Low speed idle issues

[Poppr]

Having a bit of trouble, for the first time, with my 8 year old Yamaha 90HP Inshore series motor.

Problem first occured last week. I have had the boat in the water since April and have already run about 60 galons of fuel through it so not an old fuel problem or a sloppy winterization.

Starts fine and runs great at anything over 800 RPM. No missing, skipping, etc. Below 800 RPM starts to sputter and cough a bit and will eventually stall after 30 seconds to 1 minute. Does not seem to be fuel starved as filter looks full and ball remains firm after pumping.

When running at speed have no issues what so ever.

For the entire life of the engine normal idle is 500/600 RPM.

I tried different plugs and have the same issue. Fuel filter assembly is next.

Canister is supposed to be serviceable but could not get it to budge when I tried yesterday. Taking the hole assembly off is not an issue; getting the canister to open to clean/inspect filter is the problem. Don't think the problem lies there as no fuel starvation at high speeds so I'm shy to force the issue of opening the canister.

Any other suggestions??? Cranking up the idle to 800 RPM is not really the solution I'm looking for.

Kind of need to have a more stable low speed idle so I can tube and worm as the water gets warmer on the surface.

[mctrout]

I would run a can of carb cleaner through it first and change that fuel cannister if you havent already this year as the fuel is getting worse by the day. I had a similar problem but it was the fuel ball slowly letting in air. was not hard though as yours is as stated. could be the timing off a bit, or themastats getting clogged old, etc.. good luck and keep us updated

[Poppr]

I thought about an off the shelf carb cleaner (Gumout, etc..) but was wondering if they are safe to use in a 2 stroke engine.


I thought about the "fuel issues" type idea but did not want to cry wolf.

Thought about putting a couple of gallons of premium in my tank for the 4HP and running that through the Yamaha to see if it is indeed a fuel problem.

I buy all my gas at the same place and I don't think there are any issues there as I put the same fuel in my F-150, mowers, weed eaters etc, etc..

[Mooncusser]

My first guess would have been plugs. Change them again, they're cheap. Second guess is a low-speed carb jet getting clogged. Change the filter under the cowl. Drain the carb bowls and fill them back up with fresh gas, then run the crap out of it. You will either blow-out whatever is causing the clog or you won't. If you don't, you'll have to get the carbs broken down and cleaned. I suggest finding a shop that uses a sonic cleaner to clean the carbs.

[DaleH]

Below 800 RPM starts to sputter and cough a bit and will eventually stall after 30 seconds to 1 minute.It is not uncommon to need to re-adjust a carb mixture adjustment for any older motor, at least once in its life, so maybe this is the time. That cough you're experiencing is called a "lean cough" and that's why she then stalls.

I don't have my service manual here, but I could walk you through the adjustment process as it will be the same for your V4 as my V6 regardless of brand or horsepower.

Good suggestion on the plugs as the wrong plug or gap can cause similar problems. I'd also ask when the last water pump service was, as t-stats can get stuck in the open position (fine for cruise & WOT speeds) but it makes the OB run cold at idle speeds and that can cause similar sneezing/idle issues.

I thought about an off the shelf carb cleaner (Gumout, etc..) but was wondering if they are safe to use in a 2 stroke engine"Seafoam" (liquid) and "Deep Creep" (aerosol) by the Seafoam Company (~$6 @ NAPA or other auto parts stores) have been around for > 70 years now and the man who invented it actually presented to no less than ol' man Ole Evinrude himself ... as a magic solvent to cure fuel-related varnish, octane, preservation, and carbon build-up issues that outboards had way back then ... and that we're still suffering with today :brow ! It is not only safe to use in OBs, it is the only fuel product besides PRI-G that I recommend (less stuff like Sta-Bil).

I'd agree with Mooncusser that if the idle adjustment doesn't do it then I'd rebuild the carbs.

1) If your plug/gap is OK, then try Seafoam, using 1 can to 1 gallon of gas in a pony tank, using your fuel line from your built-in tank, if that's what you have. Run for 1/4 tank @ high idle and shut-off for 15 minutes, then repeat. The boat MUST be in the water, as you want/need backpressure on the exhaust - DO NOT use muffs. Repeat for another 1/4 tank. Repeat the wait (as this is when it goes to work). Repeat another 1/4 tank and the wait, repeat ... until done. Re-connect your main tank and cruise around at headway speed only for 15 minutes, then proceed up to cruise speed, but avoid faster or WOT throttle for this trip. You can spray Deep Creep down the carb throats, but that doesn't pull it through the manifold or float/jet orifices, so use the aux tank method if you can.

