Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

Fuel pump control unit AKA Revolution sensor

fuel pump control fail no start module power

  • Please log in to reply
3 replies to this topic

#1 zstalker

zstalker

    USMB is life!

  • Members
  • 215 posts
  • Eagle Mountain

Posted 31 January 2014 - 03:45 PM

1984 GL-10 Hardtop Coupe FWD.  EA81, Carter/Weber carburetor.

Fuel pump isn't operating.  If I provide fuel down the carburetor the engine will run properly until I stop fueling.  Replaced fuel pump, and distributor (to provide proper ignition signal, the shaft had some play).  I'm focusing on the Fuel Pump Control Unit (FPCU), but I'm not in a position where I can afford to experiments with a $150 new one without being fully convinced that it will remedy my situation.  I need actual diagnostic information about this box specifically.

Does anyone know the actual function of the FPCU?  First off I'm a Subaru dealership technician, so I'm certainly not shooting blind, but I can't find any actual information about the operation of the FPCU.  Using the factory service manual, Haynes, and Chiltons manuals I've been able to find almost nothing of what kind of output this module produces.  The manuals all basically say " if power and ground are there, tach signal is coming in, then the pump will run."  Yes, that's wonderful, but run how?  From what I've figured the pump produces a pulsing power signal, since the pump does nothing and blows the breaker in the Powerprobe after a moment when I supply power and ground directly to the pump.  A replacement pump (new) had the same result leading me to believe the pump needs a on-off pulsing power source to operate the plunger solenoid.

Followup question:

Has anyone ever found a way to bypass the FPCU?  if it were as easy as a switch or a relay to provide bypassed power to the pump I would have done that, but that was not successful.  Can any of the components inside the FPCU be replaced (resistors, capacitors, etc).

I implore you USMB and your fountain of knowledge!

~Erik



#2 coxy

coxy

    USMB is life!

  • Members
  • 224 posts
  • Sydney Australia

Posted 01 February 2014 - 06:05 AM

See this topic the FPCU seems simple enough just resistors a ceramic one as well (White long rectangular part) plus capacitors and a circuit board type actual relay that will have points in it, Nothing that cannot be repaired after a trip to an electronics supply house and some time with a soldering iron.

 

http://www.ultimates...t-not-starting/



#3 Gloyale

Gloyale

    It's a sickness

  • Members
  • 9,048 posts
  • Corvallis, OR PNW

Posted 02 February 2014 - 01:11 PM

You can bypass it by Jumpering the swithed 12v(B/W) into the unit over to the pump power wire(Blue/black).

 

This will run the pump with Key on......but will not provide shot off protection for a no-run situation like accident or fuel line burst.

 

There are a few different FPCU's out there......you need one from the correct EA81 model(same engine/trans/carb)....(not the EA82 ones and not the feedback ECU/Carb ones)

 

The pumps do not need anythign but regular 12v+ and a ground.  The pulsing is just to trigger the coil of the FPCU closed to complete the circuit.  If your pump isn't working or blowing fuses with straight power then something is wrong.

 

Lots of people just wire the fuel pump to a switch. 

 

I've once seen a GM 3prong oil pressure switch installed and the power for the fuel pump run through it so FP only operates when there is oil pressure.  Another good option.


Edited by Gloyale, 02 February 2014 - 01:14 PM.


#4 czny

czny

    USMB is life!

  • Silver Subscribers
  • 337 posts
  • Azusa, California

Posted 02 February 2014 - 02:23 PM

Here ya go, Chevy Vega oil pressure switch:

http://www.ebay.com/...96ac826&vxp=mtr

 

There's also these Hobbs switches:

http://www.ebay.com/...=item35b8f14bf2


Edited by czny, 02 February 2014 - 02:32 PM.






Also tagged with one or more of these keywords: fuel, pump, control, fail, no start, module, power

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users