Help :/ So Confused!!

Discussion in '1994 - 1995 Specific Tech' started by Aleftcam000, Sep 13, 2013.

  1. Hey, I'm having a handful of issues with my 95 mustang gt, the engine was rebuilt from.block up and has only 15miles of running time on her.

    My build list consists of...

    302 .30 over short block from latemodelrestoration
    E303 camshaft from latemodel aswell
    Procomp aluminum heads w/ upgraded 2.02/1.60 valves
    1.6 roller rockers, hardened pushrods etc
    Upper & lower intakes are stock to my knowledge
    Has plenium spacer between the intakes.
    65mm throttle body
    19/lb orange top/stock fuel.pump
    70mm MAF
    Bbk long tube headers
    Bbk x pipe
    Underdrive pulleys
    Smog pump/ac pulley deletes
    MSD billtet Distributor

    Now I am having overheating problems, loss of fuel for pressure under throttle, and the timing with spout connector out is good, but as soon as you put spout back in the car idles like crap, sputters, dies. But I don't think that's my issue.

    Yesterday I performed a fuel pressure test, the results..
    Fuel pressure at idle 40psi
    Fuel pressure under throttle 30-32psi around 2500-3k rpms an it starts to back fire and break up..
    FPR vacuum unhooked it didn't leak or smell of odor.

    Car will overheat extremely fast, just sitting at idle. The thermometer will open up an fan kicks on.. I reused my water pump/radiator from previous engine, both worked fine. System has been burped etc

    I know for my build I am pushing limitations of stock fuel injectors, maf and fuel pump. So I already went ahead and ordered 24lb injectors & 77m pro-m maf calibrated for injectors.

    Do I need to upgrade fuel pump?

    Am I back firing/sputtering for lack of fuel?

    Why am I overheating?

    I can't drive that car at all, backfires, sputters, hesitates around 2500-3k rpms, and then temperature gets really high ( at least on gauge cluster shows its running really hot near the L on 'normal' and sometimes past it)

    What could possible be my problem? Thanks in advanced..
  2. Here is a video of my car at idle and 2000-2500rpms when it starts to sputter/backfire/ pop etc
    Unfortunately it wasn't overheating in this video like it usually does. I just had started the car before I video taped it

    Also don't worry about oil pressure, I have a aftermarket gauge on the hood lol.noil pressure is good.
  3. You did not say whether your car is still equipped with O2 sensors and is still using them. If they are there, and are supposedly being used, then check for codes before you do anything else. You should have lean codes in memory.
  4. I've had a similar issues. The fuel pressure should increase under throttle (accelerating/high load). But, when the car is at cruise speed (low load) the fuel pressure should drop. Fuel pressure should be 40psi with the vacuum line disconnected. Your fuel pressure regulator (FPR) could be bad. Another possibility is a vacuum leak. This has similar symptoms as a bad FPR. Since you just put the top end back together that seems most likely. The gaskets between the head and lower intake can drop during reassembly. Or, forgetting to reattach a vacuum line somewhere or a broken vacuum line(s) from the EGR/AIRD/AIRB valves. Lots of possibilities. One way to find a vacuum leak is to lightly spray(mist, not squirt!) some carb cleaner around the intake area while the engine is running. The idle will increase if you have a vacuum leak. Please be careful with that technique as you can catch FIRE if you don't know what you are doing. Under idle car should be pulling 15-20hg vacuum. When you open the throttle blade, vacuum should go to zero. If vacuum increases when you open the throttle that is another sign of a vacuum leak somewhere in the system.

    Back firing is from too much fuel actually. Which would be a symptom of a vacuum leak as well. Car's computer reads a lean condition (unmeasured air) and dumps more fuel into the cylinders. The raw unburnt fuel reaches the exhaust and ignites and makes popping noises. You can check for this by pulling a spark plug after running the engine for a while and seeing if it is wet with fuel.

    As for the fuel pump your stock one will work fine with the 24lb injectors. Unlike the Fox body cars that came with 88lph pumps the SN95 cars came with 110lph pumps.

    I ran 24lb injectors with a 75mm summit racing MAF with no tune and had no issues.

    Good luck!
  5. I will look over engine for more vacuum leaks, but I feel it is closed up well.

    The fpr reads 40psi at idle with vacuum hooked up. After you unhook vacuum to fpr the psi increases to about 42-43psi, with vacuum hooked back up and giving throttle (2500/3k rpms) fuel pressure drops to 30-32psi. and doesn't increase.

    I will also pull codes, but unfortunately it will have to wait till Monday.. car is at my friends shop.
  6. Are you positive your not 180 degree's off on the dizzy? (Distributor)
    Have you ohm'd/checked voltages to the TPS/MAF/Other sensors under the hood to make sure they are in range.
    Have you pulled any codes or are you getting any CEL lights?