pre 1997 honda 5hp 4 stroke will not idle

I just bought a used 5hp honda 4 stroke and it will not idle. it will run if you turn the idle screw up so it revs high but can not get it to idle low enough. when rpms go down it stalls. will idle kind of low with choke our. i checked the spark and replaced the plug and fuel filter. i put new gas in the tank and added some fuel stabilizer. i checked the fuel flow to the carb and ran with finger over end of hose going to carb and it seems to be building some decent pressure. i tried cleaning the carb. i removed it and took out main jet and air fuel screw and sprayed them with brake cleaner. i put it back together and it still will not idle. maby i just didn't clean it enough. is the an idle or low speed jet? i didn't remove item #10 in picture of carb parts below. any advise would be greatly appreciated.

http://www.boats.net/parts/search/Honda/Outboard Engine/0/BF5AH SA VIN%23 BADS-1000001 TO BADS-1099999/CARBURETOR/parts.html

When 4 stroke outboards sit with fuel in the carburetor for long periods of time , then the small jets / passage ways tend to plug up.-------------------Check intake and exhaust valve clearance.---------------------Then revisit cleaning of the carburetor, remove item #10.----------------Bought to Hondas last year because owner could not find a shop that knew how to clean the carburetors.------------I cleaned them and motors idled OK ,----no cost fix.

do you know what the valve clearance spec is? how does item 10 come out? is there a low speed jet?
thanks for the reply.

sure there is a low speed air / fuel mixture adjustment it is either #5 or 7 should be obvious when looking at them. I think #10 just comes out as it is pushed in.

its just the air fuel mixture screw? there is not a seperate jet? yes i know the screw. its #5 and #7 is idle adjustmant. should i soak the carb in carb cleaner and is it ok to blow passeges out with compressed air?

I see lots of posts with --------" i have cleaned the carburetor 4 or 5 times , motor still does not run right "-------------Just means that work was not very thorough.-------Sorry to be so blunt.

dont be sorry. how do you thoroughly clean it? soak it in carb cleaner? blow it out with 160psi of shop air? use something stronger than brake cleaner? sorry to be blunt but your not really answering my questions.

I don't think you need to soak it in carb cleaner. I haven't worked on this particular carb but it might not take a strong solvent like that. I know the newer ones can't.

I don't think it will hurt to blow shop air through it although 160 psi sounds a bit excessive and you certainly want to avoid blowing that much pressure against the fuel inlet valve (item 2) or float.

You could have a vacuum leak with that dashpot setup. Try pinching off hose #33 in the parts picture and see if that makes a difference in the way the engine runs and idles. If it helps, then that could be a clue.

thanks jgmo. i took the carb all apart again and soaked in in solvent and blew out all the passeges. i also took out the little plug that looks like a freeze plug and cleaned the passeges in there and replaced plug with new one. i reassembled today and it is still the same. i'm not sure what the air fuel mixture srew is supposed to be set at but it does not seem to be changing anything if i adjust it when the motor is running. i was thinking of spraying brake cleaner around the intake manifold when it is running but i ran out of sunlight. i will try pinching off that hose and see. i did pull the valve cover and both the valves are closing all the way. rockers get slight looseness to them when valve is fully shut. thanks for the reply and i'll let you know what happens. i was also thinking of doing a spark test. any idea how much gap that coil should be able to spark?

Honda spark is pretty hard to see and is not what I call "hot and blue". I wouldn't try to make it jump anything other than the plug gap. The fact that yours will rev up tells me it is not likely a spark problem.

I'll be interested to see what results spraying brake kleen around the intake will yield. Instead of pinching off that hose, it would be better to just take the hose off and plug that nipple it goes on.

Did you take part #10 off and look at it this time? I haven't worked on this particular engine but that looks like the jet set tube in the ones I do work on and they can be a real pain to get clean. Also, the newer carbs use an "o" ring at the top of that tube and they tend to deteriorate and cause idling problems. I see that the tube is not available so you should be VERY careful not to damage it in any way if you do remove it.


Good luck and let us know what you find.

so plugging the vacuum port didn't make much of a difference. still wont idle down. if the intake gaskets are leaking than you would probably notice a difference in engine rpm if you sprayed brake cleaner near the leaking gasket. i have seen that work on car engines. i could not get the jet set tube out. it is stuck in the carb. i tried pushing it out with a flathead but it will not move and i feel like im going to break it. i did blow air and cleaner through it and it doesn't seem to be plugged but maby that o ring is deterioted.

Yeah, you need to be really careful with that tube. I don't even know if they used an oring on that one. It may be glued in or something. But, if you damage it, you might not be able to find a replacement. On the other hand, it could be your problem. I find those tubes cracked in the newer engines and when I have trouble getting them clean, I just replace them. But, in your case it doesn't look like you can do that.

One thing you might want to try at if you decide to take the carb apart again is look at how the idle port is delivering fuel. You can do that by squirting up into the tube and watching what comes out of the port. I use WD-40 and the little straw that comes with the can. In case you don't already know, the idle port is at the top of the carburetor throat and on the engine side of the throttle plate when the plate is closed. If you spray up into the tube (part # 10) you should see a pretty good "gurgle" of liquid coming out of the port.

