*Gen 3 Cool Fuel Module Issue*

jg300da

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Oct 9, 2006
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Well, after chasing a fuel problem around for the better part of two weeks, I finally discovered an issue that Mercruiser has known about since 2004 but is in no hurry to discuss. The early model "Gen 3 Cool Fuel Module" that many of us have on our sterndrive Searays has major design issues, and not just the issue of corrosion at the raw water coolant lines that Frank W posted a while back. A larger issue concerning the fuel itself. It seems that there is a known paint delamination issue with the inside of the module where the paint peels off the casting and clogs the fuel passages, high and low pressure fuel pumps, and fuel regulator. There are also documented cases of big blocks (8.1L) where the paint gets into the fuel rail and clogs the injectors. The service tech instructed me not to run the engine at all until the repair can be made to avoid the possibility of damaging the injectors. This service bulletin covers a large range of sterndive engines including 5.0MPI, 5.7Mag350, 6.2LMPI and 8.1L.

I spoke with my local dealer about my engine operating issue and he had the answer to my problem immediately. He didn't even have to test drive it as he has seen so many boats with the same issue in the last several years. It has to be a big problem when he told me that Mercruiser will pay for parts and labor 100%.

I am posting a link below to the service bulletin which shows the engines and serial numbers involved (notice the date on the bulletin). The service bulletin discusses how to check for proper vacuum and fuel pressure but it does NOT explain why you could be experiencing incorrect readings. Your dealer will confirm the why. I know there are some here like CincyAquaholic who have had this exact problem and have already replaced the filters and high pressure fuel pump. That is only a temporary fix as the paint will continue to delaminate and clog the fuel module. The entire module must be replaced to solve the problem. This module retails for close to $1K.

Here's the link which covers the corrosion issue but makes no mention of the paint problem:
http://www.mercruiserparts.com/bulletins/001/04//2009/EN_01.PDF
 
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How can you determine what gen 'cool fuel' we have...

The Cool Fuel Gen 3 System referred to here was introduced by Mercury in 2005. From a Sea Ray standpoint, based on owner reports, many 2005s have it and a few don't. I guess alot depends on back stock of engines at the plant when a given boat was produced. If your engines are original '98 models you do not have Cool Fuel 3 but possibly CF2. I am not as familiar with the lineage of CF2 so can't speak as to when it was introduced. My 2003 had CF2.
 
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The Cool Fuel Gen 3 System referred to here was introduced by Mercury in 2005. From a Sea Ray standpoint, based on owner reports, many 2005s have it and a few don't. I guess alot depends on back stock of engines at the plant when a given boat was produced. If your engines are original '98 models you do not have Cool Fuel 3 but possibly CF2. I am not as familiar with the lineage of CF2 so can't speak as to when it was introduced. My 2003 had CF2.
Three cheers for 2004 models. You get Smartcraft but don't get cool fuel 3. On my 2004 I have external inline fuel filters for each engine (in addition to water separator filters). That may be an indicator you don't have CF3 if you are not sure as I believe the CF3 has the fuel filter inside the module.
 
It looks as though the "Gen 3" module was introduced in 2005 and was installed for at least 3 model years or longer as my boat is a 2007. Pictures of the module can be seen in Dave's thread here...

http://clubsearay.com/showthread.ph...mpete-with-pictures?highlight=gen+fuel+filter

Daves thread covers in detail the filter changing aspect of the module but doesn't discuss the delamination issue.

If the service bulletin link doesn't work for you just google Mercruiser service bulletin 2004-06. The engines and serial number affected are listed on page 1.
 
Is ethanol the culprit here in terms of dissolving the paint?
Yes - and you dont necessasarily need to replace anything - it is possible to use a solvent to remove the paint from the inside of the fuel pump cover and re install it - the problem comes when you try to then re insall the unit onto the motor - generally, you find that the cooling hose connection is corroded/non-functional - the best fix is the retrofit housing (reload with your pumps, etc) (you dont need the hose kit they try to sell you, but get the o rings for the fuel connection) - there are also some stainless fittings available that replace the falure prone plastic ones if your housing is still good - the point is, this does not have to be an expensive fix
 
Was wondering if any Cool Fuel 3 owners got proactive and did some upgrading to their units before they failed?
 
So I have this issue. As stated before, its easy to tell. You are running and then all of a sudden you aren't. :) When the fuel pressure spikes the engine just shuts off. Relieving the pressure works to varying degrees of success to get it restarted - I have had instances where it wouldnt restart for 24 hours no matter what.

