Fuel pressure problem that i cant make heads or tails of

[Mr.Spool]

No way to be sure about 1:1 until I get a log kit. But I can tell by the adjustments I had to make to the VE table that fuel pressure is rising with boost. The higher the KPa, the more I had to lean out the car. Light load and idle, I had to add fuel to compensate for the new lower fuel pressure in those loads. It all makes sense.

I get where your coming from. a lot of these pumps flow a lot of fuel in the 50 to 60psi range and I have seen them fall off at higher pressures once you start turning it up.i just want to see your learning curve and fun curve go in the same direction.

 

[zapp240]

ttribejr, Just something to check. If you swapped the return line and vapor line, i belief the vapor line goes and stops at the top of the hanger in the tank and the return line (which is your new vapor line) vents lower into the tank. correct me if i am wrong but i heard it is smart to modify the vapor line with a hose that runs deeper into the tank, is why i held of doing this. but it sounds like it is working for you

 

[Toby_Goodmk]

ttribejr, Just something to check. If you swapped the return line and vapor line, i belief the vapor line goes and stops at the top of the hanger in the tank and the return line (which is your new vapor line) vents lower into the tank. correct me if i am wrong but i heard it is smart to modify the vapor line with a hose that runs deeper into the tank, is why i held of doing this. but it sounds like it is working for you

Interesting point, and I think it is correct. This is the factory sender, and the vent appears to be at the top. Maybe switch the vent line coming off the frame to the vent line on the sender. He may have done this to be safe. If not fuel may stir and aerate if the tank is less than full.

 

[Jerryl]

Now that the idle fuel pressure is resolved, you will need to take a look at the pressure at max volume use. The ambient pressure in the tank will drop at max volume since there is less return to the tank . . and delivery may become an issue if the vent (return line) is too small.

Also . . I wouldn't run any lower than 1/2 tank due to aeration.

TT could have reburned the chip for the higher base pressure, especially since the car is on e85.

 

[ttribejr]

I used the oem return line on the hanger. I cut off the "necked down" so it's 1/4" stray through. the vapor line on the hanger is still vented to atmosphere. I plan to throw a carburetor filter on it just for good measure.

No need for a chip, I have xfi. I know I could have tuned with higher base fuel pressure but I didn't want to push this single walbro that high. Volume typically drops off pretty hard at higher fuel pressures. With my current boost it shouldn't run past 62 psi.

 

[Pronto]

I still agree with Nick and Toby. Replace everything with An8 and 6 teflon line, wiring, pump (s) and free flowing filter. With that all done, you'll be ready for any future mods which surely will follow.

 

[ttribejr]

I still agree with Nick and Toby. Replace everything with An8 and 6 teflon line, wiring, pump (s) and free flowing filter. With that all done, you'll be ready for any future mods which surely will follow.

I agree with them too, 100%. This was nothing more than a cheap fix that is suitable for how my car stands today. I still haven't financially recuperated from buying the xfi and other parts. This simply lets me drive and enjoy the car until the next round of upgrades. Next time I address the fuel system, it will be the last time!

 

[1986 Buick GX1]

With my current boost it shouldn't run past 62 psi.

Ok that part is fixed.now the Majic question does fp rise 1to1 with boost?and do you see fp rise and not drop as you describe?

I believe Mr.Spool is wanting to make sure you have 62 psi fuel pressure and your pump is not stopping at 50 psi.

 

[ttribejr]

Yea, I know that is weighing on people's minds. I ordered the logging kit, but it hasn't even shipped yet. Probably won't have it for a week or so.

 

[Mr.Spool]

I believe Mr.Spool is wanting to make sure you have 62 psi fuel pressure and your pump is not stopping at 50 psi.

Yes sir.