1993 150hp XRI time and tune

[TKress]

tomorrow I am attempting to time and tune my XRI so I was reviewing the Seloc manual and ran across a step in the preliminary timing adjustments that states to disconnect the control unit harness connector for the ignition timing procedures. Do they mean the EFI Control Unit? I appreciate any help and Thanks.

[EuropeanAM]

If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

You will want to obtain an OEM Mercury Service Manual for these very critical procedures. Don't trust the aftermarket ones.

[TKress]

Sorry the serial # is 0D232323. The cowling says Forrest L Wood limted edition EFI and has 25th anniversary badge. The local dealership tells me its an XRI but they will not work on it anymore as it is too old for them. So I am doing this with my brother in law. Do you know a good afffordable source for the OEM manual.

[leonreno]

Only real sources are a Mercury dealer or find a used one for sale somewhere. It’s the best money you will spend on your motor, especially if you plan to do most of the servicing and fixing.

[TKress]

Don was right in getting an OEM manual. I did find some descrepencys while looking thru wiring diagrams to try and familiarize myself where sensors were located. Which also caused me to wonder if it really is an XRI or possibly a promag since the cowling has no badging to indicate what it is. So I called Mercury customer service this morning. VERY Helpful, it is an XRI, he sent me a few wiring diagrams and transferred me to publications who helped me order the correct latest edition service manual right from them. So a big shout out for Mercury customer service and thanks to you guys too for putting me on the right path. Now maybe I can figure out why it starts so hard 1st thing in the morning.

[EuropeanAM]

Shouldn't start hard- pump bulb firm, key on for at least 2 seconds, turn to start, it should fire off. If not, check Sync-n-Link Settings.

[TKress]

So I walked thru the sync n link settings with the aftermarket book but didn't need to change anything from where it was except I turned up the idle from the low 600s to the high 600s. Removed secondary water separation filter from fuel line and replaced all lines from tank to motor including new pump bulb. Still hard to start in morning. I have to put it in nuetral and advance the throttle a little past idle and sometimes more, sometimes it will stumble and slowly catch up and rev up over 5 to 10 seconds. once the temp guage starts to read then I can pull it back to idle out of gear top position. I have recieved the new OEM manual and see they are more detailed in the link and sync and will probably redo but feel confident enough that this is not my problem so I pulled out the water and air temp sensors. I tested them in near ice water, warm and hot water and found water temp sensor to be pretty close to graph but the air sensor was 17.1 Kohms at 41 degrees, 9 Kohms at 77 degrees, and 3.9 Kohms at 122 degrees. I know it is off the charts at cold but in my head it tells me if it is an issue it should read lower than the chart not higher if it is going to give me starting issue unless it is going overboard in enriching. Any ideas from here? Is the air temp sensor bad or do I keep looking.

[JOE54]

corespond ohm test for IAT in MERC MANUAL , not far off , replace pulse pump diaphram with oem kit , fuel psi test check for psi dropping at key off possible internal leak in inj housing ,,,,,, mtr sounds rich rich at start up

[TKress]

I was perusing google for similar problems others had and ran across one in the Scream and Fly forum that sounded pretty similar. His fix was the crankcase pressure check valve to the oil injection remote tank. Theory is that if the pressure does not relieve then oil seeps into the VST over a length of time giving you an overly oily gas mix. So the motor will fire up and run for a couple seconds on the left over good fuel in the lines until the oily gas mix hits the cylindrs and doesn't want to fire right kind of fouling the plugs. Does this sound like a logical scenario. Thinking I will run the boat then when done loosen the cap to relieve pressure then try it again the next day to see results.

[EuropeanAM]

I was perusing google for similar problems others had and ran across one in the <Announcements> forum that sounded pretty similar. His fix was the crankcase pressure check valve to the oil injection remote tank. Theory is that if the pressure does not relieve then oil seeps into the VST over a length of time giving you an overly oily gas mix. So the motor will fire up and run for a couple seconds on the left over good fuel in the lines until the oily gas mix hits the cylindrs and doesn't want to fire right kind of fouling the plugs. Does this sound like a logical scenario. Thinking I will run the boat then when done loosen the cap to relieve pressure then try it again the next day to see results.

Does the engine smoke heavily enough on cold start that you have people running their windshield wipers and headlights while choking, as they fumble for their cell phone to call the fire department?

All kidding aside, it would a PROFUSE amount of smoke in that case.

What is your TPS set at?

[TKress]

Usually just a little blue smoke, nothing profuse. I did try loosening the cap to let off the pressure when I put it on the trailer for the day. Ran it the next day and did not change the issue. Even though it is not my problem is it a part that should be changed proactively to the updated version to avoid problems with the oil injection system. TPS is next on my list, trying to get my hands on the test cable needed or build one if I can get the right pin connectors. Was also going to see if I can get the local shop to let me borrow or rent the ECM tester to check the MAP sensor, etc. I am not even sure they have one though. The other thing is saw out there on the WWW was something about an enrichment circuit on the ECM that can be either connected to the starter solenoid or to a key choke system. I have the key/push for choke but not sure if it is connected or not. Any recommendations there. And thanks in advance for everyones help. It is greatly appreciated.

[JOE54]

ever notice fuel in hose from vst to oil pump ???? = check valve on bottom of vst faulty , unless modified your enrichment is already connected to start mode notice yellow with red stripe wire going to efi harness from solenoid , there was a kit that MERC offered that had a diode inline so you could operate choke mode , heres a test to see if its lean at start up unplug one wire on head temp sensor and start it up cold = runs better = likely bad enrichment circuit in ECU

[TKress]

So I checked for fuel in the hose and none there. I tried unplugging the head temp sensor so the circuit was open and that didn't fix it either. Which may be a blessing in that so far the ECU checks OK. Waiting for parts to check the TPS next. When I do that I will try to pull a little vacuum on the map sensor to see if it changes how the motor is running.

[EuropeanAM]

Make sure that fitting the MAP sensor reference hose connects to is OPEN into the fuel management box, too. Seen those plug up.

Ditto for the hose going to the fuel pressure regulator.

[TKress]

Update, I went completely back thru the link and sync timing procedure with the OEM manual which is much more detailed. It definitely helped my cold starting situation but think I need to dial it in. After 1st attempt this week it stayed running but was a little rough at idle until it warmed up. Also felt it was real hesitant to start to roll over. talked to a mechanic friend and he thought I had maybe advanced it too far so I backed it off from about 4 degrees to about 8 degrees then it did not want to stay running as well the next day when I tried it. Still better than when I began weeks ago. Big question I guess is when doing the static timing adjustments should I warm the motor up 1st, Also do I follow up with the idle timing engine running on the water or is that an alternate method. I also noticed as it was being cranked the timing degrees tended to drift 1 or 2 if I did it more than about 3-5 seconds . I had to winterize it last night so I will pick this up in the spring. Planning on running the Mercury injector cleaner thru it then, readjust timing again, and will do what electrical tests I can this winter without turning the motor over. Thanks for everyones help so far I will update in the spring.

[EuropeanAM]

That may have been due to a battery that was beginning to "fall off" (partially discharged).

Cranking speed is usually great- you can check it at idle as well, just keep in mind that any advance module or idle stabilizer must be disconnected.