Free pat on the back for whoever solves my fuel starvation issue!!!!

[challngd73]

sounds like the pump is getting hot....does the fuel pressure drop at this time?    Being that it happens in normal driving as well, it is not a fuel line problem per se, but, I am surprised he did not use 3/8".

Is the return line working or is this a single line system?  Not a Walbro pump, is it?

The return line is working fine, and it is not a walbro pump.  My hope is that the old 5/16 line running from the tank to the fuel pump is sucking air, causing the fuel pressure drop and causing the pump to get hot.  I am going to test my theory today after work.

[67vertman]

it sounds like a suction problem to me.  Did you replace the line between the tank and fuel pump yet?

I had a similar problem once where the line had corrosion in it, the car would run fine then starve for fuel as the corrosion would block flow. 

Also, have you contacted F.A.S.T to see what they think?

[abodyjoe]

how close is the pump to the exhaust?  could that be heating the pump up?

[challngd73]

Fuel pump is on outside of frame rail, away from exhaust. 

Update.  I just finished up installing the new 3/8 fuel line, and no whining from pump.  Good.  Take it down the road and if I try full throttle, it falls on its face.  Won't sputter, stall, nothing, it just .... Pauses for lack of a better description.  If I back out of it, it continues to idle fine.  I am at a loss.

[Chryco Psycho]

can you watch your fuel pressure when it stumbles ?
 are you Sure it is fuel pressure related ?

[challngd73]

can you watch your fuel pressure when it stumbles ?
 are you Sure it is fuel pressure related ?

It was fuel pressure related, but now that I have put the new line on, the fuel pressure seems stable.  When I put it under load the pressure stays right around 40....but I couldn't step on the gas too hard in the driveway.  Im out of ideas.  I will double check the fuel filter again to make sure it didn't clog.

[aris_unlimited]

I know you said the tank was full, which makes this problem less likely. But do you have a tank that is set up for fuel injection? Meaning not the stock tank, but an aftermarket with baffles in it. I don't think this is the issue but seeing as how every other idea has fallen short I figured I'd throw it out there.

[jimynick]

MAP & TPS sensors all functioning as designed and within parameters? Seems like it doesn't know what to do when the throttle is opened and either of those 2 would affect it. Does this thing run an O2 sensor? Grasping at straws. 

[abodyjoe]

Fuel pump is on outside of frame rail, away from exhaust. 

Update.  I just finished up installing the new 3/8 fuel line, and no whining from pump.  Good.  Take it down the road and if I try full throttle, it falls on its face.  Won't sputter, stall, nothing, it just .... Pauses for lack of a better description.  If I back out of it, it continues to idle fine.  I am at a loss.

  is your return line 3/8 also?    if its not it may bottle neck the fuel.     also if its getting more fuel now then it may have to re-tune itself.  you may want to clear the tune and start from scratch.

[challngd73]

  is your return line 3/8 also?    if its not it may bottle neck the fuel.     also if its getting more fuel now then it may have to re-tune itself.  you may want to clear the tune and start from scratch.

The return line is 3/8 as well.  I do not believe it is a bottleneck because early on in the install, it was a bottleneck and the fuel pressure would peg out at 80 because it couldn't push the return fuel back in the tank.  It no longer does that.
  The f.a.s.t. system does run a o2 sensor, and this system is self learning so there is no tuning.  Also, I did start a new tune....same result. 
It is the factory tank, no cash for a fuel injection setup tank.  I am going to double check the in line filter, then my next step is to disconnect the fuel line from the tank and run it from a gas can, so I can eliminate the tank as a problem.

[Strawdawg]

If the fuel pressure remains the same under acceleration, you can discount a fueling problem.  Can you see the a/f ratios when this is going on?

[challngd73]

If the fuel pressure remains the same under acceleration, you can discount a fueling problem.  Can you see the a/f ratios when this is going on?

The air fuel ratio pegs when I stand on the throttle.

[Strawdawg]

to me, that means it goes lean...what does it mean to you? 

[challngd73]

to me, that means it goes lean...what does it mean to you? 

The same, but why too much air and too little fuel? 

[Strawdawg]

IF, the fuel pressure remains constant, or very nearly constant, then the delivery system should not have anything to do with it.  It takes a pretty good change to have much affect as the change percentage is a square root of the new pressure divided by the original pressure so it takes a significant change.

IF, the o2 is reading correctly, then the FAST has a problem such as tps sensor bad, or one of the others.  In this case, I would call for support/guidance.

IF, the o2 is bad, then the FAST will be adding fuel like crazy to fix the perceived problem and the exhaust will be blowing black smoke like mad.