Fuel System Trouble. Need suggestions

[ipozestu]

So thus far. I have installed 24lb injectors, 75 mm MAF(calibrated). APTEN programmed to work with the same. I know you'll say "It's over kill". None the less it is what I have, and would like to get it to work. My CEL has been coming on throwing codes left and right banks to lean. This condition seems to happen under harder than "normal" acceleration. I haven't been able to diagnose this problem while the condition is happening, but this is what I suspect. It seems that the stock fuel system cannot maintain fuel rail pressure when that large of a demand is made by the injectors. So where should I start. The filter is brand new. Should I look into a adjustable FPR, or a complete fule system up grade with new pump, filter, FPR, lines ect.
Thanks,
Jeff

 

[Alec]

You won't need new lines or filter. And the stock FPR can flow large amounts of fuel when told to do so (by the chip and MAS). I'd replace the fuel pump. If you're still lean, you'll need an adjustable FPR. If you try the FPR first, even if the stock pump can keep up, it will burn out quickly.

 

[ipozestu]

What type of option are there for fuel pumps. I know that the stockers are internal. How difficult is it to route the suction to an external pump?

 

[rydinhigh]

You can either get a lightning fuel pump ( I believe this is what Alec did) or a walbro 255 lph.

 

[Alec]

Yes, you'll want to get a new intank pump. As he said, i used a lightning pump.

Some aftermarket mustang pumps fit right in, some need a few mounting mods. What was good about the lightning pump is it was as plug and play as a fuel pump can be.

 

[ipozestu]

So I made discovery today. It was the first day this year that I had to use my A/C. As I was cruising it cut off. I was thinking what the hell. So I played a little, still nothing. Eventually I slowed down a bit and the A/C started to come back out the vents. Then came another hill. Same thing. It seemed like the blend door was opening or something. As soon as I hit a flat it came back like it was supposed to. I am beginning to think that i have a vacuum problem. I belive that under harder accelleration the vacuum should increase on the FPR causing the fuel not to by-pass to the tank. If this isn't any where on base give me a cyber slap. This seem to make sense though because when I have the lean condition come in, it is normally under harder accelleration. Is the vacuum system pretty much a dealer thing to troubleshoot? I'm not sure if I will be able to track this one down or not. Any thoughts?
Thanks,
Jeff

 

[Nate1]

I think most autoparts stores sell vaccum testers.... plus you should be throwing a CEL in a EEC-V car if it's too bad. I would check all the obvious lines for wear... PCV, brake booster, etc.
-----Nate

 

[rydinhigh]

if you had a vaccumm leak I am sure you would hear it.

 

[ipozestu]

I'm not sure if it is that kind of leak or not. I;m thinking that it might be a manifold leak. I probably screwed something up when I pulled the upper and the fuel rail, to replace the injectors.

 

[james t]

i hade the EXACT same issue with my A/C a month ago, and it was the vacuum canister "orb". it had a small hole in it. A/C would slow way down, then go to dash/floor. let off gas, it would come back fine.

as for fuel pumps, just about any stang pump will work. id say you have a vacuum issue/issues. i dont think you're making enough hp yet to need a bigger pump.

 

[Apten]

is it possible that somthing didn't go on right with the injector swap, or that you have a gasket leak somewhere? The chip was calibrated for the MAF flow sheet, so the injector values are perfect. The only other reason fuel could be off is if you have a fuel delivery issue (fuel filter, pump, bad injectors?). But if you were supplying enough fuel for the old injectors, fuel flow really hasn't changed in your system. You may have larger injectors, but the pulsewidth changes to keep them from dumping too much fuel.

you could always try putting the stock ones back in and seeing if you have a problem.