2) If that doesn't do it, PM me and I'll send you the idle mix adjustments.

3) If that doesn't do it, buy a carb rebuild kit, < $20 and pretty simple to do, but ... you need the OEM factory service manual for the model and horsepower OB you have. Note (as I write here many times) I do not recommend the Seloc or Clymer service manuals :eek: . That said, I myself would also NOT bring any OB carb to a place that used anything to clean the carb that is not listed in the factory service manual. The manuals are very specific about what should and should not be used to clean a carb. Letting a carb part sit in agressive solutions can dissolve them ... (I know that is NOT what Mooncusser was implying).

A carb still needs to be flushed even after dousing in an ultrasonic bath, as some smaller orifices (not "orifi" ;) BTW) are smaller in diameter than a human hair. If bathed "without a flush" via the path/manner/order as dictated in the manual ... you could be leaving crap in there that you've successfully dislodged ... but have no way to get it all flushed out.

Whew, back to work now ... hope this helps.

[DougBaz]

I would definitely change the fuel filter. My 2 year old 90hp evinrude had similar symptoms. My mechanic told me that since the introduction of ethanol in fuel, fuel filters have to be changed more regularly. It worked for me, pure and simple

[Soundking]

I have absolutely zero to offer this discussion....but how awesome is Dale? What a great resource he is to this site!

[Poppr]

Rascal

Sounds like the makings of a plan.

I tried to get the filter out of the assembly but that bad boy will not screw off. I'll have to get a filter and bowl assembly and then give it a try. Same with the plugs. I'll get another 3, regap, and reinstall. Might as well try the easy stuff first.

I do own a Yamaha Clymer manual and so far (no parts taken apart) it has at least given me some starting points to fix the problem. Might not be the best source out there but over the years it has allowed me to do minor maint. without $90/hour charge for a mechanic.

I was able to see that the idle adjustment screw (located on the middle carb only - makes fine adjustments for all three carbs via linkage) is not being used. It rests approximately 1/16th of an inch above the stop plate for the linkage. Also, round plastic dowell that helps for corse adjustments on the actual throttle arm had a small pit worn in place from years of vibration, I suppose. The divot on the plastic dowell is about 1/16th of an inch. Rotating the dowell by hand off the divot and the linkage moves enough for the stop plate to rest against the adjustment screw. :confused:

I'll snap some pics of my description if the rains let up. I'll also be making a trip to order the bowl and filter. I won't be surprised if is not "in stock". Might end up getting the parts online but I don't mind steering some business to the local shops if the markup is not to severe.

Filter is only $7 online so how bad can their prices be at the local shop? :rolleyes:

[Markymark]

My son's 130HP (1991) is doing the opposite,stalling at almost full throttle. We tried everything,plugs,filter(2x),had carbs removed ,cleaned,fuel pump(2x). Ran it from another tank with a bulb in the line,runs okay with the constant pressure. It's driving us crazy! We even had a "certified " Yamaha mechanic work on for hours on end,....STILL can't figure it out. :mad:

[Poppr]

Made a call to the local service ceter (Atlantic Marine - Wareham) and although the parts were not in stock they are cheap. Total was under $18 for 3 plugs, filter, and O-ring for canister. Picked up a can of the liquid cleaner - Sea Foam - from Autozone for another $6.50.

Good news --- Once I had the canister off the boat I was able to unscrew the top and not have to replace the entire assembly ($45).

Bad news --- Once I opened the filter it was full of crap. Fine, gritty particulate matter both inside and outside the filter. Meaning some was getting to the carbs. --124-3

Since the filter is on order and in Monday, I put everything back together after cleaning the filter and bowl to the best of my ability. Also gapped the three new plugs and put those in as well.

Fired up the engine with same results as previous -- still sputters and coughs at low idle and eventually stalls. So fuel flow at the filter and improperly gapped/old plugs are not the issue. Must be a low speed jet in a carb since fuel pump is able to supply proper amount at WOT and seems to be missing on one cyclender only -- at least from the sound.(???).

I could see that the screw associated with the linkage for all 3 carbs was not toucing the adjustment/stop plate (see photo) so I made a minor adjustment to at least see if that made a difference.

WOW!!! Small changes to that screw can have a drastic effect. Backed it off until it was causing the engine to idle at 800 RPM but it still sputtered a bit but at least would not stall....as quickly as it would in the backed off position I found it.

Next step is to put a gallon of gas in the pony can and run the Seafoam through it. Even if that does not do the job I figure I have saved a couple of hours of mechanic time by illiminating the easy fixes that he would charge me $$$ to try himself.

