Injection pump operation, please educate me - PeachParts Mercedes-Benz Forum

derherr65 · #1 10-08-2006, 11:56 AM

I have a 1982 300CD.(617 engine) I'd like to learn more about how the injection pump operates, and what things(boost level, temperature, ect) it compensates for, and how, and what things(wear, etc) it does not compensate for that one might have to tune or adjust as the mileage increases.

mobetta · #2 10-08-2006, 08:18 PM

well, your in the right place. use the search function. just keep on reading.

TheDon · #3 10-08-2006, 08:35 PM

Quote:

Originally Posted by derherr65

I have a 1982 300CD.(617 engine) I'd like to learn more about how the injection pump operates, and what things(boost level, temperature, ect) it compensates for, and how, and what things(wear, etc) it does not compensate for that one might have to tune or adjust as the mileage increases.

ask brandino

derherr65 · #4 10-08-2006, 08:56 PM

You know, I'd never cosidered a search! Seriously I've looked and I guess missed the thread you're thinking of. What I'm lacking most are the conditions that effect various adjustments. For example:
1) The ALDA - adds or subtracts fuel. But I find disagreement on whether it only adds/subtracts fuel pre boost or throught the range. Or perhaps(my personal guess) it adds/subtracts only a little fuel and is only noticable pre boost?
2) internal full fuel screw - adds/subtracts fuel. Once again, any relationship to boost or rpm? Linear to rpm would be my guess, but that could overfuel pre boost. Unless there's a device to reference fuel to boost... which I know there is, but what's it called?

#5 10-08-2006, 09:00 PM

Quote:

Originally Posted by derherr65

1) The ALDA - adds or subtracts fuel. But I find disagreement on whether it only adds/subtracts fuel pre boost or throught the range. Or perhaps(my personal guess) it adds/subtracts only a little fuel and is only noticable pre boost?
2) internal full fuel screw - adds/subtracts fuel. Once again, any relationship to boost or rpm? Linear to rpm would be my guess, but that could overfuel pre boost. Unless there's a device to reference fuel to boost... which I know there is, but what's it called?

The ALDA holds back fuel until you get boost. Once you get to 7-8 psi, the ALDA is no longer affecting the fuel rate.

The full load adjustment only affects the fuel at WOT. Any point between idle and WOT, only you, the ALDA, and RPM governor springs control the fuel rate. The device that references fuel to boost is the ALDA.

kip Foss · #6 10-08-2006, 09:09 PM

Get on your bicycle and go to your nearest diesel injection shop. Usually they have cut away models of pumps. Very interesting.

derherr65 · #7 10-08-2006, 09:15 PM

Interesting. This next question sounds weird even to me, but I want to be sure. The injection pump knows you are at WOT by throttle position, through the linkages?
Can you elaborate on the rpm govenor part? I haven't heard anything about that.

A cut away would be nice, wouldn't it?

#8 10-08-2006, 09:30 PM

Injection pump operation.

derherr65 · #9 10-08-2006, 09:49 PM

Now we're talking! Thanks Forced.
What's the "switchover valve" do? That thing inline between the ALDA and manifold.

#10 10-08-2006, 09:51 PM

Quote:

Originally Posted by derherr65

What's the "switchover valve" do? That thing inline between the ALDA and manifold.

http://www.peachparts.com/shopforum/showthread.php?t=166405&highlight=overboost
http://www.peachparts.com/shopforum/showthread.php?t=166612&highlight=overboost

derherr65 · #11 10-08-2006, 10:51 PM

Jeezus... I had no idea how complicated the internal controls on that injection pump are. And thanks to your links I also have a few more tests to do, like make sure the wastegate works properly.

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