Mercru 350 mag mpi ski

[muc]

Re: Mercru 350 mag mpi ski

Hondon,<br />Got that test out of the EFI 2 handbook, not real sure if it’s going to help because it sounds like you have spark during cranking. If I remember right Crusader has a CPS test that is done under load in their MEFI 4 manual – might be a more valid test for this problem.<br />My money is still on the shift interrupt circuit – but I’ve never been a good long distances troubleshooter.<br />Ah the weather. Have spent this week out on the ice putting up the fence around the docks so we can run the bubblers. It’s been below zero with -25* F wind chill. Unloaded a 41’ Carver yesterday – Travel lift didn’t like that at all! I’m sure you miss the cold.<br />Good luck, I will try to remember to look up the Crusader CPS test and post it tonight.

 

[outboardguy]

Re: Mercru 350 mag mpi ski

If I'm correct the late model merc mpi engines have a crank position sensor at the base of the timing cover behind the harmonic balancer. They do have a cam position sensor in the distributor, but it is not used. The only merc engine to use both sensors are the 8.1 engines.Just out of curiousity have you checked to see if the IAC values change as you start it. If the IAC was stuck you could always pull the PCV hose and see if it will stay running by regulating the vacuum leak with your finger.

 

[muc]

Re: Mercru 350 mag mpi ski

Hondon, Here is what I got from Crusader school.<br /> With crank sensor disconnected, test for battery voltage at A + B of harness, if you have voltage jumper A to A and B to B, ground the neg. lead of meter and put pos. to C of sensor, hand crank engine and look for the voltage to go from 0v to 7v or higher.<br />Or use the quick method---- disconnect coil wire from dist. And ground it, key on, wait for fuel pump to stop, crank for 5 seconds, let key back to on, fuel pump should run for a couple of seconds, if it does crank sensor is most likely OK

 

[muc]

Re: Mercru 350 mag mpi ski

Hondon, What did you find?

 

[piratedude]

Re: Mercru 350 mag mpi ski

ahhh- love reading about problems w/ fuel injected engines...keeps boat mechanics happy...and rich. thank god we dont have smog checks for boats...yet.

 

[1Moredrift]

Re: Mercru 350 mag mpi ski

My 350 Mag MPI Horizon was having the sluggishness/surging symptoms this summer that eventually moved to backfiring and hard starts and ended where you seem to be with the motor firing with key turned and dieing when released. My mercruiser service shop spent alot of time and eventually replaced the distributor, coil and ECM. Fortunately it was covered under warranty.<br /><br />I don't know if there are any problems with the ECM in these motors, but I doubt Mercury would be quick to admit it if there was. I think the ECM was about $2K.<br /><br />I am not a mechanic, but I thought this might light a bulb over one of the many knowledgeable people on this board. Hope this helps.

 

[hondon]

Re: Mercru 350 mag mpi ski

Here we go .I " borrowed " a compatible ECM from a unit that we just recieved for stock.No change.Pouring through manual # 36 I ca'nt find any indication that a faulty CPS would cause a fault code even while running.Ohms test are not as stated here and I still am not finding those values in my manuals and Merc tech has not called me back with a few numbers to compare but I did just call them today.I have ordered a CPS.That is practically inaccessable on this unit and not something we could swap /troubleshoot.We'll see .Thanks.

 

[K Hultgre]

Re: Mercru 350 mag mpi ski

Bump.<br /><br />dont just leave me sitting on the edge of my seat.

 

[hondon]

Re: Mercru 350 mag mpi ski

Sorry for the long pause but I walked away from this unit for a couple of weeks and then my computer went down.Here's how it all worked out.I got the correct harness for the DDT and again read no codes or faults but was happy with it's ease of use and extra functions.I ended up popping up the rails and cleaning each injector as well as the muffler for the IAC with a little carb cleaner.The thing fired off like a roman candle.Thanks to all and I'll keep you all posted as to how things go this spring.That might be interesting.Thanks again.Don.