FMU - Boost Forum

Forum Post / Reply
You must log in before you can post or reply to messages.
FMU
Monday, May 01, 2006 4:54 PM
OK, so i got this FMU, i know its is made to increase the level of fuel in the engine when under boost. There is a in port out port and a vacuum port. But i have no damn idea how it operates. Its not a pump, or a pressure regulator so how exactly does it push out more fuel?

thanks everyone

Re: FMU
Monday, May 01, 2006 5:48 PM
it goes in-line with the return system. It pretty much clamps the return line when boost hits so that there is a greater resistance with the same amount of force from the fuel pump, increasing fuel pressure at the rail.

Best example I can think of........ Turn on the water hose at your house. Poke a hole in the hose somewhere..... turn it on..... water drips out of the hole you made.... go put your finger over the end of the hose and the little hole will spray water out with much more pressure.

Some newer cars have returnless fuel systems that modify fuel pressure by pulsing the pump. J's don't.... your car uses a fuel pressure regulator to modify fuel pressure. It is the same concept of an FMU, just it does not account for possitive pressure, only levels of vacuum. It will allow a certain amount of fuel pass it and return to the tank to keep the correct pressure in the rail and lessen the size and cost of the fuel injectors because they don't have to have such wide operating parameters. The computer knows the fuel pressure because it will always have a constant relation between it and manifold vacuum which is read by the MAP, assuming the fuel pump and FPR is working properly and there are no restrictions in the line. Since there is no actual fuel pressure gauge needed, adding an FMU will further restrict the return line, raising fuel pressure, without the computer ever knowing and trying to correct it.



Cardomain|Myspace

Re: FMU
Monday, May 01, 2006 5:59 PM
Got ya, that makes sense i was confused as to how it would work with the stock fuel pressure regulator. I have been running lean, i assume that this will help my problem while in boost. Also do you know where i can pick up some bigger injectors for a good price. Im runing 6lbs of boost.

thanks,
Re: FMU
Tuesday, May 02, 2006 6:49 AM
Bryan Doucet wrote:Got ya, that makes sense i was confused as to how it would work with the stock fuel pressure regulator. I have been running lean, i assume that this will help my problem while in boost. Also do you know where i can pick up some bigger injectors for a good price. Im runing 6lbs of boost.

thanks,

Please fill out your registry.... and fill it out with "detail" not just I have a turbo....



P&P Tuning
420.5whp / 359.8wtq

Forum Post / Reply
You must log in before you can post or reply to messages.

 

Start New Topic Advanced Search