Looking for the 5a fuse (to my automatic choke, which might be behind the glove box), might also be inside the FPCU (Fuel Pump Control Unit) which seems to be a rotational sensor for the distributor.  I assume it senses rotation from the distributor and kicks the fuel pump on. And if there is no rotation it will not flood the engine with fuel causing an unsafe situation. 
 

Anyone know if this is the FPCU and if the 5a fuse is inside? 

Edited September 5, 20205 yr by NuclearDeLorean

No that is not the FPCU. But the real FPCU doesn't have any fuses in it. 

GD

Edited September 4, 20205 yr by GeneralDisorder

AH HA! Do you know where the 5a fuse is?? 

No. What are you working on? Year and model, type of carb (Feedback or non, Hitachi, Carter-Weber, etc)?

GD

1981 Brat ea81 with no voltage to my automatic choke. Hitachi. I found this fuse in the FSM:

no one can tell me where it is. No one can tell me what that black box is. So I’m about to run a switch to 12v and hard wire it. 

Edited September 4, 20205 yr by NuclearDeLorean

The fuse is likely in a special fuse holder behind the tray under the glove box. 

GD

DUDE. I did not know about the special tray under the glove box. AMAZING. Checking when I get home. Thank you!

It's a first gen thing. I have a customer with a '79 that I work on occasionally. I had to re-wire a lot of that crap into a waterproof fuse panel due to windshield leakage. 

GD

You were right my friend! Found a blown fuse that looked old old old. Got a new 5a fuse in, I now have 12v to my choke. And it is functioning normally. Awesome!

Would still love to know where the FPCU resides in an 1981 Brat GL

On the gen 2 body they were mounted to the hood release bracket by the driver's left knee. 

GD

Does anyone have a photo of the FPCU? I looked by the hood release and thats where the box in the above photos was. I think the box is for the windshield wipers. but who knows!

Some models did not have such an obvious device.

I was sure my RHD AUDM 84 Brumby had one up above brake pedal. When I went looking specifically to reclaim unit from 1 month younger Sportswagon - definitely not one there. Don't know if pump itself had a safety device

There has to be a rotational sensor somewhere in the car to cut off the pump as to not dump fuel in a non-start situation. There has to be.

59 minutes ago, NuclearDeLorean said:

There has to be a rotational sensor somewhere in the car to cut off the pump as to not dump fuel in a non-start situation. There has to be.

There doesn't *have* to be anything. You can run the fuel pump during cranking with the ignition switch and then transition to fuel pump power based on oil pressure. Many designs used this method - heck my 86 Trans Am had a backup fuel pump power fed by an oil pressure switch. Primary power was from a relay controlled by the fuel injection management. Which could be thought of as a very advanced form of integrated rev sensor for fuel pump control - but the engine would start without that if you cranked it sufficiently to build oil pressure and activate the backup fuel pump power circuit. 

Looking back into the dim recesses of my Subaru diagnostic memory banks...... I recall that most of the first gen's had a fuel pump power that was supplied by the voltage regulator. Such that the pump runs when cranking and when the engine starts the voltage regulator supplies fuel pump power as long as the alternator is charging. When the alternator stops charging (or malfunctions), you lose the fuel pump power. Which makes for fun diagnostics because everyone assumes they have a fuel pump problem because it gets power while cranking...... you can see where this goes down the troubleshooting rabbit hole. Ultimately it's usually a failed alt or VR. 

Many ways to skin that cat. Don't assume it has to be a solid state FPCU just because that's the only solution to the problem you have encountered. 

You (and probably me too!) would be amazed at the $hit I've forgotten over the years about those cars. I honestly have no interest in wrenching on them anymore though. 

GD

Edited September 10, 20205 yr by GeneralDisorder

1 hour ago, NuclearDeLorean said:

There has to be a rotational sensor somewhere in the car to cut off the pump as to not dump fuel in a non-start situation. There has to be.

No there doesn’t as GD said. 

They would’ve added these devices as they became aware of crash safety. 

In Oz is seems like hey didn’t become a thing in our EA81s until 1984 or mid 1983 onwards. 

My brumby running an 82 coupe long dash does not have the fuel cut relay, but the original 1991 dash did. I’m not going to chase the rabbit down the wiring hole of retro fitting this device, but I will fit an EJ that will do that for me  

Cheers 

Bennie

 

19 hours ago, NuclearDeLorean said:

There has to be a rotational sensor somewhere in the car to cut off the pump as to not dump fuel in a non-start situation. There has to be.

Thinking you are typically one-eyed like most of us and only thinking forum specific models, then someone mentions other breeds

Late 70s and into the eighties here in Australia we built cars with mechanical fuel pumps running off the camshaft, yet we had British stuff like one of the most sweetest sounding 3.0 litre V8 in form of Triumph Stag. From memory they used a working oil pressure switch to power up an electric fuel pump, or maybe that was limited to their 2500 mechanical fuel injected I6 ? Triumph also used a mechanical upside down switch. A dead weight in a switch to disconnect should vehicle end up the wrong way up.

GDs suggestion of alternator charging control might explain one wire off the alternator off our MYs

Thank you for the reply. I currently don’t have an issue with the unit. My car is running and I’m happy. I’m just curious. I didn’t mean say that it HAS to have that exact thing... 

I also found a green mystery box under the driver seat.

I’m just curious, that’s it. 

Edited September 11, 20205 yr by NuclearDeLorean

Pull the passenger front seat to see if anything else is hidden. I think over the models Fuji placed power window control boxes under seats, maybe power mirror units as well, maybe central locking. Not the best place when some of us find selves in deep waters. A mate was following bigger, heavier club members on a drive taking in a river bed. The Brumby started to float !

There is a module under the drivers seat. A green box. Mystery. The ECU seems to be behind the passenger seat.

As far as I know there can be found online both the factory service manuals and the parts manuals which are also called catalogs. They’ll help a lot. 

and the parts catalogue !!

That I would love to grab

This is the FPCU on my '83 GL Wagon.

Bottom row; BU/RD, hot when cranking. BK hot w/ign. on.

Top row; BK, GRND w/ign. on., YEL, ign. pulse from coil/ dist. module.

Quit pumping gas twice yesterday. Installing temporary jumpers to attempt "in flight" diagnosis when it quits again. 

 

Thank you Dwayne!

I'll keep an eye out. Also, I was able to get my hands on a parts catalog. THAT IS RIGHT LADIES AND GENTLEMEN, I have a 1980 and 1981 Subaru Parts catalog from Subaru.

I'll look up that part number and see if it might be close to mine! I also have a box under my driver seat that looks similiar. I'll let you know! Thank you!!!!!!!

On 9/16/2020 at 11:45 PM, Step-a-toe said:

and the parts catalogue !!

That I would love to grab

Just scored one