location of fuel supply valve and fuel filter on Merc 8.1 DTS

One known problem with these coolers is that they were painted badly at the manucaturer and some spray went inside the cool fuel unit casting. This has resulted in a lot of cases where the paint has peeled off from gasoline reaction and clogged the fuel filters. If the "grass cuttings" material was black I would suggest it may be that paint issue. A change of filters should help that a lot. If it is not black then it could be something else from a bad fuel batch to bad choice of additive or something from inside the fuel tank my bet is that it is paint from the cool fuel unit though.
Stabil additive - the bottle will tell you what to add to the tank of 100 gallons, it seems like you have added 75 percent fresh fuel and in my mind that should be enough with additive for you to have confidence on fuel quality for the tanks going forward. Someone else may have a different opinion.

Fresh fuel - additive - clean disc filters - most of the cooler paint removed - suction out the filter chamber when yOu change the discs to remove water and crap - I would bet you are good to go :smt038
 
Out of interest do you have ethanol in your fuel? Luckily we don't where I boat ......yet.

Anyway Stabil Marine might help, although I did see a post on this forum the other day whereby the Starbrite enzyme fuel treatment sorted out someone's engine stumbling woes.

Found it - and in particular post #23
http://clubsearay.com/showthread.ph...king?highlight=stabrite+enzyme+fuel+treatment

FWIW comparison of fuel treatments:

http://tommarlowe.blogspot.com.au/

Might want to inspect your new filters every so often and replace as necessary until you are confident you have clean fuel.

Similarly, you might want to change the filters on the genset. Have you had this running yet?
 
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The paint chips that clog your fuel pressure regulator are downstream of the filters, they wont show in the 2 filters. Symptoms of that would be skyhigh fuel pressure measured at the fuel rail, or you can take off the FPR and look at it

I wouldn't sweat that yet, just do what was mentioned above
 
juggernaut1 said:
Out of interest do you have ethanol in your fuel? Luckily we don't where I boat ......yet.

Anyway Stabil Marine might help, although I did see a post on this forum the other day whereby the Starbrite enzyme fuel treatment sorted out someone's engine stumbling woes.

Found it - and in particular post #23
http://clubsearay.com/showthread.ph...king?highlight=stabrite+enzyme+fuel+treatment

FWIW comparison of fuel treatments:

http://tommarlowe.blogspot.com.au/

Might want to inspect your new filters every so often and replace as necessary until you are confident you have clean fuel.

Similarly, you might want to change the filters on the genset. Have you had this running yet?
Click to expand...


I had non ethanol fuel delivered so I think I am safe on this front.

Interestingly enough I have been running the gen frequently and it has not sputtered out... yet. I do plan on changing the filter on the generator. I can't read the part number on the canister so I have not bought/replaced/tackled it yet, but it is on my lengthy and growing list of "to dos"
 
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scoflaw said:
The paint chips that clog your fuel pressure regulator are downstream of the filters, they wont show in the 2 filters. Symptoms of that would be skyhigh fuel pressure measured at the fuel rail, or you can take off the FPR and look at it
Click to expand...

Not on mine scoflo - I just had my fuel coolers off last month for other issues - and found this problem on my filters, the chamber itself had been painted and the flakes were mainly on the disc with some traces on the cylinder filter in the cooler. Most of the filter chamber had been spray painted. To be fair it was not affecting fuel pressure at the rail - nonetheless there was enough paint in the disc filter.
 
SeaAyeOwe said:
Not on mine scoflo - I just had my fuel coolers off last month for other issues - and found this problem on my filters, the chamber itself had been painted and the flakes were mainly on the disc with some traces on the cylinder filter in the cooler. Most of the filter chamber had been spray painted. To be fair it was not affecting fuel pressure at the rail - nonetheless there was enough paint in the disc filter.
Click to expand...

When I had mine off last year the paint was flaking off the cover only, big flakes, and when that comes off it's downstream of the filters.
I see black on my filters when I change them, but not flakes, that blackness is coming from the fuel lines upstream that are disintegrating from the ethanol, are you sure it's paint and not rubber?
 
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scoflaw said:
When I had mine off last year the paint was flaking off the cover only, big flakes, and when that comes off it's downstream of the filters.
I see black on my filters when I change them, but not flakes, that blackness is coming from the fuel lines upstream that are disintegrating from the ethanol, are you sure it's paint and not rubber?
Click to expand...

Absolutely without doubt paint flakes from inside the cooler, it was visible inside the chamber where it had flaked off. I used solvent to clean the remnants best I could.
 
OK guys, I am starting to get frustrated here...

I followed all the steps to begin to start to install the filter discs

1) turned off fuel valve
2) disconnected cool fuel module harness (there are two connectors opposite of each other)
3) cranked the engine
4) turned everything to "off position"
5) unscrewed filter

AND A SHI* LOAD OF GASOLINE FLOWED OUT AGAIN!!!

I gave up, put everything back together and cleaned the dangerous mess in my bilge.

Also, added some Sta-Bil which some of got on my fiberglass and left fluorescent yellow stains, hope they come out.

