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We have a nautique sv211 with 330 Excalibur motor. We have been having reduced fuel pressure after varying run times. The boat will perform amazing for an undermined amount of time. Sometimes it’s 5 minutes, other times it’s 15 minutes then fuel pressure drops from 60 psi to 30 psi and sometimes lower. Which reduces drive ability and rpm’s. After which the boat will be sluggish and intermittent. If the boat is keyed off and the pumps are reprimed the problem goes away but then comes back 5-10 minutes later. I have replaced the entire fuel system(high and low pressure pumps, check valve, hoses,filters, fuel pressure control valve, new injectors and cleaned fuel rail) also drained acetoneed and refilled the gas tank with high grade gasoline. The problem persist.
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Ok. So you confirmed a pressure drop. Did you dye test for leaks? Also, how is the pickup tube inside the FCC? -
The tube inside fcc is in good condition strong no cracks no soft spots no fraying. I have not tested with dye, thinking that if it were leaking I would not have an intermittent issues that happen with no consistent trigger. Like it’s not at exactly 4000rpm or when pushing down the throttle. It holds pressure for sometimes up to 30 mins.Comment
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Probably not but leak is the next easiest thing to address so it needs to be ruled out.Comment
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Some things you can try to help narrow down the issue. I use a small auxiliary fuel tank to help diagnose issue like this. My tank is rigged up with it's own fuel pump and an adjustable fuel pressure regulator. For PCM engine with a FCC, I set the regulator to 5 psi and connect the tank to the input of the FCC. If the problem goes away, then I know the issue is before the FCC. If not, then the issue is after the FCC.
Using the same auxiliary tank, set the pressure regulator to 60psi and connect it directly to the fuel rail. See if the problem still occurs. If so, it's most likely a problem with the fuel pressure regulator. But it can also be an issue with an injector staying open. Which can be an injector issue or an electrical issue relative to the power feeding the injector(s).
Another way to determine you have a regulator issue, is to disconnect the fuel return line from the pressure regulator and use a temporary line to feed the return line into a suitable container. I use my portable tank. Watch the flow of excess fuel as your run the engine. When the problem occurs, if you get an increase in return volume, then something isn't right with the pressure regulator.
If you post back what you see with these tests, I may be able to suggest further things to check.Comment
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