01' MCM5.0 EFI runs rough

[shmart2]

After 45 minutes or so. under load, at about 32MPH, in Sea Ray 240, engine suddenly wants to stall. Will still run at low RPM, at a speed barely over no-wake. Can not go above 1800 RPM or so without shaking up boat and crew. Here's what I have already done:<br />1. Installed new water seperator/filter, spark plugs, distributor cap and rotor. Pulled plugs to check for moisture after running in slip at idle, (wanted to and did stall,) and found at least 3 or 4 plugs black and wet after only a short time. Bought it used with low hours this season, now has just over 200 hours, had 96 on her when we got her.<br />2. Mechanics at my marina say that it COULD be one or more bad spark wires or "The Box," that they say is an amplifier for the ignition. It could also possibly be a bad sensor that is designed to cut back to 4 cylinders (I'm told,) in the event of a overheating condition. Am hoping to solve problem before she is hauled/winterized, which is scheduled for the next week to 10 days. Thanks much in advance.

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

"The Box," that they say is an amplifier for the ignition.

Find a Mercruiser dealer with experience with EFI engines. Obviously with their "Box" statement they don't have a clue. The "Box" is the ECM (Electronic Control Module) It controls everything on the engine including alarms, fuel pumps, ignition timing, etc, using the TPI's MAP sensors, Fuel injectors, power relays..... It's basically the computer that controls every aspect of the engines operation.<br />EFI's are not an engine designed for DIY work or those without experience.

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

hello<br /> I am with don. time to find a dealer that has experience with EFI. last o1 EFI problem I had came up from florida with 7 pages of printouts and all kinds of work had been done. seems no one actually tested anything. we ran the boat and as it was failing the fuel pressure stayed correct the pulsewidth whent wide and the IAC went to almost 90% you could hear the air screamin through the throttle plate. computer had no codes and the customer was saying its running out of gas. I said no the fuel rail pressure is fine. the coil was arcing from the secondary tower to the primary tower. took 45 min to find and isolate a problem the guy had lived with all the way up the intercoastal.if the diagnostic codes dont tell you whats broke they at least tell you what aint.the best tool an EFI tech has is his brain. all else is just an aid. cause see them onboard puters are rather stupid. as the engine RPM slowed and the TPS value remains the same the puter will start altering air and fuel to try to make the engine perform in a preset map. it doesnot know the coil was arcing.

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

I'm not sure about your experience with the EFI engines rodbolt, but I Never get lucky enough to have a trouble code set.....I always have to go searching.

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

Thanks for the FAST responses, Don S. and rodbolt. I spoke to the marina/dealer we bought it from today to see if the first owner had purchased an extended warranty, which of course, he had not. I'm not sure (doubtful) that this would be a warranty issue or not, but thought I should ask. Since I had relaced the cap, rotor, plugs and seperator myself, I was concerned the dealer may balk at working on it since I had done those repairs myself. The concensus seems to be that my local Mercruiser dealer, who are very well respected and have a reciprocal/gentlemans' agreement with our marina,(they use our ramp, our marina buys parts from them,) is the place to go. That being said, here is my question: Since they will have to use THEIR trailor to go the 2 or so miles to their shop, (not water accessable,) which I have no idea yet will cost, and since the minor repairs I have already made are basic tune-up items, should I go ahead and replace the spark plug wires and/or coil first? Is it still possible that the problem could be one of these, or am I throwing good money after bad? Could the problem still be water in the fuel, even though the seperator was already replaced? I would like your opinons before I call the Merc shop- they are (I'm sure) very busy with winterizations now and may not be able to get to it immediately anyway. Thanks again, Eric

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

Thanks for the FAST responses, Don S. and rodbolt. I spoke to the marina/dealer we bought it from today to see if the first owner had purchased an extended warranty, which of course, he had not. I'm not sure (doubtful) that this would be a warranty issue or not, but thought I should ask. Since I had relaced the cap, rotor, plugs and seperator myself, I was concerned the dealer may balk at working on it since I had done those repairs myself. The concensus seems to be that my local Mercruiser dealer, who are very well respected and have a reciprocal/gentlemans' agreement with our marina,(they use our ramp, our marina buys parts from them,) is the place to go. That being said, here is my question: Since they will have to use THEIR trailor to go the 2 or so miles to their shop, (not water accessable,) which I have no idea yet will cost, and since the minor repairs I have already made are basic tune-up items, should I go ahead and replace the spark plug wires and/or coil first? Is it still possible that the problem could be one of these, or am I throwing good money after bad? Could the problem still be water in the fuel, even though the seperator was already replaced? I would like your opinons before I call the Merc shop- they are (I'm sure) very busy with winterizations now and may not be able to get to it immediately anyway. Thanks again, Eric

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

Eric, what's the serial number of your engine. Is it TBI or MPI?<br />Don't become a parts changer and hope you hit the problem, that usually doesn't do anything but get expensive.

