1993 Ford Mustang Fuel Pressure Regulator

Tiny
AJNASEEM
  • MEMBER
  • 1993 FORD MUSTANG
  • 135,000 MILES
This is a long shot and I hope a tech can give me a clue. Due to fuel pressure being low, I pulled my vac to the FPR and the car runs much better now. When the vac is connected the fuel pressure is low. Can I drive the car with no vac but there is air going out. I got a new FPR but the PSI is still low and I am forced to drive with no vac line. Please, please help me find out what could be causing low fuel and I need some assurance that I can drive with no vac line. Is it safe to drive with no vac line. It seems it only pushes out air. Is it unsafe to drive with the vac leak?

Thanks - AJ, proud owner of classic 3g mustang!
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Friday, September 20th, 2013 AT 8:06 AM

3 Replies

Tiny
HMAC300
  • EXPERT
You either have a bad regulator or pump. If you are going to run without vacuum all you are doing is giving it higher pressure to begin with. Replace the pump. Or you don't want to fix pump put a screw in vacuum line it won't last long though with low pressure
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Friday, September 20th, 2013 AT 10:27 AM
Tiny
AJNASEEM
  • MEMBER
Thanks, mac. I did get a new regulator but there was no change. I am still running with no vac line but air is going out. What happens if air just goes out? Seems like higher PSI gives me more boost. Old motor can't run on low fuel. I have a new pump too but old cat and carb have high NOX. With vac line out, the car runs with good power. What's with the vac line. If the vac line lowers fuel pressure and car can't drive should I get an adjustable fuel pressure regulator like an Aeromotive. That way I can control the pressure and have a good setting that makes old 3.4L run on higher PSI. And why is there air in vac line and what is source? Is it okay to just let air go out? Why plug it and let air be trapped? I can recheck pump and let you know if it is new and working. But why would vac line increase or decrease pressure to give power for car to drive. Seems like a minor fix but can't seem to pin down.
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Friday, September 20th, 2013 AT 11:20 AM
Tiny
HMAC300
  • EXPERT
Read my reply over, you need anew pump not a regulator
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Friday, September 20th, 2013 AT 12:26 PM

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