95 70hp Johnson idles briefly and quits

[gjsentilles]

1995 70hp Johnson idles briefly (10-20 secs) then quits. Can keep it running with the primer if I catch it quick enough, but eventually (5-10 secs) dies. Should say when it is running it doesn't seem to be running on all cylinders. Can then wait a few minutes and repeat over and over and over... I have checked the fuel pump by disconnecting and cranking, seems to be good flow. I removed the number 1 carb and it was immaculate. I haven't checked the other two as I am doing this on the water and is very difficult. Timing light shows spark on all plugs. Timing at idle (when it runs long enough to check) is -4. compression test looked good although my tester isn't the best. I changed to another fuel tank and different fuel. Did notice a slight differnce (ran a little longer) at first but then returned to the pattern described above.<br /><br />For what its worth, when I first started chasing this problem, after being stranded on the water, I had and inconsistent spark. I eventually traced this to a flaky connection from the powerpak to the sensor screwed into the top cylinder head. After fixing this it began to start more consistently but the idle problem remains.<br /><br />Also the VRO has been removed and plugged on this engine by a previous owner. Other than that the engine is very clean and shows little wear.<br /><br />Thanks for any help.

 

[BIG GAZZA]

Re: 95 70hp Johnson idles briefly and quits

From experience this sounds very much like the dreaded plastic carby drama.If you have the plastic bowl on your carbs you will have the plastic emulsion tube that goes thru the guts of your carb if so this tube is extremely susceptable to failure if it is no good you will be able to push your finger nail into it & it will be quite soft.

 

[ob]

Re: 95 70hp Johnson idles briefly and quits

strugglehome, If you say you can get motor to settle out briefly by bummping primer button it sounds to me as if you have fuel delivery problem.At best it may just be a mixture adjustment problem ,but more than likely your fixed jets are obstructed with tarnished or gummed fuel/oil residue.I don't believe you have plastic bowls on 95 model 70 hp.mine is 70 hp evinrude 95 model. Motors are virtually identical.I had several carb adjustment issues with my unit when purchased new. Have since then worked the bugs out.My mixture adj. screws were opened originally 3 turns out when new. Since then I now run with them at around 4 turns out on each carb.Your problems could be a combination of both adjustment and or obstructed fuel flow through carbs or faulty disconnect valves at motor or tank.any fuel leaks apparent around primer solenoid or carb inlets?Check pickup in tank. Does primer bulb stay firm after priming and attempting to start?also check to see if the carb syncro roller on starboard side of engine when in nuetral is aligned with the scribed line on fiber linkage plate. this was also way off on mine when purchased new.

 

[gjsentilles]

Re: 95 70hp Johnson idles briefly and quits

Well I don't have the plastic carb bowls. I don't believe it is carb adjustment since it was running fine before the incident. I did check the adjustment screws and they varied in turns. Top is about 2.5, middle is 3 and bottom is 4 turns out from being snug against spring.<br /><br />I do see a small leak around primer solenoid but only when I move it to the manual start position.<br /><br />The primer bulb does NOT seem to stay firm after starting. It also doesn't get as firm as when the line is completely disconnected from the engine.<br /><br />It seems to always have some give even after pumping it up, however, no leaks are apparent if I keep pumping. It is as though I am feeling the give in all the connecting rubber fuel lines in the fuel system. This could be normal, I don't know.<br /><br />The carb linkage looks correct.<br /><br />I was able to keep it running for over a minute by carefully hitting the primer on a regular basis and advance the throttle enough to provide more air. Could it be getting too much fuel?<br /><br />I also tried placing my hand over each carb barrel while someone else cranked and could see lots of fuel was drawn into the carb throat. This made me feel like the carb were not clogged. Am I wrong?<br /><br />Today I will try to bypass the fuel pump and then bulb pump fuel directly into the carb feed lines.<br /><br />Does anyone think this could be some sort of ignition problem? It doesn't make sense to me but I am really baffled as to what is going on.<br /><br />Thanks for everyones help.

 

[ob]

Re: 95 70hp Johnson idles briefly and quits

If primer bulb feels spongy after priming and won't stay firm you could also have a needle valve not seating in one or more of your carb bowls.Also,I would back all three adj. screws out 3/1/2 turns and water check motor for operation.

 

[gjsentilles]

Re: 95 70hp Johnson idles briefly and quits

Well I actually fixed this a while back but haven't had internet access to let y'all know what was wrong. The local service guy had me change the fuel pump and spark plugs -- no difference. Then I noticed I was losing spark on number 2, which returned when I tapped the side of the Powerpak, so I replaced the Powerpak -- no difference. Then after conversation with the mechanic again and stressing to him that I thought the timing was off he said "they told us in training that the problem in never under the flywheel" but in practice we have had a few. I removed the flywheel and found that the round doughnut magnet glued to the center of the flywheel had slipped about a half an inch (seems to me it should be keyed). Restored the magnet to what I thought was the correct position and that solved all the problems I have reported here. In other words the timing was off. I think the quick start circuit was confusing the issue by allowing the motor to run momentarily and then quit. Just a guess. Whew! What a saga!?<br /><br />Thanks again to everyone.