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93 Cobra Hard Starting and....

Discussion in 'Fox-Body Cobras' started by robertlyons, Oct 1, 2017.

  1. robertlyons

    robertlyons Member Established Member

    Messages:
    68
    Joined:
    May 26, 2003
    Location:
    Piscataway, NJ
    Guys,

    Looking for ideas. For background, my CObra has about 22K miles on it, mostly on the road course. After a bunch of medical issues, the Cobra is lucky to get 50 miles on it for the past 7 years or so. Up till 6 weeks ago, car was running fine.

    Installed a dual bank A/F gauge. Noticed both banks register lean (21-22) until car warms up, then drops to 15-16. SInce I had a Pro-M 75 bullet w/ CObra calibration on it, I figure that's normal. Reason why I installed the gauge is because I bought a K-B blower when they stopped making the 5.0 version, and I was going to have my old buddy Chris Winter install it (I know, but I don't have the time). Anyway, I decided to do some of the work up front and swapped my Texas Turbo (!) underdrive crank pulley for a stock GT and removed my strut tower brace. Now the car is hard as hell to start.

    So, I decide to put the stock MAF back on the car, after disconnecting the battery for a week. Car is still hard as hell to start, but after starting lean, car drops to 14.5/15.5 once warm. Way back when, I put a K-B adjustable fuel pressure regulator on the car (1995?). So, I decide to screw it in a 1/2 turn and see what happens. Fuel pressure increases from about 30-31 at idle to 32 (Autometer electric FP gauge, installed in the fuel rail). Wait a touch, restart, car is still hard to start but sounds better. So, I decide to turn it another 1/2. Car sounds a bit rougher, fuel pressure dropped to just about 20 PSI! If I step on the pedal, the car sounds powerless and the A/F gauge shows real lean. I shut it down, and walk away before I make shit worse. But I did look at the regulator again, and when I go to make sure the vacuum line is on completely (it looked "off"), I see the fitting pulled out of the regulator. I used some hi-temp sealer to reglue the fitting and walk away, this time for good.

    I have a feeling the regulator is shot, so I ordered a replacement. I also have a set of rebuilt and flow matched injectors I bought several years back that I'll install. And, to be complete, I'm going to change the O2 sensors and fuel filter.

    Now, for the opinions. Does it sound right for the Cobra to start that lean, then come into "normal" range once it warms (wish I installed that gauge years ago)? If I remember, a stock CObra is around 32 PSI of fuel pressure on the rail at idle, is my memory correct? And why does everyone think the car became so hard to start once I swapped on the GT crank pulley? And, finally, does anyone have any ideas for me? I figure once I do the parts swap, I'll also turn the timing down to stock, hoping that will allow the car to turn over easier.
     
  2. WillyB93

    WillyB93 Active Member Established Member

    Messages:
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    Joined:
    Apr 12, 2010
    Location:
    IN
    Are you sure you got the distributor set correctly, If you have it off a tooth or so it may make it hard to start.
     
  3. robertlyons

    robertlyons Member Established Member

    Messages:
    68
    Joined:
    May 26, 2003
    Location:
    Piscataway, NJ
    Didn't touch the distributor or the balancer (FMS). Just changed the crack pulley. I do have a Crane CD Ignition with an in-car timing adjuster. Had the base timing set at 14, going to turn it back down to 10 when I do the parts swap.
     
  4. robertlyons

    robertlyons Member Established Member

    Messages:
    68
    Joined:
    May 26, 2003
    Location:
    Piscataway, NJ
    Well, swapped in a new fuel filter, O2 sensors and adjustable fuel pressure regulator. Also turned down timing 4 degrees. Turned pressure regulator all the way up, car is still lean and pressure is no higher than 26 PSI. At this point, I am figuring the fuel pump is either clogged or dying. Anyone else have any ideas?
     
  5. 02_Lightning

    02_Lightning Active Member Established Member

    Messages:
    1,138
    Joined:
    Jan 28, 2001
    I had a 93Cobra that was VERY hard to start under 35 degrees or so. It ended up being a bad fuel pressure regulator. When it was cold, I would take a hair drier to it and warm it up before trying to start. Still had some trouble, but once it fired, held 2500 rpm for a minute and it smoothed out. It was like a carbureted engine not tuned right and had gas smell of being rich. This only happened when I was warming it up in storage.
     
  6. Handlebar Moustache

    Handlebar Moustache New Member Established Member

    Messages:
    10
    Joined:
    Jul 29, 2017
    Location:
    Louisiana
    No change in the difficulty of starting after the timing adjustment, FPR, new filter, and 02 sensor? When you say hard to start, do you mean the starter motor seems to be having a hard time turning the engine over, or are you just having to crank it a lot to get it to finally fire up?

    I have had a tempermental fuel pump that was weak and would not self-prime (which caused hard starting), but only when I had less than 1/4 tank of gas. So...how much gas do you have in the tank? How old is the gas? After you get it fired up and then you shut it down, will it start right back up, or is it still hard to start?
     
  7. robertlyons

    robertlyons Member Established Member

    Messages:
    68
    Joined:
    May 26, 2003
    Location:
    Piscataway, NJ
    No change after the parts swap. Starter motor turning just fine, car is hard to fire. Once started, runs very lean (over 18 as per the wideband) and fuel pressure gauge is low (24 PSI), and that's with the FPR turned all the way up. If I let it run enough to warm, the wideband will get in the mid 16's. And it's still hard to fire even when warm.

    I'm pretty convinced it's the fuel pump. Got a new one, just waiting for a spot in my buddy's shop to open so I can swap it in comfort.
     

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