Help with a 6hp merc

oldtimer · 09-03-2009, 04:06 PM

I have problems with my 1986 mercury 6hp serial A0963511. Hard to describe the problem, it starts great, idles a little on the high side, but starts popping after just a few seconds. It like I said makes a pretty loud pop noise, every few seconds (4-10) and seems to slow down, like its shuts off but right away runs again, every time it pops it blows a stream of smoke out the exhaust. I am afraid to take it out on the lake, or rev it up in the barrel. I had to put a stator on the first of last year and two years before that also, it ran ok after that, but haven’t used it much. If I had this problem on a car I would be looking at the ignition, but where on a boat motor? I do have a spark tester and seems to have a good spark all of the time. The compression is 90# in both cylinders, but tester is suspect, as I had a bad bottom valve stem and only the one I could get to work was the stem in the release valve. Evidently they take a special valve stem for compression testers. I checked the timing and it is about 2 degrees advanced from the 6 degrees recommended at idle, the idling would not slow enough to put the mark on the 6 degrees. Appears to me you can’t really change the timing anyway, factory set? Carburetor was serviced 4 years ago, but they did a lousy job. Brought it back and wouldn’t start. I found they lost and didn’t replace the spring under the choke primer. I just looked at the carb. and blew it out, it was very clean. I did put it together without new gaskets, only putting vaseline on them. This was yesterday after the problem had started. I sure can’t figure how to check the float height, and the (new) plugs seem to be pretty wet. The gas is new, and correct mix. I have changed the tanks and have a new hose assembly. With a clear hose I was getting quite a lot of bubbles in the gas line, so hooked direct from the gas tank to the carburetor bypassing the fittings and the fuel filter. No improvement in the popping. Any suggestions will be appreciated. Thanks

xtreme76 · 09-03-2009, 06:12 PM

It sure sounds like timing in my un-expert opinion. Is it a 2 cylinder? Are the plug wires switched around?
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try asking here Mercury & Mariner Outboards - iboats Boating Forums

H2only · 09-03-2009, 09:30 PM

could it be running lean?

skeeter85 · 09-03-2009, 10:52 PM

PM mercman. He'd be the one to ask.

Harold · 09-04-2009, 12:48 AM

Sounds like it's "choking"!

Mel at Mel's Marine in McCook always took care of my '57 Johnson 5.5HP, but he was "old" twenty years ago! I'm sure Mercman or other techs on this forum will take care of you!

Good Luck!

Harold F.

papaw t · 09-04-2009, 05:51 AM

Sounds like it is running short of fuel.

H2only · 09-04-2009, 08:52 AM

Quote:

Originally Posted by papaw t

Sounds like it is running short of fuel.

you mean "lean"

I still say its running lean

papaw t · 09-05-2009, 03:12 PM

just agreeing

oldtimer · 09-05-2009, 05:03 PM

Thank you all for your good advise and ideas. It seems like the general consensus is a lean condition. I pulled the carb again today and looked at the reed valves, they are fine. I am going to order a carb rebuilt kit and hit it once more, if no go will take it in. Again thanksluck

MERCMAN · 09-21-2009, 08:28 PM

I would have to say the fuel pump. But you should have no air in the fuel line when its running.

let me know!

09-03-2009, 04:06 PM	#1 (permalink)
oldtimer oldtimer has no status. Member Join Date: Mar 2007 Location: south central nebr Posts: 47 Thanks: 45 Thanked 3 Times in 3 Posts	Help with a 6hp merc I have problems with my 1986 mercury 6hp serial A0963511. Hard to describe the problem, it starts great, idles a little on the high side, but starts popping after just a few seconds. It like I said makes a pretty loud pop noise, every few seconds (4-10) and seems to slow down, like its shuts off but right away runs again, every time it pops it blows a stream of smoke out the exhaust. I am afraid to take it out on the lake, or rev it up in the barrel. I had to put a stator on the first of last year and two years before that also, it ran ok after that, but haven’t used it much. If I had this problem on a car I would be looking at the ignition, but where on a boat motor? I do have a spark tester and seems to have a good spark all of the time. The compression is 90# in both cylinders, but tester is suspect, as I had a bad bottom valve stem and only the one I could get to work was the stem in the release valve. Evidently they take a special valve stem for compression testers. I checked the timing and it is about 2 degrees advanced from the 6 degrees recommended at idle, the idling would not slow enough to put the mark on the 6 degrees. Appears to me you can’t really change the timing anyway, factory set? Carburetor was serviced 4 years ago, but they did a lousy job. Brought it back and wouldn’t start. I found they lost and didn’t replace the spring under the choke primer. I just looked at the carb. and blew it out, it was very clean. I did put it together without new gaskets, only putting vaseline on them. This was yesterday after the problem had started. I sure can’t figure how to check the float height, and the (new) plugs seem to be pretty wet. The gas is new, and correct mix. I have changed the tanks and have a new hose assembly. With a clear hose I was getting quite a lot of bubbles in the gas line, so hooked direct from the gas tank to the carburetor bypassing the fittings and the fuel filter. No improvement in the popping. Any suggestions will be appreciated. Thanks

