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85 K5 Build (What to do this summer...)

I agree, you should be seeing 55psi. I'm a bit surprised the FiTech tech didn't point that out as an issue.
 
Forgive me for not taking the time to look backwards at your fuel setup, but do you have any rubber line that can be getting sucked down?
 
I always see 55psi on mine.

Dropping fuel pressure like that has an effect on spray pattern at the very minimum, I would be concerned about that.
 
I always see 55psi on mine.

Dropping fuel pressure like that has an effect on spray pattern at the very minimum, I would be concerned about that.
I am concerned, thinking of trying different pump. Are you useing a intank pump? Just looking for one that will for sure fit my 87 sending unit. The pump I'm useing now is a airtex e3270
 
What concerns me is that I replace pump and get same psi. The pump Im useing is a higher psi. Should I try to find higher psi pump? The e3270 pump is also a replacement pump for 96+ vortecs
https://www.carid.com/airtex/electric-fuel-pump-mpn-e3270.html

Interesting that pump is a replacement for the 96+ vortecs just like the 381. If that's the case, why isn't the psi up around 55? Sounds like a weak pump if it's falling off and not keeping up as the consumption increases.

And I've never messed with the pulse width, I assume yours is set to factory spec?
 
Interesting that pump is a replacement for the 96+ vortecs just like the 381. If that's the case, why isn't the psi up around 55? Sounds like a weak pump if it's falling off and not keeping up as the consumption increases.

And I've never messed with the pulse width, I assume yours is set to factory spec?
Exactly, yea tried at a few different settings 70-100 and with no change. Maybe it is weak. was the spare pump I had for my k5.
 
I'm also going to plug the return line on TBI and see if pressure will then go up too. Maybe regulator in tbi is stuck open. On my fcc before I removed it had similar fuel pressure on the high side.
 
sure sounds like a bad pump unless there is a bottleneck in the fuel system somewhere.
 
Didnt get any updates and had no idea @skunked and @down4thakrown had said anything.
I agree, you should be seeing 55psi. I'm a bit surprised the FiTech tech didn't point that out as an issue.
Mine also is around 45psi with gauge mounted on TBI. It will drop to about 40 under throttle.
I was told by FiTech I should get 43PSI at the throttle body, Maybe its lower because I have the Go Street 400hp EFI
 
Forgive me for not taking the time to look backwards at your fuel setup, but do you have any rubber line that can be getting sucked down?
I am using high pressure line that is really hard to even squish so I dont think so. Its the line that came with FiTech system
 
Taking a break from the FiTech today and was wondering if anyone had suggestions on how to build some sliders that I can jack from. mine now are pretty flimsy. How many .120 wall 2x2 supports should i run to the frame?
 
Didnt get any updates and had no idea @skunked and @down4thakrown had said anything.


I was told by FiTech I should get 43PSI at the throttle body, Maybe its lower because I have the Go Street 400hp EFI

interesting about the PSI, makes sense since they didn't make issue of it.

and we used the same fitech line, no issues to report.
 
Taking a break from the FiTech today and was wondering if anyone had suggestions on how to build some sliders that I can jack from. mine now are pretty flimsy. How many .120 wall 2x2 supports should i run to the frame?

most do 4.

If you can triangulate them it helps so they're not all straight to the frame. Also, tieing them into the body (use bushings if necessary) is a good way to reinforce them. Let me see if I can find a pic of muddysubs design, it was pretty clean.

you have the 600hp setup?

My truck is yes. We used a 400hp kit on another car, however I did not put a fuel gauge on that one.
 

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