FI Pump Adjustments

[jlennon3]

I was reading the injection pump article in latest Pagoda World, and it got me wondering. When the car was originally assembled at the factory, did they tweak the various injection pump settings to get the engine running optimally? And if the factory did, it seems a rebuilt pump would also need to be adjusted once reinstalled in the car (similar to the adjustments outlined in the Pagoda World article). Anyone have any insight on this???

[jeffc280sl]

Hi John,

I don't believe the fip pumps were tuned on the production cars.  I'll bet there were tests done on a small percentage of production cars and that information was used by Bosch to adjust over time their flow test bench specs.  The lack of documentation on the fip in the BBB indicates to me that MB considered it a black box.  Other than idle adjustment MB did not need to maintain the fip because they were so reliable.  If there were problems MB would install a new or rebuilt and recalibrated pump from Bosch.  In my opinion Bosch was responsible for delivering fully operation black box fip to the MB production line.  They had been doing that for years with the diesel pumps.

[Shvegel]

Jeff is right. Usually what happens is the pump is adjusted to give a certain amount of CC's of fuel per a set number of revolutions of the pump shaft. For example they would set the pump so each cylinder would give 35cc of fuel at idle throttle setting per 1000 revolutions.

This would be repeated for a few other throttle settings and engine speeds.

Needles to say the pump is set to a general baseline and there would be room for fine tuning if you had the desire.

[jeffc280sl]

Shvegel,

I'm glad you concur.  I don't see how it could be otherwise.
 

[glenn]

Hi, After 40 plus years-- bet your FIP has been adjusted, tweeked, fiddled, tuned, calibrated, cultured, fondled, etc, etc. ..   Even after all this they still work.  A tribute to Bosch. ..

[ja17]

Hello,

Stu Ritter a very experienced and respected MB Independant Tech and Shop Owner, wrote and excellent four page write up in "The Star Magazine" (Novenber/December 2003). Concerning the final tweeking of a new or rebuilt fuel injection pump....... "this procedure cannot be done on a fuel injection pump stand, only on the engine the pump is mated to. This takes into account variances within the engine, the injection pump and the injection nozzles."  The article is very good with photos and charts.  There is a nice CO chart for these engines by year, load and vacuum.

[wwheeler]

I wonder if you can still get the article from MBCA?

[ja17]

Hello Wallace,

You can get on the MBCA website to see if the back issues  are still available.

If not email me your address and I will send you a copy out of mine.

[glenn]

Just looked at the Ritter article(in the 'The Star' file).  It is good on the linkages, but doesn't cover setting the idle speed - min fuel/air(lambda) to max at 800 rpm, then 50 rpm reduction to 750.  It covers mid and upper load ranges.  But getting the idle adjustment right is the best aid to easy starting.

[wwheeler]

I looked at my Jan/Feb '10 Star and in the last pages are listed all of the back issues available. The Nov/Dec '03 is remarkably still available for $5. Thanks for the lead Joe!