maybe the impact stressed the metal fuel line under the car, creating a pinhole leak, stalling the engine. Changing the fuel filter wouldn't have helped. I'd suggest verifying the filter is installed correctly with the correct seals and the mating surfaces are clean and verify there are no bubbles in the return line.

I just can't see how that impact can clog the air intake or exhaust, or destroy an IP or turbo, change the timing, make the valves go out of adjustment etc etc.

barry12345 · #52 02-18-2013, 01:29 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.

vstech · #53 02-18-2013, 01:42 PM

car off.
one person pushing on the accelerator pedal,
one person looking at the ip linkage, and throttle stop. does the pedal push the linkage to the stop?

kerry · #54 02-18-2013, 01:57 PM

Didn't he state that the linkage is moving to the stop earlier in this thread?

marco5 · #55 02-18-2013, 02:01 PM

do a compression test.

vstech · #56 02-18-2013, 02:23 PM

Quote:

Originally Posted by kerry

Didn't he state that the linkage is moving to the stop earlier in this thread?

he said while turning the linkage by hand it did, but I can't find anywhere on here that he used the pedal for this test...

funola · #57 02-18-2013, 02:48 PM

Quote:

Originally Posted by vstech

he said while turning the linkage by hand it did, but I can't find anywhere on here that he used the pedal for this test...

If turning the linkage by hand can only achieve 1800 RPM, what makes you think using the pedal will do better?

kerry · #58 02-18-2013, 04:17 PM

What would a compression test indicate? Engines with poor compression will typically not start, but if they do, they will wind up to high rpm's with no problem.

tiger64 · #59 02-18-2013, 04:32 PM

Could you have somehow damaged the hose/line that allows the tank to breath. I seem to remember a similar issue where a very strong vacuum was created when I had a line pinched. See if the issue is still there without the fuel cap. Just a thought based on root cause reasoning

kerry · #60 02-18-2013, 05:55 PM

Quote:

Originally Posted by tiger64

Could you have somehow damaged the hose/line that allows the tank to breath. I seem to remember a similar issue where a very strong vacuum was created when I had a line pinched. See if the issue is still there without the fuel cap. Just a thought based on root cause reasoning

This was ruled out when he ran it on a separate bottle of diesel.