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Yamaha F115TXRC Starting Problem

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scott046

New member
Reaching out to anyone who can help shed some light on a recent problem I've encountered with my old friend the Yamaha F115TXRC model. Recently the engine created a rough idle and eventually wouldn't start.....after checking the fuel lines and replacing the separator I was able to get it started again and it ran fine for a 30 minute run home WOT.....after putting the boat on the lift, still in the water, I tried to start it again with no luck.....so I proceeded with the following steps and results:

1) Changed the Low Pressure fuel pump first off.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
2) Spark Plugs checked/replaced....not real bad but replaced none-the-less...in line fuel filter replaced inside the bottle....mid line fuel filter replaced between the Low Pressure pump and the VST....and the thermostat was replaced....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
3) Replaced the IAC and the Fuel Pressure Regulator the next day.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
4) Removed and thoroughly cleaned the VST, replacing the High Pressure fuel pump and cleaning the needled points etc.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
5) Replaced several runs of fuel line and the bulb.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
6) Injectors pulled during VST cleaning and the injectors got a thorough home style cleaning, one was plugged and cleaned out nicely....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem.....yes, I have thrown enough parts at it and am seeking support and any ideas before I throw anything else at it...

Does anyone have any ideas on what else should be checked or replaced? Why would it run so great after anyone service task and then limp out and fail to start again after sitting 15 minutes....any help appreciate.....Thank you.
 
scott046 said:
Reaching out to anyone who can help shed some light on a recent problem I've encountered with my old friend the Yamaha F115TXRC model. Recently the engine created a rough idle and eventually wouldn't start.....after checking the fuel lines and replacing the separator I was able to get it started again and it ran fine for a 30 minute run home WOT.....after putting the boat on the lift, still in the water, I tried to start it again with no luck.....so I proceeded with the following steps and results:

1) Changed the Low Pressure fuel pump first off.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
2) Spark Plugs checked/replaced....not real bad but replaced none-the-less...in line fuel filter replaced inside the bottle....mid line fuel filter replaced between the Low Pressure pump and the VST....and the thermostat was replaced....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
3) Replaced the IAC and the Fuel Pressure Regulator the next day.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
4) Removed and thoroughly cleaned the VST, replacing the High Pressure fuel pump and cleaning the needled points etc.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
5) Replaced several runs of fuel line and the bulb.....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem....
6) Injectors pulled during VST cleaning and the injectors got a thorough home style cleaning, one was plugged and cleaned out nicely....engine ran great again for 20-30 minutes and after stopping and killing the engine multiple times it started right up.....but after shutting the engine off for about 15 minutes it would crank but wouldn't turnover/start again....also when trying to start after a 15 minute off period, the bulb was slightly soft and not as hard when as it was when I first started the engine w/o a problem.....yes, I have thrown enough parts at it and am seeking support and any ideas before I throw anything else at it...

Does anyone have any ideas on what else should be checked or replaced? Why would it run so great after anyone service task and then limp out and fail to start again after sitting 15 minutes....any help appreciate.....Thank you.
Click to expand...

One additional note to consider to the long list of repair attempts. I DID NOT replace the external intake filter located just above the VST tank.
 
Which "separator"did you replace? And I'm assuming you have a nice big Racor or equivalent diesel-type water separator fuel filter somewhere in the fuel line between the tank and the motor?

Also assume you've cleaned any water out of the fuel filter at the left rear of the engine? I'm assuming one's there since my 2007 F115TXR has got one there; and if it fills enough with water you'll get a constant dribble of water to the injectors. If you don't have a big water separator as I mentioned, just the engine ones, that can tend to mess everything up and a system like you have gave me the symptoms you're describing until I put a big Racor water separator in the line from the tank to the motor.

If you've got water in your tank because there was a leak or simply because you got some ethanol gas by mistake, it's hygroscopic as all get-out (means it sucks water into the gas right out of the air!). You could have a bunch of water in your fuel tank, and that's really the problem: you keep running water/gas into your motor.

I don't know about all the parts you're replacing, but I DO know that if you get the engine revving high enough (you're saying WOT running is OK, right?), then it'll burn a small amount of water coming in with the fuel and not sputter a bit. Mine did. It had the exact symptoms you're describing.

When you start the engine cold, any water in the fuel filter/separator has SEPARATED so that the gas is on top and the water at the bottom. That's why it starts when it's cold, but doesn't after turning it off for 15 minutes; because it's still HOT then. I think maybe after 15 minutes, the engine is still so hot that the water in the filter/separator is kind of "mixed" with the gas. Engines don't bang over on that mixture.

When you perform one of the repair actions you described, the motor is cold the next time you start it, and starts because the gas has separated and floated to the top of the water in the filter; it's not mixed with the water yet. The water will come in in a while, and mix with the gas, but your motor can handle a small dribble of water with the fuel IF IT'S ALREADY WARM.

I learned the hard way by just relying on the engine water filter/separator that it can work this way. Put on a big Racor, and found I had a LOT of water in my ethanol-horsemanure fuel. Drained the water out of the Racor (frequently, big visible bowl so it's easy to see how much water you've got in your separator), burned my way through that tankful, then never again filled with ethanol; ethanol-free all the way now!

