I just went to adjust my fuel pressure for the first time. I bought my TPI setup used so I do not know who's Adj fuel pressure reg I have. Anyway, when I turn the adjusting screw just a tiny amount, the pressure jumps like 5 psi. seems like going from 40 psi to 60 only takes less than an eight of a turn?? Is it supposed to be this sensitive?? Thanks

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Dave Zelinka

 

NO. Something is definitely not right.

 

Mine is like that too and has been ever since I bought it like 1 1/2 yrs ago. It is made by crane cams.

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'89 Formula 383 TPI

 

I disassembled my regulator and here are my thoughts. It is the type that uses the stock diagphram. There are two springs in the mechanism. The large(visible) spring is the one that works against the vacuum port and there is a small soft spring that actually pushes the little plunger against the return port in the regulator(very bottom). The small spring has very little travel and therefore it bottoms out before it has time to raise the pressure very much. When this happens the pressure to overcome this goes WAY UP and thus the pressure goes way up. I do not think it is a good design. In my opinion, the regulator port spring should be changed to a higher spring rate and this would work much better. I guess since it is so hard to do this(impossibe??) they don't make em that way.

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Dave Zelinka

 

Thanks guys!! my regulator is made by Crane I think based on the picture in the Summit catalog. I recently bought a used fuel rail that came with a different regulator and I swapped it in last night. It has a black cover and an allen head adjusting screw. It works alot better. It seems the adjustment works real goodfrom 30 psi to about 44 psi, after that it gets very touchy. Looking at the design, I think this is due to the small spring at the bottom running out of travel. At this point the pressure shoots up. Also, I noted that with high pressure setting the vacuum corection does not work very well at all. With 17" of idle vacuum, the pressure reading should drop about 7 psi when vacuum is connected. When my pressure was set high, it would only drop a few psi and it caused a lean condition when the throttle was depressed from a steady cruise. I have it set now to 44 psi and will see how this does.

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Dave Zelinka