Tohhatsu 9.8 starts, runs, dies

Some time ago (can't find the thread and don't see a search bar) I asked why my Tohatsu 9.8 newer model, runs then dies.I was advised to clean the carb. Did this 3 times. No go. Finally ordered a rebuild kit. Started and runs, but only at 1000 rpms to the best of my guesstimate, however as soon as I lower the idle by backing out the idle adjustment screw, it dies. As soon as I put it in gear it dies. When I full throttle it, it bogs down.

I was super surprised that the rebuild kit sent the rubber gasket to the bowl folded in half so it was very hard to get to lay down properly, took me 30 minutes of continuously re-laying it into the groove, (actually only a half-groove) before I could place the 2 parts of the carb together, and yes I am sure that it stayed flat.

The other thing that super surprised me was that it came without the 2 end gaskets to the carb; the manifold gasket and the air cleaner gasket. I mean if I'm taking the carb out to rebuild it, am I not putting it back together?

These end gaskets are worn, and my worry is that they are bleeding too much air. Is there another kit which includes these gaskets?

It still sounds like your carb has clogged arteries. Did you completely disassemble both main and idle jets, remove the emulsion tube "nozzle", and do a 4-hour soak in real carb dip, followed by a blow-out of all passages with carb spray? If not, you need to do that; If you did, then you may need a new carburetor.

The o-ring for the carb bowl is a soft, silicone-like material. I've never gotten one that was folded, but it wouldn't bother me if I did, as you can roll it in the opposite direction to take some of the set out of it.

There isn't any air cleaner gasket at all. There is an o-ring in a groove of the air silencer, but we never take those out -- just leave it there. Even so, it would work 100% perfectly without any o-ring there at all. As for the carb base gasket, there are two gaskets, and a thermal insulator that sandwich between the carb and the intake manifold. They seldom need to replaced, but an experienced mechanic would have a couple on hand regardless. Are you missing that black plastic thermal spacer?

At this point, maybe it would be a good idea to see a dealer. He will have the Factory service manual that explains the procedures, and should have the expertise to get you running again.

I don't believe you mentioned that I needed to remove the emulsion tube nozzle when I first posted this, nor did you mention that I needed to disassemble both main and idle jets. I believe you said that I need to soak the carb in carb cleaner and left it at that. I could be mistaken. But now that you have asked let me ask you, once I opened the carb with the 4 stainless bolts at the 4 corners, I saw 2 slotted screws which were turned down quite tight into the body of the carb and were located pretty much centered out in the carb, not the lower bowl half. I took them out and soaked using CRC carb cleaner, overnight, approximately 6 hours, then replaced the rubber o-ring on the largest slotted screw and tightened it back all the way down. Were these 2 screws the main and idle jets? And if so is there a required amount of turn they need to be set at? So I did not remove the emulsion tube nozzle and I don't know where that is. I see the fuel tube, and there is 1 other bolt that was so tight into the side of the carb body that I left it alone. It might be 5/16" across? Slotted.

As I mentioned both carb end gaskets (the paper thin ones) are worn and appear to need replacing. It would seem normal to replace these. Is it possible, as I previously asked, that these could be bleeding air and causing rough idle and bogging down when in full throttle? What kit would I order for these?

To answer your question yes I have the black plastic thermal spacer and the air chamber (sorry I think I called this the air cleaner in my original post), serves as the thermal spacer at the intake end.

After all the work I've done on this I do not wish now to take it in. I am getting fairly familiar with this little carb. Is there a way to view a service manual for this online here without buying one? If not do you recommend one and are they available here?

By the way I did on the first of 3 soaks blow it out, and on the last soak cleaned it out with a new toothbrush to remove dry flaky particles.

Thanks again for all your help

Complete disassembly means just that. It's clear from your post that you are unfamiliar with carburetor design, and hence don't understand what the jets and nozzle are, nor how they operate. That's OK, since many have never worked on a carb, what with today's fuel-injected motors and such.

The main jet has an o-ring on it (a new one comes in the kit), and it retains the nozzle in the carb. The low speed jet is covered by a brass plug. All this stuff needs to come out when cleaning. Is that CRC stuff intended as a carb dip (1-gallon can with a strainer basket? If not, it is not aggressive enough to dissolve the varnishing in the carb. If it is real carb dip, 6 hours or more submersion time in summer heat may destroy the carb casting, by etching the anodizing from it.

Again, the carb details should be clear in the Factory service manual. Its' copyrighter, so not available online. You need to buy one.

The air box at the carb throat is only a silencer and backfire arrestor. It will run fine even without that piece installed. Your issue is just that the cleaning has not been adequate yet.

A toothbrush will do nothing, and if the carb spray is used, it would melt the nylon bristles in any case. We're talking clearances in 1/10 of a htousandth of an inch and smaller here.

Ok I will open it up for a 4th time and then blow it out with an air hose set at no more than 40lns pressure. What tool do I use to clean away the loose dry flakes that the carb cleaner leaves?. How can I tell if I have etched the anodizing?

