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Cleaning a Tohatsu carburetor? (Update redux)

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OJ
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Response Posted - 09/26/2011 : 16:54:10

I would imagine that Tohatsu and Nissan are beginning to hate this thread by now . . .

Edited by - OJ on 09/26/2011 17:19:01

delliottg
Former Mainsheet C250 Tech Editor

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Response Posted - 09/26/2011 : 16:55:03

Jeff,
I'm sure it's a plugged low speed jet as well, but since I have a brass plug over the top of the jet, there's no way to access it from the outside of the carb. You implied that you can get to it from the inside, does that mean I can run a wire up the little tiny holes in the throat of the carburetor on right by the butterfly valve on the manifold (not choke) side? There are two maybe 1/64" or maybe slightly larger, holes right above where the butterfly valve rotates (roughly, don't have it in front of me).

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Sloop Smitten
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Response Posted - 09/27/2011 : 08:53:44

The jet under the plug needs to be removed and cleaned. A maintenance shop will remove the plug, clean it and replace the jet along with a new plug. You can do this your self or have them do it. The plug can be purchased along with the new jet. The jet and plug are inside the carburetor bowl so you will need to remove the carburetor to access them. Tampering with emission controls is illegal but cleaning the jet is certainly not tampering. The jet is non-adjustable. Whether the plug is required by law is debatable. Probably on a new engine it is but after that there is no agency verifying if a jet plug has been removed. By the way, this is not a Tohatsu/Nissan specific problem. Honda's and, I would venture just about all, emission controlled outboards have a similar jet with a plug to prevent tampering.

Edited by - Sloop Smitten on 09/27/2011 08:56:25

dmpilc
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Response Posted - 09/27/2011 : 09:13:36

On my Nissan 9.8, 2008 model, the carb has to be removed from the engine (2 bolts) and the bowl must be removed in order to get to the jets. Each jet is held in by a separate screw. The jets were removed and cleaned. Our marina manager took a spare piece of 14 gauge wire, stripped off the insulation, separated the strands, and leaving one single strand, twisted together 2, 3, and 4 strands. These were used to ream our the jets. He cleaned the bowl and reassembled everything.
BTW, I took the motor off of the boat for this exercise, didn't want to risk losing a part overboard. also, I had a spare low idle jet on hand in case it needed to be replaced.

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DaveR
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Response Posted - 09/27/2011 : 14:15:29

Listen to the Daves! Quit talking and start dipping!!

You still need to take the carb apart and remove the float and the float jet seat.

Edited by - DaveR on 09/27/2011 14:18:32

delliottg
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Response Posted - 09/27/2011 : 14:58:39

Oh trust me, it's in the dip, been there since Saturday afternoon. I give it a good twirl every morning as I walk out the garage door to make sure there aren't any bubbles to keep it from actively working on the jets.

While searching for other carburetor related stuff, this thread came up:

http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=21840 which I read with interest.

It sounds like I can get to my jets from the inside of the carb? I know at least the high speed jet has a screw head on the brass plug (under the float), but not so sure about the low speed jet. If they're not adjustable, I'm fine with removing the threaded plugs and backing the jets out to clean them with a wire. Can anyone confirm this is correct? I thought I had to drill them from the outside to get the brass plug out, which I'm not so willing to do.

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Sloop Smitten
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Response Posted - 09/27/2011 : 15:15:29

Honda engines have the plug on the outside that needs to be drilled to remove. It appears the Tohatsu carbs plugs are slotted and threaded to allow removal and reassembly. See items 1-1 and 1-2 below.

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Davy J
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Response Posted - 09/27/2011 : 15:20:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">It sounds like I can get to my jets from the inside of the carb?<hr height="1" noshade id="quote"></blockquote id="quote">
You must disassemble the carb to get at the slow speed jet. After removing the carb, turn it upside down, remove the bowl and the float and float valve. The main jet is located in the center and the slow jet is under the screw next to it. You must remove the screw and then unscrew the jet beneath it. As mentioned earlier, use a very fine wire and clean out the holes, then soak it carb cleaner.

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Davy J
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Response Posted - 09/27/2011 : 15:23:55

Joe's diagram is directly out of the Tohatsu service manual. Item 1-6 is the slow speed jet.

