df 175 cutting out at 1,700 rpms and up

[TSMBC277]

I have a 2008 df175 motor cutting out with 1 inch of air in top of inline filter canister. my port df175 has only about 1/8 inch of air at the top of its inline filter canister and runs fine. I have replaced the fuel line from racor fuel filter,primer bulb with oem bulb, switch low pressure fuel filter from the port motor and still have starboard motor cutting out at 1700 rpm+ Is there supposed to be some air bubbles and a 1 inch air gap in top of filter canister? I also have 90 gallon aluminum gas tank for each motor and switched fuel lines from the port to the starboard with same cutting out problem. I cannot find the tank vent. I was told that some tank manufacturer's don't install them anymore due to moisture getting to the ethanol gas and causing water fuel seperation. I was on ethanol gas but drain all that out and put 90 octane non ethanol gas in and still cutting out. someone said that the tank anti siphon valve could be sticking and causing a vaccum in the line . Need some help

[Harper]

You cannot substitute the S3212 for the S3213. The S3212 has 1"-12 threads, and the S3213 has 11/16"-16 threads.

So as I understand it, you have the 1" airspace at the top of the Racor filter and not the low pressure filter on the engine? In any case, you indicate that you've switched tanks, etc, between the two engines, which I assume means that by doing so, you also switched inline fuel filters, so it sounds to me that you're problem has to do with something in the engine itself rather than the fuel system. Have you done any investigating of the VST in the faulty engine? I'd start there. Check your fuel pressure at the rail, the float in the VST, needle and seat, and high pressure pump. And you haven't mentioned any fault codes....no alarms or flashing lights?

Might also pull the intake manifold for and see that all your plastic VSV shut-off valves are in place. There's been a number of folks reporting that they come off and are ingested by the engine, or get stuck in the intake valve areas. Seems like something like that would have issues at all RPMs, but who knows?

[TSMBC277]

starboar motor skipping at low rpms

does the plastic inline filter canister on the df175 located in the back of the motor supposed to have air in the top section. I have about 1 inch air gap and some small bubbles coming in from the fuel line. Is this normal and could this cause a problem My port engine has about 1/8 inch air gap and runs fine. The only fuel line I have not replaced is from the primer bulb through the motor compartment to the plastic inline filter canister. is this fuel line 5/16 inch and is it a oem part? Also I found a black round washer/spacer? stuck on the bottom of one of the spark plugs and had to dig if off the base of the plug with a long wire hook. Is this a resistor at the base of the plug? none of the other plugs had this stuck on the plugs. The 4 inch rubber plug wire boot has a metal spring contact at the upper end of the boot and this spacer/washer/resistor? is at the base of the plug. is it required? could it cause arcing at the bottom of the boot or is a spacer? what is this. I don't think the port motor has them on the plugs

[Harper]

Now that I've answered your question about the Racor fuel filters, how about taking it out of your signature block? It's confusing to see it there, as if you wanted an answer.

There should not be bubbles entering the low pressure fuel filter. Check htose fuel lines especially prior to the low pressure pump, and pull the low pressure pump and check it out. Might be a loss of seal between the pump body and the top piece that is attached with, I think, 4 screws. You probably can't fix the pump, only replace it.