Having issues with idle psi. Interesting to say the least...

MrOneEyedBoh · Nov 17, 2013

Okay here is a run down. I bought the truck with 36k on it in Feb this year. Fast forward to early November this year. I installed the Edge Fuel pressure sender and FORD blue spring at the same time. I never checked stock fuel psi.

The fuel psi with the FORD blue spring was 59-60 idle and 51-52 WOT. The first weird thing was the PSI would get a FAST intermittent drop to 34-35 during WOT runs. So I thought maybe the HFCM was going bad ( due to the intermittent drop during WOT runs and lower than usual PSI's with the FORD blue spring ). So then I replaced it with a new HFCM today ( OEM ) . I primed it, got the air out etc etc. Still the same pressures as before, but NO drop during the WOT runs. Now the pressures are 60.5-ish idle and 52.3 at WOT sustained.

So I had a brand new International spring kit here and installed that to maybe bump up the idle psi. I thought there could have been a bad spring in the package or whatever. I installed the International spring and it bumped the damn idle to 100 psi. W T F..

So I then went back to the Blue FORD spring and its at 60ish again at idle.

Does anyone know WTF is up? Anyone on here have an Edge CTS with the ISSPRO fuel sender ( came with my Edge kit ) and is willing to try this International spring to see what their idle gets to?

Trqmnstr · Nov 18, 2013

I get an occasional sharp drop to the 30's in first gear WOT but it jumps back up to the mid 50's as soon as it hits second. Maybe my FICM is ****tin out.

I would also get spikes too 100 on my Glow**** gauge untill the sending unit took a dump completely. New sender and its all good, get a hold of isspro and see what ohms the sender is supposed to be without power and with power. Could be a bad sending unit.

MrOneEyedBoh · Nov 18, 2013

No I dont think the sender is bad. The ford spring gives me 60 idle and 52 WOT, the International was 100ish idle. I went back to the ford spring and well back to the 60 idle and 52 WOT.

Mdub707 · Nov 19, 2013

So what is it you're wanting to know? Sounds like your fuel pressure is fine with the blue spring installed right? Can you see a visible difference between your Ford Blue spring and the International spring? I thought these were cross reference P/N's. Suppose it could be out of a different engine though? Sure it was installed correctly?

MrOneEyedBoh · Nov 19, 2013

Yeah the international was 1-1.25 coils longer... The Ford spring was installed about 1 week ago, so I know it didnt compress that much in that short time span.

Im trying to find someone that would take this international spring and try it in their system to see if they get the 40psi idle jump like I did...

And Im positive it was installed correctly, thats the first thing I did was put the spring in the bucket on the cover ( it was already seated into the brass seat ) and then went in towards the housing and bolted it up.

Edited: The reason why I changed out the Ford spring was because my idle was only at 60 psi. Others were seeing that 70psi mark and I too wanted to be a bit higher to lessen the threshold of dropping too low with the fuel PSI at WOT.

Also worth noting ... Take a look at the included instructions in the International bag. They show a different regulator, same part number. What Im wondering is if this spring works in both our motor and whatever motor is depicted in that image. We know the Gillette spring is 100 psi, so maybe International is deeming that 100psi is okay? Dont know, just worth noting.

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Mdub707 · Nov 19, 2013

Raising the idle pressure likely wont change that drop you see under WOT. It fixes pressure issues, but can't make up for a volume issue. I wouldn't mind testing it in my truck... I've run that pressure on my veggie system for a while anyway.

That's the same P/N I have written down here too for a cross reference... hmmm Weird. I mean if the spring is longer that makes sense why the pressure was higher...

MrOneEyedBoh · Nov 20, 2013

Yeah. What PSI are you seeing at idle. Thats what Im concerned about, not the quick drop.

That 100psi idle is crazy lol

Gary · Nov 20, 2013

Ok, So you said " the international was 1-1.25 coils longer" , then they are obviously two different springs. To me, the Ford spring seems like your pressure is slightly lower then what I have seen, and the International is much higher... I don't know if that higher pressure is a problem or not.
Does the instructions with the International have any pressure specs?
What year is your truck? 03-04's have a plastic cup under the spring and I have seen a two trucks with low fuel pressure after the blue spring was installed and that plastic cup was the problem.

Mdub707 · Nov 20, 2013

I believe my idle pressure on diesel is around 68psi. I'm reading at the bowl. It can drop to around 50 or so when I hammer on it. Reading pressure at the back of the heads that 68 drops to 25 under WOT. Most people will never read back there though...

MrOneEyedBoh · Nov 20, 2013

My truck is an 06, so no plastic cup needed.

And yeah I have mine tied in at the test port on the fuel bowl. So you wanna throw this thing in there and see if you get a spike like I did? The International was 1-1.25 coils longer for me, hopefully the same for you.