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Hi - I have a 19 ft 1989 Donzi with 4.3 Liter OMC Cobra 6 cyl - 2 barrel Carb. The engine isn't hitting on all six cylinders.The third plug from front on the right side (with oper looking forward) the electrode was burned down to ceramic others OK After I inst 6 nw plugs the cylinder still wasn't firing. I started the engine and removed the wires one at a time and noticed no difference when I got to that cyl. I changed the wire with another, to verify wire not the problem, still a problem with this cylinder. Inspected inside the distributor and noticed no problem with rotor or cap. I got some good Marine cylinder spray and removed the plug from the bad cylinder and sprayed inside the cylinder, let it sit overnight,bumped engine to clean, repl plug and started it the next morning.Then sprayed the entire can down the carborator to clean the cylinders, at high RPM. Took it on test run and it still wasn't hitting on that Cyl. Help!! Steve Elmore

Submitted: 24 days and 16 hours ago.

Category: Boat

Value: $15

Status: CLOSED

Year : 1989
Make (other): Donzi 19 Boat
Engine: 4.3 Ltr OMC Cobra

Already Tried:
See Question. I think Cylinder may be "gunked" up keeping it from firing.

Posted by ALL Around Tech 24 days and 16 hours ago.

Answer

Hello Steve,

First thing I would do is a compression test and or a leak down test need to make sure you do not have a compression problem or valve problem.

Please at least do a compression test on all cylinders and let me know the readings and after that we can proceed.

Thanks,
Joe

24 days and 16 hours ago.

Reply

Thanks Joe - I have left the boat in storage now for the winter - I'll try to get to it to do the test - but it'll probably take some time.
Thx
SE

Accepted Answer

Ok since it will be awhile most times the questions close after a couple of days if no replay......Get an inline spark tester or timing light and attach to that plug wire and see if you actually have a ignition missfire, if not then perform a cylinder compression test and a cylinder leak down test would be nice as well.

Thanks,
Joe

Accepts:
Expert:	ALL Around Tech
Pos. Feedback:	97.8 %
Answered:	10/28/2009

Marine Mechanic

ASE, electronics, Marine inboards and electronics, automotive drivability, all around repair tech,

Posted by ALL Around Tech 24 days and 15 hours ago.

Answer

Yes, even if this page closes then just hang on to an email or copy the entire web address at the top of the page and paste it into word or paint or notepad and name it something you can relate to this, then when you need help again just copy and paste that full web address into the address bar at the top of your internet and then it should bring you back to this page, you should be able then to reopen question or just post back again which will open the question back up and should send me an email as soon as I see it I will contact you back!

Thanks again,
Joe

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Year : 1989
Make (other): Donzi 19 Boat
Engine: 4.3 Ltr OMC Cobra

Already Tried:
See Question. I think Cylinder may be "gunked" up keeping it from firing.

Answer

Hello Steve,

First thing I would do is a compression test and or a leak down test need to make sure you do not have a compression problem or valve problem.

Please at least do a compression test on all cylinders and let me know the readings and after that we can proceed.

Thanks,
Joe

Reply

Thanks Joe - I have left the boat in storage now for the winter - I'll try to get to it to do the test - but it'll probably take some time.
Thx
SE

Accepted Answer

Answer

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Optional Information

Year : 1989Make (other): Donzi 19 BoatEngine: 4.3 Ltr OMC Cobra Already Tried: See Question. I think Cylinder may be "gunked" up keeping it from firing.

Answer

Hello Steve, First thing I would do is a compression test and or a leak down test need to make sure you do not have a compression problem or valve problem. Please at least do a compression test on all cylinders and let me know the readings and after that we can proceed. Thanks,Joe

Reply

Thanks Joe - I have left the boat in storage now for the winter - I'll try to get to it to do the test - but it'll probably take some time. ThxSE

Accepted Answer

Answer

Related Boat Questions

Year : 1989
Make (other): Donzi 19 Boat
Engine: 4.3 Ltr OMC Cobra

Already Tried:
See Question. I think Cylinder may be "gunked" up keeping it from firing.

Hello Steve,

First thing I would do is a compression test and or a leak down test need to make sure you do not have a compression problem or valve problem.

Please at least do a compression test on all cylinders and let me know the readings and after that we can proceed.

Thanks,
Joe

Thanks Joe - I have left the boat in storage now for the winter - I'll try to get to it to do the test - but it'll probably take some time.
Thx
SE