Fuel Pressure Regulator shot??

[9eightGTEE]

So i think my fuel pressure regulator is shot. The car feels like it miss fires. So I went and took the vacum line off the regulator and it smoothed out. Then next time i start up the car the problem came back. Messed with the regulator again and it fixed it. Then I would drive around and it would miss fire again, then Smooth out, so its not a constant problem i dont know what the hell is wrong. I think the regulator is shot cause my gauge says im running lower then stock fuel pressure but im burning soooooooooooo rich that my tail pipes that i just washed yesterday are black along with some of my back bumper.

So today i drive down to my summer class, about 35 miles away. I used a half tank of gas ONE WAY. I also noticed my fuel pressure gauge.. When i hit the gas, the fuel pressure goes down instead of going up.

WHAT IS GOING ONNNN

 

[9eightGTEE]

ttt

 

[RaceDvr50]

What regulator are you running, what pressure, which size injectors? How far does it fall when you step on it?

 

[9eightGTEE]

Its an aeromotive. I have 30lb injectors, and at idle its 30 PSI and when i hit the gas pedel it jumps down to 26PSI

 

[jrichker]

How is your MAF calibration? does it match the injector rating? Is the MAF element clean?

Symptoms of fuel pressure regulator failure: remove the vacuum line from the regulator and inspect for fuel escaping while the pump is running.

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

 

[9eightGTEE]

How is your MAF calibration? does it match the injector rating?

Fuel pressure regulator failed. Remove the vacuum line from the regulator and inspect for fuel escaping while the pump is running.

yea the maf matches the injectors. I checked the vacuum line and no fuel is escaping.. This is an issue that has just come up. I have been running this combo for a while now.. So its not anything new that i added that could have caused this problem

 

[RaceDvr50]

Yeah you regulator might be going bad but also your fuel pump might not be cutting the mustard. 30psi it a full 10psi low and the fuel with dribble out of the injectors instead of spray properly. Have you tried turning it back up? Maybe it vibrated loose and backed off a bit.

 

[RaceDvr50]

Yeah you regulator might be going bad but also your fuel pump might not be cutting the mustard. 30psi it a full 10psi low and the fuel with dribble out of the injectors instead of spray properly. Have you tried turning it back up? Maybe it vibrated loose and backed off a bit.

 

[9eightGTEE]

well im going crank it back up to 40 right now.. but what i dont get is if its drippling out, why would i be using soo much gas

 

[9eightGTEE]

ttt

 

[jrichker]

Dump the codes. It isn't hard to do. There can be problems that don't set the check engine light that will kill your fuel mileage.

 

[HISSIN50]

well im going crank it back up to 40 right now.. but what i dont get is if its drippling out, why would i be using soo much gas

I think what the guys are getting at that it's not a direct correlation between your FP and milage - the issue might lie in poor stoichiometry due to sensory or other input that's deficient.

EDIT: Jrichker posted while I was eating. Nevermind.

Good luck.

 

[RaceDvr50]

If the fuel isn't spraying right it won't burn right. Your O2 sensor is monitoring the gasses in your exhaust it's not looking for unburned fuel that is passing. That can screw up it's readings and it can put the computer in dummy mode with too much fuel so you don't melt down your engine (this would produce a code) or just mess it up enough to keep pouring more fuel into it (might not produce a code). We know that the fuel pressure for those injectors needs to be at least 40psi so start there and see what it's doing then. At least then you can narrow your problem down, if it's a bad pump you might not be able to get it back to 40psi. And yes if you should check your codes, always a good idea.