F225 TXRC bogging down - fuel rail pressure question

[99yam40]

I am thinking that something like that could leak very easy and cause the motor to catch on fire

[boscoe99]

I am thinking that something like that could leak very easy and cause the motor to catch on fire

Why is that?

[Crazy Train]

myself I would test the rail pressure at the RPM and LOAD when it fails.
otherwise the test is a teat on a boar hog.
that vacuum sense line on the regulator allows for about 5PSI more rail pressure at or near WOT or when rapidly accelerating.

Rodbolt: Agree: my first entry where I quoted RPMs and fuel rail psi was underway/under load...NOT in neutral. So, the at-load at RPM, from 2000 to 4200 RPM, rail pressure was 48 psi. Thanks.

[99yam40]

Why is that?

As an aside, it would be nice if the VST could be modified with maybe a 1 inch diameter side access 'hatch', like a screw on gas cap, level with the HP pump filter so that the filter and VST interior could be inspected without ripping the VST off the engine.

I would think anything below the liquid level like a gas cap has a very good possibility of leaking liquid fuel

[fairdeal]

I it would be nice if the VST could be modified with maybe a 1 inch diameter side access 'hatch', like a screw on gas cap, level with the HP pump filter so that the filter and VST interior could be inspected without ripping the VST off the engine.

Anybody else remember the Holley "Visi-flow" used on Fords and IHCs?

[boscoe99]

The HP pump filter does not really need to be within the VST.

Gasoline initially entering the VST has been filtered by the primary fuel filter. That gasoline having normally already having been filtered by a boat mounted water separating fuel filter.

The HP pump filter I suppose it to try and capture any contaminates that have gotten into the fuel system either from the pump itself or down stream from the pump. An external filter could be mounted adjacent to the VST to filter any bypassed gasoline that needs to re-enter the VST.

Were I the engineer that is the way I would do it. But if I owned the company there would no VST installed at all.

[boscoe99]

Anybody else remember the Holley "Visi-flow" used on Fords and IHCs?

I also remember glass bowl gascolators.

[TownsendsFJR1300]

Anybody else remember the Holley "Visi-flow" used on Fords and IHCs?

I don't remember the above carb but Holly and others DO have a see thru "plug" (approx 1" across) for adjusting the float level correctly(with the carb installed), see below.

For the OP, did you drain the VST and see if any crap came out?

Should be one screw on the bottom and a hose connected. Obviously catch what comes out in a small clean container.

I'll drain mine occasionally AND prime the bulb to push fuel thru it for inspection/flush..


.

[Crazy Train]

I don't remember the above carb but Holly and others DO have a see thru "plug" (approx 1" across) for adjusting the float level correctly(with the carb installed), see below.

For the OP, did you drain the VST and see if any crap came out?

Should be one screw on the bottom and a hose connected. Obviously catch what comes out in a small clean container.

I'll drain mine occasionally AND prime the bulb to push fuel thru it for inspection/flush..


.

I did drain the VST into a separate cup: no visible crap. I have a screw on the side but not a place to connect a hose. I use a 6 inch long 'chute' that drains into the cup. I did not pump the bulb to push the gas through since I was by myself and had to hold the cup, but will do that next time with help.

For VST access, I was also thinking of 1 inch diameter tube, threaded on the outside, that is capped off with a female cap similar to a wide-mouth oil container, but that visi flow window would be perfect - clear to see in AND access to suction off the HP pump screen and VST bottom.

Thanks!

[99yam40]

those float chambers are not under pressure like the VST is.

[TownsendsFJR1300]

those float chambers are not under pressure like the VST is.

The VST isn't under pressure(not much to speak of till the float shuts off the needle valve)... It's got a needle and float and a vent:

2004 F225TXRC Yamaha Outboard FUEL INJECTION PUMP 1 Diagram and Parts



Maybe a misunderstanding, or I missed something..

[TownsendsFJR1300]

For VST access, I was also thinking of 1 inch diameter tube, threaded on the outside, that is capped off with a female cap similar to a wide-mouth oil container, but that visi flow window would be perfect - clear to see in AND access to suction off the HP pump screen and VST bottom.

Once the VST is clean, you shouldn't have to go in there again (any time soon) with proper filter changes, etc...

I've never changed /checked the VST filter on my engine (original owner) but I keep after exterior filters, drain the VST on occasion and use fuel additives (Non-ethanol fuel too).

BTW, it has been mentioned in previous posts you can spray carb cleaner up the drain in the VST. Wether the spray would actually hit the filter, dunno for your engine. Probably couldn't hurt(and easy too).

.

[99yam40]

The VST isn't under pressure(not much to speak of till the float shuts off the needle valve)... It's got a needle and float and a vent:

\ Maybe a misunderstanding, or I missed something..

I am under the impression that the VST is not open to outside air until a relief valve opens. fuel in VST does not evaperate away like a carb bowl

[pstephens46]

I am under the impression that the VST is not open to outside air until a relief valve opens. fuel in VST does not evaperate away like a carb bowl

Interesting. Not sure what vents when it is being filled. There is a break "valve" to vent to intake. 10 psi according to Fairdeal.

At any rate, not that big a headache to remove VST to clean. Now those little screws and funky gasket can be aggravating.

[boscoe99]

In most Yams the VST is vented to the atmosphere via the charcoal cannister in the vapor recovery system.

I seem to recall some early models not using the vapor recovery system simply vented the VST directly to the atmosphere.