99 Johnson 115HP Starts, idles, but won't stay running at high RPM.

[wharfcreek]

1999 Johnson 115HP model J115SLEU. Purchased last year and ran fine for the remainder of last season. Has seen very limited use this year so far pending fall 'trolling' season. (20' MayCraft). Took a joy-ride some time in July and again in August....but been sitting on a lift pretty much unused all this season. So, finally ready to go fishing, made plans to go yesterday, and 'started' the boat and let it idle some over this past weekend. Feeling confident, we got ready to leave yesterday am and boat was VERY difficult to start (also a new problem). After finally getting it running and idling smoothly we headed out the creek. Got boat up on plane for all of about 5 seconds and then it just dropped it's nose and quit running. A complete stall. Restarted, got it up on plane again, and it dropped out immediately again. Repeated this several times and decided to call it quits on the fishing trip. I did have my friend at the helm while I tried pumping the bulb and I think that got it running better, but I couldn't stay pumping it.....and we were almost back home. But, I was thinking 'fuel pump'....so after my friend left, I started making calls. Was advised to try a separate fuel tank with new line and fresh new gas. Did all that and problem persisted. I even eliminated the bulb and went with a direct line from tank to engine. Same problem.

NOTE: When I first purchased this boat the 'check engine' light was on and a warning horn went off for about 10 seconds upon start-up. The horn quit, but re-sounded about 2 minutes later.....quit for a few more minutes, then went off a third time...then quit altogether. Check engine light stays on. Prior owner indicated that the boat did NOT have a 'check engine' circuit in this 115 HP model,and this condition was an anomaly not to be concerned with. Boat ran fine, so I ignored it. This same condition has existed since I bought the boat....and a local boat Tech indicated that prior owner was, in fact, correct. So, at this point, I'm incline to think my current problem is NOT related to this check engine light or warning horn. However, I mention it only for information purposes.

So, just to wrap up, when engine first starts after warm-up, it starts easily, doesn't smoke all to badly, and idles smoothly. I could probably idle around all day, however when attempting to get up and run, it just dies out. This would typically seem like a 'fuel starvation' problem in my book.....but I'm looking for some confirmation. Also, I'll note that another friend has indicated that perhaps my VRO pump is the problem? Not sure what that is, but evidently it's both the 'fuel pump' AND the Oil Injection Pump in one component assembly. It's also expensive, like $500? Anyway, not looking to spend that if possible, but if necessary, then so be it. I'd like to solve all 3 problems: Check engine light, warning horns, and poor running at high RPM. If I had to live with two of the 3 problems, then the poor running is what needs to be fixed. Also, if anyone can actually confirm that in fact the 115 HP engine does NOT have the Check Engine Light circuitry...that would be good to know. Any further help is GREATLY appreciated. Many thanks, Tom D.

 

[jakedaawg]

Plumb a clear vinly hose in right before the OMS pump. Tee a vacuum guage in and report back the in/Hg. This would be on the fuel "in" line.

 

[jakedaawg]

The above may be wasted time but will not hurt. i am pretty sure the v-4's didn't have a fuel restriction alarm but I have been wrong before. In the absence of a V motor expert the above test will provide insight. This is where I would start would it be one of mine.

A well maintained modern VRO or OMS pump is incerdibly reliable. After 20 some years working with them they seem to fail to too much oil as opposed to too little. I will take heat for that but it is true to my experience. They are pretty mis-understood.

 

[wharfcreek]

So is there any reason I need to use a 'clear vinyl' hose for this? Is the objective here to be able to see the 'suction' being created by the fuel pump? If so, would it not be OK to just do this with regular fuel line? Also, I'm not so sure I know what an OMS pump is? And, I'm not sure I understand the meaning of your comment about the failure of a VRO pump being too much or too little oil. I'm thinking I'm dealing with a 'too little' fuel problem here. Can't that VRO pump be the source of that problem as well? Thanks, Tom D.

 

[jakedaawg]

You use a clear line to see if there is an air leak, not really necessary here but if you're gonna make the tool make it right so you will have it for the future. Usually a check engine light is a fuel restriction hence the vacuum gauge. Although in hind sight I really dont think the v-4's had that switch. The OMS is the VRO. It is the fuel as well as oil pump. I included the line about the reliability of VRO pumps because many people believe you need to get rid of these pumps due to their less than steller reputation, however...like I said...they are very reliable.

I am wondering if you may not have two seperate issues. 1. being a fuel pressure issue by the statement that if you pump the bulb it stays running. and 2. by the possible fact that your system check guage sounds an alarm and lights a light ( check engine) for a sensor that i am not sure you have.

 

[racerone]

Hpw old is the fuel ?---Was fuel sitting in the carburetors when boat was " un used " ?----Have you checked for water in the fuel ?------Have you checked filter in the oil tank ( if equipped ) with filter ?