How Does Fuel Pump Know When To Turn On?!?

[AccordB20A]

recently swapped my b20a in my 86 si accord to a20a2 because the b20a had a blown head gasket and injection issues. i did it the cheapo way by just changing the engine, left the fuel lines and wiring harness there for when ive finished rebuilding my b20a everythings good apart from the fuel pump how does it know when to turn on. this is my work car and i have the fuel pump hooked up to the ignition to pump the gas so i can drive it but im sure it never allways runs all the time...any ideas where to hook the wires up to??

engine is a20a2 manual box single carb

[SteveDX89]

The fuel pump turns on when you turn the ignition. That's how it "knows" to turn on. On FI Accords, it goes through the main relay. Not sure how it works on the carb Accords. Sounds like you picked the wrong engine to put in. I think you'll have to convert your wiring to the carb wiring, which is a major pain and it would have been easier to just buy an FI engine.

[AccordB20A]

yeah its a temporary setup so i can still use the car to go to work until i get the b20a back in. the motor came out of a nz new accord ....with no features and stuff. i swapped the fuel pumps over aswell to get the motor running. i spose i will just leave the fuel pump running all the time i dont do long drives so im sure it will work. thanks :D

[A20A1]

Can't you just add the B20 intake manifold and run EFI

Although I dunno how the EGR pipe and all the seosors will swap over from the B20 to the A20A2.

[pimp86LX]

just wire up the pump on its own switch, a'la race cars.

[Vanilla Sky]

when you turn the car on, the fuel cutoff relay (carb) or main relay runs the pump for a couple seconds to prime. when the car is cranking, the fuel pump is running. when in the III position (on), the coil sends a signal to the relay and the relay keeps sending voltage to the pump to keep it running.

[AccordB20A]

yeah i got it on a switch at the mo, still playing around with wires to get it to work properly, i thought about the intake EFI but sumones dad told me since the ecu is programed for the engine it came on it might not run other engines?? i dont know if this is true but id love to have efi back i just love the induction sound aye, everyone thought my car was vtec cause it sounded so simular and was damn quick :D

i bought the car for 150$ all it had was a rust hole in the boot and blown head gasket it was a b20a with auto box. then i decided to make it manual...since automatics arent fast... so i asked my mate how much hed sell me the box outta this 1987 b18a twin carb vigor he had and i bought that, bolted the flywheel and clutch and all on and away it went i was stoked cause it boosted hard even with a blown head gasket...yeh i know i love to yabber on about my car hahaha

[logic]

First of all if you got an EFI fuel pump on a carbed engine, you're probably looking at a flooding problem because EFI pumps run about 3x as much fuel pressure as carbed pumps and the floats won't be able to shut off that much pressure.

Secondly, how in the he11 did you get a vigor tranny to mate to an accord engine?!?!?!?!?!?!?

Thirdly, (as stated by Vanilla Sky) EFI is precisely controlled due to the pressure and the fact that they already have all that electronics anyway... The pump runs about two seconds when the key hits II to build pressure, then when you're cranking and running, the computer runs the pump according to engine rpm so if the engine dies the pump stops... carbed engines just run when the key is on...

[AccordB20A]

in answer to the seconds question below....all i did was ask a mate if he could find a manual gearbox for a b20a he sed his mate has a dohx vigor tht may have the same engine and it was 5speed so i took a look. the engine "LOOKED" the same but i read the code and it sed b18a not b20a and it had twin carbs not efi. knowing that b20a manual box's r hard to find i sed i dunno if it will fit but we tried it anyway, onbolted the torque converter off the b20a and slapped on the b18a's flywheel and clutch, then the gearbox just slid on and the bolts lined up and we all laffed for a while cause it fitted. i was stoked....payed $80 for the gearbox too

and about the fuel pump...i took the efi pump of and stuck the one off the carby'd car on so it would work (useing the efi fuel return line since tis the same as the carbyd versions main fuel line) the day i got it started. sounds like there is no problem with running the fuel pump whyen the key is on.


thanks guys

[A20A1]

You can use the EFI pump.


What confuses me on this setup is how the fuel will want to enter the reg... wont it just favor the return line... or does the return line have it's own reg or restriction?



PARTS:

1) Holley fuel pressure regulator part #HLY-12-804 on summitracing.com
2) Fuel Lines
3) Fuel PSI Gauge
4) Fuel "T" Fitting
5) EFI Fuel Filter

Run Fuel Line from Fuel Filter to Right Side "T" Fitting
Run Fuel Return Line to Left Side "T" Fitting
Run Fuel Line From Bottom of "T" Fitting into the bottom of the regulator.

DOUBLE CHECK ANY FLOW MARKINGS/DIRECTIONS ON THE REGULATOR
FUEL SUPPLY FROM "T" FITTING goes on bottom port on REGULATOR
FUEL PSI GAUGE goes on right side of REGULATOR
FUEL SUPPLY TO CARB goes on left side of REGULATOR

[AccordB20A]

HAHA this was the 1st thread i ever made back in the day when i registered, Nice to know that my engine rebuild has been sitting around for that long!!!!

[2oodoor]

hey nostolgia at it's best