PvillKnight7

iTrader: (16)

The question is what's the difference between a Fuel Pressure Regulator and a Fuel Managment Unit? Tell me if this is right...A FPR keeps a constant set pressure to the fuel injectors so when they pulse they spray more fuel then at a lower pressure. A FMU supplies fuel in relation to the manifold pressure (boost). There is a vacumn line to the FMU and when the pressure increases, the FMU increases the fuel pressure. Was that right? Whats the advantages/ disadvantages of the two systems. Also, which is better for a 2nd gen with an upgraded turbo and running about 15-25 psi?
Thanks,
Ryan

Evil Aviator

http://www.brownsword.ca/fmus.html

PvillKnight7

iTrader: (16)

Thanks, but why would someone use a FMU on a turbo car when they seem to do a poor job at maintaing the desired A/F ration under boost? I bought a car with an FMU and am installing Haltech's E6K. Will the FMU work with Haltech until I replace it with a FPR?

KevinK2

High gain FMU's are a very crude way to add fuel. Bell Engin'g used them when selling add on turbo kits for non-turbo cars that already were at limits of the stock injectors. He was usually going for just 5-7 psi boost.

Best to use oem type fpr with a proper programable ecu like the haltech.

PvillKnight7

iTrader: (16)

So the FMU is just a cheap way to get more fuel out of already maxed out stock fuel injectors. I helped my friend turbo his civic but I didnt really understand how the FMU he was using was supposed to supply the additional fuel he was going to need. He only ran 7.5psi. So I can use my stock FPR with the E6K and remove the FMU?

Evil Aviator

You may want to check with the Haltech subforum, but I think that the E6K will work OK with a rising-rate FPR because you are tuning each map point for injector pulsewidth, regardless of the fuel pressure. Just as long as the pressure is consistent at each map point, it should work as far as I can tell. I'm not exactly an expert on the subject, but it may be possible to simply disconnect the pressure line to make the rising-rate FPR into a regular FPR. Personally, I would replace it with a new, more reliable and non-restrictive FPR, but that's just me.

The rising-rate FPR was originally designed for a blow-through carb setup which requires a boost in fuel pressure to counteract the boost in the manifold pressure. When it comes to fuel injection, like KevinK2 posted, the rising-rate FPR is really intended as more of a band-aid for budget forced induction kits.

The SX FPR is good:
http://www.essexind.com/sx_main.htm

PvillKnight7

iTrader: (16)

Yea, I read the info on that website you posted. It was very helpful. I understand what your saying about using the rising-rate FPR as a regular FPR. Im guessing I should rig a pressure gauge on the fuel line after the rising-rate FPR if I disconnect the pressure line....I'll get a 'real' FPR eventually....
Thanks,
Ryan