91 Merc v135 still acting up
 

I thought I had solved my problems but after a long trip and breaking down I guess not. So far Ive rebuilt the carbs, fuel pump and installed a new rectifier and checked all fuel lines, filters and tank. Ive squeezed the bulb while its almost dying but that doesn't seem to do anything. The problem only arises after running for at least a 1/2. It will run flawlessly at 30 mph but when I back off the throttle it sputters at slower speeds. After shutting down it will barely idle and just dies if I try to give it gas. I'm assuming this is some type of iginition problem since I imagine if it was fuel the problem would be more consistent??? Unfortunately it looks like I will have to break down again to duplicate and check the problem. I'm planning to bring my spark tester and an extra coil hoping that its just a bad coil. Is there anything else i should check while this is happening? I'm also wondering if the oiling system could cause this problem after running for a while. Ive noticed some oil lying in the bottom of the cowl and it is a bit smokey at startup but not too bad once running. I guess I'll pull the plugs and see if they are fouled. If anyone can give me any suggestions on what to test or look for when this happens i'd appreciate it.

find out if you are dropping a cylider and which one. Buy a set of ignition pliers, they have rubber coated handles and they are made for grabbing spark plug wires so you can pull one wire off at a time to see which cylinder is dead( it wont make any difference when its pulled off). Take a sugestion, hook a string to those pliers, you will eventually get hit by the ignition, it only hurts for a short while, but you tend to throw the pliers in the water when you get zapped

And don't worry, you won't pee on yourself.
THE SHOCK LOCKS UP EVERYTHING!!

If you do get shocked, that cyl is firing,
proceed to the next one.............

Wouldn't the spark checker do the same thing minus the shock?

Yea but not as fun!! Have you ck the stator??

I will try to test the stator tomorrow although I will probably have to do it while the problem is occuring. BTW how do you check the stator. Ive read the seloc manual but its a bit confusing.

Ohm meter for resistance checks, and then a PRV for total output. MERC's are known for stator problems as they use a split stator system. One side handles the 3000 RPM's- and the other side handles 3000 RPM's+. The high RPM side normally causes the most grief from what I have heard, but a low side can definately cause trouble.

when you find a dead cylinder by pulling the spark plug wire, you can determine if its dead from lack of fire, or some other issue. If you find you have two cylinders that have no fire, you look at the trigger, three on one side, look at the switch box. If you have two side by side that have fire but are dead, you may have a flooding carb( or no fule to the carb). You can fine tune your diagnosis by using a spray bottle with soem gas in it. Once you find the offending cylinders, spray a little gas down the carb throat, if the cylinder picks up, you know its not getting fuel. You get the idea?

Sounds like some good advice. Now all I have to do is go break down.

I started it up today in my driveway and there was massive grey/blue smoke for the first few seconds. Would this indicate a carb being flooded? I just rebuilt them a few weeks ago but this problem was happening before the rebuild. The only thing I did before that was rebuild the fuel pump. Is it possible to screw that up and cause the problems I'm having. I hate second guessing myself but everything ive done has been a first for me.

Fuel pump is a definate possibility. Does this engine have oil injection on it?

Yes it has oil injection. I already replaced the crank case check valve.

Have you checked to make sure your not pumping oil back into the crankcase from your oil tank? I had the real bad smoky starts on mine and found that I was overfilling my oil tank and it was pumping oil back into the crankcase when I shut it off.

My tank is only half full and the color of the smoke leads me to believe its burning excess gas. I did have the fast idle lever up pretty high so it kind of roared to life. POssibly that had something to do with all the smoke. I guess I'll look at the carbs and fuel pump one more time before taking it out again.

Is it possible the float levels wee set wrong during the carbs rebuild? Allowing to much gas into the cylyinders and loading the engine down at idle/start up. I suspect if this was the case you would see gas coming out of the carbs at low speed as well.


Kamikaze

The floats were right on the money so I didn't make any adjustments. I went and restarted the motor without lifting up the high speed idle lever and there was very little smoke. I'll let it sit overnight and try again tomorrow. I plan to take it out on friday and see what happens after running for a while.

check the stator

I didn't take it out today but did run it in my driveway and pulled the plug wires. Here's what I found. All had spark. Cylinders 4, 5, and 6 caused the engine to noticeably bog down when I pulled the wires. 1,2,and 3 did not cause the same change in engine speed. They did however have spark and when I put the wire close enough to the plug the spark jumped and caused a slight pick up in rpm's. Can anyone tell me what this means???

how are you numbering your cylinders?

port 2, 4, 6 starboard 1, 3, 5

if compresion is ok, try squirting gas in the carb throats while its running, see if they pick up those cylinders