So for some reason my fuel pressure is really high. When I am sitting there in neutral and rev up to like 4k my fuel pressure gauge says +6 BAR. I allready replaced the fuel pressure regulator and fuel pressure soleniod (both stock). All the lines seem to be in good shape (return) and there is no clog in the return line. The vacuum lines are all routed just like stock.

I have a Walbro 255, Fuel Rail, 700cc injectors, and UTEC

Please help, this is not good getting 50 miles to half a tank of gas!

Chris

 

That's @90psi of fuel pressure. Definitely not supposed to have that much.

I would guess it has something do with your fuel tuning in the UTEC if you have eliminated all mechanical possibilities. Try posting this in the UTEC forum and see if anyone who knows that system can help you.

 

Your fuel pressure is a result of using the Walbro with a stock fuel pressure regulator, stock solenoid, and stock lines. Under those circumstances the only way you can increase fuel volume is by increasing fuel pressure, because the physical size of the system is essentially stock. Where did you expect the extra fuel to go? Higher pressure in the system, which causes your injectors to inject that much more fuel every time they open. Have you measured your fuel pressure at various RPMs and load? Is your car running very rich? Did you tune after installing the Walbro, based on higher pressure?

When you rev the car, the fuel relay gives the pump high voltage, and the Walbro 255 produces substantially more pressure than the stock pump into the stock fuel system. When you're revving in neutral, your motor is not under load or building as much boost, so it's not using as much fuel as it would if, for example, you were pulling hard in 3rd. The fuel it's pumped to the rail, but has not needed to push through the injectors is bypassed by the fuel pressure regulator back to the tank.

Fuel pressure is the result of the pressure and volume limitations of the fuel pump. Too little fuel pressure is caused by not enough pump (your motor needs more fuel volume @ the specified pressure than your pump can provide). The solution is to install a bigger pump, and, if necessary, bigger lines, fuel rail, etc. When you do so, you size the system to the maximum fuel volume @ specified pressure that you need. When you're using less than maximum, the rest of the fuel has to be relieved (sent back to the tank) by the adjustable fuel pressure regulator in order to keep the pressure from going higher than you want it to. So, if you have too much pressure, it is controlled by the fuel pressure regulator, and, on occasion, by limitations in the size of the pressure relief (return line). An adjustable fuel pressure regulator might get your fuel pressure back where it should be.