09-03-2009, 09:30 PM	#3 (permalink)
H2only H2only has no status. Member Join Date: Sep 2007 Location: Lincoln, NE Posts: 1,692 Thanks: 86 Thanked 305 Times in 209 Posts	could it be running lean? __________________ "A government big enough to give you everything you want, is big enough to take away everything you have." - Thomas Jefferson

09-03-2009, 10:52 PM	#4 (permalink)
skeeter85 skeeter85 is winter blows Member Join Date: Jun 2008 Location: Bellevue, NE Posts: 1,275 Thanks: 288 Thanked 423 Times in 269 Posts	PM mercman. He'd be the one to ask. __________________ dave Tell a man there are 100 billion stars in the universe and he will believe you. Tell a man a bench has wet paint and he'll have to touch it to be sure.

09-04-2009, 12:48 AM	#5 (permalink)
Harold Harold is missing his friend, OBG. 2008 Catch and Continue Finalist Join Date: Aug 2006 Location: Kearney Certified Youth Fishing Instructor NEFGA Line Recycling Volunteer Posts: 2,395 Thanks: 1,783 Thanked 718 Times in 416 Posts	Sounds like it's "choking"! Mel at Mel's Marine in McCook always took care of my '57 Johnson 5.5HP, but he was "old" twenty years ago! I'm sure Mercman or other techs on this forum will take care of you! Good Luck! Harold F. __________________ "If I had a picture, I wouldn't have given you 1,000 words..." (OBG) "Perhaps a better way of measuring wealth is by the number of unique experiences you have had..." Esther Dyson These are OUR FISHERIES! Report All Violations! .............1-800-742-SNAP

09-21-2009, 08:28 PM	#10 (permalink)
MERCMAN MERCMAN is Too many boats so little time. Member Join Date: Apr 2007 Location: Nebraska city Posts: 196 Thanks: 7 Thanked 8 Times in 6 Posts	I would have to say the fuel pump. But you should have no air in the fuel line when its running. let me know! __________________ The worst day of fishing beats the best day of work!

09-03-2009, 06:12 PM	#2 (permalink)
xtreme76 xtreme76 is waiting for april Member Join Date: Jun 2008 Location: Central Ne Volunteer Hunter Education Instructor Posts: 163 Thanks: 81 Thanked 46 Times in 36 Posts	It sure sounds like timing in my un-expert opinion. Is it a 2 cylinder? Are the plug wires switched around? - try asking here Mercury & Mariner Outboards - iboats Boating Forums

09-04-2009, 05:51 AM	#6 (permalink)
papaw t papaw t is waiting for the next opportunity! Member Join Date: Jun 2008 Location: Lindsay Posts: 179 Thanks: 29 Thanked 33 Times in 24 Posts	Sounds like it is running short of fuel.

09-05-2009, 03:12 PM	#8 (permalink)
papaw t papaw t is waiting for the next opportunity! Member Join Date: Jun 2008 Location: Lindsay Posts: 179 Thanks: 29 Thanked 33 Times in 24 Posts	just agreeing

09-05-2009, 05:03 PM	#9 (permalink)
oldtimer oldtimer has no status. Member Join Date: Mar 2007 Location: south central nebr Posts: 47 Thanks: 45 Thanked 3 Times in 3 Posts	Thank you all for your good advise and ideas. It seems like the general consensus is a lean condition. I pulled the carb again today and looked at the reed valves, they are fine. I am going to order a carb rebuilt kit and hit it once more, if no go will take it in. Again thanksluck

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