F115TRLA (2002) Stalls / Dies

[Little Fish]

After going through my spring maintenance routine (new plugs, engine oil, lower unit oil, engine filters and water/fuel separator filter) I had a very difficult time getting the engine started. I clean the injectors and ultimately took the engine to a Yamaha tech who went through the VST tank. After he completed the work he ran the engine and reported it purred like a kitten.

On my first trip out on the water I was running at 4200-4400 rpms and the engine hiccupped and died. I was able to restart and get to my end destination, but later in the day it did the same thing and finally would not start at all. I was on the water at a dock so couldn't completely trouble shoot the problem, but was able to pull all the injectors and clean them with carb cleaner and compressed air. I also blew fuel through the rail by turning the engine over to clean out any crud. I reassembled everything and once again the engine started and purred like a kitten....until it died 3-4 minutes later. After letting it sit it would start again, then die again. I have my boat at home now and it does the same thing....the engine starts and runs well until it dies. The engines appears to run well until it warms up.

I have a Seloc manual and plan to start testing individual components (to the extent that I can), but thought I would ask if anyone has had a similar problem before I start trouble shooting.

I checked the spark on each cylinder with an inline tester (after the engine died) and all cylinders are getting spark although cylinder 4 appears to be a little weaker than the rest. I have not checked the fuel rail pressure, but ordered a fuel pressure gauge and will check pressure when it arrives. My initial thoughts are that the fuel pressure regulator is going bad or maybe the ignition coils are starting to fail, but these are only educated guesses at this point.

Any thoughts regarding the most likely cause of the problem?

Thanks in advance.

James

[ausnoelm]

I doubt the coils are faulty, weak or anything else.

[rodbolt17]

my guess would be a fuel issue,water,debris.
possible a key switch failure.
pull the stop lanyard and crank it. you should get an alarm.

[Little Fish]

Thanks for the input. I will run through the list and test pressure on the rail once fuel test gauge arrives

I will report back in a few days.

[Little Fish]

Rodbolt17....I think I am zeroing in on the problem (I think I have a high pressure fuel pump issue).

Do you know if the fuel pumps used in later model engines (say 2006 or newer) will work in earlier engines? The parts numbers are almost identical

68V-13907-00-00 (part for my engine)
68V-13907-03-00 (part for newer engines)

I ordered the -03- version of the pump and just want to confirm it will work.

Thanks,
LF

[boscoe99]

The -03-00 is the latest part number pump. It will work.

If you order a -00-00, a -01-00 or a -02-00 you will get a -03-00.

Some change for some unknown reason.

[Little Fish]

Thank you.

[Little Fish]

I think the problem is fixed, but have not taken the boat out on the water yet to run it at higher RPMs. If I run into the same problems again I will be back.

Recap: The problem started after doing my spring maintenance when I took my first trip on the water. The engine initially ran fine, but stalled a couple of times when I was running at roughly 4K rpms. Initially I was able to restart the engine, but after running it up to closer to 5K rpms the engine stalled. I was able to restart the engine several times and it would run for 5 minutes or so then die. Eventually it would only run for 30 seconds then die. I cleaned the fuel system (VST tank, injectors, fuel rail, fuel/water cooler etc.) The boat ran again, but eventually I had the same problem. I tested the HP pump (outside of the engine) and it seemed to operate just fine so my first fix was to replace the fuel regulator valve. Again the boat ran fine, but eventually I got to the point where it would only run for 30 seconds and die. After talking with the local shop (who asked if I had ever run the VST tank dry) I decided maybe the HP was bad. It was my understanding that the HP pump usually runs or it doesn't run. In my case I believe the pump craps out at higher RPMs....in other words an intermittent problem. After replacing the HP pump everything is running fine again.

Now here is where I made some mistakes. Over the years it hasn't been uncommon for me to accidently run one of my fuel tanks runs dry. I usually shut down the engine, switch tanks, pump the primer bulb and then start the motor again. Then this spring when I replaced the water/fuel separator I failed to pump the priming bulb before starting the engine. When I went to pump the bulb I noticed the fuel valve was in the off position so basically I was trying to start the engine with very little or no fuel in the VST tank. Since the engine is 14 years old and VST tank has gone dry on multiple occasions (especially this past spring) I think the HP pump decided to start acting up.

Hopefully the problem is fixed and the lesson learned is to NEVER turn the engine on when the VST tank is less than full.

James