interesting fuel rail findings
01-24-2005, 01:54 PM
#1
interesting fuel rail findings
This was done to a 3rd gen by Scott (aka Boosted Maxima). While taking the heads off and such he noticed that the fuel rail looked quite well... poorly made. Basically the way it was designed the front cylinders are getting plenty of fuel but the rears not as well. He noticed that the front was running quite rich while the rears weren't near as rich. When you start making a lot of power this most like could mean bad things. (I myself notice some pinging even though my afr is something like 10:1... this most likely could be the reason since the knock sensor is located on the rear of the engine which is the side that would have the fuel issues). This should fix it up quite well. Here is a writeup and pictures on what he did to cure the issue.
Originally Posted by Boosted Maxima
Here's the write up and supporting pictures as promised on the dual inlet fuel rail system and reasons for doing so.
1: Take apart plenum and injector rail
2: using a tubing cutter cut the fuel rail/s opposite the inlet/return lines "only the very tip needs to be cut off" where for some reason it's crimped down as pictured. Use a drill bit or rat tailed file to open up tube on the inside the rest of the way so it's a smooth entry on both sides of the fuel rail.
3: Install a 3/8 T fitting between the rails with 3/8 FUEL INJECTION HOSE. Not regular 3/8 fuel line.. it will burst! Or braded hose eather way is fine. Assemble as pictured using the old hose you removed as a guide to how long to make the ends connecting eather side of the T fitting. (has to be same leingth to fit back on intake...
4: Use another T fitting or connect directly to your aftermarket FPR using two inlets. I'm going to use a T fitting I'd rather have a Y fitting but I have not located one yet that is avalb. everywhere.
Parts list:
8 or so 3/8 fuel injection hose clamps
6 ft or so of 3/8 Fuel Injection hose
1 T fitting and one Y fitting or another T or connect to FPR.
I found all my parts as above at Advance Auto. The T's are in the "help" section and the hose is by request behind the counter.
Hope this helps us in the fuel delivery area on boosted cars!
1: Take apart plenum and injector rail
2: using a tubing cutter cut the fuel rail/s opposite the inlet/return lines "only the very tip needs to be cut off" where for some reason it's crimped down as pictured. Use a drill bit or rat tailed file to open up tube on the inside the rest of the way so it's a smooth entry on both sides of the fuel rail.
3: Install a 3/8 T fitting between the rails with 3/8 FUEL INJECTION HOSE. Not regular 3/8 fuel line.. it will burst! Or braded hose eather way is fine. Assemble as pictured using the old hose you removed as a guide to how long to make the ends connecting eather side of the T fitting. (has to be same leingth to fit back on intake...
4: Use another T fitting or connect directly to your aftermarket FPR using two inlets. I'm going to use a T fitting I'd rather have a Y fitting but I have not located one yet that is avalb. everywhere.
Parts list:
8 or so 3/8 fuel injection hose clamps
6 ft or so of 3/8 Fuel Injection hose
1 T fitting and one Y fitting or another T or connect to FPR.
I found all my parts as above at Advance Auto. The T's are in the "help" section and the hose is by request behind the counter.
Hope this helps us in the fuel delivery area on boosted cars!
01-24-2005, 02:04 PM
#2
Um how does the fuel run out of the rail? Looks like it runs out on two sides. But only one side has the pressure regulator. I would think he would need to run the two outlet sides of the rail into one and run that one into the FPR.
01-24-2005, 02:10 PM
#3
i think he might be using an aftermarket fpr which would allow two return lines.
i'm trying to think up a way to do this using the stock fpr. (if he is using an aftermarket one his is most likely just hollowed out)
i'm trying to think up a way to do this using the stock fpr. (if he is using an aftermarket one his is most likely just hollowed out)
01-24-2005, 02:11 PM
#4
The pressure will stay the same on both ends of the rail that.. the highest the pressure will get is what the regulator stays at. the front bank will just not have a return line. the rear bank with the pressure regulator on it will regulat both front and rear rails.
the only drawback to doing that is that the bank with no outlet on the end (the front one in this case) does not have a way to flow back to the tank. this may cause some issues with fuel temperature getting too high as the stuff sits in the fuel rail for a while before it goes into the injectors.. the rear half has continuous flow to it so it will run the hot fuel back into the tank and get cooled off.
the only drawback to doing that is that the bank with no outlet on the end (the front one in this case) does not have a way to flow back to the tank. this may cause some issues with fuel temperature getting too high as the stuff sits in the fuel rail for a while before it goes into the injectors.. the rear half has continuous flow to it so it will run the hot fuel back into the tank and get cooled off.
