Possible fuel pump problem?

[MEDIC151]

I don't know if this is the definition of vapor lock or not, but here is my problem. Out on the lake the other day for the first time and boat started and ran fine for the first hour or so. I tried to start it and it fired, ran really rough, then died and wouldn't start again. I got a tow back in.

I changed the fuel filter and took it back to the lake on sunday. Started fine so I thought it was fixed. Same scenario as above but this time I checked the valve stem looking thing at the fuel rail and vapor came out with very little liquid gas. The fuel pump was very hot and the motor temp showed just under 180. I left the cover open and let it cool to about 145 and depressed the valve stem at the fuel rail till all the vapor was gone and raw fuel came out. It started just fine and ran great. Put it on the trailer and took it home.

My question is this I guess.
Why would it start this after 3 years of running fine and starting fine with no change in the motor temp? Is this just a fuel pump issue like needing to be changed? Also, can I get a lower temp thermostat to put in also to help with the temp around the motor since the pump is so close to the block.

Any help is appreciated.

Thanks

Medic

[mmandley]

I don't know if this is the definition of vapor lock or not, but here is my problem. Out on the lake the other day for the first time and boat started and ran fine for the first hour or so. I tried to start it and it fired, ran really rough, then died and wouldn't start again. I got a tow back in.

I changed the fuel filter and took it back to the lake on sunday. Started fine so I thought it was fixed. Same scenario as above but this time I checked the valve stem looking thing at the fuel rail and vapor came out with very little liquid gas. The fuel pump was very hot and the motor temp showed just under 180. I left the cover open and let it cool to about 145 and depressed the valve stem at the fuel rail till all the vapor was gone and raw fuel came out. It started just fine and ran great. Put it on the trailer and took it home.

My question is this I guess.
Why would it start this after 3 years of running fine and starting fine with no change in the motor temp? Is this just a fuel pump issue like needing to be changed? Also, can I get a lower temp thermostat to put in also to help with the temp around the motor since the pump is so close to the block.

Any help is appreciated.

Thanks

Medic

Only thing i can think of that would have changed your fuel issues over the last 3 years is the addition of more ethanol.

As for changing the Thermostat to run the engine cooler, it would help but not like your thinking. All it would do it take the engine longer to each operating temp and such. The engine will still give off a very similar amount of residual heat.

I dont have any good ideas right now as to help prevent this issue. So fare it has been wide spread with boats 2 to 3 seasons old.

[xlvgg]

I have a 07 XLV. Last July I was at Lake Powell adn the first morning we put her in and went ahead of the house boat to look for a beach to park the house boat on. We ran for about 45 min cruising around. We went back to the marina and when the house boat was ready to leave the boat wouldn't start. I called my dealer and they told me to put a cold towel around the pump. I did and after a little while it started and ran fine. This happened again later in the day so I called a shop in Page, Bill and Tony's boat shop, awesome people. He worked on the boat late into the night and then early in the morning and had it all ready to go. He said that in the fuel line there is a safety ball that stops back flow into the fuel tank. He said it was wedged to tightly in the line so he loosened it a little. I thought he was going to charge me a ton. Not so 300 bucks. It has ran great ever since. Never have noticed the problem again.

[zabooda]

It's the gas. The way gas is blended seems to change each year. People are having problems with messing systems up after leaving the gas in for a few months even with Stabil. I did find this website to be interesting:

http://www.randakks.com/TechTip56.htm

[MEDIC151]

So if I drain the tank and put in fresh gas this will fix it? I guess provided the backflow is not messed up also. I am still running on the fuel from last seasons winterization which was a full tank and stabil. I just can't see why it is vaporizing the fuel in a contained area under pressure. I guess that will be a cheaper fix to start with.

[zabooda]

The people I'm seeing having fuel problems are draining the tank and using Seafoam. I'm not sure what that is but it appears to clean the parts.

[gcnettl]

If you have a fuel/water separator, this is suspect to vapor lock. I'm not sure of the specs on the fuel pressure, but you may buy or use a loaner fuel pressure gauge from auto zone to check your fuel pressure at that valve.

However, you should get fresh fuel when you depress that valve anytime after running. Maybe your pump is getting hot and not working?

As far as the thermostat, I would not recommend changing it or running without, as it brings your trans fluid up to operating temperature as well as maintaining engine temperature.

[MEDIC151]

I know the fuel pump is getting hot, but I can hear it charge the line everytime I turn the ignition on. It just seems to me that somewhere after the pump and before the fuel rails, it is vaporizing and not allowing the injectors to open. As soon as the vapor is released, it starts right up and runs fine.

Thanks for the suggestions, keep em coming. Hopefully I will get this resolved and let everyone know the fix just in case this happens to someone else.

[gcnettl]

Fuel Pressure Regulator Test
This test checks the operation of the fuel pressure regulator to make sure it changes line pressure in response to changes in engine vacuum. This is necessary to maintain the proper operating pressure behind the injectors and to compensate for changes in engine load.

With the engine running, disconnect the vacuum hose from the pressure regulator. As a rule, fuel system pressure should increase 8 to 12 psi with the line disconnected. No change would indicate a faulty pressure regulator, or a leaky or plugged vacuum line.

If the diaphragm inside the regulator is leaking, engine vacuum will suck raw fuel into the intake manifold through the vacuum hose (look for fuel inside the hose).

http://www.boatfix.com/merc/Bullet/99/99_07.pdf - For mercruiser engines, but same principle.



Supra recommends that after running, in other words once engine has ran and has become hot, normal operating temperature, to not suddenly kill it but rather let it idle for a little bit, blowers on. After killing engine, leave blowers on while sitting. This greatly lowers the engine compartment temperature, thereby cooling everything in it.

Indmar makes a two pump system to solve this, if it gets to that.

Winter fuel has a different volatility than summer fuel. In other words, gas supplied in the winter is more volatile than gas supplied in the summer. This is for better starting in the winter, among other reasons. There is a rating assigned to this, TPV. So, if you have winter gas, in other words, the gas you filled it with when winterizing in the fall, then this gas is more volatile than summertime gas. This winter gas will vaporize more quickly than summer gas. Additives in gasolines also change volatilities in fuel. Additives are constantly changing, so what might not have been a problem last year, could be a problem this year.

Location of the fuel filter can also affect the temperature of the gas before it reaches the fuel rail, or if the pump is not located in the tank, then the gas before it reaches the fuel pump. In other words, a fuel filter would be better placed near the tank, not in the engine compartment.

As your boat is out in the heat of the day, the fluids inside of it warm, as well as fuel in the tank. This affects vaporization.

I feel your problem is only vapor lock, and if you follow the instructions on cooling down your engine and using your blowers, and getting fresh gas, the problem will be solved.

If you wanted, I don't really see where it would hurt for maybe a 170 or 160 temp thermostat swap. These engines are designed to operate in that range, 165 to 180, along with the trans. This would lower temperature as well.

The fuel rail is very suspect to get hot, and combined with other conditions, the fuel there can be really hot.

[MEDIC151]

Thanks, I think that is the problem exactly. I am going to drain the tank and replace the fuel. If that doesn't work, I'll move on to the next solution. The fuel filter is right by the tank, so I don't think that it is affected as much by the heat as the rails are. I'll keep everyone updated with the results.