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Trash in the pickup,mud?,A little rust particles??, Sludge....Partially submerged motor.

Changed fuel pressure regulator (Real fun to get to)! Not it. Pressure still drops after the pump shuts off. Must be that the pressure is backfeeding through the main fuel pump. Am still occassionaly experiencing a hard start after sitting for a while. What I've been doing is letting the pump cycle once without attempting to start then start it during the second cycle. It sounds like the pump(s) are really laboring and almost cavitating the first time as they cycle. Sounds much better on the second cycle. Runs great once the engine starts. The only thing that hasn't been changed is the main fuel pump.

One interesting thing I saw on the code history with Diacom hooked up was an occurence for a "fuel pump" something? I almost overlooked it as the std codes that always come up "fuel level chkd hi", pitot, trim, steering, etc. Everything else looked normal on that occurence. I forgot to save it before I cleared the history or I would post. I didn't think Smartcraft was tied into the fuel system at all????

It's really not a big deal other than it never used to do this until the middle of this year. Any expert advise? I'm tired of replacing expensive non returnable parts.

Quote:

Originally Posted by Nordicflame (Post 2242168)

The symtoms your explaining point to a cam or crank sensor. There is another recent thread on here stating that Merc told the particular shop that the crank sensor will not throw a code but will inhibit to 90%.
We have experienced the exact same symtoms as you are explaining on another boat. The boat shut down just like someone shut off the key at 3500rpm. Started right back up and then quit and progressively got worse. It stored some cam sensor errors but was told those are common (and they are as I've seen them on my own and I haven't had any problems) but did not show as active until I got it running crappy on the hose. It then showed as an active code. We replaced the cam sensor and it fired up and ran like new. For a week or two anyway. The problem recurred and at that point we changed out both the crank and cam sensor and it has run with no issues for a year.
Got to love these electronics!!

Dave

I had the same type errors where it was giving me crank sensor and cam sensor errors. my real issue was the trim limit sending unit portside (NOT the gauge sending unit stbside). the limit sender is tied into the 5 volt reference system and when it is dirty or failing, it can cause really strange symtoms and trigger false hard codes. one thing i remember is that it totally acted like it was starving for fuel and it also totally lost spark at random times with no warning. just for elimination, it wouldn't cost you anything to disconnect that 3 wire unit in order to make sure.

i realize that you're probably past this stage but sometimes it's the simple things that can throw ya when you think you're looking for a "bigger" problem. good luck!

How About A Baf Fuel Pressure Regulator Or A Bad
Check Valve In The Tank Mounted Fuel Pump

Changed fuel pressure reg. No tank mounted pump, boost pump has een changed.

I'd put my bet on either the high pressure pump or a leaky injector. The pressure loss may cause the fuel to vapourize which in turn creates a hard starting situation.
Do you have a fuel shut off valve that you can close to prevent fuel from re-entering the tank backwards? Try that and check pressure at the same time ...

Not a leaky injector. Pulled the rail and checked that while pressurized. No leaks.
That thought crossed my mind with the fuel shut off. I will try shuting the manual valve between the tank and boost pump as soon as the pumps cycle aff and see if it traps the pressure. I will probably try pulling fuel from a 5 gal can to see if that eliminates anything.

Why does merc no longer offer just the high pressure cool fuel gen 2 pump, pn 861156A1? They want you to get the pump and fuel cooler together. pn 861156AO2.
Based on the service bulletin the fuel cooler looks exactly the same as it is now.
http://www.mercruiserparts.com/bulle...2004/EN_05.PDF
Unless the cooler and the pump are one piece now and get away from that stupid 90 deg elbow w/ o rings I can't see the advantage.
Does anyone know how to get just the pump?

Changed my high pressure pump (lots of fun) and that was it! Now the fuel rail maintains 40 psi after the pump shuts off. Haven't had a chance to take it for a ride, but I bed it surely takes care of my hot start problem. It was weird because it made full pressure when running, must have had a bad internal check valve or something like that. Hopefuly this helps someone else down the road.

P.S I have a brand new fuel cooler to get rid of that merc makes you buy with the pump . I still don't get it, its exactly the same as the original. If anyone needs one let me know.

The check valves in those pumps are not at all fail safe. Running dry or water in the fuel increases the risk of a failure.

Regarding the fuel pump/cooler kit I think it came alive due to an upgrade that I seem to have forgotten the details about right now. If the pump fails (again) after this upgrade you'll once more be forced to buy the complete upgrade kit. Can't understand why the pump only is not available ...