Thread: Fuel Pump 101
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Old 08-11-2008, 03:14 PM
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boofer boofer is offline
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Join Date: Jul 2007
Boat: 2005 X-2 MCX
Location: Knoxville, TN
Posts: 314
Bigmac, I am pretty certain that the filter is not restricting the flow of fuel at any level. I poured gas into a pan to about 3 inches deep. I placed the filter in the pan and it immediately filled up with gas. I was expecting to see it trickle in, but that was not the case. The level of the gas inside the filter equaled the level of gas on the outside of the filter within milliseconds. So, the filter does not restrict fuel. By the way, this is the replacement filter I used on my old module only a few months ago prior to replacing the whole fuel module. The new module came with a new filter.

I am really puzzled though by this small black disk. I cannot see any useful purpose. I basically used the same pan of gas. I slowly sunk the bottom of the module in the pan of gas (without the pump so that I could see the gas). Gas would not populate the small area at the bottom of the module until the module was all the way in the gas. I cannot recall now if I had the filter attached. I do not think that it was attached since I was trying to see what effect this disk has on flow to the pump. Basically the disk floats. When there is sufficient gas to float it, it will unplug the hole allowing fuel to go to the pump. If it is not floating the hole is closed and fuel will not get to the pump. Plus, I would gander that the pump is able to somewhat pull this small "valve" open when it is running. But, that would make it a restriction. I cannot really say one way or the other what the purpose of this disk is. It would keep air out of the pump at low fuel levels. But, regardless, air in the pump or no fuel available to the pump equals overheat.

Bear, it is the fuel that goes through the pump that cools the pump. The fuel on the outside can aide in cooling, but the pump is designed to be actively cooled by the flow of fuel through the pump.

I am 50/50 with that "newer" fuel hose form the pump to the regulator. The old hose was definitely "substantial," but it did have the noticeable kink. The new hose is much stiffer than it looks. And it flexes well. I wonder if the corrugation helps reduce the flow to the regulator and eases the job of the regulator without creating any backpressure. But, one of the board members posted his problems with the dual pump (Milinium?) setup on his boat. Here is the link to his post.

Remember, the Carter brochure is just that; a brochure. The electrical issue (melted contacts) was experienced by a board member. He posted pictures just recently. But, I did learn that the pump was too restrictive and easily clogged which led to the high failure rate. I believe that I found this while researching the GM problems with the Carter pumps and the MC representative echoed the same information to me in the email. The pump was redesigned to be less restrictive and more tolerant of debris. When I say "debris," we are talking microscopic.

What I see for now is a poorly designed pump. It was replaced in GM motors. So, why not do it in ours? I am still awaiting a reply to my question as to whether or not my new module came with the newer turbine style pump. If not, then I must really question MC's policies. They apparently thought there was enough of a problem to use a different pump(s) on newer boats. If they are not actively trying to get these newer pumps in older boats (replacement modules with the newer pumps) then I must call foul.
Common sense is the least common of all the senses.

Last edited by boofer; 08-11-2008 at 03:21 PM.
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