Rpm a on 250xb

[Jlbryant]

[COLOR=rgba(0, 0, 0, 0.701961)]2001 Mercury 250xb OT235539. Having a idle problem. I took the intake off to see what reeds were in it and while I had it off I cleaned the intake real good and got all the carbon off. I put it back on and changed out all my fuel lines except the thick walls in the boat itself. And I did turn the tps up a tad bit. I was running yesterday and it would Turn 5900-6k going one way down the lake and only 5100 going back. I made several big loops and it did it Everytime (i know it's was weird and made no sense). I'm lost, did me turning the tps up cause this? I did it so it would idle in gear and it still won't...[/COLOR]

[cbailey]

Did you take the reed blocks completely off and look at them? I would set tps per mercury spec and leave it there. If the idle rpm is low, isnt there a idle adjustment screw that will allow you to increase idle speed?

[Savage]

[COLOR=rgba(0, 0, 0, 0.701961)]2001 Mercury 250xb OT235539. Having a idle problem. I took the intake off to see what reeds were in it and while I had it off I cleaned the intake real good and got all the carbon off. I put it back on and changed out all my fuel lines except the thick walls in the boat itself. And I did turn the tps up a tad bit. I was running yesterday and it would Turn 5900-6k going one way down the lake and only 5100 going back. I made several big loops and it did it Everytime (i know it's was weird and made no sense). I'm lost, did me turning the tps up cause this? I did it so it would idle in gear and it still won't...[/COLOR]

The TPS doesn't care or know which direction you were heading. Did you have current, waves, or wind to contend with?

[Jlbryant]

The TPS doesn't care or know which direction you were heading. Did you have current, waves, or wind to contend with?

There was no wind and it was perfect chop. Last time out before I cleaned intake boat went 83.7 with 2 people and 20gals of gas.

[Jlbryant]

Did you take the reed blocks completely off and look at them? I would set tps per mercury spec and leave it there. If the idle rpm is low, isnt there a idle adjustment screw that will allow you to increase idle speed?

No i didn't take the reed block off

[cbailey]

if you suspect that the reeds are burnt, reed blocks need to be removed for inspection. it is difficult to tell otherwise. burnt reeds or blocks WILL cause an idling problem and speed wont change that much but from an idle and midrange, quite a bit. I would put tps back where it was and look at the fuel system before I did anything else, from tank to engine. idling problem can be caused by bad plugs also, which can be affected by bad reeds.

[Jlbryant]

if you suspect that the reeds are burnt, reed blocks need to be removed for inspection. it is difficult to tell otherwise. burnt reeds or blocks WILL cause an idling problem and speed wont change that much but from an idle and midrange, quite a bit. I would put tps back where it was and look at the fuel system before I did anything else, from tank to engine. idling problem can be caused by bad plugs also, which can be affected by bad reeds.

Yea I'm hoping its a fuel problem. It shot out of the hole as normal. Idk its wired. I'm gonna pump the tanks back out and start with fresh fuel.

[kllr bee]

Factory setting on TPS is .95 I set my 250XB at 1.01 to prevent lean sneeze. With what you said about different speed one way than the other, a stator can run perfect cool and then heat up and miss on one or more cylinders when hot you may be making good run heating stator then turn around and it be heated and missing. Only way to know is try another stator. First try new QL7CC Champion plugs. These motors eat plugs.
Richard

[blazer250]

I was thinking the stator also. Isn't there a way you an test it

[kllr bee]

Not so easy if it is happening when it gets hot.
Richard

[EuropeanAM]

Not so easy if it is happening when it gets hot.
Richard

+1.... however, RESISTANCE tests (and VISUAL inspection for ANY discoloration of windings, or melting) can be helpful. Not foolproof- but helpful.

100% agree with the comments above in regards to the reeds, and the TPS adjustment.

Reeds/blocks must be REMOVED from the engine to properly inspect. And they MUST be 100% intact, no missing material, and sealing properly to achieve proper performance.

TPS absolutely MUST be set within the recommended range (.95 VDC, +/- .05 VDC). Normally going to be in the .96-.98 VDC range for best overall performance.

INJECTORS are another area to consider. WHEN were your injectors last serviced (and CALIBRATED)? Recommended every 2 years, or 200 hours (whichever occurs FIRST) on this design injector.

And as stated above- CHAMPION- QL77CC Spark plugs ONLY (make sure you try a FRESH set of them). Definitely replace at LEAST annually.

On your fuel lines- make sure you performed ALL (every single) recommended item found here:

http://www.bbcboards.net/mercury-3-l...tem-first.html

[All Age Dog]

i love these ultra strong motors and want to know what ya find out.

[Jlbryant]

I did power tune the motor to get rid of carbon. After that I did put the old spark plugs back in it and ran it threw the motor until it burnt all of it out. Then I replaced the plugs with ql77cc and maybe I didn't get all the power tune out and it fouled the new plugs out

[EuropeanAM]

That's certainly a possibility... power-tune (which is a GREAT product BTW) will do a number on spark plugs (makes a nice "candy-coating" on the plug).

[Jlbryant]

It did it again this weekend. I ran I don't know 6 miles down river and it ran fine turned 6k the whole time and half way back it shut down to 5100rpm.

[EuropeanAM]

Factory setting on TPS is .95 I set my 250XB at 1.01 to prevent lean sneeze. With what you said about different speed one way than the other, a stator can run perfect cool and then heat up and miss on one or more cylinders when hot you may be making good run heating stator then turn around and it be heated and missing. Only way to know is try another stator. First try new QL7CC Champion plugs. These motors eat plugs.
Richard

I would recommend inspecting/testing the stator (especially a VISUAL inspection with flywheel removed, watching for any signs of discoloration to any bobbin). Each "bobbin" is wired independently... so loss of ONE will result in loss of spark to one cylinder.

[Jlbryant]

I would recommend inspecting/testing the stator (especially a VISUAL inspection with flywheel removed, watching for any signs of discoloration to any bobbin). Each "bobbin" is wired independently... so loss of ONE will result in loss of spark to one cylinder.

Is there a Teat I can do with a meter?

[EuropeanAM]

Yes, you can test resistance on each winding (but that won't help much if it's an INTERMITTENT or "heat induced" failure).

Resistance testing, combined with VISUAL inspection is usually best.

[swolt45]

Time for a 300xs

[EuropeanAM]

Any updates?