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delliottg
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Response Posted - 09/27/2011 : 15:46:33

Yep, thanks guys, I'll be looking at this tonight. I printed out the parts list booklet last night.

I appreciate you guys sticking with the thread and keeping the suggestions coming, it means a lot to me.

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delliottg
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Response Posted - 09/27/2011 : 20:41:35

Took it out of the dip when I got home this evening, and backed off the brass plugs and jets. There was a bit of varnish around the threads at the base of the brass plugs, and some staining on the jets themselves, but nothing that stuck out at me. I cleaned everything as best I could, and ran wire through the ports in the jets. I used Q-tips down in the barrels that the jets go in, and made sure that no residue from the cotton was left behind. After that, I left all the jets & plugs out and put everything back in the dip for a couple more days.

I was surprised at how dirty the dip was, I was expecting it to be fairly clear, but maybe not (or they sold me a can of used dip). Anyone got any experience here?

Anyway, if this doesn't fix it, I'm either going to take the carb to a shop, or just buy a new one.

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Sloop Smitten
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Response Posted - 09/28/2011 : 08:19:57

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Anyway, if this doesn't fix it, I'm either going to take the carb to a shop, or just buy a new one.<hr height="1" noshade id="quote"></blockquote id="quote">
Before I spent that money I would purchase a new idle jet and replace the old one. Even after I cleaned mine on my old Honda it would only last a few weeks before the same symptoms returned. The new jet has been in there three years now without a problem. The fellow sailor I sold the Honda to has never touched that jet.

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Dave5041
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Response Posted - 09/28/2011 : 09:46:08

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I would purchase a new idle jet and replace the old one<hr height="1" noshade id="quote"></blockquote id="quote">

Very good advice. Jets are very small and critical; even a fine wire can scratch it enough to make it hard to adjust and provide a place for crud to start accumulating.

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delliottg
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Response Posted - 10/09/2011 : 17:25:14

Well, got the new jets in the mail yesterday, put the carb back together with all new float, gaskets, even bolts. Installed it about 90 minutes ago, and the engine's been running pretty happily since. I think the idle return spring is sticky, since it doesn't want idle down completely until you coax it a bit. A shot of WD-40 should fix that. I think I'm going to need to adjust the slow speed idle up just a bit, it'll die most of the time when the idle is too low. This isn't overly surprising with new jets in it, I'd expect a bit of adjustment. The good thing is, it'll idle again. Of course I don't trust it yet, this is pretty much what happened last time, and the next time I was back to square one again. Hopefully this is the last time I'll have to do this for several years.

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Sloop Smitten
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Response Posted - 10/10/2011 : 08:20:08

David,
I was wondering if all those parts came in a kit or if you ordered each separately? Any idea how much for just the idle jet? I think a good maintenance item would be to add some SeaFoam (or just about any fuel injector cleaner product) every time you add gas. That should help reduce the accumulation of whatever is building up in the jet orifice. I'm glad you didn't have to replace the entire carburetor. At the very least I bet you feel real confident now about digging into that carb!

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delliottg
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Response Posted - 10/10/2011 : 10:09:53

Joe,
I think the slow speed jet was $8 or so from iBoats.com, and the "main nozzle" (high speed jet) was $11 or so. No, they don't come in a kit, you have to order them separately. The rebuild kit includes a new gasket for the carburetor body, as well as for the main nozzle, which has an O-ring around it's brass cap. There's another gasket for the overflow (?) on top of the carb, all new bolts, SS pivot bar for the float, float, and float needle valve. No instructions (for any of them). I also bought intake manifold gaskets (2) as the old ones got torn up during the removal. It takes two on either side of the plastic spacer.

I dumped an entire can of Seafoam into my 3 gallon tank (way-way-way overkill), which I think might be contributing to my low speed idle issue, but not sure. I also added more Stabil (probably more overkill).

I can get the carb off and on the engine in about 10 minutes now, even taking care to make sure it doesn't drop in the drink (I'm doing this while leaning over the stern).

I plan to write up a complete list of parts, and how-to once I'm confident the fix has taken.

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