I attached a photo of the center carb/ linkage with this post. Hopefully I labled the parts correctly so anyone can "see" what I'm talking about. If I used the wrong names for parts I appologize in advance. :)

Enough for today. The current squall and late hour make it :-% time!

[DaleH]

This reply below is in response to Marymark's question about a 1991 130hp OB that is stalling at almost full throttle ... and not Poppr's low speed idle issue ... sorry to derail the original thread ...

Wow, sounds like a weak fuel pump, but it looks like you tried that already.

OK, please clarify for me. First, describe the "stall"? Is it a flat out stall and die or does it stumble for a bit? 1) When she stalls, does the primer bulb in the existing fuel line from the built-in (I assume) tank ever go flat? 2) When you say it worked on the other tank with "constant pressure" did you mean to imply you had to pump the primer bulb in that fuel line to keep her going?

If "yes" to #1 and "no" to #2, then I'd look at your fuel vent line. Have you ever tried running her with the gas tank fill port open?

If "no" to #1 and "yes" to #2, then that sounds like a fuel delievery problem. Whereas you've already replaced the fuel pump (twice yet), if those are original hoses and the boat has been running ethanol fuel, the interior of the hoses could be breaking down due to the ethanol. This can serve as a fuel restriction and causes the boat to run lean (which is not good for an OB). I know one guy who was chasing a phantom "fuel restiction" alarm where it gave off an alarm and had with a similar failure mode you have (stall @ high throttle). I don't believe Yams had such alarms on their pre-saltwater series OBs as OMCs did. He finally ended up curing it by replacing the fuel delivery lines all the way from the tank to the OB.

If "no" to both #1 and #2, does this happen all of the time or some of the time? Intermittant issues are the toughest to diagnose, but in this case would actually point you towards the culprit. If it happens all of the time, I'd start at your fuel tank and work towards the motor. You might have a partially clogged anti-siphon valve where your fuel line connects to the fitting on top of the fuel tank. Actually, to be more precise, the fitting itself IS the a-s valve, see picture #1 attached below. Clean out if/as needed.

If it doesn't happen all of the time, I'd have you check the fuel pick-up line that is in the tank. This is where that a-s fitting goes into this little square housing that is screwed into the welded boss on top of the tank, see picture #2 attached below. To get this out and check it you first need to remove the gasline and take basic precautions of working around fuel, e.g., shutoff battery switch, no sources of electrical or other energy (even battery powered tools), no smoking, and watch out for clothes that create static electricity, etc. Also not that a full tank is safer to work on than an empty one. Get 2 open end/box or 2 large crescent wrenches and put them onto that fitting 180-degrees apart. Turn them together to get that fitting out, using the 2 in tandem so you do not wrench that block off the boss while removing.

Make sure the fuel pick-up line is free & clear and if running a Racor-type fuel/water separator filter, remove the screen on the bottom if equipped. I have removed many of these for people where these have been gunked up with crap ... much of it looking like "naval" lint ... thank me for the visual ;) later.

One side comment, have you ever pulled the plugs immediately after having this happen? I'd run for a while on plane at speeds where it doesn't happen, like between 3800 to 4800, stop and check a plug or two or all, and see if they're "dirty". Then run at high speed until it happens. Shutdown, toss the anchor and pull those same plugs. If sparkly clean, or if some are, then it could be a loss of spark @ advanced throttle and that washes off the plugs. This could be one or more coils or other electrical part in the high voltage loop (stator, timer base) breaking down.

That's the best that I can do for now. Please address the questions I pose above, if you care to, and let us know how you make out by replying here. That helps preserves the integrity of the R-T archives for future posters who may experience a similar issue.

[Markymark]

What we did was ,tried using a portable gas tank with the "bulb". Worked good,ran okay.
Flat out + die in the begining
Now it will not stay in the high RPM's.
What is the next to look for or check out ? Thanks

[Poppr]

RR

My thoughts are the same on keeping the post going and accurate for future visitors. Similar message boards have saved me $$$ on fixes to my F-150. Might be a good idea for folks to concentrate on one engine though. I think you have some of my symptoms confused with markymarks.

Back to a basic description of the problem I'm having and parts swapped as some replies and suggestions I'm getting are off track.

At initial cold start engine fires and runs at approx 1000RPM for no more than 5 -10 seconds. Idle then comes down to the normal level of about 500/600 RPM. It is during the fall to 500 that it begins to cough and seem like it is misfiring on a cylinder. After 15-20 seconds of coughing it quits...unless I play with the throttle to keep it alive. If I advance the throttle in idle I get all the RPMs I can handle and it runs smooth. If I put it into gear and motor away from the pier I have no problems....even when traveling fairly slow through no wake areas (1200-1500RPM). WOT...forget about it. Runs like a champ att that pace (4400 RPM) but I normally only run it up to 3300/3500 to plane at about 25kts.