Check it out; this happened to me.

With Warm Aloha, Tim
 
Thank you Tim - appreciate the reply and will again review fuel quality and consider clean tank and starting with pure Rex fuel
Kaimana said:
Which "separator"did you replace? And I'm assuming you have a nice big Racor or equivalent diesel-type water separator fuel filter somewhere in the fuel line between the tank and the motor?

Also assume you've cleaned any water out of the fuel filter at the left rear of the engine? I'm assuming one's there since my 2007 F115TXR has got one there; and if it fills enough with water you'll get a constant dribble of water to the injectors. If you don't have a big water separator as I mentioned, just the engine ones, that can tend to mess everything up and a system like you have gave me the symptoms you're describing until I put a big Racor water separator in the line from the tank to the motor.

If you've got water in your tank because there was a leak or simply because you got some ethanol gas by mistake, it's hygroscopic as all get-out (means it sucks water into the gas right out of the air!). You could have a bunch of water in your fuel tank, and that's really the problem: you keep running water/gas into your motor.

I don't know about all the parts you're replacing, but I DO know that if you get the engine revving high enough (you're saying WOT running is OK, right?), then it'll burn a small amount of water coming in with the fuel and not sputter a bit. Mine did. It had the exact symptoms you're describing.

When you start the engine cold, any water in the fuel filter/separator has SEPARATED so that the gas is on top and the water at the bottom. That's why it starts when it's cold, but doesn't after turning it off for 15 minutes; because it's still HOT then. I think maybe after 15 minutes, the engine is still so hot that the water in the filter/separator is kind of "mixed" with the gas. Engines don't bang over on that mixture.

When you perform one of the repair actions you described, the motor is cold the next time you start it, and starts because the gas has separated and floated to the top of the water in the filter; it's not mixed with the water yet. The water will come in in a while, and mix with the gas, but your motor can handle a small dribble of water with the fuel IF IT'S ALREADY WARM.

I learned the hard way by just relying on the engine water filter/separator that it can work this way. Put on a big Racor, and found I had a LOT of water in my ethanol-horsemanure fuel. Drained the water out of the Racor (frequently, big visible bowl so it's easy to see how much water you've got in your separator), burned my way through that tankful, then never again filled with ethanol; ethanol-free all the way now!

Check it out; this happened to me.

With Warm Aloha, Tim
Click to expand...
 
Thanks again Tim - I replaced the primary fuel separator and have even tried running the engine off an external fuel tank after cleaning out the separator to ensure no fuel was contaminated - unfortunately, the same problem exists, runs great for 10-15 minutes but after warm up she becomes fuel starved and I can't isolate what's causing this problem - could it be electronical (maybe the relay)?

Kaimana said:
Which "separator"did you replace? And I'm assuming you have a nice big Racor or equivalent diesel-type water separator fuel filter somewhere in the fuel line between the tank and the motor?

Also assume you've cleaned any water out of the fuel filter at the left rear of the engine? I'm assuming one's there since my 2007 F115TXR has got one there; and if it fills enough with water you'll get a constant dribble of water to the injectors. If you don't have a big water separator as I mentioned, just the engine ones, that can tend to mess everything up and a system like you have gave me the symptoms you're describing until I put a big Racor water separator in the line from the tank to the motor.

If you've got water in your tank because there was a leak or simply because you got some ethanol gas by mistake, it's hygroscopic as all get-out (means it sucks water into the gas right out of the air!). You could have a bunch of water in your fuel tank, and that's really the problem: you keep running water/gas into your motor.

I don't know about all the parts you're replacing, but I DO know that if you get the engine revving high enough (you're saying WOT running is OK, right?), then it'll burn a small amount of water coming in with the fuel and not sputter a bit. Mine did. It had the exact symptoms you're describing.

When you start the engine cold, any water in the fuel filter/separator has SEPARATED so that the gas is on top and the water at the bottom. That's why it starts when it's cold, but doesn't after turning it off for 15 minutes; because it's still HOT then. I think maybe after 15 minutes, the engine is still so hot that the water in the filter/separator is kind of "mixed" with the gas. Engines don't bang over on that mixture.

When you perform one of the repair actions you described, the motor is cold the next time you start it, and starts because the gas has separated and floated to the top of the water in the filter; it's not mixed with the water yet. The water will come in in a while, and mix with the gas, but your motor can handle a small dribble of water with the fuel IF IT'S ALREADY WARM.

I learned the hard way by just relying on the engine water filter/separator that it can work this way. Put on a big Racor, and found I had a LOT of water in my ethanol-horsemanure fuel. Drained the water out of the Racor (frequently, big visible bowl so it's easy to see how much water you've got in your separator), burned my way through that tankful, then never again filled with ethanol; ethanol-free all the way now!

Check it out; this happened to me.

With Warm Aloha, Tim
Click to expand...
 
Put a fuel pressure gauge on it run it, get it hot, shut it down, let it sit then check the fuel pressure when you try to start it.... If it is a "no start" purge the fuel from the gauge and see if it starts.

Stop throwing parts at it.
 
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