Problems with idle...

[wilkin250r]

I have a 1988 Force 125 that I've been working on for quite some time. After replacing the entire ignition system, and a complete carb rebuild, I FINALLY got it to start, for the first time since I've had it.<br /><br />However, it will only run at 1/8 throttle, about 1500RPMs. It will not idle. The first and obvious solution would be to check the idle mixture screw on the carbs.<br /><br />I tried that, but I still have the problem, it will NOT idle. What other solutions could there be?<br /><br />Perhaps I still have a dead cylinder? Bad compression? Reeds?<br /><br />I want to do a little homework here and get some possible avenues to check BEFORE I dig into this thing again, rather than post a new question each time I try something.

 

[steelespike]

Re: Problems with idle...

If you had bad reeds it would be spitting out the carbs.Check your compression at least 100 lbs <br />and within 10% cylinder to cylinder.Check spark on each cylinder.Be sure you work from a manual.<br /> Carefully spray fuel mix into the carbs and note its effect.Double check your float settings make note of proper measurements.Make sure of the timing and carb/spark sync.

 

[The Marine Doctor]

Re: Problems with idle...

Yep...until such time as you check the compression..we will all be guessing.<br /><br />TMD

 

[wilkin250r]

Re: Problems with idle...

Ok, here's all the information I could muster...<br /><br />The compression is a strong 130 in all cylinders. I have good spark on all cylinders.<br /><br />So the problem would have to be in the carbs, or timing, correct?<br /><br />I rebuilt the carbs and checked all fuel passages for blockage. No problems.<br /><br />So that leaves timing?<br /><br />I was having problems with the ignition earlier, and this is a 1988. I have a 1989 that originally came on the boat, and it has a bad cylinder, so I swapped the entire ignition system. I was told that all blue powerpack sytems are the same, correct?<br /><br />So, to re-cap the problem, I can start the motor at 1/4 throttle, but it will not idle. I cannot get the RPM's below 1500 or it will die. I tried to adjust the timing, and the more I advanced it, the better it ran. In fact, if I advance it 2/3 of full advance, THEN it will idle.<br /><br />The obvious problem with that is, I cannot idle at 2/3 full advance, or else I can only open the carbs 1/3.<br /><br />So can the problem really be in the 1989 ignition? I thought they were all the same?<br /><br />Please help, I've really gone as far as I can, and I'm running out of patience.

 

[seldont]

Re: Problems with idle...

Fuel pickup problem or maybe a fuel pump diaphragm. Maybe the bulb in the fuel line or the fuel filter?? Check all those things. Just a suggestion.

 

[wilkin250r]

Re: Problems with idle...

I've replaced both the bulb and the inline fuel filter. I haven't checked the fuel pump, but it seems to run fine after I get it started, so that would indicate the fuel pump works fine, right?

 

[seldont]

Re: Problems with idle...

I may be off the target but if you say it will not idle down below 1500 my question is how does it run at high rpm?? I have not had that problem on on outboard but I did work on a jetski with that problem and it had a bad crankshaft seal allowing it to draw air into the crankcase. It idled very fast and did not want to idle down very well without dying. The only way to slow the idle was to almost completely cut the gas supply and then it would die. Somebody check me on this as it is just an idea but to me the symptoms sound like it. Is it hard to start?? If I am right that goes along with an air leak into the crankcase.

 

[wilkin250r]

Re: Problems with idle...

It seems to run normally at high rpms, although it has a weird knock every once in a while coming from inside the engine.<br /><br />I was told that this motor had a complete powerhead rebuild, and with exception of the ignition problem I had, I don't see any evidence contrary to that.<br /><br />Even if it were a crankcase leak, why would the engine run fine with the timing advanced by 2/3 ?<br /><br />I haven't had it in the water yet, all these tests have been done in neutral using a horse trough as a test tank. Excpet for this idleing problem, it seems to throttle up and down just fine, although I don't know if it has any power to it, I'm hoping to find that out next weekend.

 

[eurolarva]

Re: Problems with idle...

My first post on Iboats was very similar to your problem. Mine is a 1967 45HP chrysler. I only have one carb but could not get an idle. Had to keep pulsing the choke to keep motor from killing so I could switch it into forward and it would run great at higher throttle. I rebuilt the fuel pump the carb, replaced all fuel lines and started with fresh gas and oil mix and new plugs. Before I did all this I had the idle adjust screw 6 turns out. Now I am at 3/4 turn and it runs great. I am sure your problem could be any number of problems but the fuel pump diaphram is cheap and so is new fuel line hoses and clamps.<br />If you take the fuel pump apart I would not mess with the press fit fuel seats unless you can see the springs arent working or the gaskets are visably broken. Taking them out without breaking them is tricky. The seats are also kind of hard to find if you break one.<br />Good Luck

 

[wilkin250r]

Re: Problems with idle...

Thanks, I'll keep that in mind. I've rebuilt the carbs already, and I know my fuel lines are in good shape, but a fuel pump rebuild can't hurt anything.<br /><br />I'm still real curious about this timing advance issue...

