Aico

My car doesn't seem to have a FPR, while it does have a Mikuni carb. So the carb might be getting to much fuel so I want to put in a FPR. Where do I put the FPR? On the fuel returnline or where the fuel is coming in the carb?

Most FPR's don't have a pressuregauge, but do I really need one? The FPR I can get has a max of 5psi and 4.5psi is the target with Mikuni's right?

Dan_s_young

iTrader: (1)

Hey, for a aftermarket intake/carb setup you should be running a FPR. Most people are using the Holley FPR from summitracing.com. The FPR installs in the fuel line that is going to the carb, and should be installed as close as possible to the carb. You should also get a gauge so you can get your fuel pressure as close as you can to the desired point.

Heres a picture of where I decided to put my holley FPR.

SparkienSuggah

a pressure gauge isnt critical, but may help with diagnosing problems, or tuning if you have an adjustible FPR. you can install any fuel pressure gauge after the FPR, just splice it inline with the high side of the system - it could even be inside the car.
(WARNING and DANGER: running fuel lines inside your car on a permenent baisis is asking them the leak and spray gasoline into your car where you are not protected from its dangerous side effects, including but not limited to: a euphoric feeling and loss of brain cells, fire and gas rashes)

trochoid

iTrader: (6)

The type of fuel system your are running will dictate the placement of the fpr. In Dan's pic above, he is running a deadhead system, with proper placement of the fpr. On a return style system, you run the fpr and fuel pressure gauge after the carb. My preference on fpr's is one that has an extra port for the fpg.

With the variations between fuel pumps, in regards to thier pressure and flow charateristics, an fpr is a must. They are relatively cheap and make tuning that much easier. A return style system is needed if the pump has a high volume flow and no internal bypass.

Iirc, fuel pressure on the Mikuni is in the 2.8-4.5 range. I do know that at 12 psi, fuel runs out of the velocity stacks. I discovered that one before I could get the fpr turned down, while setting up a new fuel pump.

Aico

I live in Europe so basicly no Holley over here. How can you see if the pump has an internal bypass? I think it would be easier for me to keep the returnline and just put the FPR there. If the car runs fine then I can always change it later.

How does a FPR work anyway? Is it open and will it start to close at like 5psi?

trochoid

iTrader: (6)

Depending on the pump, it should say in the specs if it has an internal bypass. I prefer running a return line because the constant flow of gas through the pump helps cool it and the pump will last longer.

An fpr has a spring in it and the pressure will push the spring and open the fpr, very simple device, no rocket science here.

I'm sure you have Google in Europe, try that for locating an fpr in the EU. I would pick one that has 3 out ports. 1 for the carb, 1 for the fpg and 1 for the return line. there will be a 4th port that is in only, for the supply.

borgue

hey buddy im in the uk and got a holley reg from summit,

it worked out half the price of one over here even with express shipping
and took 3days to get here.

highly recommended.

Ollie.

85TIIDEVIL

iTrader: (2)

Huh...??? Isn't that for fuel injection...???

I using a return line and my FPR and FP gauge is before the carb on the inline / feed side. I am running a YAW Nikki.

SparkienSuggah

both for carb and for fuel injection, the pressure regulator should be after the fuel delivery device.

a flow regulator would be before the device, but thats pretty much just for welders. with a carb, very little pressure is required to have them operate, and it could be that there is enough restriction in your return line for it to be fine. try swapping your regulator setup and see what happens.

85TIIDEVIL

iTrader: (2)

My return line is huge so there's definatly no restrictions there. And my car pretty much runs flawlessly right now with the regulator before the carb. What would switching it around do..?