175 johnson popping at idle and shutting off.

[knot right]

i have a 175 johnson that pops at idle but revs out fine and popping goes away on higher rpms. what causes this and how do i fix ?

 

[henrye718]

Re: 175 johnson popping at idle and shutting off.

that suggests to rich or lean a fuel mixture. I forget which, no matter either adjust the carb low speed screw, there are instructions on how to do this somewhere on the forums.

BUT there is most likly a reason for the mixture going wrong, dirty carbs, air leaks etc. etc. so you may want to go that route first, not easy but right.

I would first check\change the plugs, fuel filter and make sure I have good fuel and decarb the engine to start with a clean slate.

Goodluck..

 

[bktheking]

Re: 175 johnson popping at idle and shutting off.

It's running lean at idle, idle circuit is probably dirty and requires a cleaning.

 

[wilde1j]

Re: 175 johnson popping at idle and shutting off.

It's lean ... carbs need to be disassembled and cleaned properly.

 

[knot right]

Re: 175 johnson popping at idle and shutting off.

ok, it was running good at idle but wouldnt go above 3000 rpms so i changed the plugs and wires and now the rpms rev out very high but the idle pops and stalls the motor.

 

[bktheking]

Re: 175 johnson popping at idle and shutting off.

Fact still remains if it pops and stalls it isn't getting enough fuel at idle.

 

[tashasdaddy]

Re: 175 johnson popping at idle and shutting off.

check the flywheel woodruff key, and the timing.

 

[emdsapmgr]

Re: 175 johnson popping at idle and shutting off.

Also, check to make sure the correct power pack leads go to the correct coils and that they are on the correct plugs . If you have one mismatched, (feeding the wrong spark plug) you can get popping. The pack leads are color coded.

 

[knot right]

Re: 175 johnson popping at idle and shutting off.

how do i know witch wire goes to witch coil ? they are colored from the power pack ( orange with green stripe,blue stripe and solid orange )but the wires going to the coils are all solid orange. however they are diff on each side.the solid is in the center on one side and on top on the other. but whats strange is i didnt touch the power wires just the spark plugs and wires and it ran smooth at idle before.is it possable that the plugs or wires where bad and the person i got it from adjusted the carbs or timing to run smooth on the cylinders that where firing and now that all cylinders are firing its all out of wack.i dont know much about this stuff so if that sounds off the wall im sorry. but thanks for the help. hopefully i can get this running right so i can use it.

 

[daselbee]

Re: 175 johnson popping at idle and shutting off.

Ignition coil wire connections from power pack(s) are :

Top coils/cyls have the orange/blue wire from the pack.
Middle coils/cyls have the solid orange wire from the pack.
Bottom coils/cyls have the orange/green wire from the pack.

And wiring mess up here will cause the engine to backfire.

 

[knot right]

Re: 175 johnson popping at idle and shutting off.

ok, the popping is fixed. it was two power wires switched on the coils but it still dont get the rpms it should. slugish getting up on a plain and not very high rpm's at wot. i checked the prop specs for that boat and motor and they recommend a 14" / 17 deg prop. i have a 15/17 on there so i dont think that would be the problem.where do i look next.? thanks

 

[bgewin]

Re: 175 johnson popping at idle and shutting off.

Hey I know this is kind of an old thread. We had a similar situation and the problem was a chunk of muck in the gas screen, which was sitting right over the fuel intake. It'd do ok at first and then starve itself. Definitely check the gas screen/filter if you haven't already.

 

[emdsapmgr]

Re: 175 johnson popping at idle and shutting off.

You may be dropping a cylinder. When you are out next time and have the engine under load, put an inductive timing light on each of the plugwires. Check for misfires or no fire at all. If you have good spark on all, then start looking at the fuel system.