Problem started last week. Already had the boat on the water for over 2 months...live adjacent to a ramp so I only drop it in to fish. I'm on my third or 4th gallon of TC-3 two cycle oil if anyone wants to do the math on the amount of fresh gas I have put in. Oil injected 90HP Yamaha's are pretty fuel efficient so that puts my total fuel at somewhere around ??? so I dont think it is an "old gas" issue.

Initial symptom was a tough time getting it started. By tough I mean it was not just the "prime the bulb turn the key" that it usually was. After cranking it for 20 seconds and only getting a cough or two I took off the cowling to do a visual inspection. Filter assy was full, plug wires checked, no other obvious disconnects so I primed bulb again and retry. Started but stalled after 30 seconds. Primed bulb again and it felt soft. It was then I noticed a small amount of fuel escaping at the point where the line mates to the engine connection. Put on a new zip tie and all OK. Ran great.

Next trip no issues.

Next trip took a second extra to start but ran well except I noticed it had stalled tied up to the pier while I parked the truck (1-2 minutes max). Turned the key and it fired right up so I thought little about it.

Next trip the same thing happened and during the trip I tried to idle it while working a rip....it stalled. Duplicated that problem at a couple of more rips during the day. Decided it was time to try some quick fixes and look for ideas on reel-time.

I have not replaced the fuel pump -- only filter is on order. New plugs are installed now. New plugs were also installed in April when I started to get ready for fish so initial symptoms were occuring with plugs that had 15-20 trips (or so) on them. I also thuroughly cleaned present filter and bowl so as to not make the problem worse while I wait for my new filter.

No problems with getting fuel to the filter. I make that statement for a couple of reasons. While putting the new zip tie on the bulb connector I gave it a squeeze. I would not recommend anyone to do that --- I verified that gas goes everywhere if you are not careful. :eek: Seondly, after cleaning filter and bowl it only took a gentle squeeze or two to fill the fuel line and bowl. Also, have a separate vent port below the fuel fill port and I have checked for obstructions.

Only after the plugs and cleaning the filter did I start to make any adjustment screw changes. Currently, idle is not where I found it set but is now set at 800RPM and I am going to try Seafoam treatment tomorrow a.m.

Also, I have not drained/flushed the carb bowls...yet. That sounds like a good idea though. Just have to make sure I'm messing with the correct screw on the carbs.

Besides that I think I have it all covered and laid out for any fresh eyes to look at and offer suggestions.

[Fin Addiction]

I just spent 3 days this past week dealing with a similar issue on my Yammie 115 2 stroke on my skiff....I got water in the gas bad and the motor wouldnt even pop. I drained the tank and put in new filter and new gas...Still no pop....Next was new plugs....It fired right up but would not idle at all.....I played around with it for awhile, drained the float bowls but still no idle....No manual so I decided to take the idle needle valves out individually but first I cranked them in to see how many turns out they were so I knew how to reset them....One and a half turns on my motor....Took them out and sprayed Brake Parts Cleaner with the little high pressure tube into the needle valve hole....I really worked it in there....Did all 4, reset the needle valves, cranked over and she hummed at 600 RPM like she is supposed to......Definently worth a shot before rebuilding the carbs....

[Markymark]

on the 130...


engine will hold high rpm's (57-58) as long as the primer bulb is used to force fuel. this just keems me thinking carb or fuel related, since it will hold the high revs as long as fuel is forced; it does not seem electrical because the forced fuel is the only variable that effects the performance.


i think floats, but i had them apart and looked fine last night, as per the manual specs. also made sure the fuel lines on the engine were clear; the oither lines i ignore since the problem was the same using an auxilary fuel tank. squeeze, full rpms. no squeeze, lose rpms after a few seconds.

[DaleH]

Yam 130hp stalling @ WOT:

on the 130...
squeeze - full rpms. no squeeze - lose rpms after a few seconds.Wow, Id go back to your original mechanic and talk firmly. That's classic fuel pump symptoms ... and you say he replaced it twice already ... :confused:

[Poppr]

Just got done draining the 3 carbs and forcing fuel through by pumping bulb. Did one carb at a time.

Top carb had the most crap in it. Same particulate matter that was in the filter. Middle carb had some as well and lower carb had the least.....from a visual inspection of the rags I used during the process.

Fired up the engine to see if that fixed the issue and no go. Same problem, although it did seem to run longer than before at the 500 RPM before deciding to quit.

