Jerky throttle after new plugs

Two Peas

Member
Jun 24, 2008
914
Niagara River, ON
Boat Info
360DA 2002, Raymarine C80, SR50 Weather, Radome, DSC, Baltik 9'6" with 6hp Tohatsu
Engines
8.1 Horizons w/V-Drives
Yesterday I replaced all 16 plugs with AC-Delcos that many other CSR members have bought. I made sure they were gapped at 0.060. Both engines fired up right away and seemed to idle perfectly.

Today I fired them up and they start perfectly. After warming to 160 degrees, I decided to run the throttles up a bit. The rpms go smoothly to 1000 from idle at 660. Then they move up to about 1200. When I try to advance to 1500, they don't respond like they usually do, but instead jump from 1200 to 1700 as I move the throttles forward. I can't get smooth response between 1200 and 1700. I didn't try to go past about 1800 (all at the dock).

If it was a loosely seated wire, I wouldn't expect it to happen identically on both engines, which is what is happening.

Any ideas?
 
I didn't get a chance to take it out yet - hopefully tomorrow.
 
Scott, great instincts. I took the boat out today and burned 30 gallons, and she performed flawlessly. It must just be an issue at idle, and probably isn't really an issue....
 

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