As I mentioned both carb end gaskets (the paper thin ones) are worn and appear to need replacing. It would seem normal to replace these. Is it possible, as I previously asked, that these could be bleeding air and causing rough idle and bogging down when in full throttle? What kit would I order for these?

Were these 2 screws the main and idle jets? And if so is there a required amount of turn they need to be set at?

If the carb cleaner leaves loose, dry flakes, it's not anything that you want anywhere near that carburetor. If the aluminum starts to loose its silvery, shiny appearance, and begins to take on a dull gray look, you have burned off the anodizing. At that point, you have a piece of scrap aluminum. What kind of cleaner are you using? You should be using the kind that comes in 1- and 5-gallon cans at the auto parts houses, and includes a strainer basket for all the small parts. We usually use Gunk, Tyme, or Berryman's products.

How on earth did those base gaskets get "worn"? They are clamped between the intake manifold, thermal insulator, and carb base. They don't move, and shouldn't wear. If you need new ones, you can order a couple of 3V1020110 carb gaskets for $1.30 each, from any dealer, including me. Yes, if the gaskets are damaged, you could get an idle or low speed issue, but they would not affect higher speeds at all. So no, their condition would not cause a WOT bogging.

Since it appears you are doing this work without the aid of the Factory service manual, at least take a look at the parts catalog at http://www.internetoutboards.com/PartsCatalogMenu.htm to see what parts are contained inside the carb. I suspect that you never did get to the slow jet at all. It must be unscrewed (with a small stout screwdriver) after the brass plug is removed. It sounds as though you may have pulled the main jet, and the brass plug that covers the low speed jet, but never unscrewed the low speed jet.

Then, after everything has been disassembled, you submerge everything (except the rubber bits) in the carb dip for 4 hours at room temperature. After the egg timer is done, you can blow it all out, using a full can of the generic carb spray. With some brands of dip, they recommend that you wash it out with water to remove the last of the liquid. In our shop, no one has enough guts to take all those small parts to the stationary sink and possibly lose some of them down the drain, so we blow it out with carb spray.

The jets are fixed. The metering is accomplished by the small hole in the center of the brass jet. They are screwed in, firmly, until they bottom out.

HTH (hope this helps).

WOW!!! Finally a thorough response, thanks a bunch.

The only thing is I was able to wire brush out the interior of the carb with a very fine soft stainless brush, which my Nephew (diesel mechanic) recommended. After that I blew it all out with an air hose set at 40lbs, like I said, after checking every orifice, there are quite a few, I then placed the worn gasket at the intake side back, and put it all back together. So we were out all day today fishing, before I read this at 4PM Monday, and it ran like a top. Runs like a brand new motor.

I only wish you had mentioned all of this in answer to my questions much earlier, but doesn't matter cause I was able to get it done and without the Service Manual. But thank you sincerely for your tips. By the way the carb cleaner is made by CRC called TYME, as you mentioned, kind of late, but thanks anyway. It's great stuff. Not environmentally safe but it works if you need it. The Berryman's didn't work for me and I don't think it was a product failure, rather I think as I said earlier, that I believe the two gallons I purchased were both used and returned dirty from cleaning another carb cause both gallons had lots of sludgy floaty things in them. And I told the auto parts store that and then stopped by 2 days and a week later just to see if they had placed it back on the shelf and they had not. Here's the website for the cleaner I used: http://www.crcindustries.com/hd/content/prod_detail.aspx?PN=14101&S=N

So thanks again for your time and suggestions. I'm sure you have done a lot for many others and may i sya that we all appreciate your clear instructions when asked.

Glad it worked out for you

I still always recommend having the Factory service manual on hand; pays for itself in short order, especially if you ever have any more work to do.

Yes, Tyme is a good cleaner for these. Many of these cleaners will absorb water from the air, and that can make that sludgy look. It also slows the cleaner down. You need to keep the cleaner tightly covered when not in use.

As for that service manual, was it here I noticed it is being sold as a manual for all Tohatsu motors? Can that really be as complete and detailed as a single engine (or engine series) manual? Yah I just looked it up, a good price but is this what a service technician would use? [FONT=Arial, Helvetica, sans-serif]Covers All Models, 1992 Thru 2009. Covers all 2-140 Hp, 2-stroke models and 4-stroke models including EFI and TLDA. for $26.95.[/FONT]

No.

The now-obsolete (thanks to the EPA) 2-stroke manuals were consolidated into two rather thick manuals; one for 1-and 2-cylinder motors, and another for 3- and 4-cylinder motors. Each family of 4-stroke and TLDA motor has its own manual.

In your case, you would order:
SERVICE MANUAL - TOHATSU - 8/9.8A3 4STR. Covers 8A3 & 9.8A3 4-stroke models. Part# 003-21056-1. $27.58.

Thanks for this info, and I'm sure this would have been most helpful at the very start of my thread. I'll link to this Mr Marine Chandler.