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ecj

fuel rail valve

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ecj

Does anyone know if the shraeder valve on the fuel rail is "special" as it is in the fuel system? Or is a run of the mill "Air" type valve. Thanks.

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Pistol Pete

The valve itself is a common schrader valve. Any "air type valve" tools will fit it. However, if you plan on pulling the core out, the seal on it is special to deal with gas.

What's your real question?

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ecj

The valve itself is a common schrader valve. Any "air type valve" tools will fit it. However, if you plan on pulling the core out, the seal on it is special to deal with gas.

What's your real question?

Thanks for the quick reply, I seem to be getting air in my fuel system. The know shraeder valve is an unlikley candidate as fuel would probably spray out, but if it is an easy elimination I would replace it. I have had surging rpm and have replaced alot. Fuel pick-up, fuel hoses, fuel pump, fuel filters, pressure regulator, injectors cleaned, new ECM, plugs, cap, rotor, wires.

I know that's a long list, it got better, the rpm band that it will not hold now is 2900-3100, (it used to be in 1800-2200, 2800-3200, and other transient bands.) When the fuel system is bled, it runs perfectly. We are bleeding it by porting fuel via a pressure guage which is attached to fuel rail while underway.

Monsoon II, 99 sunsetter VLX

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Marine Specialty

From my understanding of fuel systems the schrader is under pressure so fuel would come out the valve if it was leaking. I would look at the throttle position or the map sensors. They could be faulty and giving the ecu a false reading. Just a thought.

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ecj

From my understanding of fuel systems the schrader is under pressure so fuel would come out the valve if it was leaking. I would look at the throttle position or the map sensors. They could be faulty and giving the ecu a false reading. Just a thought.

Thanks for the input, I forgot to add that to the litany, I replaced TPS and MAP sensors, the search continues!

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Bake's Marine

Thanks for the quick reply, I seem to be getting air in my fuel system. The know shraeder valve is an unlikley candidate as fuel would probably spray out, but if it is an easy elimination I would replace it. I have had surging rpm and have replaced alot. Fuel pick-up, fuel hoses, fuel pump, fuel filters, pressure regulator, injectors cleaned, new ECM, plugs, cap, rotor, wires.

I know that's a long list, it got better, the rpm band that it will not hold now is 2900-3100, (it used to be in 1800-2200, 2800-3200, and other transient bands.) When the fuel system is bled, it runs perfectly. We are bleeding it by porting fuel via a pressure guage which is attached to fuel rail while underway.

Monsoon II, 99 sunsetter VLX

Air in the system can only get introduced before the fuel pump, after the fuel pump (the rail, schrader valve, regulator, etc) are under pressure so if you had a leak you would be leaking fuel at that point.

I would be suspect to a loose hose clamp, fitting or filter somewhere on your supply line since it is under suction and can bring air into the system. I would start at your pump (mounted right above your oil filter) and work your way back. I've seen the fuel filter rot out (from water) and make little pin holes in the filter before. So make sure both of your fuel filters have been serviced. Fuel Filter #1 Fuel filter # 2

You also have the dreaded check ball valve at the fuel tank main supply fitting. Inside the fitting there is a check valve and a spring that is notorious for gumming up and creating cavitation issues in the fuel because they don't open all the way (creating air bubbles in the air line) As a dealer we can't remove them because they are a coast guard regulation, but as a owner of the boat Whistling.gif

Hope this helps you out.

-Paul

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ecj

Air in the system can only get introduced before the fuel pump, after the fuel pump (the rail, schrader valve, regulator, etc) are under pressure so if you had a leak you would be leaking fuel at that point.

I would be suspect to a loose hose clamp, fitting or filter somewhere on your supply line since it is under suction and can bring air into the system. I would start at your pump (mounted right above your oil filter) and work your way back. I've seen the fuel filter rot out (from water) and make little pin holes in the filter before. So make sure both of your fuel filters have been serviced. Fuel Filter #1 Fuel filter # 2

You also have the dreaded check ball valve at the fuel tank main supply fitting. Inside the fitting there is a check valve and a spring that is notorious for gumming up and creating cavitation issues in the fuel because they don't open all the way (creating air bubbles in the air line) As a dealer we can't remove them because they are a coast guard regulation, but as a owner of the boat Whistling.gif

Hope this helps you out.

-Paul

Thank you for your input, I was out of town and didn't see your response until today. That does help, I will look at the fuel shutoff valve. I replaced the fuel lines, filters and pump, a mechanic started on it replaced the fuel pick-up and I don't know if he did anything with the shutoff, it was mentioned. Last time we lake tested it, replacing the shraeder valve had no effect, but just attaching the fitting for a pressure guage and not even attaching the guage itself on the fuel rail, smoothed it out, (the fitting depressed the fuel rail shraeder and included approx 4" of hose), I am thinking it was acting as an air accumulator. The strange thing, if it is air in the fuel system, would it make it run poorly in all ranges, or could it affect a small band like I now have, namely 2900 to 3100 rpm?

Thanks again for the suggestions.

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