I have the Aeromotive adjustable fuel pressure regulator and with the mods in my sig wanted to know what would be the best fuel pressure at idle? The reason I ask about setting it at idle is that it doesn’t hold pressure with the key on and from what I have searched on this board it is normal for this unit. I have a gauge but can’t read it inside of the car when I’m at WOT.

 

Set the fuel pressure to 45 PSI at idle with the vacuum line to the regulator unplugged. The pressure should drop to around 40 PSI when the line is reattached.

 

Shouldn't I have the pressure set a little bit higher than that? 45 psi is close to stock settings.

 

It won't really matter. The computer will read the change in fuel and simply decrease the injector pulse width to get it back to where it was.

 

So the afpr is just a waste of money? I guess what I'am thinking is if the fuel pressure is increased the injectors will be able to inject more fuel faster. I know the pcm will set the pulse width, but if there is more pressure when the injector is opened shouldn't more fuel flow and at a faster rate?

 

I have an Aeromotive and I have my fuel pressure set at 37 PSI. Normally, you will make more power with a lower fuel pressure with the LT1 cars. It is normal for the Aeromotive regulators to not hold pressure. I called Aeromotive and spoke with them and they said that they designed the regulator to build pressure when the car is running and then to bleed off when its not.

 

It is for an LT1. The last aeromotive LT1 regulator I bought was $150 +change, and it broke on me. I took it back and put on the stock regulator and it works great.

When the first afprs came out, they were for TPI cars which used a much less sophisticated computer. Anyways, the computer wouldn't really adjust very quickly so the afpr was a good mod. The newer computers are much smarter and will adjust very quickly to a change in fuel pressure. You can still use it at the track, just adjust the pressure up before your run and it should help a little bit.

 

Unless you are running large injectors that need the pressure, yes.

 

So my next question is how does the pcm adjust to higher fuel pressure? Does it just change the pulse width to limit how much fuel is flowed through the injector?

 

With exception to 93's of course. The computer can't/won't compensate for the fuel pressure change in a 93.

 

True, but the discussion was about a 1994.

 

True, true. I was just throwing that out there with hopes of helping people to expand their knowledge some. Every little bit helps, right??

 

I haven't had the chance to check my fuel pressure but what are some symptoms of the 'check ball' fault? Also, would this cause my low MPH problem, running out of fuel that is?