old 3 hp toro 92908-low speed on max throttle

In the B&S forum, I got 56 views and not one comment. I hope for a better result here.

I have an old 3 hp toro 92908, self propelled, auto choke, fwd, b&s eng #1842-02. I have kept it running over the years with routine maintainance only, no major repairs. I keep the gas tank empty in the winter and fuel it in the spring. A year ago I replaced diaphragm with oe B&s, and it has run perfectly since. This spring, it started on the first pull after winter, but has a low, even idle speed at max throttle, just like at min throttle. The choke plate is closed, and snaps back properly when I open it by hand. Oddly, the idle becomes full speed when I manually open the plate to full vertical position while the engine is cold, not hot, on a fresh start. If I let it get hot with the choke plate held open, until hot, to get it to maintain full rpms, I am able to mow at full speed, and stop and start with no problem. I get no surges or roughness. There is no reason to think I have accidentally turned the idle speed or mixtures screws while in storage, and I find it hard to believe the NEW diaphragm has failed. Any suggestions to solve this problem appreciated.

First of all you will get help if you provide us with good info. 92908 is not a Toro number, it is a Briggs and Stratton engine model number and the 1842-02 is the type number. Second, you need to download a Briggs service manual for a L-Head engine. This will give you the info you need to fix your problem. Finally, if the diaphragm and gasket were not installed in the correct order or if the tank is warped, it will contribute to you problem. As to having 56 hits, but no comments is probably due to nonmember view, but not allowed to comment. The Techs on this site are very busy at this time of the year and don't waste their time when poor info is provided.

You are correct. The Toro model number is 16320, with all the other info I provided being accurate regarding the B&S engine. That was an over-sight on my part. Surely though, a working knowledge of small gas engines and troubleshooting them can be attempted w/o a model number. I described the problem very clearly and am certainly willing to clarify where necessary. Further info that might be useful is the choke plate springs back from vertical to horizontal easily, so I believe the new diaphragm and spring are intact. It has worked perfectly for a year after my diaphragm change and never overheated, so I don't think there has been new warping of the tank. I can try fiddling with the idle mixture screw, but there is no way it has been touched to change the mixture so dramatically that I would have the problem as I stated. That's where your expertise with small engines and their quirks comes into play, something that can't be downloaded from a manual. I have the original user instructions, which do not deal with this problem. I hope this corrects your concern about "poor info provided".

To me one of two things are happening. First, when you replaced the diaphragm, did you preload the choke before you tightened down the carb to the tank? Second, have you checked for a warped tank? Either one of these conditions will cause your problem.

Hey Rivets. The guy also has another thread that I have been responding in. And people wander why we get upset when people post in multiple locations

http://www.lawnmowerforum.com/showthread.php/41960-low-speed-on-max-throttle

No wonder things don't make sense. I saw the other one, but if I see you have replied I didn't open it, as not to step on your toes. If he would get the service manual, he would probably solve his problem, but if you confuse engine numbers with unit numbers it may not help.

Hey,Rivets and Ilengine:
All I'm trying to do is get a little help here. Yes, I originally posted in the B&S forum but got no reply after a week. I then defaulted to a post in the toro forum, more specific to my mower, out of frustration at 50+ hits with no replies. These were NOT simultaneous duplicate posts, but separate and independent followup posts in a frustrating attempt to get help. If you guys have the time to banter back and forth in my post, then I would hope you also have the time to engage in a productive assistance to my problem.

For all the energy expended here so far, I would certainly like to know if the suggestion of preloading the choke during diaphragm install makes sense to either of you, when I clearly stated that the new diaphragm functioned flawlessly for 2 years after install, so it was clearly properly preloaded, or I would have had problems immediately. Is this not true? Regarding a warped tank, how did it get warped if there has been no overheating situation and no overtorquing, since overtorqueing would have occurred during the diaphragm install, and again, the problem should have been apparent immediately?

You are talking an aluminum carb attached to the top of an aluminum fuel tank so either or both could warp, but it could be just the diaphragm has failed after two years, and may need to be replaced again. they like to stretch around the choke link and not work correctly. The preloading is not our suggestions it is actually part of the instructions that come with the diaphragm. it is on the card that protects the diaphragm in the box.


Rivets and I are both techs with busy schedules so sometimes we may look at a thread and think we will let somebody flesh out the minor stuff before responding,and we tend to stay out of each others way because we both feel the other person can handle what is going on. . I have just dealt with 8 inches of rain in the past week which has delayed parts deliveries by three days, and that is on top of the 2 weeks I am behind on repairs which delays repairs even further. So we can get a little short on patience when people don't supply us the information we request, or fail to answer questions.

Just a little rant, so don't take it personal.

I agree with IL post, with one addition. Between the two of us we probably 75+ years of experience working on small engines. The engine you have has been around for at least 25 years and I'll bet that between us we have worked on over 300 of those carb tank set-ups. In this case we really know what we are talking about. Like IL, I am extremely busy at work (50 hour weeks and running 3+ weeks behind) which means the people in our areas really trust us and are willing to wait for a job done right. Both of us come here to help and believe it or not sometimes it is nice to talk to others who know what we are going though. If you don't want to believe what we are telling you, that is your option, as we are not perfect and may be giving bad advise. Bad mouthing me, tells me that it is time to get out of the thread and I hope that another member can help you. As for IL and me bantering in your thread, I apologize to you if you feel we are wasting your time with our posts. Good Luck.

My rant is over.

And I will stick my bib in as well.
There is something like 4000 members on this forum.
Some like me browse so I get a window with all the new threads since I last opened the window.
You are playing with an engine that would be older than a lot of people on this forum.
I for one have never seen one and I am also a tech although a tad newer to the game than many others here.
Our time is WORTH MONEY and we give it here FOR FREE so sit back and be patient.
Of the 50 people who viewed your post , 51 probably had no idea what sort of carb you were talking about.
YOU HAD NO IDEA SO WHAT MAKES YOU THINK THE 50 WHO VIEWED YOUR POST HAD ANY IDEA EITHER ???????????????????????

And I for one did not reply because what you were describing made absolutely no sense to me particularly when you were talking about moving the choke butterfly.
It sounded more like you were actually tanking about the throttle butterfly but so as not to cause any confusion I made no reply.
In the emojies is this nice POLITE little way of bumping your post back up the top again.
:anyone:

Right now the PEOPLE WHO PAY for my time are waiting 3 to 5 days before I can get back to them.
Now I know you want t right now and you want it for free but just sit back & wait.
Do exactly as asked and we will do our best to help you.

And there are moderators on the forum who go through the posts and check for unanswered posts then move them to another directory if they feel it might get a better response for you.
I for one and I am sure the other Techs on here have been approached by the administrators of the PAY FOR ANSWERS sites to go over to them so think yourself lucky we are here.

OTOH when people have a whinge about not being responded to I usually make a point of deliberately ignoring them as do many other Techs on the forum.