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

hello<br /> thats one of the beauties of EFI. it will tolerate water some. if you catch and dump the filter it will purge itself cause it does not rely on intake vacum and atmospheric pressure to move fuel. for a short time it will inject water as well as anyother fluids.now to get back to the other. the marinias I work for will put you on the clock from the time the driver leaves the marina till the time the boat is there and some will also charge an equipment use fee.<br /> coils are cheap.<br /> if it will run well for 45 min I doubt the computer will tell them much other than there is no problem with the motor. that is my normal experience. the guy that came in with all the printouts was mad and the marina owner was aghast when I looked them over and told him at least there is nothing wrong with the motor.<br /><br /> Dons I am like you. I dont think the laptop has ever told me whats wrong but it quickly eliminates what aint .<br /> most inexperienced techs listen to much at the seminars but I found a working knowledge of how the thing works is better than a laptop.<br /> another funny story is a guy showed up last spring complaing his TBI 5.7 volvo would only run about 2500 rpm. two other dealerships had charged him for computer diagnostics and replaced some parts and he still had the problem. took me 11 minutes to find it. I removed the flame arrestor and started the motor and lo and behold one injector was not spraying. replaced them both and sent a happy fisherman on down to the inlet. problem is the computer is really stupid when it comes to a fouled or stuck injector.

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

I love it. I accuse people all the time of over thinking a problem and not checking the basics first, and looking for the obvious.<br />Well, I just did it....again <br />

After 45 minutes or so. under load, at about 32MPH, in Sea Ray 240, engine suddenly wants to stall. Will still run at low RPM, at a speed barely over no-wake. Can not go above 1800 RPM or so without shaking up boat and crew.

How about a plugged fuel vent, or a partially plugged fuel pickup tube screen......<br />VENT.<br />You use a lot of fuel and it creates a vacuum and won't allow the electric fuel pumps to pull the fuel from the tank.<br />PICKUP<br />after running for a while it picks up the junk in the bottom of the tank and blocks the fuel flow to the pump.<br />Either one will go away after the engine is off for a while.<br /><br />Just a thought.

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

The engine serial # is OM017554. Does TBI mean 2 barrell? (Sorry, I have to plead stupid on that one,) but it definately has a 2 barrell, not MPI. BTW, as of yesterday, after replacing the plugs, rotor and cap, it started easilly, ran smoothly for a minute or 2, (in the slip, not under load and at idle,) then went right back to the same rough condition, with light blue smoke. It seems to be pulling in plenty of fuel, just not burning it. I first started her, walked away for a few minutes to clean up and allow her to warm up, and came back to find her stalled. Was then more difficult to start, and you could definately hear air sucking through- it seems like there just wasn't enough spark/no spark at some cylinders(?) to burn fuel, hence the wet plugs that had just been replaced. Also, the mechanic at the marina did remove the flame arrestor while she was running rough and seemed to agree that fuel to the carb was not the problem. What began as the problem described originally, that the roughness began after 45 minutes or so, the first 20 in the no-wake zone, followed by 25 to 35 under load at about 3/4 throttle, is now acting the same almost immediately after starting, under no load in the slip. At least it can be witnessed and hopefully diagnosed easier. Thanks again for all of the advice and keep it coming if you can. I'm learning alot about the boat I didn't know and can hopefully make the job easier for whoever repairs her, if I can't do it myself. All the best, Eric

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

The engine serial # is OM017554. Does TBI mean 2 barrell? (Sorry, I have to plead stupid on that one,) but it definately has a 2 barrell, not MPI. BTW, as of yesterday, after replacing the plugs, rotor and cap, it started easilly, ran smoothly for a minute or 2, (in the slip, not under load and at idle,) then went right back to the same rough condition, with light blue smoke. It seems to be pulling in plenty of fuel, just not burning it. I first started her, walked away for a few minutes to clean up and allow her to warm up, and came back to find her stalled. Was then more difficult to start, and you could definately hear air sucking through- it seems like there just wasn't enough spark/no spark at some cylinders(?) to burn fuel, hence the wet plugs that had just been replaced. Also, the mechanic at the marina did remove the flame arrestor while she was running rough and seemed to agree that fuel to the carb was not the problem. What began as the problem described originally, that the roughness began after 45 minutes or so, the first 20 in the no-wake zone, followed by 25 to 35 under load at about 3/4 throttle, is now acting the same almost immediately after starting, under no load in the slip. At least it can be witnessed and hopefully diagnosed easier. Thanks again for all of the advice and keep it coming if you can. I'm learning alot about the boat I didn't know and can hopefully make the job easier for whoever repairs her, if I can't do it myself. All the best, Eric

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

First off Eric, when you hit the "Add Reply" button, only click it once. If you double click it like a link, you will have a double post.......<br />Here is something you can do to test the fuel system. Get an outboard tank and fill it with new clean fuel. Then hook the hose up directly to the fuel filter on the engine. Then give it another try in the slip. If the idle smooths out, we might have a place to start looking for the problem.

