I'm going to run my E99 motor that has AB injectors in it with a PMT1 pcm (2000 m/y). I got a riff raff FPx on order and I'm hoping it will make the truck easier to fire up for the first time when I install the motor but I'm also hoping to up the fuel pressure to make my old 130cc AB injectors behave like newer 160cc AD injectors (like what the PCM is expecting).

Any idea which fuel pressure setting will accomplish making my cc flow closer to newer injector flow rates?

Here are my choices:
55-60 psi silver spring
61-65 psi gold spring
66-72 psi black spring

 

Everything you described won't make a bit of difference given those fuel pressures or by having a FPx.

An FPx and bumping up the fuel pressure won't make the truck "easier" to start, since the PCM never once looks at fuel pressure to determine injection firing while cranking, and fuel pressure doesn't have any bearing on starting. If you can supply enough fuel at zero PSI to allow the truck to idle, it will start and idle exactly the same as it would at 50, 75, or 100 psi.

In addition, bumping up fuel pressure and adding an FPx will not cause old and/or smaller injectors to behave like newer and/or larger injectors. The injector capacity and nozzle size is what it is. You can't change those parameters external of the injector.

Lastly, the PCM doesn't care about the slight difference in overall injector capacity of AB's vs AD's. Differences in RWHP is negligible too.

So what is the purpose of the FPx and bumping up the fuel pressure? The FPx is simply designed to get rid of the deadhead rail system from Ford, which in turn helps in some cases to "smooth" out the idle quality of the truck a bit, and to help reduce the issue of #8 injector starvation that causes idle cackle, which Ford decided to "fix" with LL injectors instead of doing the fuel system up the right way.

As for fuel pressure, most instances are simply to bump it back up to IH specs, since Ford has it set low to begin with, and over time the spring weakens and fuel pressure tends to drop over time. By bumping up fuel pressure, again the "smoothness" of the engine can be tweaked, but it's not a huge difference by any stretch of the imagination.


Now... AB's vs. AD's. The difference is actually smaller than what you stated. AD's flow around 130cc's per 1000 shots, while AB's flow around 140cc's per 1000 shots (given perfect scenarios, in real life most flow a little less). Coupled with the stock nozzle size, you'll see a few HP difference at the rear wheels.... that's it. Most people can't even tell the difference going from one to the other. To the point that it isn't even worth the effort of swapping out from AB's to AD's in the first place. And the PCM doesn't care, since they still flow almost identical except for the peak capacity. But the PCM has no clue what size injectors are in the engine, and doesn't know when each injector is completely empty. The PCM only does what it's programed to do - hold an injector open for "x" amount of time given "y" amount of pedal position while seeing "z" amount of injection pressure at any given RPM's.

Hopefully that makes things a bit more clear. There's nothing wrong with those mods, just don't expect to happen what you're trying for.

 

Curtis got that backward a bit...

AB's flow 120-130 per 1000...

AD's flow 140 per 1000...

 

Oh man, I keep thinking like a gas moror, I forgot how the injectors were designed

I was thinking first startup would be easier because it would let the air out of the heads if I cycle the key a few times. Not right either though?

 

Coffee hadn't kicked in yet.

 

By the time the glow plug light goes off, you're pressurized and ready to go.

 

I've got the engine in the garage tore apart so the fuel rails are completely empty. When i get the motor in or if my wife runs it out of fuel will it make a difference? BTW, thanks for that info on swapping ab for ad's, I was wondering if that would make a difference

 

Dont let your wife run out of fuel... Its easy to start no matter... If your out of fuel, turn the key on and listen for the fuel pump. When it turns off, do it again, and again, and again and then once more. Then your entire fuel system is primed and ready to go.

 

Thanks, do you know of a way to prime the oil system or have any recommendations?

 

If you want to you can fill the HPO res, however its not necessary...

With the key off, jump the starter solenoid on the passenger fire wall. Crank for about 15 seconds and wait a minute or so, do this three or four times. Then crank the truck normal. It should fire in a few seconds.

 

Is there actually any advantage to running higher than stock fuel pressure? I did some searching and couldnt find anything solid

 

Nope...



HOWEVER...

Every injector likes a different fuel pressure level... When I ran stock the sweet number on my truck was 72psi... On my wifes excursion it was 65psi...

With stage 2's it was 68psi, with the hybrids its 65psi...

But anything above 50-60 psi is fine. More then 75 and all your doing is over working the fuel pump.