Nissan rough idle

[Englishbob]

Nissan 90 hp 1996 n90a. Poor idle and missfire upto 2000 rpm. Runs great there after. Replaced plugs. I cleaned carbs. Checked fuel pump for leaks. Replaced idle mix screws. New fuel. Any suggestions welcome. Compression test 140 all three cyl

 

[pvanv]

Re: Nissan rough idle

What method did you use to clean the carbs? Did you check link and sync? Did you adjust idle mixture?

 

[Englishbob]

Re: Nissan rough idle

I used carb cleaner and air line after complete tear down. I am not sure if I linked and synced correctly. I set mixture to 1and half turns out on all 3.

 

[Englishbob]

Re: Nissan rough idle

Update. I decided to check for air leaks around the carbs using some wd40. The idle was affected by this on all 3 carbs. It was
Most noticeable on the top of carbs by the plate that covers the rubber discs. This suggests to me i need to get a full carb kit.
It took 3 weeks to get the idle screws from the nearest dealer,any suggestions where to get parts quicker.

 

[pvanv]

Re: Nissan rough idle

New kits may help. But just carb spray is not an adequate cleaning, and may yet be your solution. Carb spray is not aggressive enough. You must fully disassemble all the carbs (including jets and emulsion tube nozzles), and soak for 4 hours in real carb dip... and THEN blow out liberally with generic carb spray. Then reassemble, paying close attention to float height. If you want a carb kit (does all the carbs), order 3B7871221M CARBURETOR REPAIR KIT M90A, $152.04 from any dealer, including several forum members -- even me.

 

[Englishbob]

Re: Nissan rough idle

Okay, thanks. I will try the dip and let you know if it helps.