Motor not running fast enough

[10point]

I have a 1974 9.9 evinrude. Motor was running rough and I found I had to tigthen up the fuel filter so gas wouldn't leak out and it is now running really good and starting fine but just not going real fast. Any ideas on what I should look for? I might also add that it is running pretty slow in neutral also.

 

[Daviet]

Re: Motor not running fast enough

Is it running on both cylinders, check spark and compression.

 

[10point]

Re: Motor not running fast enough

Is it running on both cylinders, check spark and compression.

I checked spark a few weeks ago and it was fine. Not sure I can check the compression. Don't you need some type of gauge or something?

 

[bktheking]

Re: Motor not running fast enough

Compression gauge will do it, usually when they aren't running up to speed they aren't firing on both cylinders, the prop is slipping or the motor isn't the proper height on the transom.

Fire it up and pull a plug wire off, it should run on one cylinder, do it for both cylinders, if it dies then there is either a spark issue, water intrusion or a reed problem.

 

[Daviet]

Re: Motor not running fast enough

Easy enough to recheck spark, make sure it jumps a 7/16 gap and is bright blue.
Yes, you need a compression tester to check compression. Some auto parts stores rent or loan them out, check your local auto parts stores.

 

[AlTn]

Re: Motor not running fast enough

the fuel filter leaking...was it the screen on the fuel pump...or an inline filter?..if on the fuel pump, remove the pump from the block leaving the fuel line from the tank attached and disconnect the line to the carb from the pump. Pump the primer bulb from the tank while holding your thumb over the barb for the carb side. Any fuel leaking under pressure needs to be addressed.If an inline filter...is it clogged?...just trying to eliminate the fp as a possible problem. If fuel to the pump and no restrictions or leaks, put a line to the carb side of the pump...remove the spark plugs first... pull the motor through a few times and see how the pump functions. You should see pretty strong and steady pulses...if they seem to wane...your pump may need rebuilding or replacing...a couple of more "free" checks

 

[10point]

Re: Motor not running fast enough

the fuel filter leaking...was it the screen on the fuel pump...or an inline filter?..if on the fuel pump, remove the pump from the block leaving the fuel line from the tank attached and disconnect the line to the carb from the pump. Pump the primer bulb from the tank while holding your thumb over the barb for the carb side. Any fuel leaking under pressure needs to be addressed.If an inline filter...is it clogged?...just trying to eliminate the fp as a possible problem. If fuel to the pump and no restrictions or leaks, put a line to the carb side of the pump...remove the spark plugs first... pull the motor through a few times and see how the pump functions. You should see pretty strong and steady pulses...if they seem to wane...your pump may need rebuilding or replacing...a couple of more "free" checks

I actually replaced the fuel pump a few weeks ago.

 

[AlTn]

Re: Motor not running fast enough

ok....did it affect the running" at all after replacement?...seems BK and Daviet both have you going in the right direction...post back results...compression testers with a flex hose can be "borrowed" at many auto parts stores...deposit required which will be refunded upon return

 

[10point]

Re: Motor not running fast enough

ok....did it affect the running" at all after replacement?...seems BK and Daviet both have you going in the right direction...post back results...compression testers with a flex hose can be "borrowed" at many auto parts stores...deposit required which will be refunded upon return

Yes, before I replaced it was like shaking and running slow. Know it is running slow but not shaking becuase it is no longer leaking gas. Is it pretty easy to test the compression if I can get a tester. I have no idea how that is done but I can probably learn. I should add that when I run it out of the water with the muffs on it seems to be running fine.

 

[Daviet]

Re: Motor not running fast enough

The only thing different about running on the muffs is that you don't have backpressure on the exhaust system.
What does the lower plug look like, thinking maybe a lower crankshaft seal might be leaking.

 

[10point]

Re: Motor not running fast enough

The only thing different about running on the muffs is that you don't have backpressure on the exhaust system.
What does the lower plug look like, thinking maybe a lower crankshaft seal might be leaking.

Not sure, when you say lower plug does that mean spark plug? I can try to look at them tonight.

 

[10point]

Re: Motor not running fast enough

Ok guys I just looked at my plugs and the lower one was a lot more gassy or oilly then the top one. When I have it running if I unhook the plug wires from the bottom it stops running but not when I remove the top one. Does this mean anything?

 

[oldgradywhite]

Re: Motor not running fast enough

could be a bad coil or cdi box I think you got one on that. Make sure the one cylinder that firing has bright blue spark the will jump a 7/16 gap. But if you want to find the problem you will need a dva meter. other then that your guessing.

 

[10point]

Re: Motor not running fast enough

could be a bad coil or cdi box I think you got one on that. Make sure the one cylinder that firing has bright blue spark the will jump a 7/16 gap. But if you want to find the problem you will need a dva meter. other then that your guessing.

Should it not be stopping when I unplug the spark plug cable?

 

[bktheking]

Re: Motor not running fast enough

could be a bad coil or cdi box I think you got one on that. Make sure the one cylinder that firing has bright blue spark the will jump a 7/16 gap. But if you want to find the problem you will need a dva meter. other then that your guessing.

74 doesn't have a cdi box, points and condensor. Recheck your spark, if you have spark on the bottom cylinder and it won't run it's either being put out by too much gas or water. If it were a seal the plug would be lean would it not, it would be pulling in more air than fuel and wouldn't be soaked. I just went through this same issue with my 76 15 hp, had great spark on both but wouldn't run on the bottom cylinder, had a worn out water grommet and a zip tie stuck in the reed plate causing it to get WAY more fuel than it needed.

 

[bktheking]

Re: Motor not running fast enough

Should it not be stopping when I unplug the spark plug cable?

Nope, these twins should fire on one plug, I did the test after I repaired mine. It would run with either plug pulled off, no power mind you but it would start. That's how you know there is an issue, they idle rough, don't sound right on muffs and have 1/3 of the power they normally have.