Thread: Synthetic 2 Stroke Oils - Current Minor Engine Issue

Originally Posted by Baitwaster

is this yours? C60ELRY


I cant find any oil related parts for this model (except trim pump). Ebay has a mechanical injector for a 4 cyl yammy which does not fit yours but looks like it might be something that can be disassembled, inspected and possibly rebuilt.

Are you sure your oil is not vacuumed by the carbs? I don't think I've ever seen this and sounds like an awful idea because if the lines got a little bit clogged the engine wouldn't get sufficient oil, but then again if this IS how yours works then it could be your problem.

I dunno, oil is probably not the problem. Sounds like you've been through all the potential water problems.
That leaves electrical. So bad sensor which you swapped. Its possible you swapped in a bad one but not likely.
It could be the wrong sensor.
There could be a problem in the sensor circuit. The sensors basically change resistance with temp change (thermistor is one way). There are two types where R (resistance) rises with T(temp) and one that decreases. We don't really care which one you have, but I think yours might rise with T. So we need to look for conditions that could trick your computer into thinking that R has increased above normal operating temp.
Corrosion is the first and most obvious symptom. Check inside all the wiring connectors. A nick in wire insulation allows moisture to enter and slowly corrode the wire internally and is almost impossible to spot, usually the wire will harden though. I would run nice new temporary wires if at all possible (try to match the wire gauge) and or measure the existing wires for resistance, which should be close to 0 ohms, anything under 15 ohm would suggest its ok.
The computer (or simple alarm circuit) may be at fault, either by corrosion, or weak parts. All electronic components are rated to be accurate +/- of spec to a certain percent (100 ohm resistor may actually be 95 ohm). With time, components become further out of spec. This is why a perfectly good radio that was buried on a shelf in the back of a store room might not work when its finally dug out. (your stuff is 20 years old (mine too))
It wouldn't hurt to inspect all your battery connections too. This includes the connections inside the motor, fuse panel, etc. A poor ground could mess with the computer.

Is it safe to say I'm interested in this? Keep us posted.

Yamahas and Suzukis use a variable rate gear driven oil pump, with small hoses that dispense oil into the intake behind each carb. There are several sensors that monitor oil flow, oil level, water temperature, etc.

They are one of the best oil injection systems ever made, although the electrical side of the them can be tough to troubeshoot because they are so complex.

I was leaning toward electrical as well, but since it seems to be consistent and repeatable, I'm not so sure. I think an electrical fault would be random.

C60tlrx I beleive.

Originally Posted by Atimm693

Yamahas and Suzukis use a variable rate gear driven oil pump, with small hoses that dispense oil into the intake behind each carb. There are several sensors that monitor oil flow, oil level, water temperature, etc.

They are one of the best oil injection systems ever made, although the electrical side of the them can be tough to troubeshoot because they are so complex.

I was leaning toward electrical as well, but since it seems to be consistent and repeatable, I'm not so sure. I think an electrical fault would be random.

Electrical could be random but increased resistance in the circuit causing early alarms wouldn't have to be random though. I like this line of thinking/argument though... points more towards the computer/electronics portion.

Actually.. my car (Buick Enclave) had a recall for the air bag sensors. The problem they found was in the occupancy sensor and pretensioner. The SRS system monitors these down to the 1/2 ohm which seems a little silly but whatever. The connectors under the seats were causing a slightly higher resistance and would kick the airbag lights on. The GM fix was to cut out the connectors and solder the wires back together.
I think you should look very closely at the connections. If your engine is not over heating, then you have increased resistance in the temp sensor circuit which is causing a lower threshold for normal op temp.

I have switched the wires from the temp sensor to the oil level sensor. The alarm did not follow. There is only one alarm circuit. You get the same noise whethrr you have low oil level or overheat condition.

I have a sierra gauge and yamaha adapter coming. That will tell me water pressure.

The water pump plastic housing should be delivered today.

After this saturday i plan to pull it all back apart. Head, exhaust cover and lower unit just to look again for anything that could be blocking water flow.

Ill try the hot water and ohmeter trick on the sensor as well while i have it out of the engine.

I didn't read all this thread but the TLR 3 cylinders are notorious for collecting debris under side water jacket plate. The plate corrodes out very easily. $35 for new one, does not come with gaskets. I have a 90 powerhead in my shop now, less than 100 hours but a hole corroded in between dividers under same side plate. I replaced the powerhead, only way to stand behind job but saved the old powerhead as a spare. Used a epoxy to repair hole just can't warrant that. I have 2 TLR's from the same era and have rebuilt several. These engines are 6-7 psi cooling pressure. Yamaha sent out a TSB addressing that these engines are not recommended to install a water pressure gauge. I have done it anyway numerous times using a factory mercury gauge 0-15 psi. Gives a lot of needle movement to see if your pumping water. These engines were used extensively on fly fishing micro skiffs.

Thermoswitch closes at ~180F. Thermostat started opening at 130f.

I'm going to try to attach some pictures of the head, head cover and exhaust plate and cover. New gaskets on the way.

Even more perplexing, everything looks good to me. All the little orifices were open. Nothing clogged, nothing looked damaged.

Water always comes out the tell-tale, except when it gets real hot and it started to steam a bit. I immediately shut it down then.

Runs like a top at wot. Idles fine when cold. Alarms after warm and idling.

What am i missing?