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Discussion Starter #1
I had my TU cal and gauges installed yesterday. While tuning base fuel pressure, we noticed the gauge would read no more than 40psi with the AFPR set to max.

Had the vac line to the regulator unplugged while trying to set the pressure. With it off, the car would die so it had to be manually plugged to keep it running. Any chance it would make a difference if I reset the SMEC and fire the car up with the line unplugged?

I have a new Walbro 255lph fuel pump in the system along with a Holley AFPR. Both are direct replacement style units.

I believe I still have the original FPR somewhere. If anyone has some ideas before I start swapping parts, it would be appreciated.

btw, how safe am I assuming 40psi base? The system does run on the lean side idling. I am also nowhere near the boost level that the cal is designed to run.
 

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cant help you much other than to chime in an make an observation there does seem to be a spat of probs with Accufab brand AFPR's....mine also is causing probs...with my stock original unit, base fp was rock solid steady....swaped in the Accufab and fp now bounces 2-3 psi no matter where i set the fp. very frustrating.

i think we both may have faulty AFPR's.
 

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definelty try swaping to the stock fpr to make sure you can get 55 from that, and rule out anything else(besides the regulator). Also, are you sure the fpr you are using is not meant for carborated aplications?
 

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Check to see if its got the correct fuel pump...... TBI pumps only run 40psi even with the rising rate of the stock fuel pressure regulator, i found that out the hard way!
 

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The small peice of hose that connects the pump to the sender inside the tank is known to leak if not properly clamped. It'll hold pressure to a certain point then bleed off, sometimes (more likely) will completely pop off.
 

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Seems like an awfully easy test to swap the stock FPR back on and see where you're at. Also, you shouldn't need an AFPR with the TU unit, should you?
 

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Discussion Starter #9
^No, you're right, there isn't a need. It was a last minute decision to have one because I intended to run an FWD cal.
 

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Guys your making this problem much harder to diagnos then is necessary. Simply grab a pair of needle nose pliers and with the car running and the gauge hooked up momentarily "PINCH" off the return line coming out of the regulator. The pressure should immediatly shoot up to 90psi.
If the pressure shoots up FAST, then the pump is good and the regulator is bad.
If the pressure only rises slowly and won't even come close to coming up to 90psi then the pump is bad.
Remember just because a part is new, doesn't mean its good. I have seen far too many bad fuel pumps that were new.

Do this simple test first.

Nick A.
 

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Discussion Starter #11
^Yeah the shop guy did actually pinch off the return line and the needle didn't move. I just didn't look at this thread for a while since it was done.

So my pump is bunk, eh?
 

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yes there is a problem with the fuel pump. Pull it out and make sure its all hooked up properly, if it is, then the pump is bad. Also just check to make sure the fuel filter isn't hooked up backwards. That will screw things up as well.

Nick A.
 
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