I installed the blue spring upgrade about 2 months ago and my fuel pressure has been fine at 65 psi since then. Today I got in the truck and it was 80. What's going on?

 

Maybe your sending unit is starting to go? Seems like I read on here a couple of months go where someone was getting some atmospheric numbers on their fuel pressure gauge. Went back to the sending unit was "ohm-ing out". What brand gauge/sending unit are you using? I know this guy contacted the manufacturer of the gauge and they gave him some spec number to check for with the sending unit. That's how he figured out it was the sending unit and not the gauge or actual fuel pressure.

 

Glowshift

I'm thinking/hoping its the sending unit as well

 

Just left work and now its 90...

 

Have a fire extinguisher with you?

 

According to Navastar the 6.0 fuel system is designed for a max fuel delivery pressure of 120 psi. Ford recommends, I believe, 75 psi max to CTA. I put in the GDS spring and mine went to 105 psi actual gauge pressure. Man, you sure could tell the difference betwen the standard 45 psi with the OEM fuel pressure regulator and the 105 psi withthe GDS fuel pressure regulator spring. The acceleration and power was awesome. I now have an AD2 with an adjustable regulator that I run at 75 psi and it runs good.

DSMMH

 

Ok its definitely the gauge/sending unit then because it got up to 95 and there was no difference in acceleration over when it used to be 45.

 

I'm going to assume you've got an electric sending unit; I'd contact Glowshift and see what the spec is on that dude. I don't think 90+ psi is safe on these motors...there is a point were the o-rings are going to blow off the injectors. Navistar might have designed 'em for 120 psi...but then they don't lift the heads or blow the EGR's like the Fords seem to.

 

I have never seen a max reading from Ford,only a minimum reading. Now I have seen a International max of 70PSI not the 120PSI stated in earlier posts. What does your guage read with KOEO ?

 

I have never heard of the 120 psig limit either - would love to see a reference. As you said Len, I have seen the International limit of 70 psig published.

I BELIEVE that the fuel pump itself regulates to a max of apprx. 100 psig output w/ a "recirculation loop" - by design. I will have to verify this though (CRS syndrome). It is further regulated by the fuel pressure regulator on the side of the upper fuel filter.

I have seen a Ford "upper pressure" limit defined, but I failed to document the reference ..... doesn't happen often - lol, but it sure is dissapointing when I can't track these things down!!

So - going on memory, it was close enough (if not exact) to the International limit.

 

yes its the sending unit. tomorrow it will be at 100 psi and wont move. ive been through 3 of them. they arent that great. if you want to test it to make sure its the sending unit take the power wire from the sending unit and ground it out. if the gauge falls to 0 then its the sending unit. thats per glowshifts instructions. then call glowshift and they will send you a new sending unit for free in the mail. like i said ive been through 3 of them so i know the procedure by now

 

mark I have seen miss installed regulator springs dead heading the pump at just over 100 psi.
also as far as I know the frame mount pump is a ford deal. navistar uses a engine mount pump thats gear driven it is a combo unit with the powersteering pump

 

Thanks Moe!

I was not aware that International had a different fuel pump. I guess I just assumed that since the fuel filter pack was the same, so was the pump set-up. Good to know.

 

It just hit me Moe -

The International version of our 6.0L is the VT365. I just remembered a piece of advice I got a LONG time ago ......

The VT275 is the INTERNATIONAL "small truck" version of the VT365 w/ six cylinders instead of 8 - downsized by International. The fuel filters for this VT275 engine EXACTLY MATCH our 6.0L engine filters!!! If you specify fuel filter for the VT365 (even though this is actually the Ford 6.0L full size International 8 cylinder engine), it will be one filter AND, the wrong one at that. They will give you a Luberfiner filter, not Racor if you ask for a VT365.

 

Back to 80 today...ill be calling glowshift on monday