 

[dmann]

Re: Problems with idle...

May want to check and make sure the starter is not staying engaged. The starter gear should drop back away from the flywheel after is starts. If it stays engaged the extra drag could affect the idle. A long shot but it happened to me when the nut on the top of the starter gear came off.<br /><br />Good Luck.

 

[roscoe]

Re: Problems with idle...

I would set the timing to factory/manual specs, then work from there.<br /><br />Timing is something that is just not going to cure another problem, and can mask the real problem, by appearing to give you a better running engine. The "knock" may be a result of the advanced timing.<br /><br />Set back to spec.<br />Try running and spraying fuel mix into carbs with a small squirt bottle. <br /><br />It doesn't take much of a piece of dirt to plug up a carb jet.

 

[wilkin250r]

Re: Problems with idle...

I've made sure the flywheel key isn't sheered, and that the timing mark and TDC on #1 line up correctly.<br /><br />I've been told to check for a vacuum leak, how do I go about doing that? I know cars have vacuum lines and such, but an outboard motor?

 

[seldont]

Re: Problems with idle...

Wilkin,I may have slightly misunderstood your first post. I thought your engine would not idle back down. Apparently yours does but just dies when it gets down to a slow speed. I my limited experience a symptom of a vacuum leak at a crankshaft seal or a crankcase sealing surface is when one is hard to start then after starting idles way too fast even when the carbs have been adjusted somewhere near correctly. This is caused by too much air entering the crankcase which leans out the mixture and causes a fast idle. I found you can spray WD-40 around all such areas and it will change the idle and slow it down some momentarily when you find the offending area or conversely starting fluid used the same way will cause it to speed up. That being said your problem seems to me to be a low speed fuel delivery problem. Either fuel delivery to the carbs or the carbs themselves. Are the carbs the originals with the engine? And have the jets ever been changed?? Have you been able to confirm the carbs are getting a proper supply of fuel? And are the floats adjusted properly. Is it too lean at idle or too rich? Can you accelerate the engine from the 1500 rpm area on up??

 

[wilkin250r]

Re: Problems with idle...

Right. It will throttle up and down just fine, the RPMS rise and fall just fine, as long as I keep the RPMs above 1500. If I close the throttles all the way, the motor dies, it will not idle.<br /><br />I tried two sets of carbs, the original carbs that were on it, and another set from a 1989 (remember, this motor is an 88). With the 89 carbs, I pulled them apart and cleaned them, including the low-speed mixture screw and fuel passage, before I installed them. Same result with either set of carbs. Throttles up and down, but will not idle, regardless of the position of the idle mixture screw.<br /><br />I did not get to put the boat in the water this weekend, so I still don't know if it actually has power at the higher rpms.

 

[koikrazy]

Re: Problems with idle...

I have a 85 force with the same problem it just will not idle down low enough. H rebuilt it and it still has the same problem. I just learned there are ridges inside the valve body and they have to be sharp not rounded out on the tips of them the more rounded they are the worse the idle problem is i'm looking for a good valve body for my force now I hope this helps<br /><br />steve

 

[clanton]

Re: Problems with idle...

Are you soaking the carbs in carb cleaner. Some carbs have steel tipped float needle, with an oring inside the carb body, if you soak these carbs, the cleaner will ruin the seal. replace the fuel pump diaphram. Koikrazy email photo of carb with number on carb, point out the worn ridges. clanton@earthlink.net

 

[jim dozier]

Re: Problems with idle...

Put this engine in the water or a test tank (not a garden hose/muffs) and check the idle. Do not try to tune an engine in the driveway on the hose. While you may indeed have some problems that need to be adddressed, I think you will find the rpms drop when you put it in the water and there is backpressure on the exhaust. Idle adjustments should be done with the engine under load in gear in the water.<br /><br />If you still have a problem, I agree with others above that the first thing you need to do with a manual is to make sure the ignition timing linkage is properly synchronized with the throttle linkage. Once you know that they are synchronized you may have to have another look at the idle circuits on your carb. If you go back in the carb, replace whatever comes in a rebuild kit and clean all orifices with carb cleaner and compressed air. Carb rebuilds aren't beauty contests, its the parts of the orifices you can't see sometimes that are the most crucial.

 

[walleyehed]

Re: Problems with idle...

http://www.boatmotors.com/manuals.html <br /> http://www.outboardrepairs.com/carburetors/

 

[wilkin250r]

Re: Problems with idle...

I have the manual, which is the only reason I have gotten this far. I've worked many a motorcycle, so I'm familiar with small carb. setup and cleaning. The weather is cold, so it looks to be a while before I'll be able to get this boat in the water. I don't have a true test tank, but I do have a large unused horse trough I can muscle to the rear of this boat, and that should provide sufficient backpressue.<br /><br />The only other suggestion I heard from somebody is the fuel recirculation system. Any thoughts if this might be the culprit?