350 mcx issue - advice would be appreciated

(wickedforce) · (wickedforce) **Join Date: Oct 2007** 10-21-2010, 11:56 AM

Hey guys, Kyle here from South Africa. I read this forum all the time, dont comment too much but realise this is the place to be to get any info or questions answered. Was wondering if any of you could help me out.

I have a 2006 X1. The fuel pump packed up 6 months ago. Its the 350MCX, only has 170 hours on. I replaced the impellers every 50 hours but have not yet replaced the plugs. Anyway, once I replaced the pump, the engine starts up when its cold, but when its warm and I switch off, it just turns over and does not fire up. However when the engine is running its not missing at all and sounds super healthy.

There arent too many qualified mechanics down south and any advice would be appreciated.

Shot,
Kyle

(tailgate) · (tailgate) **Join Date: Apr 2007** 10-21-2010, 12:54 PM

Possibly Vapor lock?
http://en.wikipedia.org/wiki/Vapor_lock

People with my boat (08 'ba LSV) have complained that it happens, they can pour water on the fuel filter and that will resolve it... Ive never had it happen though.

(shawndoggy) · (shawndoggy) **Join Date: Nov 2009** 10-21-2010, 2:03 PM

Had a similar experience with my malibu this spring. Thread here: http://www.themalibucrew.com/forums/...an-hour-today/

I'd suggest reading through that for some troubleshooting guidance.

My problem ended up being related to a low voltage condition. Voltage was good enough to turn over the motor, but not good enough for the ecu to tell the motor to fire.

(hco) · (hco) **Join Date: Jun 2006** 10-21-2010, 2:21 PM

It shouldn't be vapor lock, the fuel pump is inside of the tank.

(brucemac) · (brucemac) **Join Date: Dec 2005** 10-21-2010, 2:32 PM

i would post your question on mastercraft teamtalk if you haven't already. someone there will be able to help you trouble-shoot.

it almost sounds like you have the wrong replacement pump installed or possibly you are having issues with the pump again. did you replace this yourself? if so did you replace the entire pump module/canister or just the pump inside the canister itself? i've read of some folks who've replaced just the pump and have had issues with the flex tube line that runs from the pump to the regulator. i've also heard of folks installing the wrong fuel pump and having psi issues for a given motor; i.e., not enough PSI to the fuel rails.

(rektek) · (rektek) **Join Date: Aug 2005** 10-24-2010, 9:48 PM

put a fuel gauge on that rail and let us know what you see ?

(njskier) · (njskier) **Join Date: Jul 2005** 10-31-2010, 8:47 PM

IF you're having the hot-start problem with less than 1/2 tank of gas your fuel pump could be getting hot. Did you change the fuel filter when the pump was changed? The fuel filter only comes into play when the tank is low on fuel (less than 1/2 tank) If you sometimes run your tank low on fuel it can shorten the life of your fuel pump. Check your fuel pressure when it acts up and doesn't start. You may need a fuel pump again or perhaps just the filter.

(njskier) · (njskier) **Join Date: Jul 2005** 10-31-2010, 8:50 PM

One more thing to check when it doesn't start is your kill switch (lanyard)
Try to wiggle it when it won't start....they have been known to go bad sometimes.

(wickedforce) · (wickedforce) **Join Date: Oct 2007** 11-02-2010, 4:47 AM

Hey Guys, thanks for all the info and various items to check. In the end it was Bruce Mac who was 100% correct. I had gone to the local automotive shop and bought a similar submersible pump with the same PSI. but was the wrong thing to do.

Changing the entire pump module solved all the problems. Now running like it was new. Bring on the summer.

Thanks again.
Kyle