The engines fired up, like they did last time after they stalled, but I don't want to not change these filter discs before I take the boat out again. I am very frustrated.
 
SeaGreg said:
OK guys, I am starting to get frustrated here...

I followed all the steps to begin to start to install the filter discs

1) turned off fuel valve
2) disconnected cool fuel module harness (there are two connectors opposite of each other)
3) cranked the engine
4) turned everything to "off position"
5) unscrewed filter

AND A SHI* LOAD OF GASOLINE FLOWED OUT AGAIN!!!

I gave up, put everything back together and cleaned the dangerous mess in my bilge.

Also, added some Sta-Bil which some of got on my fiberglass and left fluorescent yellow stains, hope they come out.

The engines fired up, like they did last time after they stalled, but I don't want to not change these filter discs before I take the boat out again. I am very frustrated.
Click to expand...
Like mentioned, I don't touch the fuel valve, don't disconnect anything, don't crank the engine. Just unscrew the 3 bolts and lift the cover off.
 
So that tells you your electric fuel valve isn't working as it should be. Another issue you have going on

Can you get it to shut down manually?
 
scoflaw said:
So that tells you your electric fuel valve isn't working as it should be. Another issue you have going on
Click to expand...

What are the odds that is the case on both engines?

The only way I have been able to manage the fuel flow is by unscrewing the hose from top of fuel tank.
 
I am not that familiar with that valve. Can you turn it off, start engine and run it out of fuel? Then change filter?

If it was my boat I would take it one step at a time, figure what's up with the valve
 
After a three week business trip I am finally able to get back to the boat and try to get this filter replacement going again... going to call mercruiser and see what they have to say and will keep you all posted. As always, thank you for your help and expertise, I've missed the boat and the forum while traveling and am excited to get back in the swing of things with this boat!

Greg
 
Spoke to Mercury, they are saying it sounds like it is an issue with the fuel supply shut off valve. What are the odds that both would be faulty?
 
You can go back in and change the disk filter and not the first filter you already changed. You do not have a spin on filter - they sold you something you do not need.
I have an electric fuel solenoid valve on my 8.1 to prevent flow. You can use vice grips and spare tubing/cardboard to clamp the inlet fuel line (spare tubing/cardboard to keep from damaging the actual hose when you clamp it). You should unplug the wire on the cool fuel module and start your boat for 10 seconds or so to depressurize the module before opening it.

I will be surprised if the filter change fixes the issue. I just went through a long troubleshooting exercise on 2 different 8.1 engines. One, the cool fuel module itself was bad, the other had 3 injectors go bad.
 
I will be surprised if the filter change fixes the issue. I just went through a long troubleshooting exercise on 2 different 8.1 engines. One, the cool fuel module itself was bad, the other had 3 injectors go bad.[/QUOTE]

I just spoke to a Mercruiser mechanic and he advised me to have the modules removed, inspected, troubleshooting done and repaired/replaced if necessary. I think after your comment this is going to be my best and safest bet... thank you.
 
Have you measured pressure at the fuel rail - didn't see in your post if you did.
If you have 40 psi at the rail, pump likely is fine, and I would bet you have injector issues.

There are some lengthy posts that it did on the troubleshooting on the 2 boats I was part of.

Boat one - fuel rail pressure would go to zero when the engine sputtered. After it would sit a while, it would go back up to 40 and run fine for hours/days, then fail again - that one the cool fuel module was faulty.

Boat 2 - pressure at the rail was always 40. Engine would get a serious miss and have no power. Came and went a few times, then became a constant issue. long story short - 3 bad fuel injectors.

If you have not measured it, start checking fuel pressure at the rail when it is running, and when it fails. Fuel modules are ~$900 each so you don't want to change them if they are fine.
 
I have not measured the pressure at the fuel rail. To be honest I am quite the novice when it comes to my knowledge of the engines and systems and I also have limited tools that I need to slowly build up. As of now my greatest strengths have been repairing and replacing simple systems on board as well as cosmetics. The engines make me a bit nervous as I try to learn my way around them and I am trying to read as much as I can to get comfortable diagnosing and servicing issues.

I have sent in a work order in to Miami Marine Specialist to have the fuel modules removed and taken back to his shop (as per his suggestion) and inspected. He performed compression tests and oil samples on the boat pre purchase and I feel that I have formed a strong enough relationship with him that he will not have me replace parts unnecessarily. He not only came highly recommended from a few colleagues in the industry but has also been rather helpful with answering questions for me "off the clock" since I started chasing this boat few months back. So I guess I will have to wait and see, another weekend without use of the boat, what the outcome of this next step will be. I am so eager to finally use the boat with my family that it is driving me a bit crazy, especially after being away from it for 3 weeks!
 
I would have done some trouble shooting while the fuel system was intact.
See why your fuel valves are not turning off.
Check your fuel pressure to see if the pumps are working
Change the cup filter that you missed.

The module costs $900 because it has the 2 pumps in it, so the chances of all 3 components of the CF3 failing together are slim to none.
If your mechanic has your best interest in mind , he knows this. Of course plug and play is easy for him.
 
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