Ok so I have a dilemma with my car, its a built GSR turbo with an aeromotive 340 fuel pump, ID 1000 injectors, aeromotive FPR, AEM fuel rail, oem fuel filter and stainless steel feed and return lines. My issue is that on 14psi I was at 90% duty cycle on the injectors. Im wondering if anyone might have any insight as to why I would be at that high of a duty cycle and at that low boost? I've seen many people hit 500 easily with stock fuel systems and just an upgraded fuel pump. So please let me know if you have or known anyone that has had this same problem and how they fixed it. Also I'm using pump gas.

 

What is your base fuel pressure set at? And are you running a dedicated vacuum line to the fpr?

 

Base fuel pressure is set at 46 or 48 I believe, and I know for a fact that I'm not running a dedicated vacuum line to the fpr.

 

14 PSI on a decent sized turbo can easily put you in the 450 range... so what turbo? and what engine management?

 

I should of mentioned the whole set up, but its a Precision 6262, AFI ramhorn and S300, at 14psi I made 440hp and 287tq. So you were very close by saying the 450 range.

 

Try making the fpr feel speshul by giving it a line to call its own. You will need to watch the gauge for pressure loss during a pull. The easiest way to do that is while it's on the dyno.

 

Once I get home I will do that, and as well upgrade my fuel filter. Besides that is there anything else I can look into that may be causing high duty cycle?

 

Yes there is something wrong. I made about the same power on the same injectors using ETHANOL! Gasoline should give you about 30% more head room.

 

Yeah I know it sucks!! Specially when other people are making same or more hp than I am on stock fuel systems and just an upgraded pump. So definitely something is wrong.

 

S300 should be showing correct DC, so check your fuel map numbers for some increases where you'd normally see fuel consumption flattening out. You may be dropping pressure up top.

 

The fuel pressure was dropping as well. From what I remember on the last run pulled, the fuel pressure did drop and thats why he couldn't go past 14psi. What could be the cause of the fuel pressure dropping? Would that involve the such high duty cycle? From what I was able to research. I did find that a clogged fuel filter could cause fuel pressure drop (correct me if im wrong) and mine is pretty old. So thats why I plant to change it out as well. So far thanks for all your information given, keep it coming

 

Yea, with pressure dropping up top, more duty cycle is required to keep up.

 

Well I was wrong! It does appear I do have a dedicated vacuum line from the intake manifold to the fpr. So is that a good setup for the fpr vacuum line, or is there a better way of doing it? Here are some pics of the my fuel system setup. Let me know what you think and if there is any better way of setting it up. With that being said, anybody out there have anymore ideas on what may be causing the high duty cycle??

 

Well, we need you to confirm how badly fuel pressure is dropping. What's the psi difference? You have plenty of fuel pump to keep pressure up, so right now the fpr is my number one suspect. I mean, if your problem still persists after you change that old fuel filter.

 

LOL I see the problem. Does anybody else?

 

No, can't see pics at the moment. Please do tell.

 

Idk, but I'm guessing the map sensor hasn't been unplugged the whole time...

What do you spy?

 

Looks like that fpr is sending fuel back to the tank before it can reach the injectors.

 

uh... you need the regulator connected to the other end of the rail.

 

I wish it was that, but I have gm3 bar. I just left it like that because i still have the stock TB

 

So it would be better then if its connected on the other end of the rail then? Also what if I mount it on the firewall like most people do? Would that work better as well than the way I have it now?

 

mounting location doesn't matter as long as the feed for the regulator is after the rail.

 

The FPR controls the fuel pressure and it is upstream of the injectors. Meaning the pressurized fuel is between the pump and the FPR. The Injectors are seeing virtually no pressure as they are on the return side of the FPR. I suspect the fuel pressure at the injectors is around 14psi as that was the maximum boost pressure you could fuel. Injectors cant inject fuel into a higher pressure volume.

Move the FPR downstream of the injectors and you will have to retune your entire fuel map.

 

[QUOTE=Muckman;46859141]The FPR controls the fuel pressure and it is upstream of the injectors. Meaning the pressurized fuel is between the pump and the FPR. The Injectors are seeing virtually no pressure as they are on the return side of the FPR. I suspect the fuel pressure at the injectors is around 14psi as that was the maximum boost pressure you could fuel. Injectors cant inject fuel into a higher pressure volume.

Move the FPR downstream of the injectors and you will have to retune your entire fuel map.[/QUOTE

Right now I have the FPR mounted on the passenger side of the fuel rail as you can see in the pics. If I mount it on the driver side of the fuel rail and then have it return from there would that be sufficient not to effect any of the fuel pressure going to the injectors?

 

Do as muckman said and put the regulator on the right side of the rail. The only other thing you could do is leave the fpr where its at since you already have the return line ran. Run the feed like from the fuel filter to the right side of the fuel rail. Bottom line is the regulator has to be in line after the injectors.