5.0 starts only at full or half throttle.

[mustang112]

ive been building a 306 and i can only get it to start at full or half throttle. i have a adjustable fuel pressure regulator but i dont have a gauge to check it. what do you guys think it is? to much fuel? not enough? vac leak? thanks, adam

[Rick93coupe]

You really need a gauge, even a rail mount would work fine. Without knowing where it set at, you can't really begin to diagnose whether or not it's a problem. Did the problem start after installing the AFPR?

[NXcoupe]

Rick hit the nail on the head. Yes, I would say theres really nothing we can do to help you until you get that set correctly. It's just a cheap gauge from Summit or Jegs. I think we even have them on the shelf, or you could call Craig and see if he has one.

[Mista Bone]

Screw those cheap 1.5" fuel pressure gauges.........get a real gauge.

2 5/8" Liquid filled, only need to buy one. I bet I bought 4-5 1.5" Gauges from Craig and Jegs @ $20 each.

[RACEME]

I had that problem with my 95 years ago. It had an aeromotive fuel pressure regulator, and the diaphram had failed in it. It would only start at full throttle like a flooded carb car. You can put a stock fuel pressure regulator on just to get it running if money is tight.

[mustang112]

ive never had this car running yet so thats why i dont know what the problem is yet. im trying to see if a buddy has a gauge i coul borrow before i buy one but im thinking its fuel pressure. like raceme said its like its flooded and after it starts at full throttle you can go to half throttle and it be fine but any lower and it dies. so my guess is to much pressure? but ill have to wait till i get a gauge to see lol thanks guys!

[rush88GT]

Have you checked the throttle position sensor?

[Rick93coupe]

Have you checked the throttle position sensor?

Yep that could be it too, the tps could be out of adjustment. That's an easy check before you buy a gauge.

[mustang112]

ok, ill be back in town to check it all on thursday i think so ill keep you all updated.

[Paul408Notch]

If it takes full throttle to start it, you may be getting into the "clear flood" area of the computer. When you hold the throttle past 90% or so (usually) the EEC won't fire the injectors. This is to try to burn out flooded cylinders. If that's when it's starting up, I'd drop the fuel pressure a turn or so. If you're just having to pump the throttle to start it, you may need to add a bit of fuel.

[mustang112]

If it takes full throttle to start it, you may be getting into the "clear flood" area of the computer. When you hold the throttle past 90% or so (usually) the EEC won't fire the injectors. This is to try to burn out flooded cylinders. If that's when it's starting up, I'd drop the fuel pressure a turn or so. If you're just having to pump the throttle to start it, you may need to add a bit of fuel.

its only starting at full throttle and i can let it out to about half throttle and any more it dies. i dont have a gauge to check it yet so when i get one ill let you all know if thats the problem..... thanks, adam

[chad393na]

IAC (idle air control) motor may be stuck shut.

[mrstang-gt-46]

mass air sensor

[mustang112]

mass air sensor

can you explain? the car was not mass air originally but i bought the kit for it and bought a mass air thats made for it and everything.

[NXcoupe]

Adjust your fuel pressure first, then start working your way from there. You'll be jumping all over that car if you don't take one step at a time. Once you adjust the fuel pressure, with the vacuum line off the fuel pressure regulator, then put it back on after you adjust it, if you adjust it with it running that is. Then if the problem still persists, check your idle voltage on your TPS, if it is around 1 volt then it's cool, it should also go up in voltage as you open the throttle up to around 4.7 volts. If that is all good, then unplug the mass air and see if it will start and run without flooding, if it does, then you have an issue in that wiring or the sensor.

[cobra429boss]

motor is just tellin you it wants raced lol hope ya figure it out