5.0 carbureted Q6 bogging and slight backfires at full throttle

[maddog2112]

Took the 06 Q6 5.0 out for it`s first fishing trip today and it started and was running fine. I took it easy first couple hours,25-30mph but on the way in I decided to air it out a little. I took the throttle all the way forward and I felt a couple of bogs and what sounded like small backfires. I couldn`t believe it at first so I tried it again with same result.. when I brought it back to idle, she stalled. She started normally and I opened the engine compartment. At idle she sounded fine and when increasing throttle in neutral all normal, so I closed her up and jam the throttle forward as if skiing. Bog bog, small backfires. Any ideas out there? She was fully winterized last fall with stabilizer installed. All fluids changed and new plugs. A week ago I had her on the muffs for the first time this season to start her up and make sure she was running right. She was. Thats why I was so surprised today. Thx for all responses.

 

[maddog2112]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

A couple of extra points. I had no problems starting all morning, but after the bogging when getting her ready for trailering, she shut off several times while shifting into forward or reverse and the engine was warmed up already. She has never shutoff like that before. Could this be a shift cable problem?

 

[yourboatmyboat]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

Even though you added treatment to your gas last fall the gas still will get stale on you. I would change the filter , add maybe some treatment such as heat, and add fresh gas.

 

[maddog2112]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

I believe I found the problem, but probably wont know for sure until I can get it on the water for test. I did add some fresh gas before going out yesterday. I popped the distributor cap off and the inside was very wet. Seems the cap base gasket had deteriorated, (probably due to my washing the engine off a month ago), and there was quite a bit of droplets inside. The electrodes also were green tipped with corrosion. I bought a cap and rotor kit from searay, and put them on today. Tommorrow I will start her on the muffs and thoroughly spray out the carb, with cleaner. I will also add some more dry gas and hope for the best. My chev tahoe is in the shop for a little body damage repair so I won`t be able to put her on the water until next week. I will keep u all posted.

 

[maddog2112]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

I feel like I am almost talking to myself, but thats good news, as not too many of you have probably ever had this problem. I started her up on muffs today and she started right up, and sounded great . I let her warm up until the choke kicked down, and then shifted into forward and reverse. No stall. Shut her off and started a few times. She sparked right up. I won`t know about full throttle on the water until next week, but so far so good. I will keep you all posted as this can be a good learning experience for future reference. Thx all.

 

[Hashi]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

Although you may be talking alone, we are all listening. Thanks for posting and keep us all updated on your WOT problem.

 

[maddog2112]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

Thanks Hashi. That`s what is so great about having our own Tahoe forum. It`s all about sharing our fun and learning experiences.

 

[mandopickr]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

I have (had, just sold it, great boat) a 06 carbed 4.3 Q6. I had some minor problems with starting, and then stalling in gear when I first put my boat in after not having been run for a week or so. I took it in for service a couple of years back, and there was a service bulletin on some carb issues. I don't remember the details of the bulletin, but the mechanic's work eliminated the problem. I don't know how easy it is to find the service bulletin from Mercury, but you might see what you can find.

 

[maddog2112]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

Thx Mandpickr, i`ll look into that. I`m waiting for this darn rain to stop and the lake levels to recede so I can get her out for a test run. Thx

 

[maddog2112]

Re: 5.0 carbureted Q6 bogging and slight backfires at full throttle

I finally got my boat out after the last stumbling ,backfiring at full throttle incident. I am glad to report that the new rotor, and distributor cap, which was corroded and wet on the inside, was the problem. She ran like a top thru all throttle ranges. As an added bonus, she starts immeadiately everytime, even when cold and idles quite smoothly. I wanted to make sure and report back for further reference to anyone who may run into the same problem in the future.Thx all for responses in troubleshooting this problem.