Fuel Supply (IP) problem on W-124

[Chris_]

I just did the wastegate modification to my 92 300D - It was by all accounts a success...as for the boost pressure it appears to be satisfactory ( my all purpose shop vacuum pressure gauge only goes up to 10 on the positive side and it pins it ). I took the control signal for the wastegate actuator off of the intake and it seems to work fine.

! Please note that I did shorten the rod length by the 10 mm suggested earlier in this thread but actually that was not necessary nor helpful unless a person has the 6 x 1.0 metric die that is required to cut additional threads on the shaft. The reason for this conclusion is that before I cut the 10mm off the shaft the adjustable tip was able to bottom out on the threads with the locknut removed and this was also the case after I cut the 10mm off. the end result is this... with the locknut in place which it is necessary there is aproximately 3mm of shorter rod length that is required to achienve the closed and slight pretension load on the wastegate arm ( at rest position of wastegate)... so what I did was I placed one flat washer and one lockwasher on each of the threaded mounting shafts of the actuator and then offered the actuator to the mounting bracket this effectively shortened the rod lenght the required distance without the need for the die ( the only one that I was missing from my set... isnt it alway like that ). hope this helps someone in there efforts.

I have another problem ( as my poor power was only moderately improved by this modification ) - I believe it stems from the fuel supply side... I will detail what I know here and if anyone can provide any input it would be greatly appreciated.

1) the Alda is defintely getting complete signal from the intake manifold ( ihave it run direct form maniflok to ALDA diaphram.
1.1) I checed the ALDA diaphram to ensure that the diaphram is infact holding pressure ( not leaking internally )
2) the fuel stop lever at idle hovers near the stop position and raises up as the RPM increases ( no I did not change the fuel stop valve ) - ( someone else did before I got the car )... the car shuts off fine with the key as it always has.
2.1) the fuel stop lever has always ( for the last two years ) since I purchased the car had this same behavior ( in that the lever oscilates on Rpm increase and decrease as in the case when I am under the hood and applying light throttle pressure and then allow it to snap back to idle.
2.2) When I first got the car and up unitl about 6 months ago the car had amazing power right off the line and right through the power band ( almost unnaturaly so ) as compared to my 91 300D and it got 34 + mpg ( now gets 27 mpg at best ).
2.3) back to current manifestations... if I wire up the stop lever in the full run position ( which is not as far up as the 91 is in while running ) I get noticeably better low RPM power but still not fabulous.
3) yes I have wired the throttle butterfly in the open position and I removed the vacuum supply at the vacuum pump and plugged it thereby eleminating completely any vacuum supply to the whole computer related control system

So does anyone have any understanding of the function of the internal linkage of the fuel supply control side ( ie: the alda - fuel stop lever and electrical connector immediately behind the fule shut off valve ) of the injection pump. How they relate in a fashion that may at least in principal explain the situation I have. To clarify I have about a 17 sec to 60 mph from a stop to full throttle acceleration. This time was only improved by about 5 seconds by doing the modification ( before the modification it was about 22 seconds ).

My thought is to change the fuel shut off valve as it seems to me that must have been put in wrong but it does not explain why it was working extraordinarily well with it installed in this same functional state.

4) last detail that might be helpful is that the car often but not always throws substantial black smoke on downshift and heavy acceleration... the experience can be equated to the city bus on takeoff ( we have all at one time or another been behind them...not a nice experience to be sure )

any thoughts will be greatly appreciated

Thankyou one and all

[gsxr]

Originally Posted by Chris_

I have another problem ( as my poor power was only moderately improved by this modification ) - I believe it stems from the fuel supply side... I will detail what I know here and if anyone can provide any input it would be greatly appreciated.

1) the Alda is defintely getting complete signal from the intake manifold ( ihave it run direct form maniflok to ALDA diaphram.
1.1) I checed the ALDA diaphram to ensure that the diaphram is infact holding pressure ( not leaking internally )
2) the fuel stop lever at idle hovers near the stop position and raises up as the RPM increases ( no I did not change the fuel stop valve ) - ( someone else did before I got the car )... the car shuts off fine with the key as it always has.
2.1) the fuel stop lever has always ( for the last two years ) since I purchased the car had this same behavior ( in that the lever oscilates on Rpm increase and decrease as in the case when I am under the hood and applying light throttle pressure and then allow it to snap back to idle.
2.2) When I first got the car and up unitl about 6 months ago the car had amazing power right off the line and right through the power band ( almost unnaturaly so ) as compared to my 91 300D and it got 34 + mpg ( now gets 27 mpg at best ).
2.3) back to current manifestations... if I wire up the stop lever in the full run position ( which is not as far up as the 91 is in while running ) I get noticeably better low RPM power but still not fabulous.
3) yes I have wired the throttle butterfly in the open position and I removed the vacuum supply at the vacuum pump and plugged it thereby eleminating completely any vacuum supply to the whole computer related control system



So does anyone have any understanding of the function of the internal linkage of the fuel supply control side ( ie: the alda - fuel stop lever and electrical connector immediately behind the fule shut off valve ) of the injection pump. How they relate in a fashion that may at least in principal explain the situation I have. To clarify I have about a 17 sec to 60 mph from a stop to full throttle acceleration. This time was only improved by about 5 seconds by doing the modification ( before the modification it was about 22 seconds ).

My thought is to change the fuel shut off valve as it seems to me that must have been put in wrong but it does not explain why it was working extraordinarily well with it installed in this same functional state.

