Fmu only 20psi of FP? - Boost Forum

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Fmu only 20psi of FP?
Tuesday, May 27, 2014 10:03 AM
I asked this question in my other thread in general, but I figure in the boost forum maybe someone could help me.
I have...

Manifold to a tee, one leg to BOV, another leg to fmu.

I took off the vaccum line from the fmu set idle to 35psi. Connected it back up and it dropped to like 19-20 ish. I thought it was supposed to be at 35? So how do I get it to idle at 35? I have the check valve installed so it vents but doesn't let air in. I have that installed on the barb with the needle valve. I have tried searching but I have never seen a picture of the fmu hahn gave me anywhere it looks nothing like the one in the directions. Any help would be good. Kinda sucks to be just stuck

Re: Fmu only 20psi of FP?
Wednesday, May 28, 2014 10:49 AM
You always set idle fuel pressure with no vacuum. 35psi is too low for any Jbody motor. No vacuum is like WOT on a n/a engine. SO if you want it at 35psi at idle you need it to be higher with no vacuum.

Does that make sense?

Truly for a Ecotec your fuel pressure at idle with no vacuum should be around 60psi.



FU Tuning



Re: Fmu only 20psi of FP?
Tuesday, June 03, 2014 11:09 PM
Yeah that makes sense cause with no vacuum line hooked up it's like passing through the 0 point. But it I set it at 35psi with no vacuum line and I hooked it back up it dropped to like 19psi. That seems wayy too low. But I think I'm gonna hook up the regulator from the compressor, with a restrictor and try that. Hahn kinda tells you how to set it but the directions they give you from begi completely contradict that. I'm sure I'll figure it out tho, I always do.
Re: Fmu only 20psi of FP?
Sunday, June 08, 2014 10:38 AM
I do not trust nor listen to Hahn.



FU Tuning



Re: Fmu only 20psi of FP?
Sunday, June 08, 2014 1:08 PM
is the FMU hooked in to the return line or the feed line? it supposed to be in the return....



RIP silver car. You will be missed.
Re: Fmu only 20psi of FP?
Saturday, June 14, 2014 8:08 PM
Fmu was hooked up right. Turns out hahn is using it the exact opposite it's supposed to be used according to the begi directions. Any way got it all hooked up and it's gtg only thing is now the base fuel pressure has been getting like a psi higher each day I run the car which is weird, also had a random misfire happen only one time but I think the plugs are the stock delcos with over 100k on em so time for the new. Probably gonna run some ngk ltr6ix-11 @ .035. Hopefully it should be smooth from there. Wish I had better traction!
Re: Fmu only 20psi of FP?
Sunday, June 15, 2014 6:44 AM
Look at the NGK 3787. They come gapped already in the right range
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