bogging/sputtering after tune up on supercharged foxbody

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Posted by JSJ 5.0 (Member # 11950) on :

Need help car started to bog/sputter after tune up

info before tune up. 92 foxbody with vortech v1. Stock 19lb injectors, fmu, vortech external fuel pump, vortech ignition box, msd boost knob set at 1 1/2, bbk fpr with guage. 6lb pully. Fuel pressure at 40psi with vac unplugged, timing at 10. Wideban would be 13 idle 11/12 wot

Tune up consists of autolite 3923 gap at .35 Bbk 255 intank fuel pump, motorcraft fuel filter, cap/rotor.

After tune up wideban at 15 idle and starts to climb up to 17 with throttle. Car bogs between 2k-4k. Car idles fine. I'm stuck. What can it be. I rechecked everything. Seems like it's not building boost anymore too. No vac leaks. Please help. Thanks

Posted by racsirx (Member # 1710) on :

What heads? Wrong plugs if are using gt40 or stock heads.

Posted by JSJ 5.0 (Member # 11950) on :

Stock heads. What plugs are the correct ones and what gap. Thanks

Posted by 92_5.0 (Member # 7624) on :

I'm pretty sure that with stock heads you should run autolite 23's not 3923's and you should be good with the gap at 35. But I'm sure Lee (racsirx) will chime in with a definite answer [patriot]

[ 2014-08-14, 04:04 PM: Message edited by: 92_5.0 ]

Posted by SmokinLX (Member # 1684) on :

quote:
Originally posted by 92_5.0:
I'm pretty sure that with stock heads you should run autolite 23's not 3923's and you should be good with the gap at 35. But I'm sure Lee (racsirx) will chime in with a definite answer

Pretty sure the 3923's or 23's are the rite ones which is one range colder than the 3924's. To the original poster these are the same plugs that you used before the swap rite? Recheck the plug wires and if You replaced the filter make sure it's installed in the rite direction.

Posted by racsirx (Member # 1710) on :

Spark Plugs:
Autolite 25 is stock for 86-93 Mustangs.
Autolite 24 is a heat range colder and is good for Nitrous or Blower Applications with stock heads
Autolite 3924 fits many aftermarket heads like AFR, TFS, etc.
Autolite 3923 is one range colder.

For a blower setup I gap them at .032
For a turbo setup I gap them at .028

Posted by JSJ 5.0 (Member # 11950) on :

Put autolite 24 and gapped them at .032 and still getting the same bogging/supptering. Any help?

Posted by racsirx (Member # 1710) on :

Do you a fuel pressure gauge in the car? Have you tried running without the MSD?

Posted by JSJ 5.0 (Member # 11950) on :

Yea. I rechecked my fuel pressure. Around 32-35 I idle with vac off 40-42 but when I rev the motor psi drops around 10 psi on gauge.

Posted by racsirx (Member # 1710) on :

quote:
Originally posted by JSJ 5.0:
Yea. I rechecked my fuel pressure. Around 32-35 I idle with vac off 40-42 but when I rev the motor psi drops around 10 psi on gauge.

Fuel pump

Posted by Fostang (Member # 3752) on :

I concurr.

I had problems with the fuel pump in the vette this weekend at pebble beach and it did the same shit when it got hot.

Luckily I was able to keep driving once it sat but still nerve wrecking.

Looks like you and I are swapping pumps in the near future lol

[ 2014-08-17, 10:29 PM: Message edited by: Fostang ]

Posted by JSJ 5.0 (Member # 11950) on :

I just put in a new bbk intank 255 fuel pump with the tune up. How can I check/know if the external fuel pump took a shit? If the external fuel pump took a shit would it cost this bogging problem? I was looking through old post here and people had problems with knicked fuel lines when reinstalling the gas tank back after a fuel pump install.

Posted by Fostang (Member # 3752) on :

Why do you have 2 pumps?

At your hp level just an intank hi-pressure will work.

Posted by 92_5.0 (Member # 7624) on :

+1 ditch the external pump [patriot]

Posted by Built88LX (Member # 10758) on :

quote:
Originally posted by 92_5.0:
+1 ditch the external pump

+2 no need for external pump bbk 255 should be plenty of fuel for your setup

Posted by racsirx (Member # 1710) on :

I haven't had an inline pump go bad on me but I have disconnected power to an inline pump on a few cars and didn't have a problem having the car run fine like this, I have had problems with FMUs, that's the main reason I don't use them anymore but these new style pumps shouldn't have a problem with them, back in the day FMUs would cause pumps to lock up and drop fuel pressure that's when they came out with recalibrating kits for the FMU so they wouldn't spike to 100psi which would cause some pumps to lock up, FMS 190 fuel pumps were know for that, but that's probably not your problem, I would take inline pump out and see if the problem will go away, otherwise change the intank pump, I would still keep two pump setup if you wanted to upgrade your setup, it's still a lot to ask from one intank fuel pump, you can never have enough fuel pump.

[ 2014-08-21, 10:00 AM: Message edited by: racsirx ]

Posted by JSJ 5.0 (Member # 11950) on :

I disconnect power to the external pump and still have the same issue. How can I check if the fmu or fpr took a shit on me?

Posted by racsirx (Member # 1710) on :

quote:
Originally posted by JSJ 5.0:
I disconnect power to the external pump and still have the same issue. How can I check if the fmu or fpr took a shit on me?

But did you take it out completely out of the system? Did you double check the install on the intank fuel pump? You can remove vacuum from the FMU or unbolt it from the system, I still think the problem is with the intank fuel pump, unless you are having wiring problems to the fuel pump.

Posted by Fostang (Member # 3752) on :

See this is where I kinda disagree from lee.

Yes you can never have enough pump but why put a 255lph pump then restrict it by putting a 190lph infront of it.

Your creating a choke look up bernoullis principle.

Now if you did 2 pumps the way to run them is with 2 feeds from the tank one to each one. Then Y block them to the fuel line. Which should be also be upgraded to carry the additional fuel.

Get rid of the external pump keep the 255 and eliminate one less potential problem. Then work your way up to the FMU issue.

The only reason some pumps lock up is because they have a max operating pressure which is about 100-125psi before the built in safety shut off clicks.

K. I. S. S. Keep it simple sutpid lol

[ 2014-08-21, 06:37 PM: Message edited by: Fostang ]

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