Fuel pressures

[Amhochb]

Hi there experts,
Anyone know what would cause my low pressure fuel pump pressure to run at 23psi instead of 8ish? High pressure running at a steady 55psi
Thanks for any info
I should add the screen to the inlet of the high pressure pump appears ok.

[billk2632]

Have you looked at the "Man Cave Mechanic" videos on youtube? He goes into some pretty good detail on how to check pressure, check the regulator and pump housing for paint chips. I know you checked your regulator (that will cause high pressure on the high pressure pump), did you pull the pump itself out and check the pickup screen on the bottom of the pump? I think that is where the low pressure pump would be high. Also, is the pump making noise or having a problem, or are you just checking things out?

[Amhochb]

I have seen his videos and I’ve emailed back and forth with him. He seems to be a pretty nice guy and knows these fuel systems well. He thinks maybe my float in the fuel chamber is stuck closed which he says would cause high pressure on the low pump.

I did pull the high pressure pump and looked in its screen which from what I can see is not clogged.
I started looking into this because once the boat reaches operating temp it was idling pretty erratic. Not wanting to die but not very stable.

[billk2632]

Dirty IAC / throttle body? Assuming it runs fine above idle.

[Big Block Power]

Does your idle just surge? What engine and year?

[Amhochb]

It’d go from normal to low back to normal and just keep doing that. Never really wanted to die.

Since posting this, I’ve changed the spark plugs, wires, cap, rotor, fuel filter and cleaned the hell out of the throttle body. It also had about 1/3 tank of gas I had no idea how old it was in it. I threw a can of sea foam marine and topped it off. @CBO and I took it for a test run yesterday only to find (on the ramp about 5 feet from the water) the gasket around the fuel sender was failing. Ran it back home swapped it out and made it back out for a test. Ran absolutely perfect. I wish I knew what actually fixed it but our best guess is, we were fighting bad gas. Thanks for all the input.