01-24-2005, 02:20 PM
#5
I know you can buy stand off fittings in place of the original fpr. Just install a barbed stand off fitting with a 90 deg bend that points to the other inlet fitting. so the inlet and outlets look exactly like each other.
Then run the fuel backwards from that picture. Use the FPR and the original inlet as the the inlets. Then just run that new T'd line into a FPR.
Then run the fuel backwards from that picture. Use the FPR and the original inlet as the the inlets. Then just run that new T'd line into a FPR.
01-24-2005, 02:34 PM
#7
wouldn't you think the 90 degrees press bent tubing (at the end) would cause more pressure drop than anything else?
also the FPR is suppose to be blocking fuel from going back to the tank...wouldn't it be a better idea to T off the line from the pump (feed line) to both sides...feed to the normal feed side and feed to the regulator side (assuming the stock FPR is hollow) and run the T (a Y down the line would be better than the T) back to the aftermkt FPR? both sides gets the pressure and the regulator (return) meets in the middle. (not sure this is what he's setting up).
also the FPR is suppose to be blocking fuel from going back to the tank...wouldn't it be a better idea to T off the line from the pump (feed line) to both sides...feed to the normal feed side and feed to the regulator side (assuming the stock FPR is hollow) and run the T (a Y down the line would be better than the T) back to the aftermkt FPR? both sides gets the pressure and the regulator (return) meets in the middle. (not sure this is what he's setting up).
01-24-2005, 02:39 PM
#8
Senior Member
Join Date: Feb 2004
Posts: 535
Hi,
i to have experience pinging in my car,
i have to use higher octane to stop the pinging,
mobil and other gas don't work until i use shell v power 91 octane on my car and the pinging goes away,
i don't know if i have the same setup as the picture he is showing,
i to have experience pinging in my car,
i have to use higher octane to stop the pinging,
mobil and other gas don't work until i use shell v power 91 octane on my car and the pinging goes away,
i don't know if i have the same setup as the picture he is showing,
01-24-2005, 03:00 PM
#9
Originally Posted by DanNY
wouldn't you think the 90 degrees press bent tubing (at the end) would cause more pressure drop than anything else?
also the FPR is suppose to be blocking fuel from going back to the tank...wouldn't it be a better idea to T off the line from the pump (feed line) to both sides...feed to the normal feed side and feed to the regulator side (assuming the stock FPR is hollow) and run the T (a Y down the line would be better than the T) back to the aftermkt FPR? both sides gets the pressure and the regulator (return) meets in the middle. (not sure this is what he's setting up).
also the FPR is suppose to be blocking fuel from going back to the tank...wouldn't it be a better idea to T off the line from the pump (feed line) to both sides...feed to the normal feed side and feed to the regulator side (assuming the stock FPR is hollow) and run the T (a Y down the line would be better than the T) back to the aftermkt FPR? both sides gets the pressure and the regulator (return) meets in the middle. (not sure this is what he's setting up).
that's the idea that i had (if i understand you correctly). basically:
.................... ____
fuel filter -----<____>----- fpr
is that basically what you're saying?
01-24-2005, 05:23 PM
#10
Originally Posted by mtcookson
i think he said its not really a pressure issue... moreso a volume issue.
that's the idea that i had (if i understand you correctly). basically:
.................... ____
fuel filter -----<____>----- fpr
is that basically what you're saying?
that's the idea that i had (if i understand you correctly). basically:
.................... ____
fuel filter -----<____>----- fpr
is that basically what you're saying?
01-24-2005, 06:49 PM
#11
how does that rail (which I am assuming to be VG specific) compare to a VE rail?
Personally I'd think trying to rig a center feed with the reg in between the 2 halves where he has the tee currently and dual return line would be better. or is there something here that I'm totally missing?
Personally I'd think trying to rig a center feed with the reg in between the 2 halves where he has the tee currently and dual return line would be better. or is there something here that I'm totally missing?
01-25-2005, 05:35 PM
#12
Senior Member
Join Date: Mar 2002
Location: Ontario, Canada
Posts: 1,114
If anything goes thru the fpr, than there is for sure enough fuel in the rail to feed all injectors. As an engineer, I cannot see enough reasons for it to not provide enough fuel. Pinging might be caused by other reasons, like difference in cooling or carbon deposits etc.
01-25-2005, 10:13 PM
#13
Scott proved that there were definitely issues in the rear though. The front cylinder bank was running much richer than the rear and the front even gets a bit more air. Once he gets everything put together and tests it out some more it will most likely even out... but we'll see I suppose.
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