Anyway I am curious about this part of your post:

It has to be a big problem when he told me that Mercruiser will pay for parts and labor 100%.

You did not say whether or not your engine was under warranty. I have tried, with no success, to get Mercruiser to pay for this on mine, arguing that it was obviously a design defect, they no longer make the defective part, etc. etc. .. but the answer has consistently been - out of warranty? - go scratch.

Can you clarify a little on whether it was indeed replaced free of charge, what year your engine is, and whether it was still under warranty?

Anyone else manage to get Mercury to pay for theirs?

Also for those of you that couldn't open the OP's link:

http://www.mercruiserparts.com/bulletins/001/04/2009/EN_01.PDF

At the bottom of the bulletin it states very clearly: US and Canada: The Gen III Cool Fuel Module has been redesigned as part of our ongoing product improvement activities. This is not a recall.
 
I have these poorly designed, non tested pieces of crap installed on my engines. Not only are they faulty, but they get in the way of changing an the impeller in my engines. I had a hard time reconnecting the impeller hose earlier this year and it popped off when I was driving. I decided to let the Marina put it back on. ($300) Then after getting the boat back I broke down because my engine was not getting fuel. I limped back to the marina on one engine and the marina charged me for 2 hours of labor to change a $27.00 relay for the fuel pump. That fix lasted about 10 minutes and I broke down again. I purchased another relay to try to get restarted. It didn't work. I looked at the wire houseing that the relay plugs into and noticed that one of the terminals is burnt. ( I tried to post a pic, but I have been having problems posting ever since this site upgrade to the new interface)

My new theory is that there is clog that is causing the fuel pumps to work too hard and is drawing more power than the relay can handle. After reading this post, I am thinking about taking my boat back and disasembling the Cool Fuel unit to look for delamination. I am already into this problem for $600 and my boat is not running and still have the old cool fuel unit installed. :smt013
 
No need to take it apart and look - it is delaminating. At some point it will clog the works enough to cause a fuel pressure spike.

Seriously - who decides to PAINT a part that is designed to sit in fuel 24/7/365?
 
No need to take it apart and look - it is delaminating. At some point it will clog the works enough to cause a fuel pressure spike.

Seriously - who decides to PAINT a part that is designed to sit in fuel 24/7/365?


Do you know if this replacement housing will fix the issue or is this one painted on the inside too?

The new style module will replace any older style module for service needs. In order to usethe new module on earlier applications, the cooling water hoses and various fittings mustbe replaced. Kits are available to accommodate the various possible hose configurations.Order the Gen III Cool Fuel Module with pumps and filter, or a lower module housing onlyalong with the proper hose kit for installation. One module and one kit are required per​
engine.



Lower Gen III module housing (no pumps or filter) 864650A14

http://www.mercruiserparts.com/bulletins/001/04//2009/EN_01.PDF

 
Perhaps Ididntdoit could chime in on that, as he seems to have first hand knowledge of what is involved in replacing just the housing. (I would be interested in more detail on this as well).
 
On my boat the problem surfaced when an oil anylisys showed a trace of fuel and my wife swore she could smell "exhaust fumes" when under way. A check of the fuel pressure confirmed it was high and I was "running rich". that same motor was also leaking at the water fittings. I ordered a new housing and prepared to swap it - the housings were on national backorder - I got the idea to order a complete unit (it was only a couple hundred more and available right away) so I could get the boat up and running and have the existing pumps as spares. The housing I had ordered eventually came in and I "rebult" the one I already had off (including removing all the flaking paint from the inside of the cover) and swapped it - when these units were off I also serviced the raw water pumps. The paint on the inside of the cast housing was not the problem, just the cover.

as for removal and replacement, the fuel line is a push in fit with a special o-ring and an allen head "retaining pin" kind of a wierd set-up. I took the unit off with the brackets still attached to it (unbolted them from the block). the water lines are easy to remove with the center bolt on the retainer. rather than cutting the water lines before the fittings, I used a pliers to crack them and then picked ot the pieces with a needle nose to leave the hoses as long as possible. This was to avoid buing the "hose kit" they try to sell you (that would be a ***** to install anyway). The "re-loading" of the housing is straitforward, just remember to hook up the electrical connections and dont worry about the rubber locator at the top of one of the pumps thats probably destroyed (looks like a 1" piece of hose) it is fine without it.
 

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