1998 yamaha 115 2 stroke gremlin

[njterrier]

Having an issue with the motor rough idling, coughing, stalling at idle.
Motor will fire up no problem, idle at 750 for about 10 seconds, then fall to 300 rpm and stall.
I figured that the carbs were dirty, so I brought it to the Yamaha mechanic in my area (5-star certified), he did a carb re-build, ultrasound cleaning, check of compression, CDI check, and overall check, all came back fine.
He had the boat almost the entire month of JULY. I pick the boat up last week, topped off the tank with fresh fuel, proceeded to launch, and whammo..rough idle and stall at the ramp.
Brought the boat right back to the mechanic, he re-cleaned the carbs, bowls, all new filters (10 microns) then reassured me that it will not happen again, should be no problems.
Picked the boat up again, tried another launch, same result. This time it is running even worse. Hard to start, falls off idle immediately.
I pulled the boat out again, started the boat on ear-muffs, with a pony tank attached with fresh fuel, and same result. Will not idle, however when I set at fast idle (1100-1300) rpms, she stays lit, but when I shift to neutral, she dies.
I am stumped, as the mechanic checked over the entire motor.
Is it possible he did not set a low speed idle jet correctly?, or the carbs are not tuned?.
Can bad fuel be a culpret?, or will bad fuel not even burn at higher idle speed?
I have since taken the boat back to the mechanic, and I have not heard anything back.
THX Scott

 

[rodbolt]

Re: 1998 yamaha 115 2 stroke gremlin

if you have a 5th grade reading comprehension level I can loan you the books and you can be 5 star certified in about 1.5 hours.
if you cant read and can stay awake while watching the videos it takes about 4 hours.
go find a real tech
if spark and compression are good you either have cloged pilot fuel jets or a bad fuel pump diaphram. almost anytime I do carbs I replace the fuel pump as well.

 

[njterrier]

Re: 1998 yamaha 115 2 stroke gremlin

THX for the reply RB...
Still have not gotten the boat back.
Hope they figure this out soon. I have not fished since June....

THX Scott

 

[rodbolt]

Re: 1998 yamaha 115 2 stroke gremlin

bummer

 

[njterrier]

Re: 1998 yamaha 115 2 stroke gremlin

This problem is really starting to drive me nuts.
I hope the tech test's the low pressure fuel pump. I am pretty sure it is the original. The motor is a 1998, I am the 2nd owner, and I never had anything overhauled or replaced until now.
I also have a copy of a SELOC shop manual for my motor, and I was just looking at the Carb set-up Specs for the Pilot Screw (initial low speed setting). I noticed that for my particular motor, model year 1997-98 shows a different setting than anything built later. 1997-98 3/8 - 7/8 vs 1 - 1 1/2 for the latter. Perhaps the tech looked at the wrong setting, and adjusted accordingly, and never bothered to test before closing out the job.
thx Scott

 

[njterrier]

Re: 1998 yamaha 115 2 stroke gremlin

My head is about to explode.......
I picked up the boat last Friday Aug 7th.
The shop had my boat for a week as I brought it back for the 3rd time since July 1st (same problem). The mechanic told me that I have bad fuel. He showed me samples of fuel that looked like Guiness stout. He told me that he had the boat in the water for a week, and basically used my boat as a shop boat to make deliveries to other boat owners docks and such. He basically told me that it worked perfectly, never idled rough or stalled since they were using it. He advised me to drain my fuel tanks. I had roughly 20 gallons left in a 60 gallon tank. He also advised me to put a bottle of e-zorb in the tank after I drained the fuel, and add about 10 gallons of fresh fuel, drain again, and put another 10 gallons of fresh fuel.
I did as he advised, I also changed the 10 micron fuel/water filter after I drained the tank, and I took fuel samples through-out the whole draining procedure. The only water that I saw in my fuel was left over in the filter after the procedure, and it was maybe 2-3 oz's. I emptied the filter, filled with fresh fuel, and re-installed.
I went to launch the boat last Sunday Aug 9th, guess what?, she idled rough and kept stalling at the ramp. Same damn problem. I was able to get the boat back onto the trailer, took it over to my boat yard, hooked up the motor to ear-muffs, bad idle, cough, sputter, stall. I also tried it on a pony tank, 1 gallon of fresh fuel, same outcome. I checked my plugs, they look normal. I noticed that just about she is about to stall, if I pull out the mechanical choke lever and push back in, she catches herself, and runs strong for about 10 seconds, then goes into a reduction of rpm and stalls.
I have since brought the boat to another shop, described everything that was done previously, and I am hoping that this mechanic can find the issue.
I am completely stumped. Why would the previous shop tell me that my boat has been running fine, show me fuel samples that look nothing like the fuel in my tanks? I am pretty annoyed that after 1 1/2 months there is no solution, and I am feeling as if the mechanic is just being lazy and hasn't done any work to my boat, or just did a half a*s-job and never tested anything he did.
The shop is a reputable place, and has been around a long time.
Watch this end up being a stupid 50 cent piece of tubing or a gasket causing the problem.

Scott

 

[kinggabbo]

Re: 1998 yamaha 115 2 stroke gremlin

Did you ever figure out the problem?

 

[rodbolt]

Re: 1998 yamaha 115 2 stroke gremlin

dunno if he solved the proplem but I just Re did the carbs on an F100 that I did last week.
the fine E fuel is dissolving the tank and it clogged the carbs,stuck two needle and generally made a mess.
I warrenteed the labor but he did have to pay for needles and a filter.
if he hooks his poly tank up again there wont be any more warrenty.
be aware that most poly tanks from 2000 to 2007 are having issues with this incredibly fine fuel blend, if the tank is exposed to sunlight it makes the problem worse.

 

[JustJason]

Re: 1998 yamaha 115 2 stroke gremlin

Poly tanks as in standard red plastic tanks? Is it just the cheapies like moeller or is it the oem tanks to?

 

[rodbolt]

Re: 1998 yamaha 115 2 stroke gremlin

only problems I have had with the red tanks are drawtubes failing. the other brand you mentioned wont talk to me on the phone but has been a big headache. fuel sender floats,draw tubes and tanks can and may dissolve especially if the fuel sits.

 

[JustJason]

Re: 1998 yamaha 115 2 stroke gremlin

Okay... I have seen a few fuel sender floats missing, not in the tank, and assumed disolved and passed through the fuel system. I thought you were meaning that the tanks themselves were getting "disolved" through. Causing them to leak externally... which i've never seen.

 

[rodbolt]

Re: 1998 yamaha 115 2 stroke gremlin

so far I have only seen 1 tank actually dissolve a hole in it and that was the red fiberglass tank on a 72 whaler.
however I can show you a 36 yellowfin with 3 275HP verado,s that has a dissolving fiberglass tank cause we pulled the draw tubes and they were packed with strips of loosened resin chunks.
boat now has 350 gallons of unusable contaminated fuel.
I also have a carolina skiff and an 06 bayrider with the poly tanks dissolving the bayrider it wiped two pistons on the way down.
this stuff dissolves and now CANNOT be filtered but when the fuel vaporizes it does not and starts sticking things up badly.