I'm having trouble with my 42lb injectors maxing out at high rpm and under boost, I have a 255 in the tank and a propump inline and a boost sensitive regulator, I have raised the fuel pressure to 58 with vac off and the injectors are still maxing out. It is a 302 shortblock and the rest is in my sig, Are my rails and lines too small or what's going on? I thought the stock rails could handle this type of setup?
injectors maxing out
- Thread starter Beasly B
- Start date
-
Sponsors (?)
joeyd0730
Member
try adding a fmu it will bring your press up under boost and allow more fuel in during the cycle.
VG30DE
Founding Member
How much power are you making, you shouldnt be even close to max... I run stock lines, stock filter, one pump in tank, and stock rails and I'm just maxing out now...
A FMU is a tuning band-aid that comes with the kit. Its not a permanent, nor a good solution.
A FMU is a tuning band-aid that comes with the kit. Its not a permanent, nor a good solution.
Took a while to get a reply on this so I didn't check until now. I am supposed to be making around 500ish, hp, on my PMS screen at about 58k I max out to 100% but I don't go lean. I talked to Rick Anderson about this and he said it was okay as long as I didn't go lean. I am running about 58psi fuel pressure at max boost. I have all stock fuel rails and lines, a 255 intank and a propump inline. No fmu, don't want one.
LEE93COBRA
New Member
42# injectors max out around 480-500 on blower cars. Upgrade to some 55-60 pounders and turn your fuel press back down to around 40 psi. You will be good to go after that
LordMustangGT
Member
VG30DE
Founding Member
ding ding ding we have a winner!
The stock fuel lines cant support 42's never mind bigger. If you had a gauge you could watch during the pull, I bet you're losing at least 20 psi fuel pressure by the time you hit 5 grand. This is what happens when you have stock fuel lines/rails. They just get sucked dry:
The injectors dont run out of flow, the flow to the injectors runs out. I started at 80 psi at idle, had 40 psi at 4 grand and only 25 psi by 5.5 grand (fuel pressure) with stock lines and rails.
The stock fuel lines cant support 42's never mind bigger. If you had a gauge you could watch during the pull, I bet you're losing at least 20 psi fuel pressure by the time you hit 5 grand. This is what happens when you have stock fuel lines/rails. They just get sucked dry:
The injectors dont run out of flow, the flow to the injectors runs out. I started at 80 psi at idle, had 40 psi at 4 grand and only 25 psi by 5.5 grand (fuel pressure) with stock lines and rails.
LEE93COBRA
New Member
VG30DE said:ding ding ding we have a winner!
The stock fuel lines cant support 42's never mind bigger. If you had a gauge you could watch during the pull, I bet you're losing at least 20 psi fuel pressure by the time you hit 5 grand. This is what happens when you have stock fuel lines/rails. They just get sucked dry:
The injectors dont run out of flow, the flow to the injectors runs out. I started at 80 psi at idle, had 40 psi at 4 grand and only 25 psi by 5.5 grand (fuel pressure) with stock lines and rails.
I have to disagree. I have run both 42's and 60's with stock fuel rails with no problems whatsoever. If you lose 20 psi during a pull than there is something else wrong in the fuel system. If you lost a lot of fuel psi on your combo with 42's, it was due to a faulty pump.
I could possibly see a fuel rail upgrade around 700rwhp and up but not any power level below that.
Which brings me to another question. Why in the world would you have your psi at 80? That kills injectors having that much pressure on the back side of them.
LEE93COBRA
New Member
another thing..
When I was blown and at the power level you reflect in your graph, I had 60# injectors, stock rails, stock lines, 255 intank and a KB BAP. At WOT my car would hit 50 psi of fuel and hold while maintaining low injector duty cycle.
I actually had started out with 42's but they were not enough injector for 525-530rwhp
When I was blown and at the power level you reflect in your graph, I had 60# injectors, stock rails, stock lines, 255 intank and a KB BAP. At WOT my car would hit 50 psi of fuel and hold while maintaining low injector duty cycle.
I actually had started out with 42's but they were not enough injector for 525-530rwhp
joeyd0730
Member
millhouse
Founding Member
You may be safe on the dyno but by no means is it recommended. Your likely pushing those injectors past 100% duty cycle and your fuel pressure has to be way high to compensate for your improper sized injectors.
Similar threads
