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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10597
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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i have a bayliner with 1994 mercruiser v8 i/os and i just

Resolved Question:

i have a bayliner with 1994 mercruiser v8 i/o's and i just had my spark plugs changed. i am trying to make sure that the wires were installed correctly from the cap to the plugs. the engines are running roughly and when i try to get on plain i cannot get much power and the engines start back firing. the distributer cap has two numbers on each pole one large number and one small one so i am not sure which is which. i believe the cylinder numbers are 1357 on the port side of the engine and 2468 on the starboard side going from front to back, but i have not been able to confirm that. any help would be appreciated.
Submitted: 5 years ago.
Category: Boat
Expert:  Tan replied 5 years ago.

Hi my name isXXXXX will assist you.

The correct firing order is 1-8-4-3-6-5-7-2 and the rotation on the cap to follow is the large numbers rotating in a clockwise direction. Here is a diagram. Post back if you have further questions. Numbers 5-7 are the ones that get crossed allot of the time.graphic

Edited by Tan Partin on 11/14/2010 at 1:32 PM EST
Customer: replied 5 years ago.
ok this is great that confirms the firing order and wiring. i will head to the boat this morning and double check it. if it turns out that they are wired correctly what else could be wrong with the engines not providing enough power to get on plane and back firing.
Expert:  Tan replied 5 years ago.
The next thing to check will be the fuel system for water and debris. The backfiring is either timing is off or the fuel system. The timing should set at 8* BTDC. Check you fuel filter for water, if the filter is clean run the engine on a different fuel source to eliminate the boats fuel system. If the engine runs good check the fuel tank for debris or sludge, if no change remove the carburetor disassemble, clean and install carb kit. If there is still a problem post back.
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