car doesn't run with 24Lb inj and stock FMU

[1fstlx]

I just installed 24lb'ers and now I can't run my fmu.I was told the stock fmu is for 19 or 24lb'ers ,I also put A c&l 73mm and lost 3 lbs of boost. I had a pro m 75mm and I was at 9lbs.The car runs good without the FMU but I think it's unsafe.Should I go with a 8:1 fmu , or with a fuel pressure reg. that is boost sensitive(1:1)?Where is the cheapest place to buy from?

[1sicklx]

get rid of the fmu, and dyno tune it. also c&l metters suck, get a pro-m...

[root]

1fstlx: Do you have any other motor mods than what is in your sig?

Why can't you run the FMU? It is for 19 or 24lb injectors.

How many pounds of boost are you seeing?

Ian

[1fstlx]

the only other mod is a shift kit. I'm seeing 6lbs. with my f-150 pulley. I just bought a t-5 conversion kit, headers,and a 2.75 in. blower pulley from asp.I want to fix the problem I have now before I put these on.I was seeing 9lbs of boost with the 75mm pro M. I am also running all 4" tubeing to and from the novi .I wonder how much boost I'll run with the new pulley.

[1fstlx]

If I hook up the fmu ,I get black smoke out the tail pipe,and the car will sputter real bad.

[Goliath5.0]

Sounds like you where running very rich.

What was your fuel pressure setting with the FMU installed, also do you know what your fuel pressure was under boost with your FMU?

What is your fuel pressure now without the fmu.

What is the dial set at with your MSD BTM.

What kind of spark plugs are you using? What is the gap on them?

[1fstlx]

with the fmu under boost I'm at 100 psi , and at idle I'm at 39psi. my BTM is set at 1.5 with the base at 10 deg.I was only able to run the fmu with the 19lb injectors.Now I have no fmu. The meter still reads rich. Are these auto meters accurate? There is no ping.The whole reason for the injector swap was because #8 inj. was cracked and wasn't working. I found this after running a 14.00 at 101mph in the 1/4.

[1fstlx]

I have autolite 23's at.038 gapping With no blow out as I did with stock gapping

[slider_buck]

i was also running rich with the fmu on. i ditched it and set everything up like in my sig, read it. it runs awsome now.

[Goliath5.0]

Originally posted by 1fstlx
with the fmu under boost I'm at 100 psi , and at idle I'm at 39psi. my BTM is set at 1.5 with the base at 10 deg.I was only able to run the fmu with the 19lb injectors.Now I have no fmu. The meter still reads rich. Are these auto meters accurate? There is no ping.The whole reason for the injector swap was because #8 inj. was cracked and wasn't working. I found this after running a 14.00 at 101mph in the 1/4.

(When I had the f-150 crank pulley...)

... With 30# injectors and the FMU calibrated for 30# injectors, my fuel pressure was at 39-40 psi of Fuel pressure, under full boost I was @ 80 psi. I had my initial timing setup @ 10 degress with the BTM set @ 1

That is odd. You are running way rich with the FMU. The FMU is doing its job by making sure you are getting a mess load of fuel, but I would possibly adjust your base fuel pressure a tad lower. This is just my opinion.

Because I had the same fuel pressure setting with 30# injectors and you have 24 # injectors and you're FP under boost is mad high (rich). If you were to reduce your fuel pressure down, I would do it with 1 pound @ a time and not to exceed 4 to 5 pounds!

Question, why do you have your btm set @ 1.5? What grade of fuel are you using. I would do this re-tune with ONLY 93 octance (maybe with an octane booster). May you are pulling too much timing out with that extra .5 on the knob.

Sound like to me like you have TOO MUCH FUEL, and possibly you are making it worse with that extra .5 of pulled timing on the btm.


My setting once again when I had the F-150 crank pulley installed were the following (please refer to my sig for mods):

30# injectors
FMU Calibrated for 30# injectors
Fuel Pressure 39-40 psi
Base timing set @ 10 *
MSD BTM Dialed in @ 1
Fuel Grade used in my tune: 93 octane
Spark Plug used: Autolite 3923
Spark Plug Gapped @ .038 thousandths


Someone chime in if you feel different! Lets try to help help 1fstlx here!

.038 gapping is solid! I use the same with no spark blow out as well!

[1fstlx]

Well here in Phx. Az. we only have 91 octane. I only have the btm at 1.5 for safety. at 1.0 it did ping a little the other day.I'm just trying to find out my problem before I put the 2.75 blower pulley on.I think I will just order a 1:1 boost sensitive fuel pressure regulator, and run methonal injection. I guess I will wait to run it at the track.I'll just run my 90 gt to see what she'll do.

[MINN5.0]

i had 24 lb injectors and ran my car on the dyno with the fmu. my a/f ratio was pig rich. i reset my base fuel to 54 psi and ditched the fmu. i picked up almost 70 rw torque. this was with only an 255 intank gss340 pump. my air fuel was a solid 12.5:1 all the way to redline.

you might want to try this and see. my car also likes a crap load of timing. i too have a boost retard and i didn't even need it because every time i set it to take out timing under boost, i lost hp. i made the power in my sig. off of stock electonics.

maybe i'm lucky?
just a thought. later, steve

[1fstlx]

I was thinking the same thing.I'll try adjusting the fuel pressure, as soon as I get my press. regulator.I think the boost sensitive one's adjust 1 psi for each pound of boost.(1:1).

[468LC]

Originally posted by 1fstlx
I think the boost sensitive one's adjust 1 psi for each pound of boost.(1:1).

Even the stock FPR will do this. Even after a fair amount of research I have yet to find a regualtor that won't do this

I run 30pounders on a stock long block and no FMU with a C&L maf. It was one of the best things I ever did for driveability second to the Bosch bypass.

[Goliath5.0]

From my understanding most fuel pressure regulators are already boost sensitive?!?

1fstlx, try playing around with the fuel pressure and see where your car likes the fuel pressure at.