4) last detail that might be helpful is that the car often but not always throws substantial black smoke on downshift and heavy acceleration... the experience can be equated to the city bus on takeoff ( we have all at one time or another been behind them...not a nice experience to be sure )

Wow. That is bizarre. The fuel stop lever should NOT move at all... it should be down with the key off, and fully up with the key on. Period. It sounds like the vacuum line to the vacuum shutoff pod is either not connected properly, or the ignition switch is leaking vacuum. This could be the cause of your low power... if the shutoff lever is moving down at all, it is restricting the fuel rack and reducing power. Your 17-second 0-60 time is very slow... it should be closer to 12 seconds (assuming you're anywhere near sea level). I'd also test the vac shutoff pod to see if it holds vacuum. If so, replacing the pod may not cure the problem.

I would start a new thread for this issue, and post a link here to the new thread, since this is not directly related to the wastegate swap. We can get into more details on the new thread.

[Oldwolf]

I agree with gsxr.

Disconnect the vacuum hose from the stop lever actuator. The stop lever should quit pulsating.

If it does, investigate the shut off vacuum circuit.

If it does not, there is some kind of wacky mechanical thing going on within the IP I guess.

[gsxr]

Correct. Another thing is, if you disconnect the vac hose and the lever still pulses, there could be some sort of odd crankcase pressure causing issues.

I am puzzled about why the power would not return to normal if you wired the stop lever in the "up" position and disconnected/plugged the vac line to the shutoff pod.

Have you verified that the ALDA is receiving a full boost signal, and the fitting at the manifold is not plugged up? If that checks out OK, next would be to remove the ALDA and go for a test drive. If there is no change, it's not the ALDA linkage either. If power returns to normal, either there is a lack of boost present at the ALDA, or the ALDA itself is damaged (ruptured aneroid capsule internally - a very rare failure).

[Chris_]

Thankyou very much for your input,

Yes I have verified that the ALDA is getting full boost signal.
The odd thing is that the stop lever will not raise completely to a height that matches my 91 300D ... even if it is pulled up manually.

I will check the shut off valve vacuum ... as suggested and as gsxr suggested I will if all else fails remove the ALDA and test run it .

I did check the ALDA does hold a vaccum ( applied vaccum and held it holds indefinitely - no tear in diaphram )

also I should clarify that the stop lever raises on acceleration ( momentary ) but when engine speed is reached for any given throttle position then it drops back down to just above the shut off position

thanks again for your time and suggestions

[gsxr]

Originally Posted by Chris_

Yes I have verified that the ALDA is getting full boost signal. The odd thing is that the stop lever will not raise completely to a height that matches my 91 300D ... even if it is pulled up manually.

That is suspicious. It's almost like the rack is not moving all the way to the full load position. You could check this by removing the side cover plate on the pump and moving the rack by hand, but you'll want to order a new gasket before you remove the plate. I'd do this after eliminating some other problems though.

Originally Posted by Chris_

I did check the ALDA does hold a vaccum ( applied vaccum and held it holds indefinitely - no tear in diaphram )

You need to check it with pressure, not vacuum. All this does is verify the shaft seal is not leaking. If the shaft seal does leak, you'll lose some part-throttle power, but it won't affect full throttle power. If an aneroid capsule is cracked, it will still hold pressure or vacuum, however it should actually increase fueling, not decrease it. If you remove the ALDA, make sure you can press down on the center shaft with your finger, it should move up & down. Could be that it's stuck in the down (lean) position... rare failure, but I've heard if it before. This would not explain the weird stop lever movement though.

Originally Posted by Chris_

also I should clarify that the stop lever raises on acceleration ( momentary ) but when engine speed is reached for any given throttle position then it drops back down to just above the shut off position

Yep - that is most definitely not normal, and when the lever is down like that, it's restricting the fuel rack and reducing fuel delivery. You have gone for a test drive with the lever wired into the fully-raised position, correct?

[Chris_]

Yes I have test driven it with the stop lever wired up ...as high as it will go which is about 3/4 of the way up ( using my 91 as comparison for the proper designed full range of travel ).

I also feel that there is something mechanicaly amiss with the internal linkage of the fuel metering-on-load aspect of the IP. I am not that familiar with the
internal workings of this portion of the IP but I will take alook inside the side cover once I obtain a gasket. One thought do you know is it theoretically possible to install incorrectly the shutoff valve to such an extent that it could cause restriction of full range of travel of the shut off lever ? I have changed the one on my 91 and it seemed really straight forward ( even though I read about the possiblity of error that could result in a runaway diesel- which of course gave rise to concern... ) .

That is an intersting point you brought up about the possibility that the ALDA could be physically stuck in the lean position. I am not very familiar with the internal functioning of the ALDA unit . What condtion exists in the IP when the ALDA is removed ( as was suggested earlier for testing purposes ) ? that is to say is it full lean or full rich when it is removed ? or neither ?... just trying to get my head arround the principal of its function.

also,

I did pull the vacuum line from the shutoff valve while at idle and then revved it momentarilly and the lever still oscillates with revs as described before.

I will let you know what else I find...

thankyou

[Diesel911]

So other possibles. In the first Pic I have read the Plastic Piece in the Fuel Pressure Relief/Overflow Valve warps or falls apart. Note, I don't know if this is the same as the one on your Fuel Injection Pump.

It also could be the Fuel Supply/Lift Pump


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[John Benz turbo]

have I took2 wire plug ofvacum valve behind right headlight put jumper wires on valve + - to open valve now goes to 20 psi 91 124 300 d 25 t have same problem lack of boost sometime 10 lb other times 2 lb

[compress ignite]

Reading from remote

[jbach36]

Could be caused by car not getting enough fuel. Have you ever cleaned your fuel tank strainer? Mine was clogged with algae.

As to your black smoke problem, it could be because your injectors are messed up. They're giving fuel but not in a usable mist. They could be just dumping fuel in that can't be used, so it goes out the other end as smoke. Just an uneducated guess.

jeff