Sport Jet Starting Problem

[Nate]

My 2005 200hp sport jet is have an intermittent starting problem. It will start just fine some times but then there are time it will start and die then cranks for about 10 seconds sputters and slowly builds rpms and then runs and idles fine. No other performance issues motor runs great once started, no alarms.

Its been into one of the local mercury deals 3 times now. No codes from the computer all parameters are good. Main relay is new as of last year after it left me stranded at the Jet boat weekend. TPS was replaced last July as well, and just replaced the low pressure fuel pump.

At this point I'm thinking rigging, linage out of adjustment, throttle cable stretched, maybe neutral safety switch is acting up??

Has anyone had this problem? Advice?

[kylejohnson]

Have you ran a whole tank of gas through your boat this year?

[Nate]

I have not ran a tank through it yet but I have been dealing with this problem since late last summer...

[Halibutgrove]

I have not ran a tank through it yet but I have been dealing with this problem since late last summer...

Nate, has the fuel pressure and air pressure been checked? The computer won't always throw a code for every problem. Recently had an engine in that had a faulty crank position sensor. The engine would run fine for about 30 mins but once it came up to normal operating temp the sensor would start failing. Since the error was not a sticky error, once the engine cooled off and was started again when cold the error no longer showed up. If your SPJ all of a sudden just begins to run no more then 1500 rpms and rough has heck it's a good chance the crank sensor is bad. It won't provide any warning beeps either.

[Nate]

I have been told that all pressures are in spec, and that the motor has passed all cylinder drop tests. It did get a new air injector last year...

[.338WM]

Why was the low pressure fuel pump replaced and was the fuel filter replaced at the same time?

[Nate]

LP pump was replaced because it was the original and from my research they have been know to go out and in hopes that it was part of this starting problem. The filter was replaced with the new pump.

[.338WM]

LP pump was replaced because it was the original and from my research they have been know to go out and in hopes that it was part of this starting problem. The filter was replaced with the new pump.

Ok, wanted to rule out the filter being overlooked, as is often the case, and having a filter full of pump guts.

[Nate]

Went to knik today to get the boat off the trailer and replace the bunks. Took the boat for a ride after I was finished had no problems with starting this time... turn the key and fired right up...:confused::confused:

[Nate]

Problem has come back more regularly. Recommendations for a shop? Marita has no clue!

[Alaskan XL]

Danny at Boat Shop in Fairbanks.

[Kevin Turner]

My 2005 200hp sport jet is have an intermittent starting problem. It will start just fine some times but then there are time it will start and die then cranks for about 10 seconds sputters and slowly builds rpms and then runs and idles fine. No other performance issues motor runs great once started, no alarms. At this point I'm thinking rigging, linage out of adjustment, throttle cable stretched, maybe neutral safety switch is acting up?

More details plse-
Does the issue occur more than once a trip? Or, only during the initial start up?

Rule out neutral safety if she cranks. Rule out lanyard kill switch if horn beeps when ya turn the key on. Throttle cable...not likely; easy to check.

If you haven't already tried, cycle key on-eng off several times listening for the fuel pump. It should run about three seconds then kick off. I do this on all new start ups to pressurize the fuel components.

[AK Troutbum]

Problem has come back more regularly. Recommendations for a shop? Marita has no clue!

Give akgravelpumper a call. I pm his # to you.

[Nate]

More details plse-
Does the issue occur more than once a trip? Or, only during the initial start up?

Rule out neutral safety if she cranks. Rule out lanyard kill switch if horn beeps when ya turn the key on. Throttle cable...not likely; easy to check.

If you haven't already tried, cycle key on-eng off several times listening for the fuel pump. It should run about three seconds then kick off. I do this on all new start ups to pressurize the fuel components.

Problem has come back 100%. Starting the motor takes about 10 to 20 seconds now, regardless if the motor is hot or cold.
The low pressure fuel pump is new and cycles normally and I have cycled it 3 to 4 times and that does nothing to help starting.

[Kevin Turner]

Nate-
Keyboard diagnosing can get one in trouble, however I'll point out a couple common things I look for. I have had SJ Optis that seemed to crank OK, yet would not start or were slow to start.

To fire, the Opti must first build fuel and air pressure. If we rule out fuel pressure, let's move to air pressure. While cranking, the air comp must spin fast enough to build 90 +/- psi. If the crank batt is not up to the task, it takes awhile to build pressure and maintain min voltage for the electronics.

If you have not already done so, double check the batt (should have a min of 800 CCA flooded wet cell design) and all batt cable-connections.