having engine issues.. need a little help, Fuel or ignition. 350 mag mpi

[DirtNasty]

Got my boat back put of storage this year and Im having issue when running at high rpm. the boat cranks fine, idles fine, and accelerates fine.... but once im get to around 3500 rpm and run there for a few seconds the engine bogs down and loses power and will not regain it until the it idles back down for a few seconds. It varies on length of time and rpm but usually above 3200m but have reached 4500 but every time it will it will stall.

I replaced fuel/water separator. did not help... I have pulled another in line filter and will replace it tomorrow. I crack the sep filter with engine running to see that it was getting fuel and it was getting fuel.

today I pulled the tank and drained all the fuel...every last drop was bad. Im thinking this was mainly my problem... I have experienced the exact same issue with water in fuel on my v twin mud motor.

but another concern i have is that my distributor was a but loose. I think I may have lost timing.. in fact I know i have since i moved it. before I go back out on the water I want to figure out how to time this thing. after research It looks as if I cant just hook up a timing light and twist the distributor like a truck. Is that correct? Is this something I can do or is it best to take it in to the shop. the manual says 0 deg. at idle??

also wondering if I should go ahead and change plugs since i know ive ran it with bad fuel?

[boatwakes]

Also replace the anti siphon fitting at the outlet of the fuel tank to the engine, water in gas will destroy those things too. Unfortunately, you'll need a diagnostic computer to set the timing correctly or a timing tool offered by mercruiser. You have to get the motor warmed up, put the engine in base timing mode through the computer and it will advance itself to about 1300rpm, then set the timing at 0* on the marks, lock down the distributor, take engine out of base timing mode and call it good.

[DirtNasty]

what about the jumping wires method to get in service mode as mentioned in the above link.

[boatwakes]

Interesting on the jumper wire. Use the DTC connector cap and make sure you hook it up right but that will get you there, or $17 for the tool.

[DirtNasty]

I cannot find this dlc connector anywhere??? I have looked every where and can only find one 10 pin connector and it does not look like the ones pictured

[DirtNasty]

Yep I have nothing like that anywhere on my engine

[DirtNasty]

mercruiser mpi 350 mag tow sports. 2002 model.

[DirtNasty]

Maybe this picture might help? It looks like it's attached to the side of one of the exhaust manifolds.
http://www.justanswer.com/boat/29pr8...tige-fuel.html

yes i believe that is the ecm... and it is as pictured but there is no 10 pin connector just the the two plugs on the harness that plug into the ecm and to relays that hang next to it along with the fuses

[DirtNasty]

also .... my distributor doesnt look like that... it has a flat top (cap) with the post on the sides. and has no electronics goin to it like the one shown in your pictures... i have seen in like yours in the wiring diagrams but mine is not that way. it does have a spot (1) on the side that has four male pins coming off the side of the housing similar to the way yours has 2. but there is nothing plugged in it and never has been?????

[DirtNasty]

image_2.jpegimage (2).jpegimage_1.jpeg

this is what im workin with. sorry for quality but i wanted to get something posted to try and get this figured out. obviously i have an odd ball ignition or something ....maybe its not even the original motor.. bought the boat used so you never know?

[DirtNasty]

yes i was thinking the one on the left... but it is a 4 pin with ftwo wires? not like the 10 pin with the wire colors like you have and that it shows in wire diagrams. I appreciate the help... maybe someone else will chime in. I know somebody knows the answer to this and can help me get it timed. I know its a simple deal just need the right person to chime in

[Stingreye]

Any chance someone hacked together a diy check engine light confusing things? This link explains it. http://www.pirate4x4.com/tech/billavista/MEFI/

[DirtNasty]

I'm not trying to connect anything. Was just gonna jump the wires. The point is there is no dlc connection on this engine. I'm over the timing issue. Downloaded a service manual and it says nothing about setting time on a mpi engine only carbureted versions. So any way I'm on the water agiain today with all new fuel, filters. And still have the issue of it stalling out after running at high rpm. The higher the rpm the sooner it stalls. Runs fine until it stalls. It has got to be losing file somehow. Fuel pump??? Anti siphon valve?? I know the vent is not clogged already checked that. I know it's not bad fuel. It may even be in the ignition. I checked cap and rotor. Cleaned em up good. Seemed ok not perfect but not corroded bad or anything. Also cleaned spark arrester.

So where would you start?? I'm close to taking it to shop but I really don't want to

[Ruger761]

I dont know where the pin connector is, but sure sounds like its running out of fuel to me at the higher RPMs. Id be looking to see what kind of fuel pressure its holding at the higher RPMs. On a 2002 does it have a low pressure pump and a high pressure pump or just the high pressure pump? What I'm thinking is at idle and low RPM it has enough fuel to keep the filters full and pressured, the at the high RPMs the pump isnt keeping up, sucking the filters dry, and then loosing power. Then once it drops back down the pump has enough time to catch back up. Ive seen this happen on other motors. Swapped out pumps and never had the issue again. But a $30 fuel pressure gage is cheaper to try first vs buying a $300 pump.

[DirtNasty]

as far as the ecm... it does not match any of the gm/delphi ones like you have or the ones pictured... it is a motorola i believe which might explain why none of the wiring is the same.