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Author Topic: Cummins Fuel Control  (Read 4479 times)
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I am new here and this is my first post.


Here is my problem,

I want to replace the AFC(aneroid fuel control) on a P-pump cummins engine. 

I would like to take input from boost pressure and engine RPM to control either a stepper motor or some type of variable distance solenoid(21mm thrust) to control fuel flow rather than the boost actuated AFC.

I am reading and researching this but i would appreciate any insight or direction for research or personal input. 
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 I am not sure how much speed you can get out of a linear actuator, but that might be something that would equal a variable length solenoid.

  What do modern diesel engines use for fuel control?
 
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The 6BT Cummins 12 valve engine used the P-7100 injection pump and is controlled by boost actuated diaphram to limit the overall fuel to the motor until the turbo can create pressure. 

Many people also take a more modern 24 valve cummins and put the old style pump on them.

A linear actuator is what i was trying to think of and i am unsure as to what speed it will need to move.  i do know it needs to be able to travel 21mm though. 

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  It is going to be difficult to help you with finding a fuel control valve that meets your needs here at a electronics site. However, if you can find something that would work and you need help connecting to it's electronics you are likely in the correct place.

 My suggestion is to do more research on methods used to control fuel, using a electronics. Modern semi-trucks must have something that is fully electronic that perhaps can lead you in the direction of a solution.
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cyclegadget,


there are three electronic devices on this engine; alternator, starter and fuel shutoff solenoid.   The fuel control is a boost actuated diaphram with a push rod.  No matter how much throttle you give it there will only be so much fuel delivered to the engine based on how much boost you have from the charger. 

I want to create an electronic control system for as cheap as possible to test out on an engine i am currently building up. 

Ill lay out what i think i need and you guys help me see if it is possible to do this.

Input:  Manifold pressure(< 100psi), RPM (from cam position sensor), EGT(from thermocoupler for a safety shutoff and data logging)

Output:  Precision control from a linear actuator for fuel with a 21mm throw and possibly an LCD readout stating the fuel valve percentage of movement. 

When i say precision control i am not looking for stepper motor precision by any means.  I do need to be able to take into account the manifold pressure and rpm to know how much to move the actuator. 

any help and info is much appreciated
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  All the things you list are can be done with Arduino, finding the actuator you need can be a challenge without your parts in hand.

 I am interested in the idea, so I spent some time searching. Is there anything on this page helpful? http://www.drakecontrols.com/Woodward-Engines-Diesel-Actuators
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With such a small throw would an RC servo with, say, a 100mm connecting rod provide enough linearity of control for the job?   
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i need lateral movement from an actuator with position control.  rotary stepper motors and servos will not be easy enough to work with in my opinion. 

this pq12 seems to be exactly what i have been looking for.  I have some more research to do on the original manual control valve for modification.  the only thing that worries me is the force capable and the force necessary. 
http://www.firgelli.com/products.php

My next question is a cheap pressure sensor capable of up to 100 psi for less than or near $100.  Do the exist?  I have been thinking of raping a digital tire pressure gauge from an auto parts store to keep the cost down.  the only problem is if it will be reliable and responsive enough to satisfy my needs. 

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I have used these and they work well.

http://www.digikey.com/product-detail/en/P51-100-G-A-I36-20MA-000-000/734-1032-ND/1665793

SSI have a range with different outputs, thread sizes etc.
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well it seems i have all the information i need for now except which arduino i should use to run this?  any ideas???
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and thanks a bunch lemming that was exactly what i was needing and at the right price too!!!
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the Arduino Uno seems to be what would work for my needs. 

Would i need anything to connect the linear actuator, pressure sensor, and pyrometer to the arduino? 

If i am correct i just need to plug in the wires and program it to do what i need...unless i have missed something
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  The pressure sensor will not plug directly into the Arduino, it requires at least 8volts. You will need to use your 12volt supply and a transistor/switch to turn it off and on, and a 250ohm resistor to convert the 4-20ma to 1 - 5 volts.

 The actuator will require some sort of motor driver, possibly an H-bridge style but, I haven't look over the datasheet yet.
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Hey mrgrimm, great project.

My daily driver is a 1998 Dodge Ram 2500 4x4 with a 12 valve Cummins, I haven't made any major changes, so shes basically all stock expect for the exhaust.  However, out of curiosity, will you be doing any other tuning to your p-pump?  Are you planning on just replacing the AFC diaphragm setup and controlling the foot directly?

Good luck and can't wait to see your progress.

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  Here is the force rating of the actuator: Maximum Force: 9-35N     That is Newtons of force, which is not very much. I think you need a lot more but, I can only guess.
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