Engine troubles this weekend

[tightstripes]

I tried to take my boat out most of this long weekend, and had some problems, I was wondering if anybody can try to do a quick diagnosis of what the potential issues might be.

I have a Tohatsu MD50D outboard motor (50HP)

On saturday (first time out this season), it started right up, worked fine, then it would start, idle for a little while, then die. After our fishing trip was over, i realized the the gas tank vent was closed all the way. I opened it up and put some stabalizer in the gas.

On Sunday, we took the boat out for a couple of hours and we had absolutely no problems.

Today we tried to go fishing again and the engine started, idled for less than a minute, then died. I tried to start it numerous times after and it would just try to turn over, but nothing.

Anybody have any ideas?

The person that i bought the boat from last summer, probably didn't maintain the thing that well and probably didn't do too much maintenance.

I don't know a lot about outboards, but if any of you more experienced boaters have some suggestions for things that I can try before taking it to a mechanic, i'd appreciate it.

Thanks

 

[pvanv]

Re: Engine troubles this weekend

"I have a Tohatsu MD50D outboard motor (50HP)"

You either have an MD50 (possibly an A or a B) (either of which is a TLDI), or an older M50D (possibly a D2), which is carbureted. Two completely different animals. We'll need to know which you have.

In any event, it would seem that you solved your Saturday issues by opening the tank vent. Also... Is the fuel less than 30 days old? If it's from last year, there may be issues with it. Adding stabilizer to old fuel doesn't do much, except use stabilizer. Did the primer get firm when queezing it? Have you checked/changed the water-separating filter? What do the plugs look like? If the starter is cranking but the motor is not firing, it could be a simple as the stop lanyard has come off.

 

[tightstripes]

Re: Engine troubles this weekend

Thanks for the response Paul. It's a M50D

I used a spare gas tank and added new gas and fuel stabalizer on Saturday.

I looked at the spark plugs, it looked like there was a very small amount of grease or something in them. What should i be looking for to find out if they're good or not?

Then lanyard was definitely on too.

I'll try changing the fuel water seperator and see what that does. Is there a specific type i need to buy or can i use any random one they sell at walmart.

Also in regards to buying new plugs, should any auto parts store have them or do i need to get them online?

 

[tightstripes]

Re: Engine troubles this weekend

one more question, i filled a 6 gallon tank of gas last week, but didn't add stabalizer. is it too late to add it or should i be ok??

 

[pvanv]

Re: Engine troubles this weekend

The NGK B7HS plugs (or equivalent, such as Champion L82) should be available "anywhere". Most any Tohatsu dealer, marine retail store, or auto parts house should have them. You can also run the BR7HS (with radio-suppression resistance).

In a pinch, the B8HS or BR8HS would also work, though they are a little colder, hence will foul a little faster. Many newer NGK plugs will have a -10 suffix (in the format B7HS-10), indicating that they were factory gapped at 1.0 mm.

If your plugs are really fouled, that may be the problem. However, it's guessing at this point. If the gap is bridged by deposits, there won't be any spark. Ideally, plugs will have a relatively dry, dark tan insulator. Some slimy, greasy buildup is normal after extended idling, but it should burn off after some WOT running.

The best thing to do is follow a methodical diagnosis and troubleshooting of the 3 basic systems: Fuel, Ignition, and Mechanical. The most common problems are either fuel- or ignition-related. A Factory service manual, available from any dealer, is a good thing to have at this point, as it has all the diagrams and procedures you will need for troubleshooting.

Easiest thing to check is to see if there is any spark. Remove a plug, clip it into the plug wire, hold its metal casing to block ground, crank, and in dim light, see if there is a spark. If not, that has to be corrected before going forward.

On the fuel side, you need to confirm that there is fuel being delivered to the carb bowls, and that the carb internals are clean of any varnish buildup. Of course the fuel needs to be fresh and clean. Yes, you can add stabilizer (don't overdose with stabilizer, as it doesn't help) to fuel that is a few weeks old. The fuel pump (on the lower carb) pumps to all 3 carbs; You can check for fuel by disconnecting the gas line to the upper carb (be careful of sparks -- you don't need a fire) and cranking to see if there is gas being delivered from the hose.

There are brass drain plugs on the starboard side of each carb bowl. The carbs should be drained each fall. You can pull a drain plug to see if water comes out before fuel (fuel will float on top of water). Of course, a clean, water-free on-board fuel filter is important.

If you have an aftermarket water separator filter in the gas line going to the motor, which should be cleaned or replaced every season (depending on model), you can check that for water, and if necessary, change it. Use a 10-micron filter.

If these seem like reasonable tasks, based on your skills, cool. If it seems beyond what you can comfortably do, it's time to see a dealer.