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

ROLLGUY · #1 02-19-2013, 10:32 AM

Although it seems odd that all 5 injectors would go bad at once, the injectors are the only thing in the fuel system that have not been replaced. As stated before, I have a set of rebuilt injectors, and I think I will try them on this engine. The only thing that I may loose, is just the labor. A benefit would be that I can test the rebuilt injectors before I install them in my engine. If any leaks occur, I can fix them before I install them in my engine. I may get a chance to try this on Friday, so stay tuned!

funola · #2 02-19-2013, 10:47 AM

Quote:

Originally Posted by ROLLGUY

Although it seems odd that all 5 injectors would go bad at once, the injectors are the only thing in the fuel system that have not been replaced. As stated before, I have a set of rebuilt injectors, and I think I will try them on this engine. The only thing that I may loose, is just the labor. A benefit would be that I can test the rebuilt injectors before I install them in my engine. If any leaks occur, I can fix them before I install them in my engine. I may get a chance to try this on Friday, so stay tuned!

I think it's odd also that all 5 injectors would clog equally and idle smoothly. Before you pull the injectors, start the engine then pull the return cap on #5 injector return barb and see if it is blocked. Wrap a white tissue around it and see what comes out.

I've asked this question before but do not remember an answer:

Is the engine starting immediately or does it take extended cranking to start?

ROLLGUY · #3 02-19-2013, 11:04 AM

Quote:

Originally Posted by funola

I think it's odd also that all 5 injectors would clog equally and idle smoothly. Before you pull the injectors, start the engine then pull the return cap on #5 injector return barb and see if it is blocked. Wrap a white tissue around it and see what comes out.

I've asked this question before but do not remember an answer:

Is the engine starting immediately or does it take extended cranking to start?

It starts up immediately and idles perfectly. I had also thought that maybe the return line is plugged, and the injectors are just shutting down. I had a similar problem with my Mitsubishi. I was assembling it after a rebuild, and replaced the washers between the return rail half's. I did not realize that there was tiny holes in the copper washers, and just put solid washers in. After getting it running, it would drive for about a couple miles and just slow down and quit. I found out that if the injectors can't return, the just shut down and refuse to work. I told my IP rebuilder the symptoms, and he said to check the holes in the return rail washers. I said "what holes"? He sent me some washers with holes in them, and the engine has ran great since. I don't think that directly applies here, but I certainly can try pulling of the end cap (or even the front hose) to see if the injectors are returning, or if the engine runs better.

funola · #4 02-19-2013, 11:14 AM

Quote:

Originally Posted by ROLLGUY

It starts up immediately and idles perfectly. I had also thought that maybe the return line is plugged, and the injectors are just shutting down. I had a similar problem with my Mitsubishi. I was assembling it after a rebuild, and replaced the washers between the return rail half's. I did not realize that there was tiny holes in the copper washers, and just put solid washers in. After getting it running, it would drive for about a couple miles and just slow down and quit. I found out that if the injectors can't return, the just shut down and refuse to work. I told my IP rebuilder the symptoms, and he said to check the holes in the return rail washers. I said "what holes"? He sent me some washers with holes in them, and the engine has ran great since. I don't think that directly applies here, but I certainly can try pulling of the end cap (or even the front hose) to see if the injectors are returning, or if the engine runs better.

If it starts immediately and idles perfectly, then you do not have any air in fuel issues. Have you done the fuel output test? It's in the FSM and is easy compared to swapping injectors.

Another thought, could the up down impact deform the crank bearings increasing friction? If it is a crank bearing friction issue, I'd think the starter cranking RPM would decrease and you'd feel more resistance turning the crank with a wrench. Have you noticed either?

funola · #5 02-19-2013, 12:09 PM

Quote:

Originally Posted by ROLLGUY

It starts up immediately and idles perfectly. I had also thought that maybe the return line is plugged, and the injectors are just shutting down. I had a similar problem with my Mitsubishi. I was assembling it after a rebuild, and replaced the washers between the return rail half's. I did not realize that there was tiny holes in the copper washers, and just put solid washers in. After getting it running, it would drive for about a couple miles and just slow down and quit. I found out that if the injectors can't return, the just shut down and refuse to work. I told my IP rebuilder the symptoms, and he said to check the holes in the return rail washers. I said "what holes"? He sent me some washers with holes in them, and the engine has ran great since. I don't think that directly applies here, but I certainly can try pulling of the end cap (or even the front hose) to see if the injectors are returning, or if the engine runs better.

Pulling the 1/8" return hose to the secondary filter is a better idea. Stick that in a bottle before starting. A little less messy and you capture everything that comes out.

Silber Adler · #6 02-19-2013, 12:27 PM

Could the fuel pressure relief spring be broken.

I would think that the engine would make more power than descibed with the ALDA completely closed.

For instance, On my 85 There is no boost under 60 mph because it is shunted off on the intake side of the turbo through the ARV. Yet the car would run, if abit sluggish.

ROLLGUY · #7 02-19-2013, 02:39 PM

I got everything together for replacing the injectors:

I may get a chance to do it on Thursday depending on the weather. We are supposed to get some very cold weather in the next few days, and I am not going to work on this car out in the cold. Friday should be better, so stay tuned....Rich

DeliveryValve · #8 02-19-2013, 10:50 AM

I have not read through the whole thread and not sure if this has been suggested, but it seems like you not getting a boost signal to the ALDA causing it to starve the engine of fuel. Check the condition of the line for obstructions and leaks. Also you might want to temporary bypass the switch-over valve as it maybe faulty.

ROLLGUY · #9 02-19-2013, 10:53 AM

Quote:

Originally Posted by DeliveryValve

I have not read through the whole thread and not sure if this has been suggested, but it seems like you not getting a boost signal to the ALDA causing it to starve the engine of fuel. Check the condition of the line for obstructions and leaks. Also you might want to temporary bypass the switch-over valve as it maybe faulty.

Yes, been there, done that. ALDA is getting a good signal with the OPV bypassed.

DeliveryValve · #10 02-19-2013, 11:11 AM

Quote:

Originally Posted by ROLLGUY

Yes, been there, done that. ALDA is getting a good signal with the OPV bypassed.

My feeling the ALDA is the culprit. Have you connected a boost gauge to the line to measure what kind if boost engine is producing?

.

funola · #11 02-19-2013, 11:16 AM

Quote:

Originally Posted by DeliveryValve

My feeling the ALDA is the culprit. Have you connected a boost gauge to the line to measure what kind if boost engine is producing?

.

Is the ALDA and boost in play at idle with no load? The engine won't rev past 1800 in neutral!

ROLLGUY · #12 02-19-2013, 11:30 AM

Quote:

Originally Posted by funola

Is the ALDA and boost in play at idle with no load? The engine won't rev past 1800 in neutral!

The turbo is not putting out enough boost to cause it to add any more fuel, so anything related to the turbo, ALDA, etc is irreverent. The engine runs exactly the same way with the turbo, exhaust, intake and air cleaner, and ALDA hooked up, as it did with all that stuff off (several pages of posts ago).

funola · #13 02-19-2013, 11:35 AM

Quote:

Originally Posted by ROLLGUY

The turbo is not putting out enough boost to cause it to add any more fuel, so anything related to the turbo, ALDA, etc is irreverent. The engine runs exactly the same way with the turbo, exhaust, intake and air cleaner, and ALDA hooked up, as it did with all that stuff off (several pages of posts ago).

Yes I know that. My question was to Delivery Valve.