Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

[pvanv]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

"I have been using Part# 003-21050-1 service manual for my 40B engine."

You have the manual for the MD40A, not the B. That's a problem, as there are significant differences between the A and B motors.

"Please take a look at the attached table. At a tach reading of 5000, I have only the rightmost LED lit up. Does this suggest the CPS is at fault? OR -- is this an impossible combination? I don't understand the logic of the table and need help. For a faulty CPS, must the tach be at 5000 (it is), the first LED unlit (it is), the second LED lit (it isn't) and the third LED lit (it is)?? OR does the table suggest that for a bad CPS the tach must be at 5000, and either of the two right LED's can be lit to flag this??"

The rightmost LED means there ONCE WAS a failure. If the middle LED were on, it would indicate that there is CURRENTLY a failure. Your indicators and symptoms would lead one to feel that you have an intermittent issue, possibly a marginal wiring connection.

You can test the TPS sensors, and you can test the CPS. I would also re-check and VERIFY all wiring, including crimp connections.

 

[TOHATSU GURU]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

Your back to a probable battery issue or wiring issue. Also, please remove the link to Argentina. They have no right to post the manuals online and it is illegal for them to be available as a download...

 

[rustnrot]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

I am using manual Part# 003-21050-2, a cut and paste problem, sorry. The battery is a brand new 1000 Ah so the wiring will be checked, double and triple.

I also looked at those online manuals again and there is another column of remarks in one of them, and this one is about the CPS "The lamp may show malfunction even when no faulty component or wiring exists if the engine revolution changes much." I find that interesting...implying the led can come on as a "once was" failure even in normal, routine operation. In fact, the way that is written it should always show a fault since during normal operation I think we can all agree "the engine revolution changes much". So the CPS may in fact be good and it is probably not the real problem.

I couldn't find any test in the Service Manual for the CPS -- do you simply disconnect it and check for continuity? Also, what is the gap from the CPS sensor to the flywheel teeth?

I removed the link.

 

[pvanv]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

See page 2-6 of your manual. The gap specs are 0.5 to 0.9 mm. the coil resistance specs are 531 ohms (+/- 15%) at room temperature.

Many thanks for cleaning up that link.

 

[rustnrot]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

Bad compressor!! I measured the air pressure before and it wasn't too bad (or so I thought). It measured about 65 psi, 10 psi below the low limit in the service manual. I mistakenly dismissed it as an inaccurate gauge. Then I started googling problems with Mercury Optimax compressors and found a bad idle symptom could be a bad compressor. So I (finally -- why I didn't do this sooner!) slid the belt off the compressor and turned the pulley -- yikes!

Should I:

1. Attempt to rebuild this buying parts or just buy a whole new unit? Part of the piston skirt broke off and the piston rod does not turn very well on the wrist pin. But the crank bearing surface looks good and the pulley assembly turns fine.
2. Clean the entire air manifold out?
3. Clean or replace the air injectors?
4. Does Tohatsu (or others?) offer a rebuilt compressor?

 

[pvanv]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

Normally, if the air is low, it's worth checking the air regulator first. That said, since your compressor is toast, the best thing is a new one. 3T5B100006 AIR COMPRESSOR ASSY $746.73 list. Individual parts are indeed available; You would need to determine which bits, aside from compressor crankshaft, piston (comes with the rod), rings, and cylinder, you want. Odds are that by the time you price up all the individual pieces, a new compressor will be cheaper; certainly faster and easier.

 

[rustnrot]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

Looks like about $200 in parts will fix this. That said, in the process of cleaning out the fuel rail, I noticed the air regulator filter screen has a tear in it, pic below. Tohatsu does not list the screen separately -- and so far no luck finding just the screen.

Anybody know a source of just the screen?

 

[pvanv]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

Nope. The filter comes with the regulator. of course the purpose of the filter is to extend the life of the regulator.

 

[rustnrot]

Air Injector Service Campaign

Air Injector Service Campaign

Just ran across this service campaign regarding replacement of air injectors by Tohatsu free of charge. If I'm reading the serial numbers correctly, my motor qualifies.

http://www.tohatsu.com/tech_info/injectorcampaign.html

Have any of you all performed this campaign yet? Certainly now is a good time for my air injectors to be replaced.

 

[pvanv]

Re: Air Injector Service Campaign

Re: Air Injector Service Campaign

If your MD40B was built in 2004, it is not in the affected serial number range. What is your serial number?

 

[rustnrot]

Tohatsu Nissan 40 TLDI Air Compressor Fixed

Tohatsu Nissan 40 TLDI Air Compressor Fixed

My last post to finish this thread. FYI, turns out my engine is NOT eligible for the replacement air injectors however they are not needed, the ones I have work fine.

$150 of parts for the compressor, i.e. new cylinder, piston, gaskets and it now runs great! Idles down to 700 rpm no problem.

A few lessons learned:

1. In addition to checking fault codes check fuel and air pressures as these will not necessarily result in a code. If I had checked air pressure early on (or at least turned my air compressor by hand and noticed the scraping) I could have saved alot of time.

2. The Teleflex tach, in addition to the 3 fault lights on the handle of the tiller engine works fine as a tach and as a fault indicating device on my engine. It never failed to show the correct faults, even when I induced some by disconnecting certain things like injectors, etc and looking to see if it showed them.

3. Buying the parts and fixing the air compressor was easy -- highly recommended to save money if you have reusable parts.

Thanks to all for the help.

 

[TOHATSU GURU]

Re: Tohatsu 40HP 40 TLDI Wont Run Below 2000 RPM and Requires Half Throttle To Start

1 )I would buy a new one.
2) Yes
3) Replace
4) No