1977 140Hp Evinrude Misfire Problem,wont Rev-up

[140hpevinrude1]

Hi Eveyone,
First want to thank Joe Reeves for helping me the first time with the coils hookup.
this time i need help with engine, won`t rev-up.

Here are the items i did so far, Compression on all 4 cyl. 110-115 psi., New Spark Plugs, New Coils, New Starter, Replaced Gaskets on Carbs and cleaned them really good, New Fuel Pump.

Engine Starts Just fine and keeps running on idle very good as soon as i try to give it gas it starting to missfire and running bad, when ill put the throttle back on idle it runs perfect again,

I can post a video of the problem so you guys can see as soon as i figure it how,lol
any ideas what could be wrong with it for now ,
thanks again Robert.,

 

[wired247]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

All that new stuff. Why is it there?

 

[boobie]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

Sounds like an ignition prob when under load. Maybe a bad pack ??

 

[CharlieB]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

Spark test cranking with the throttle cable disconnected, test while slowly moving timing lever to full advance then back to idle again.

Leave the spark plugs out to save wear and tear on the battery and starter.

A broken yet abutted trigger can spark fine in some positions but as the wires move with timing advance they can separate and fail to spark, so watch carefully and move the triggers wires slowly to make sure that spark stays consistant.

Do NOT assume any ignition problem, PROVE IT, as there is NO RETURN on electrical parts, prove it before ever even thinking of replacing any parts.

 

[140hpevinrude1]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

That sounds like a good idea to check it ,I'll do that first thing in the morning and post the results .

 

[emdsapmgr]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

Make sure your new coils are grounded on the head. Make sure the contact surfaces are clean. Check the spark plug wires. Possible one or two may shorting to ground (on the head or lower cowling latches.) You may be able to hear a crackling sound or see it at night. Is the link arm moving the timer base when the spark advance lever moves toward WOT?

 

[140hpevinrude1]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

just did the test like charlie B. said ,took all plugs out and had my brother crank the engine over and i had good spark at all cylinders all the time and while i was moving the timing advance level up and back .any other ideas

it has to be something else, please need more info on this ???

 

[lexer440]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

Sounds like timing is not being advanced or not adjusted correctly. just a thought on your first comment, are your plug wires going to correct plugs? ie firing in right order?

 

[140hpevinrude1]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

just a update , the test i did before with all the plugs out and i was checking for spark with the timing advance level went fine , but now i found the PROBLEM , I did the same test with the engine running on idle then i conected the timing light on cyl.1 fine, on cyl.2 fine, cyl3 was fine until i try to give it gas and then the light went out ( No Spark ) so this caused my engine to miss fire , then i did the check on cyl.4 and everything was ok again with the timing light.

Now my question is : Is the powerpack going bad that is causing the missfire at cyl.3 at higher RPM ???

I did another test just to make sure it was not the NEW coil going bad at cyl.3 so I swap it with Cyl.2 coil and I had no spark at cyl.3 again at high RPM , so its not the coil then .

 

[emdsapmgr]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

That's a valid coil test. It is possible that you have a bad pack. They typically have a higher failure rate than most of the rest of the ignition components. It's a pricey item, so you may be well served to do some electrical testing first. You can find some great troubleshooting tips from CDIelectronics.com. You may want to verify the stator and timer base before you jump into a purchase on the power pack.

 

[wired247]

Re: 1977 140Hp Evinrude Misfire Problem,wont Rev-up

Watch the engine run in the dark and look for spark coming from the wired to the engine block Sometimes you get grounding of the spark before it hits the plug. Ive had spark go straight through the boot to the engine block.