V6 EFI water cooled fuel pump

[J&K]

have a 2003 Larson with a V6 EFI , it has a water cooled fuel pump.
Only 170 hours and pump failed , It would only pump enough to barely idle. After we let it cool down it finally started after many tries. We could hear the difference in the fuel pump as it finally supplied fuel pressure.
I have heard there is a problem with these water cooled fuel pumps & also a problem with the fuel system becoming vapor locked when its run hard and hot.
Does any one know of this problem.merc says they only sell the pump with the cooler as its an upgrade?
Not only does it cost a lot, its a bugger to remove from the location under the engine.
Jeff

 

[Don S]

Re: V6 EFI water cooled fuel pump

Mercs have had a couple of different kinds of fuel coolers. Got a SN, as they really don't go by year.

 

[J&K]

Re: V6 EFI water cooled fuel pump

0M365650
thanks
Jeff

 

[Don S]

Re: V6 EFI water cooled fuel pump

You have a fuel cooler, it isn't a fuel pump cooler. It only cools the fuel going to the pump.
Is it really that hot inside the engine compartment that it could cause a vapor lock? If it is, You really need to get some ventalation to it, or cool the engine down. How hot is the engine running?
You could have a simple fuel blockage from the tank or even an air leak somewhere which would appear to act like a vapor lock, but isn't. It would also change the sound of the pump.
You need to check the engine compartment with the hatch closed to see what temps you are actually getting in there.
Also check your boats fuel system like this.
http://forums.iboats.com/showthread.php?t=283269

 

[J&K]

Re: V6 EFI water cooled fuel pump

yes its a cooler to cool the fuel after the pump on its way to the fuel rail.
the boat was running fine , i ran it hard for a few mins then stopped and shut it down.
It was sunny out but only 25 degress.
This is a new boat for me so only 5th time out, been tubing before in it running real hard and no problem.
I just removed the pump and cooler. merc only sells them as a single unit now?

 

[Don S]

Re: V6 EFI water cooled fuel pump

25?C (77?F) is not enough to cause vapor lock. You probably pulled the pump and cooler assembly for no reason. Put it back and do the tests I described and linked to earlier. (unless you just like to throw money away).
There are a lot of inexpesive things that can cause your problem, troubleshoot, don't just throw money (aka parts) at it and hope for the best.

 

[J&K]

Re: V6 EFI water cooled fuel pump

25?C (77?F) is not enough to cause vapor lock. You probably pulled the pump and cooler assembly for no reason. Put it back and do the tests I described and linked to earlier. (unless you just like to throw money away).
There are a lot of inexpesive things that can cause your problem, troubleshoot, don't just throw money (aka parts) at it and hope for the best.

In Canada merc have put out a service bulletin stating that they will only supply a fuel pump with the cooler kit now for the 2003.
Since the Larson engine compartment is made for midgets or anyone that can stand on there head for hours, I refuse to go threw that battle again unless it is new parts going back in. This boat is also used by my girlfriend and having her stranded out there on her own, is not an option. So I guess as you say I am throwing money away.
But since it?s a new boat to me I am starting with a fresh new pump that I know is ok. I have aiso replaced all fluids and water pump so what?s another item added to the list.
I would like to add a fuel pressure gauge to the fuel rail or remote location to monitor the pressure over the years to come.
Plus the sun is here and the down time is killing us lol.
Thanks for your help