Interesting Injection Pump Information

[ctaylor738]

I recently had my injection pump rebuilt by Pacific Fuel Injection.  It arrived a couple of days ago, along with a sheet of information (I assume from Bosch), attached.  This is the first time I have seen a spec for pressure.

Cheers,

CT

[garymand]

Its the fuel pump Pressures and volumes. 

Thanks ctaylor,  I like the second half of the 'Idle Speed Adjustment' paragraph that says: 

"If further adjustment is required, idle speed injector quantity may be adjusted with spring loaded idle control knob on injection pump."  

It helps with a different thread where someone doesn't understand why Bosch calls it the Idle Control Knob.

[jeffc280sl]

The instructions provided are interesting and correct in what I think is a very simplified explanation.

I stand by my comments on the earlier mentioned thread.  The last thing any owner should be adjusting is the internals of the FIP.  Do everything and I mean everything else prior to adjusting the thumb screw on the rear of the pump.  That adjustment takes care of fuel quantity across all rpm ranges.  While the FIP instructions indicate you can use this adjustment for idle it also says to use the air adjusting screw to help set idle.  I suggest you start using the air screw because its simple.  If you can borrow or use a AFR meter all the better.  IMHO the instructions while correct greatly over simplify the operation of the pump.  There should be a caveat before suggesting one use the thumb screw to adjust idle.  It should say after you should check and adjust everything I mentioned earlier in the other thread.  At that point the engine "runs properly".  If further adjustment is required idle speed injector (fuel) quantity MAY be adjusted using the idle control knob on the FIP.

If you decide to start adjusting idle with the thumb screw please take accurate notes so you can get back to where you started.  The clicks can be subtle to the touch.  If you adjust it with a rag because the engine is hot you may not feel the clicks.  If you thumb and index finger are almost blistered because you wanted to adjust it when the engine was hot you may not feel the clicks.  It is a very tight fit and an odd angle for your hands.

Chuck,

I'm glad you had your pump calibrated.  Did the company provide you with fuel flow data across rpm ranges for each injector output?  Your FIP should be perfect. 

Br,

Jeff

[Cees Klumper]

Jeff - are you sure when you say that the tumb screw adjusts the fuel quantity across the entire range? Because, to my lnowledge, it only regulates fuel quantity at idle. The shims under the barometric pressure regulator are what adjusts the entire range if I am not mistaken.

[jeffc280sl]

Hi Cees,

Let me verify and get back

[jeffc280sl]

Thank you Cees for jogging my memory.  The knurled nut thumb screw adjusts spring tension on the stylus that reads fuel mixture data from the grooves/etchings on the hockey puck.  There are three sets of adjustment screws for three different springs involved with the stylus.  They are the white, black and center thumb screw.  The center thumb screw is associated with idle adjustments. 

Sorry for the confusion.  I confused the thumb screw with the main rack adjustment screw which is also located on the rear cover.  Again sorry about that.  I think my advice in general still stands.   I would not mess with the thumb screw, which is an idle adjustment, until I checked out and tuned other issues like ignition, barometric compensator etc.  Again I would be careful making adjustments to the thumb screw and losing my place.  It is difficult to feel the clicks and easy to get lost.

[ctaylor738]

Jeff,

No, didn't get any data on flow specs.  Everyone says that Pacific is the go-to place for these pumps, so I believe it's as good as it gets.

The only adjustment that I made when I installed the rebuilt pump was to lengthen the rod that runs to the pump a tiny amount to get the ball to snap into the socket smoothly.  The car started instantly and ran well.  After the initial test drive, the idle CO was 3.9% so I left it alone.  

Cheers,

CT

[jeffc280sl]

Thanks Chuck,

I was just curious about the data.  Glad your car runs great.  The FIP is a marvel.  Tuning it is a nightmare without a factory fuel flow device.  There are so many adjustments to properly setup the FIP.  As mentioned I adjusted AFR of my pump to meet on road dynomometer specs called out in the MB manual.  It was very, very hard work.  Much better to have the pump adjusted on a calibration test stand that measures fuel flow output pressure and volume at specified rpm levels.  It is a matter of making adjustments to various settings such as white, black and other spring/screw settings to bring the pump back to factory specs which I'm sure your pump is set at.

Now that you have the calibrated pump back and you know that is a known good value have you gone back through the ignition, linkage, fuel pump  etc. gromming to make sure your engine performance is at peak levels.

[jackhughes81]

Chuck,

Can you tell me the pressure specs at the inlet of the FI Pump?..  thanks- jack
I have installed an after-market pump and need to ensure its correct.. thanks- jack

[glenn]

Those volume numbers-2 pints per 15 seconds(1 gal per minute) are for the electric fuel pump, NO?   The FIP at 15 mpg is about 8 oz per min or 1+ oz per cylinder.   The electric pump is 16 times the FIP at 60 mph.  The FIP is doing less than 1 oz per min at idle.  It is my naive assumption that Bosch adjusted the pump at their factory to put out about less than 1 oz per minute at idle(equal flow from each plunger) and about 10 oz per minute at full rack.  The weights were adjusted to fit the butterfly air curve?   The WRD, barometer, plunger helix rotation, etc lever were set for the factory condition.  I'm assuming a new factory 2(?)0SL engine would burn x oz per min at idle and y oz per min at full rack??  Any variation between 2(?)0SL engines(2%) would be taken care of by the idle knob on the FIP.    Of course, every mechanic knows how to do this better than Bosch, hence all the finely tuned SE engines out there.

[jackhughes81]

Jeff,
My FIP has been messed with by various mechanics trying to improve running performance.  They knew nothing as far as I am concerned, but now my knob has been adjusted to where I dont know where it is.  How do I get to a starting spot?  The car will not start after installation of the recommended replacement pump (here on the forum).  Is there any way the FIP adjustment could cause a no-start condition?  thanks- jack