Next step is the Seafoam treatment. Honey-do list is calling so that will have to wait until this evening. Still runs fine during all other periods except idle so I can fish with it for the time being and run the foam through this weekend.

I'll update progress as appropriate.

[Markymark]

i personally have replaced the pump, twice, most recently tuesday. new gaskets each time. theyre not that hard to install so i doubt im messing anything up.... it also doesn't seem too much like a pump because sometimes it will run crappy, although rarely, at lower rpms AFTER trying to run at W0T. today i emptied the fuel bowl, and fired the engine up without priming. the pump filled the bowl within a matter of seconds.

the engine almost seems to backfire every once in a while since the carburator work too. i think floats.


this was alright trying to solve this problem the last two months, but now with the good weather its getting miserable; nobody will look at it anytime soon. any more ideas? its got to be fuel related.

what end of the float adjustment range should it be on? i cant visualize if i would want it higher, or lower.

[DaleH]

Yam 130hp Stalling @ WOT ...

what end of the float adjustment range should it be on? i cant visualize if i would want it higher, or lower.

First, you perhaps should have started a new thread on your motor's issues, this was started for Poppr's idle issues, but since I too have replied ...

I wouldn't even attempt to set the float height without the OEM factory service manual. The only words I'd trust to be right on the Clymer or Seloc engine manuals would be the ridiculously high price.

Float is "typically" set at +/- 1/32" of the gasket surface ... but without YOUR specific manual - we don't know that. Also not stalling @ WOT could be lean burning, and that can destroy motors. Backfiring is different and I do not have my manuals here at work.

How about starting another thread?

[RogerStg]

RR


Problem started last week.

Initial symptom was a tough time getting it started. ...
It was then I noticed a small amount of fuel escaping at the point where the line mates to the engine connection. Put on a new zip tie and all OK. Ran great.

Next trip no issues.

Next trip took a second extra to start but ran well except I noticed it had stalled tied up to the pier while I parked the truck (1-2 minutes max). Turned the key and it fired right up so I thought little about it.

Next trip the same thing happened and during the trip I tried to idle it while working a rip....it stalled. Duplicated that problem at a couple of more rips during the day. Decided it was time to try some quick fixes and look for ideas on reel-time.


When you fixed the gas connection it ran fine for a few trips, then started failing again slowly. Logically that tells me that the connection (or surrounding fule line) is the problem.
I'd inspect or replace the fuel line to that fitting and use a better connection, like a metal or plastic hose clamp.

[DaleH]

I'd inspect or replace the fuel line to that fitting and use a better connection, like a metal or plastic hose clamp.
Use the plastic ones designed for round hoses that do not "bind" on the hose like a metal-banded hose clamp can.

[Markymark]

We got it figured out (hopefully)... WATER in the tank. Removed about a gallon or so. What a pain in the neck that was trying to figure that one out!!
Now , the question remains ...Who has the best + cleanest gas ? without the worry of going through this again?

[Mooncusser]

Try using very busy stations that turn over their fuel frequently. However, you do not want to fill up too soon after they have taken a fuel delivery as their tanks will be stirred up by the new fuel. You can usually ask the attendants when/if the truck has delivered recently.

[Poppr]

Sorry for not updating the thread appropriately but I believe all the actions suggested by Reel-Rascals fixed the issue.

Recap of possible solution in order of ease not necessarily the order I followed.

Replaced plugs and checked hoses
Drained carbs and replaced filter
Ran Sea-foam through the system

I use the boat alot and had got used to dealing with the issue. Did not want to take extended time off the water to take it to a shop and I'm glad I did'nt.

I found that back in late June/ early July it began to operate properly at factory set idle. Not even sure when it started working properly as I had avoided using tube/worm and idling in rips since I was annoyed with the rough idle.

I probably had a piece of dirt/laquer in one of the bowls and it was clogging up the idle jet. Guess it finally "passed" or broke down by my initial use of the Seafoam or by continued use of Stabil in all gas I add to my tank.

I'll try to be more vigilant to keep it from happening again but at least I have a good place to start working and avoid $80/hr costs of a boat yard.

[flytyre]

Markymark (or anyone else):
Facing a similar problem to this old post. How were you able to tell you had water in your tank and then how did you get it out of there?
Ryan

[Markymark]

Pumped out a little bit into a clear glas container(jar ) ,let it sit for a minute or two. The water will be found on the bottom of jar,just separate the gas form the water to another container,put gas back into tank. We did this for about an hour,removed almost all of it. Depending how much gas is in the tank,it take longer or less if you have hardly any gas in the tank.