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TLDI MD90B stalling at idle

A

Artcha

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Hi, I have a set of 2006 TLDI 90s on a Boston Whaler. Yesterday the starboard engine died when I dropped down to idle after a 45 minute run and now dies after less than a minute if running at idle, it sounds rough before dying.
I’ve pulled the plugs and they look dry and clean.

I did notice that the water stream yesterday was slightly reduced on the problem engine and it looked like a bit more water could have been coming out of the exhaust than the port engine. The other thing I’ve noticed recently is when the engine is up for a day and I put it back down into the water the slightest oil slick shows up which is why I was wondering if the plugs were fouled and a bit of the residue was getting into the water.

Fuel is clean and the port engine runs great on the same supply. I didn’t notice any change in power or imbalance when coming home yesterday (4000rpm at 27knts). Lastly I checked the oil and they are at the same level on both engines.

Unfortunately I have guests coming next week for some crabbing so really hoping to address this without pulling the boat. Any ideas or troubleshooting tips would be greatly appreciated.

thank you!
arthur
 
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I just spent some more time at the boat and I believe it’s giving off these error codes. Also I can confirm that the water coming out of the exhaust on the stalling engine is significantly more than the working port motor.
4500rpm A flashing C solid
4000rpm C solid
4000rpm A flashing C solid
4000rpm A solid C solid
7000rpm C solid

I am not sure how long the codes have been active since last reset so reset them and will see if any new ones show up. After a quick run around the bay no new codes have shown up. Also once into gear and with throttle applied it still makes similar power and does not stall. But after going back to idle the motor stalled again. Seems like you have to really jam on the throttles quick to get it into gear without stalling.
any advice would be super helpful.
 
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You did not mention, but I think your model is MD90B. Have you checked fuel and air rail pressures? Are you using the idle speed at low, medium, or high? I would start by resetting the TPS initial setting. Those indicators refer to low battery. Is it up to snuff? Must be a solid 850 cca, or 1000 if in cold weather. The 7000 indicator refers to the FFP... Possible bad line or pump.
 
pvanv said:
You did not mention, but I think your model is MD90B. Have you checked fuel and air rail pressures? Are you using the idle speed at low, medium, or high? I would start by resetting the TPS initial setting. Those indicators refer to low battery. Is it up to snuff? Must be a solid 850 cca, or 1000 if in cold weather. The 7000 indicator refers to the FFP... Possible bad line or pump.
Click to expand...

Hi, thanks for the response!
yes it’s an MD90B. The battery looks good, newer agm 1000cca and at 12.85v at rest. I purchased the boat this summer so don’t know how old that low voltage warning is.
I’ll look into idle speed this morning and post back.

Do you happen to know if it’s possible to buy a digital version of the shop manual for the MD90B?

thanks!
 
I got the TPS reset this morning and confirmed that both engines were in the low idle setting. Changing to high seems to prevent the troubled one from stalling. I also think that might address the occasional stalls I get shifting. Will keep a close eye on error codes and also test medium idle (was too stormy to take it out for a test)

I haven’t tested pressure yet, do I need the tohatsu tool for that or would something from Napa work, I’m on an island and can’t seem to find the tohatsu tool online.

The one thing that’s really clear is the starboard engine spits out a lot more water through the rear exhaust hole a few inches above the waterline than the port engine. Is this a symptom of a bigger issue? I’ll get these serviced as soon as possible but all the shops are booked out for the next month or two.

thanks very much for your help (ordering a manual as well but won’t get here for a week or two)

Arthur
 
pvanv said:
Any accurate pressure gauge will work. The cooling water should be a non issue.
Click to expand...

I’m not 100% sure the gauge I got at NAPA is totally accurate, the air measured 80psi and the fuel at 90psi, this was at medium speed idle.
I found the specs for the C version and it looks like both fuel and air might be 10psi lower than expected or my gauge is off. The difference between the two seems correct.

Any other things I can check?
 
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