2004 challenger x fuel pump problems

[pwrobel]

need help please.
2004 challenger x with mercury 250 optimax.
has anyone had any problems with these?
my boat hesitates at 5000 rpm. and dies. and will not restart. checked system and found that there was no fuel pressure. seems like one of the low pressure pulling pumps is weak. I primed the fuel system and the boat started again.

I hope someone can help me.
thanks in advance

 

[Double07]

This sounds familiar, only that mine happened before I got to 5K RPM.
In my case, it was the lift pump between the fuel tank and the VST.
I have a clear fuel filter between the tank and the lift pump, so I was able to tell that the lift pump worked intermitently as the fuel filter is always empty whenever this happened.
It turned out that the wire connector on the pump was a bit loose, so while running, the motor vibration caused intermitent connection on the loose connector, and this caused the lift pump to cut in and out.

To fix this, I bent the pins on the male connector slightly in such a way that it was pressing against the metal in the female connector when plugged in.
I also replaced the anti syphone valve in the fuel tank with a regular barbed connector as I suspected it to be a bit restrictive to fuel flow.

With this, it never died on me again. I have been out plenty of times and it is still going strong.
I suggest you check the connectors on all 3 pumps and make sure they are not loose.
if that checks out ok, I will check to see if you have an anti syphone valve and if it is obstructing flow.

-Chika

 

[pwrobel]

thank you very much for your reply. I am not sure about this anti syphon valve?
do you know what kind of pressure that pump is supposed to put out?

 

[Double07]

thank you very much for your reply. I am not sure about this anti syphon valve?
do you know what kind of pressure that pump is supposed to put out?

If the fuel line going into the lift pump is completly restricted the pump vacuum should exceed 2.5 inches (mercury) if pump is still good. However under normal circumstances, the vacuum in the line between the fuel tank and the vst should be less than 2.5 inches. If it is at or above that, then you know you have some restriction in the line (either clogged fuel filter or anti-syphone valve).

There are a couple of other things to check/clean, but I would start with the simple things first. Make sure your connectorts to your pumps are not loose (3 pumps total). Then check out the lift pump and any restriction in the line between lift pump and fuel tank.
To test out the lift pump and line restriction, you will need a fuel pressure gauge (actually vacuum gauge), a T connector, and a clear fuel line that you can pinch off easily. connect the gauge as close as possible to the pump with the T connecot, and connect the clear fuel line from the T connector to the fuel tank. idle the engine for a few mins and observe the vacuum on the gauge (should be lower than 2.5 in if no restriction). Pinch off the clear fuel line, and the vacuum should rise to above 2.5 in. if pump is good.

If this comes back within spec, then we can then check other things in the fuel system (VST, high pressure pump, fuel rail/injector/regulator)
I will also recommend the mercury optimax service manual if you dont already have one. Comes in handy.

-Chika

The anti syphone valve is actually the barbed connector on the fuel tank where the 5/16 hose from the lift pump connects to. It has a ball and a spring in such a way that it allows flow in only one direction (out of the tank ) only when vacuum is applied in the line.