Hey guys - I was hoping to get some feedback on a low fuel pressure issue I've got.
I have an isspro gauge and did the blue spring about 5 years ago. Since then my fuel pressure is in the 65psi range.

Last week it dropped to 50-55 normal driving and I figured the HFCM was on it's way out (195,000 miles). Replaced the HFCM and the pressure was a bit higher, but not back to it's usual range. Then pulling the boat home from the lake a couple days ago, I saw it at 45psi. On a couple hills it went as low as 40 psi, so I was getting gripped...coasting downhill it only went back up to 50 psi and no higher. Got 'er home and currently not driving it.

In garage with Key On Engine Off, during injector buzz, I can hear a hissing/air noise at the upper filter bowl. Also, the bowl drains empty once the pump cuts off and the sound of air stops too. Ideas here??

I am hoping it's a regulator issue, but I don't know if they are known to wear out or go bad, or if something else in the upper filter housing went bad. So I ordered a new upper fuel filter housing which also has the oil filter tower attached and I'm assuming that these new units would come with the blue spring upgrade already done.

I can check for codes tomorrow when I bring my computer home from work, so I haven't checked for codes yet. I pick up the new filter housing tomorrow and will periodically check back here during the day tomorrow.

Also, while I'm at it: the new HFCM doesn't have the heater. Can I just leave the old connector from the harness un-connected to anything?

Thanks for the help, Dan

 

I just did the oil filter/fuel filter housing and mine didn't have the blue spring. No cover either you have to add it. All it came with was the standpipe for the fuel filter bowl and o-ring underneath. Have you checked the screens in the tank? I saw a DTR video about low fuel pressure and it was the 2 screens in the pickup assembly in the tank. Just an idea.

 

It is possible that the tank foot in the fuel tank has come apart and is clogging the pick up tube slightly. Did you notice any particles in the fuel filter when you pulled it out. What was the fuel level when you noticed the problem? Was it around a 1/4 tank?

 

I've heard that hissing once before and it was when I helped a friend do his blue spring and his regulator required the black bushing that comes in the kit and we didn't install the oring that goes between the black bushing and the fuel filter housing. Installed that oring and the hissing went away.

 

Okay - thanks guys.

I'm gonna keep my fingers crossed and hopefully it's a regulator issue.

I know they have a blue spring kit in stock because I was about to buy it.

I'll respond back with an update

 

I'd replace the blue spring with a new kit... don't rule out a bad gauge either.

 

I also have a new blue spring kit waiting at the dealership.

Is there a check valve anywhere at the upper fuel filter? Built in or separate?

I am keeping fingers crossed that the new fuel filter housing and blue spring kit will fix the issue of the fuel bowl draining empty at KOEO once the pump cuts off.

the banjo bolt at the fuel line trap below - does it have a check valve?

 

Once fuel leaves the bowl and is headed toward the banjo bolt on the front of each head, it can not return to either the bowl or the tank.

The return is on the bowl, once the pressure is attained, un-used fuel is directed/vented to the return going to the tank. Why I said a new kit should fix the issue.

 

Ok cool. thanks again

 

Just wanted to follow up. When I removed the cover on the fuel pressure regulator I saw this. Installed the new blue spring kit and problem solved. Back to 60-65psi.

 

Dang it I forgot to post on this the other night. I had one same issue except it was more random and was dropping to 35psi @ any more than 1/2 throttle.
Well, glad you got it. Here's what it looked like. Not as bad as yours looked.

 

Man that is wild that o'ring looks like that. Glad to see you got her whipped. Its always nice to find that "AHA" moment when you are looking for a the cause of a problem.

 

Yeah I was a little worried because honestly I haven't had to do any repairs in a while and I felt kinda rusty going in this time. I'm just glad I have the fuel pressure gauge or I never would've known there was an issue.