# Boat inboard engine miss firing at 2000 rpms **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** engines\ **Created:** [July 16, 2010, 8:20pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944 "2010-07-16T20:20:24Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![steved530](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@steved530](https://community.cartalk.com/u/steved530)\ **Post date:** [July 16, 2010, 8:20pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/1 "2010-07-16T20:20:24Z")
I have a 2008 Searay with a 350 Mercury engine. Under 2000 rpms the engine runs fine, but over 2000 rpms the engines is miss firing, making popping noises, and the smell of fumes is great. The replacement of spark plugs did nothing to solve the problem. I also double checked that i was using a non-ethanol fuel. What next should be checked to solve this issue? ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [July 16, 2010, 8:41pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/2 "2010-07-16T20:41:08Z")
Is it fuel injected? Does it have a distributor? Is it really a small block Chevy? ---
**Author:** ![steved530](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@steved530](https://community.cartalk.com/u/steved530)\ **Post date:** [July 16, 2010, 8:50pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/3 "2010-07-16T20:50:56Z")
It is fuel injected. No distributor. Unknown. ---
**Author:** ![Goldwing](https://avatars.discourse-cdn.com/v4/letter/g/e68b1a/32.png) [@Goldwing](https://community.cartalk.com/u/Goldwing)\ **Post date:** [July 16, 2010, 8:58pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/4 "2010-07-16T20:58:06Z")
Fuel filter not allowing enough gas through at higher speeds? How old is the gas? ---
**Author:** ![steved530](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@steved530](https://community.cartalk.com/u/steved530)\ **Post date:** [July 16, 2010, 10:06pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/5 "2010-07-16T22:06:06Z")
Problem started with older gas, treated with conditioner during winter closing. Used the older gas down to less than 1/4 tank then filled with new gas. Still had same problems, but did not change the fuel filter. ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [July 16, 2010, 11:11pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/6 "2010-07-16T23:11:40Z")
How many hours are on the engine and how has it been operated, specifically, has it been run with sustained 4,000+ RPM for most of its life. If yes, unless it has roller lifters you may have a cam lobe going flat. ---
**Author:** ![Goldwing](https://avatars.discourse-cdn.com/v4/letter/g/e68b1a/32.png) [@Goldwing](https://community.cartalk.com/u/Goldwing)\ **Post date:** [July 16, 2010, 11:20pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/7 "2010-07-16T23:20:56Z")
Fuel filter could get gummed up with old gas. Hope for the cheap fix. Try a fuel filter. ---
**Author:** ![waterboy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/waterboy/32/764_2.png) [@waterboy](https://community.cartalk.com/u/waterboy)\ **Post date:** [July 17, 2010, 12:14am UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/8 "2010-07-17T00:14:13Z")
Sea foam might help. You could have water in the gas, or you could have a trip to the mechanic for proper diagnosis. ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [July 17, 2010, 12:26am UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/9 "2010-07-17T00:26:37Z")
It is indeed a Chevy 5.7L V8 converted to marine use…Hopefully, a new fuel filter cures it… ---
**Author:** ![oblivion](https://avatars.discourse-cdn.com/v4/letter/o/3ab097/32.png) [@oblivion](https://community.cartalk.com/u/oblivion)\ **Post date:** [July 17, 2010, 12:50pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/10 "2010-07-17T12:50:02Z")
I’d go through the ignition components too–coil, cap, rotor, pickup, wires. I don’t know what kind of ignition system you have on this, but it’s possible that something is weak and the problem shows up when there is high demand on the system–eg. at higher RPMs. ---
**Author:** ![steved530](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@steved530](https://community.cartalk.com/u/steved530)\ **Post date:** [July 17, 2010, 7:37pm UTC](https://community.cartalk.com/t/boat-inboard-engine-miss-firing-at-2000-rpms/51944/11 "2010-07-17T19:37:42Z")
Have placed the boat in the hands of a new mechanic and provided him with all your comments. This is the second mechanic. Thanks for the comments. I will post the cure when it is found!