trouble with a merc 150 xr6

[basscat22]

Im having trouble with my 2001 xr6. Its starts and runs fine in the morning but the later in the day it get the worse it get. Ill start it and it will idel ruff like its loaded up or missing on a cyinder. Then when I gun it it starts spittin and spattering. then its like it just clears out because it screams on the top end. and runs ok when slowing down. then its a 50/50 shot that its going to do it again when i start it back up. Ive put new plugs, primer, fuel filter, and run quickkleen. Im about to take it to the shop. but Im hoping someone has an answer. Ive been reading on bbc that other people are having the same trouble and it just happen with this motor. but ive never had it this bad.

[Bass Cat Boats]

just a guess……………….powerpak, coil

[Bass Cat Boats]

fuel accelerator pump is our guess. Were going for the carb rebuild.Last edited by Bass Cat Boats on June 17th, 2008, 6:57 pm, edited 1 time in total.

[oldtimer57]

A couple of things to consider. 1. I had an intermittent coil in m XR6. It would run fine, then run like an 85hp motor, then back to normal, etc. Finally caught it missing at idle and starting pulling plug wires until I found the cylinder that was missing. Replaced that coil and the problem went away. 2. I use one of the glass/ceramic fuel filters. If you use one of those, run the motor with the hat (cowl cover) off and watch the filter as you get on it. See lots of bubbles? Find the air leak. Could be a line cut by a clamp on the powerhead, could be the o-rings in the tank-to-engine connection, could be in the line from the tank to the motor including the primer bulb. And it could always be the fuel pump itself if the diaphram has ever dried out and developed a crack. If someone asks me to check this kind of problem, I ususally replace the fuel line from the pump to the filter with clear line, then I can see what is going thru the motor. The filter will always have air in it, but the fuel in the line ought to be clear of bubbles. If that fails, out comes my inductive timing light. I go from wire to wire and run the motor to see if one is not firing. You can also do a quick sanity check on all connections under the cowl, paying particular attention to the switch-packs where they have bolts that hold them to the block. These are important connections as well as they are the switch pack grounds, and if they are rattling around you can destroy the motor as this will screw up spark timing. It could also simply be time for a carb rebuild. If the needle/seats wear or crack, fuel/oil can run into the crankcase depending on how you leave the motor while you fish. If you tilt it up, the fuel should run out into the silencer and into the cowl and not cause much of a problem. If you “tuck it in” to be ready for the next take off, you can load up the crankcase with raw fuel and oil and it will be sluggish on takeoff, if the needle/seats are leaking. If that all sounds foreign to you, a trip to the shop would be the best idea. 2008 Pantera Classic2014 Mercury Pro XS 200

[basscat22]

thanks for the great reply. I can do some stuff but Im not going to tear into those carbs. Is there a way that they can hook it up and see whats going on. I seen a big plug on the side of the motor with a cap on it. When I replaced the primer I replaced the fuel line and all and it stays hard. Is there a low idle stater on this motor. I read of a guy having a bad one and his motor was doing the same thing. If I take it to the shop i dont want to be going back and forth as they eliminate problems.

[LA Elwood]

My 04 is doing the same thing and i am like you….I dont want to spend a bunch of money on the shop trying to make it reproduce the problem. It starts on about the second or third run for the day. I hope someone figures this out and if mine finally hard breaks and I have it fixed I will let the others know. ElwoodElwood…..Bass Cat Proud

[Bass Cat Boats]

Im hearing that it could be vapor lock because of the ethanol in the fuel. They said to pump the primer bulb before you start it. Than should break the lock. thats going to be a pain in the butt because my primer is under the deck lid. I hope there is another fix

[Bass Cat Boats]

If it is a vapor lock, which would only be a starting issue, here is a fix that would suffice on a replacement part we have done before. Run a Y or T Connectors into each side of the primer bulb, then hook a small electric fuel pump in line there mounted under the splashwell. Turn the pump on before you fire the engine, and turn it off. The primer bulb will then prevent the backflow of fuel, and the fuel pump would prime the engine as it is loosing prime for the reason of the vapor and fuel gassing. We dont suggest this unless there is no other remedy. Though that is if you finally determine that this is the issue. Check all of the fuel lines for a leak, and tighten all the clamps. We suspect it is an accelerator pump or carb issue and that would be easily remedied with a rebuild and that we do suggest. BCB

[oldtimer57]

Im not aware of a “low idle stator” on the XR6. While I have not worked on every model made, the ones I have worked on use the usual trigger ring under the flywheel that is mechanically moved by a long lever driven by the throttle cable. There are some potential electronic issues I have seen. On early XR6s, merc added an electronic module to advance the spark when the motor is put into gear. This is the way you adjust the idle on a 2-cycle, and advancing the spark was done to combat the high resistance of the big pitch props used on bass boats. Ive seen one go bad and totally screw up the timing. It connects to the switch boxes, and while I cant recall for the life of me how much advance/retard it was capable of, it was used as an RPM limiter on the older XR6 motors. No idea whether this was continued to the end of the manufacture or not… A timing light on #1 will show if the timing is way out, which will certainly make it run poorly. But normally this does not suddenly “fix itself” as you are describing. Your case sounds more like fuel than ignition IMHO…2008 Pantera Classic2014 Mercury Pro XS 200

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