I like to "backflush" that port by taking the idle mix screw off and then hold that straw over the port and hold my finger over the end of the tube and see that fluid comes out of the idle mix screw cavity. Then I do the same thing but this time I hold my finger over the idle mix screw opening and see that fluid squirts out of the tube.

Then, I hold my finger over the tube and squirt into the idle mix cavity to observe fluid coming out of the idle port. Then, finger over the idle mix cavity and squirt into the tube. I do this many times sometimes to get the passages cleaned out. It's a real pain but it works.

I also prop the throttle plate open and observe the high speed and intermediate ports while fingering and squirting in a similar manner. This almost always works to clear the passages.

Sorry for all the words but I wanted to explain it the best I could. That's about all I can think of to tell you to try since it doesn't seem to be a vacuum leak.

thank you so much for the great explanation. im going to go pull the carb now and i will try that tomorrow. i'll let yo know what happens.

i tried cleaning the carb like you explained and i can not get the fluid to flow from the tube to the idle port. it only sprays straight out the other side of the tube. is that tube supposed to let fuel out the side/ middle of the tube and up to the idle port/ idle mixe screw area? i tried backflushing it and blew it out with air and i still cant get the fluid to make it up to the port. Honda said they can get that tube but im not sure how to get the tube out and not damage the carb.

That tube is the path fuel has to take to get from the bowl to the ports in the throat. Were you able to get liquid to flow from the high speed or intermediate ports or have you tried that yet?

The deal is, I always remove that tube and shove the straw up into the hole it occupies to spray and flush.. I didn't tell you to do that because you said you couldn't get the tube out. I was hoping that if I told you to spray with it in place, we would get lucky and you would get the passages cleared out. I was afraid you would break the tube and then not be able to get a new one. If Honda can get you one, then maybe it's time to take that puppy out and replace it.

Do you have a dealer close by? Maybe they could give you a tip on getting it out. The ones I deal with have a little flat "ledge" that you can see at the top of the carb throat when you look in from the front. I take a small, flat bladed screwdriver and wedge the blade between that little ledge on the tube and the top of the carb throat and then give it a twist. They pop right out since what is mainly holding them in place is the teeny-weeny oring at the top. The trouble is, I don't know if that's what will work on yours since the parts picture doesn't show an oring.

I should have told you to take the main jet out and spray from the very bottom of the tube. I guess I just assumed that you knew that since you had the carb apart more than once. Is that the way you are trying it? It's tough doing this long distance and trying to communicate technique.

That tube does have a bunch of little holes on the side that the spray will come out of but I was hoping that the pressure would be enough to clear it out.

You should be able to see fluid come out of the idle screw cavity if you carefully put the straw over the little hole and pull the trigger. Are you getting any from there? If not, then that port is plugged for sure. One way to clear it is to get some very small gauge, multi-stranded automotive electrical wire and take one of the strands and use it as a probe to push through that port and passageway. You need to be careful though not to break the wire off in there. You might not ever get it out.

I'm not sure what else to tell you try at this point. Let me know what you're thinking though and maybe we can figure it out.

thank you so much for responding again. i tried with the main jet in and with it removed. it is defenatly not getting fuel up to the idle screw cavity. that makes sense why its not idling and when the motor is running i can take that screw right out and it does not make a difference in the way it runs. that has to be the problem. im going to try to get the tube out again and its either coming out or something is going to break. worst case i have to buy a new carb but im almost expecting that i'll have to do that but hoping not to. i'll let you know what happens. do you know if there is a spec adjustment for that screw or does it change the idle speed?

Yes, they always give you a "turn count" for initially setting the idle mix. Of course, I don't know what that is for your motor. I would try seating it and then backing out 1 1/4 turn. That should put you in the ballpark to get it started and then you can tweak it from there. If it just won't run from there, I'd go to 2 1/4 turns out and try it again. That is if all the rest of the carb is up to snuff.

One thing you might try is to use a soldering iron pressed the tube to heat it up. That might break up any adhesive that may have been used to hold it in place. Heat it up and then let it cool a couple of times and then try working it out.

I would try the little wire trick first before forcing the tube but you may be correct in that the tube just plain needs to come out no matter what. Once you see how small the hole that goes up through the center is, then you'll understand why I tell people to run Sea Foam in their gasoline and to always drain their float chamber before putting the motor away. It's just as important as a fresh water flush after running in salt water to keep the engine purring.
Good luck. We're rooting for ya!

so i put some good force on the tube was able to get it out. looks like some of the holes in the tube were plugged. cleaned that up and sprayed out the passages going up to the idle ports. it took a bit but got them clear. i didn't see any o-ring in there. looks like the tube bottems out on a brass insert. i just put it back together and reinstalled it and she purres like a kitten on cat-nip. thank you so much jgmo and racerone. the info and response time was better than i could have asked for. not only did you save me from using my electric motor only on this weekends fishing trip but saved me a bunch of cash. the local dealer said they charge around $200 for carb clean and tune.

Glad you finally licked it. Good news for you....bad news for the dealer. $200 huh? I'm going to have to raise my prices!
Anyway,
Happy boating until the "next time".