 

[waterone1@aol.com]

Re: 01' MCM5.0 EFI runs rough

Don and Rodbolt, I am "throwing this one out there" for you to think about because I am not familiar with the ecm on these newer boats and am not qualified to give advice. Doesn't This one have a "limp home mode" that if the water temp or oil pressure is not right, it will do something to the ignition to limit the rpms to just above idle to prevent engine damage, while still getting the boat home???? Any way possible that one of these sensors or parameters might be off to cause this??

 

[rodbolt]

Re: 01' MCM5.0 EFI runs rough

hello<br /> nope not really<br /> I looked for seriel #om017554 and could not find it. the TBI looks like a 2bbl carb to some people. if its efi and you could hear it sucking air it tells a story.<br /> either the ign is weak and as the plugs foul the ecu will open up the IAC and increase fuel delvery pulsewitdh to try to make the rpms match the TPS setting. this will also occur if its running out of fuel. the air whisleting through the IAC tells a story. I hope your tech can understand it.<br /> I just did another merc yesterday that another dealer has been messing with . a 4.3 with a mercarb, would start idle and die. I found dirty connectores on the oil pressure switch for the electric fuel pump. when the key is turned to start the pump is energized by the start circuits and with the key in the run position the power goes from the ign circuit via the pressure switch. with bad connections the pump would quit and the carb would run out of fuel. the EFI works similar.<br /> like DonS says. dont overthink it. most problems are low tech. but to many techs have quit looking at low tech and get baffeled by the high tech.

 

[muc]

Re: 01' MCM5.0 EFI runs rough

This engine had the dist. sensor replaced in 2001 under warr. Sound like he got a bad one. they are cheap,easy + a common failure. When your guessing thats a good place to start!

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

muc<br />If you look back in your service bulletins you will find where they changed the sensors from gray to black because there was a problem with the gray one.<br />See bulletin 99-4<br />Not a reason to change a $47 sensor and a $48 coil...there is almost a hundred bucks. Enough money for a qualified tech to find the real problem.<br /><br />waterone1<br />Had it went into limp mode, the computer readout would have shown it.

 

[muc]

Re: 01' MCM5.0 EFI runs rough

Don S<br />Black sensor has been superseded; it now has a new p\n and a heavy ground wire. They seem to be holding up better.<br />As far as having a qualified tech look at it. Shmart2 needs a haul-out and transport on dealer trailer or service call. Well over a $100.00 where I work.<br />I agree he should stay away from the boys at the marina, looks like they don’t have a clue.<br />As to what his problem is could be many things even something as simple as a bad 10 pin connection.<br />I still feel that in this case to throw a $50.00 sensor at it and see what happens is in the best interest of Shmart2

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

OK, Here's the latest. I visited the Merc dealer today. Can't look at it until spring, busy with winterizations and doesn't want to de-winterize too early (during winter,) and does not have a trailer available. Also would not be able to take off of blocks at yard. The boat is scheduled to be hauled next Sunday (11/14.) He mentioned the possible clogged fuel vent which I can check tomorrow by taking off the gas cap in the slip. I think the problem is ignition related. Should I spring for the coil as a last attempt to correct the problem myself? Does the fact that it runs poorly even at idle in the slip (not after 45 minutes or so under load,) still indicate a possible weak coil? I will feel really stupid if I go to the time and expense of finally getting her to their shop in the spring only to find she has a weak coil. I asked about the sensor and he said if it was bad, the boat would not start- it either works or it doesn't. Again, thanks for all of the advice. If nothing else, I have learned alot and will surely have an easier time diagnosing future problems. All the best, Eric

 

[shmart2]

Re: 01' MCM5.0 EFI runs rough

OK, Here's the latest. I visited the Merc dealer today. Can't look at it until spring, busy with winterizations and doesn't want to de-winterize too early (during winter,) and does not have a trailer available. Also would not be able to take off of blocks at yard. The boat is scheduled to be hauled next Sunday (11/14.) He mentioned the possible clogged fuel vent which I can check tomorrow by taking off the gas cap in the slip. I think the problem is ignition related. Should I spring for the coil as a last attempt to correct the problem myself? Does the fact that it runs poorly even at idle in the slip (not after 45 minutes or so under load,) still indicate a possible weak coil? I will feel really stupid if I go to the time and expense of finally getting her to their shop in the spring only to find she has a weak coil. I asked about the sensor and he said if it was bad, the boat would not start- it either works or it doesn't. Again, thanks for all of the advice. If nothing else, I have learned alot and will surely have an easier time diagnosing future problems. All the best, Eric

 

[Don S]

Re: 01' MCM5.0 EFI runs rough

Checking for a vent problem while on blocks will be a waste of time when running the engine with the fill cap off. You won't use enough fuel to cause the engine to shut down without the load of the boat on plane at 3000+ rpm. You have a drivability problem that will have to be tested and checked "On the Water" and until it is, you won't know for sure. <br />As far as replacing the coil, and the sensor, and anything else you want to replace, I don't care personally. That decision is completely up to you. I just gave an opinion.<br /><br />And Why do you always have a double post???? Are you double clicking the add reply button?