Mercury Pro XS Starting Issue

[MetsFan9]

Was on the water today, was hot 92 the high even up in the adirondack mountains. After fishing my last area went to fire up and leave and the 2015 Mercury Pro XS 150 would not stay running. First try wouldnt crank. Then the next 4 attempts it would start rev high up for about 2-3 seconds and cut out. Put the trolling motor down and started on my way, about 10 mins later tried again, did the same, third attempt it started slow but kept running. Once it started motor ran perfect, stopped at two other areas around the launch, motor started fine. Up till today never had any issues. Not sure what happened. Never turned the key and saw the motor rev so high.

2015 Mercury Pro XS 150
Serial # 2B111889

[SilverFox579]

I'm a broken record, did you pump the bulb before starting? Today's fuels will vaporize in the line, leaving your pulse pump trying to pull vapors through the line and it's designed to work with liquid fuel.

[MetsFan9]

Sure did, ball was pumped. Actually when it happened, initially, I pumped the ball, then turned the key and the motor acted as if the hot foot was to the floor for about 2-3 seconds. Motor would then quit. Did this about four more times in a row before it got running. Once started it ran perfect.

[leonreno]

I would say fuel problem, could be pump, leaking line, diaphragm. Need to check fuel/air pressure when starting and running (if possible) and after motor off. Also double check the hot foot linkages for correct travel.

[MetsFan9]

Well its at the marina now so I assume they will find and resolve the issue. Nothing a few dollars cant fix

[leonreno]

Well its at the marina now so I assume they will find and resolve the issue. Nothing a few dollars cant fix

That’s always the hope anyway. Let us know what the find.

[EuropeanAM]

Test air/fuel pressures and record results:

-At idle or Cranking Speed

-Under Acceleration (if possible)

-5/10/15 seconds after shutdown.

Lack of air pressure will also cause low or little fuel pressure.

[SilverFox579]

That’s always the hope anyway. Let us know what the find.

^^^^

[MetsFan9]

Will do guys, thanks! Prolly wont be for a few weeks, sure they are busy right now with everything slowly re-opening up here.

[MetsFan9]

Just to report back, they didn't find anything wrong. Nothing came back on the computer, no issues they could uncover, nor could they simulate the issue. They did recommend that I use Quick Kleen and triple the dosage to clean it out. Motor has 120 hours and only 40 minutes open throttle (not many big lakes here). SO I was told to run it with the Quick Kleen and start using higher octane (ethanol free). Hoping I don't run into the same issue next trip.

[krindgen]

I'm a broken record, did you pump the bulb before starting? Today's fuels will vaporize in the line, leaving your pulse pump trying to pull vapors through the line and it's designed to work with liquid fuel.

I have gone through a couple trips, a new battery, and one trip to the shop to get this in my dense German head. Recently. This is new to me since my last OMC, in 19yrs, I may have primed the bulb three times. This XS seems sensitive. Mechanic also told me to try and keep that bulb oriented in the boat with the arrow pointing up to maintain prime better. I have to work on that, but I'd make dam sure you've primed the bulb and it's hard. Mad at myself for irritating three trips.

[krindgen]

Just to report back, they didn't find anything wrong. Nothing came back on the computer, no issues they could uncover, nor could they simulate the issue. They did recommend that I use Quick Kleen and triple the dosage to clean it out. Motor has 120 hours and only 40 minutes open throttle (not many big lakes here). SO I was told to run it with the Quick Kleen and start using higher octane (ethanol free). Hoping I don't run into the same issue next trip.

Hmmm, not sure about that higher, cooler burning, octane fuel for an XS. And triple dosage, hmmm on that one too.

[MetsFan9]

Said he thought injectors may be dirty, said to load it up with quick kleen and run it thru. Ive always run 87 with no issues, and used merc fuel additives on each fill up. Also said i dont have enough time with the rpms above 4000, need to get some time on the engine running it open. Which is true, most lakes i fish are smaller so my run time at higher rpms is limited. I know the ProXS needs to run.

[MetsFan9]

My primer bulb is never firm, always stays squishy after i pump it

[krindgen]

Said he thought injectors may be dirty, said to load it up with quick kleen and run it thru. Ive always run 87 with no issues, and used merc fuel additives on each fill up. Also said i dont have enough time with the rpms above 4000, need to get some time on the engine running it open. Which is true, most lakes i fish are smaller so my run time at higher rpms is limited. I know the ProXS needs to run.

Could be that you're in need of injector rebuild. I believe it's around 5 yrs recommended, maybe sooner if doing a lot of idling. I'd take 'er somewhere big enough to be able to open 'er up with a tank of well treated fuel. See what happens. Maybe even dose the cylinders overnite with de-carb.

[MetsFan9]

I don't idle much, what is considered idling. I mean I rarely am idling around graphing, or navigating no wake zones. Just not busting WOT non stop - most lake I am running 40mph plus. Didn't realize I had to hammer down constantly.

[MetsFan9]

Injector rebuild? They did not mention anything like that, other than to run it thru. They went thru everthing

[SilverFox579]

I don't idle much, what is considered idling. I mean I rarely am idling around graphing, or navigating no wake zones. Just not busting WOT non stop - most lake I am running 40mph plus. Didn't realize I had to hammer down constantly.

You don't. Spend as little time as necessary under 1500rpm, as much time as possible around 4500 - 4800rpm, 87 octane fuel using the cocktail posted in the FAQ. High octane fuel won't help the issue and may only make it worse. Everything you need to know about fuel and additives is covered here - Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations

[MetsFan9]

Was planning to treat the gas I have with the quick kleen and let her run in that range till most of the tank is empty this weekend. Sticking with 87, up till last week never had an issue. Have always used Merc additives, will try the cocktail on the next tank, have about 15 gallons to burn thru on this one. See how it behaves on this, and then next full it I will run the cocktail.

Least it eventually started, once the surge and shut off 2 seconds later ended, it ran perfect and stopped and started after that without issue, they also took it out and didn't have the issue either. Who knows

[krindgen]

Was planning to treat the gas I have with the quick kleen and let her run in that range till most of the tank is empty this weekend. Sticking with 87, up till last week never had an issue. Have always used Merc additives, will try the cocktail on the next tank, have about 15 gallons to burn thru on this one. See how it behaves on this, and then next full it I will run the cocktail.

Least it eventually started, once the surge and shut off 2 seconds later ended, it ran perfect and stopped and started after that without issue, they also took it out and didn't have the issue either. Who knows

Prime fishing time up there so don't waste it.