Mercury 5 HP 4-stroke won't start

[robinfla52]

I actually have a Tohatsu MFS5C. New carb, fuel pump, spark plug. Spark is strong. I spray fuel into spark plug hole, put plug back in. Pull cord and nothing, doesn't even fire up once. Same with start fluid. Flywheel never removed so I don't think it can be timing issue. I did ohm test on plug: .441 ohms. But when I check continuity I get no beeping sound. I pump primer bulb and fuel shoots out. Carb bowl has fuel. I am really puzzled.

 

[racerone]

How did it run for you last season?----What happened?-----Compression tested ?----Flywheel key checked?----Valve timing checked?

 

[Chris1956]

if it doesn't pop with starting fluid, you do not have any spark. period

 

[robinfla52]

I totally agree with you. That's what I don't understand, I take the plug out and ground it and pull cord and I get blue spark. I am going to wait until dark tonight and check again. Hard to do things without a helper.

 

[racerone]

Does spark jump a gap of 3/8" (9 mm ) on a test device?

 

[Mc Tool]

Stuck valve ? Stick your finger in the plug hole ,give it a pull on the starter and see if there is any compression .

if it doesn't pop with starting fluid, you do not have any spark. period

2nd line original post "spark is strong "

 

[Chris1956]

if a valve was stuck, and spark was present, the engine would backfire or catch on fire. your spark is going away under compression or for some other reason. Keep a fire extinguisher close by

 

[robinfla52]

I have compression. Last night when it was darker I could see bright spark in tester and on plug itself. I used a dva to measure voltage from spark plug wire. I got 65 vdc when pulling cord. I'm older and that's the best I could pull it. I have never had it running as a friend gave to me to get it running. It was log model and I installed a new gas carburetor. I did the same on another identical motor with no problems. Ran like a top. It certainly should at least "pop" once after inserting gas or starter fluid into cylinder, but nothing!

 

[robinfla52]

Anybody think I should take to a professional. I might still be able to make some money from it if I get it running. Only have $200 invested

 

[Chris1956]

there are rare cases where the spark plug is broken, or doesn't make a good ground to the head. make sure both are clean

 

[racerone]

You have no spark or spark at the wrong time !!!!

 

[Mc Tool]

if a valve was stuck, and spark was present, the engine would backfire or catch on fire. your spark is going away under compression or for some other reason. Keep a fire extinguisher close by

Maybe ....just maybe but if it already flooded most likely not Just remembering ALL the hundreds of stuck valves (mostly lawn mowers and other similar type side valve motors ) and I dont recall them popping off....just chuffing out the exhaust or (way less often ) the carb .

 

[robinfla52]

Maybe ....just maybe but if it already flooded most likely not Just remembering ALL the hundreds of stuck valves (mostly lawn mowers and other similar type side valve motors ) and I dont recall them popping off....just chuffing out the exhaust or (way less often ) the carb .

Maybe you can hear in the videos what it sounds like. How would I go about getting them unstuck if possible?

 

[robinfla52]

Maybe you can hear in the videos what it sounds like. How would I go about getting them unstuck if possible? Motor has never been disassembled so I don't think it is timing.

 

[racerone]

Remove valve cover.----Check valve operation / clearance.

 

[Mc Tool]

Yep ,if one of them is stuck it will have way to much valve clearance .....but if you do have compression they aint stuck . Usually its the exhaust that sticks open or part open .