Go Fast Civic

Is there a way to check if an FMU is bad ?

PrecisionH23a

All FMU's are bad

Go Fast Civic

Yeah not the best, but its the only thing i have for now. Seriously, is there a way to test them?

Go Fast Civic

anyone ?

TRE_

i dont think that FMU's really go bad... you could take the top off and make sure the disc and everything is in there maybe?

Cramerox

yes check the diaphram for any rips.
If your car bogs- then fmu could be getting stuck.

Sonny

You need an underhood fuel pressure gauge and a mighty-vac style pump.

With the engine idling, pull the vacuum line off of the FMU. Hook up your mighty vac. As you apply pressure to the FMU, the fuel pressure should rise. If you have a 12:1 disk, putting 1 psi of pressure into the FMU should raise the fuel pressure by 12 psi. 2 psi of pressure will raise it by 24 psi, etc.

Your call will stall after a certain point from all of the excess fuel.

Sonny

Go Fast Civic

thanks for your input guys its not a problem of running rich is a problem of running lean https://honda-tech.com/zerothread?id=1068379 thats the only weak link that i can find, if its not that then i dont know. would you be able to suck on the vacume line and create 1-2 psi ?

Go Fast Civic

i ran 10lbs of pressure via a tire pump to the fmu while the car was running. the car seemed to bog down a little but not much though, if the fmu was working correctly then wouldn't the car stall ?

Go Fast Civic

slowpokesi

i took mine all apart because i thought it was broken, i really dont see how one could be defective unless the rubber peice was torn, or if the slug was somehow jammed.

how do you know your running lean? do you have a wideband or a crappy autometer a/f gauge.

Go Fast Civic

i took mine apart too and it all looks great, just like new. you can tell your car is running lean by the way it bucks and runs like ****. yeah i have an A/F guage too, but i dont just go by that.