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Author Topic:   2005 Mercury 90-HP FOURSTROKE

wezie posted 03-23-2010 03:20 PM ET (US)
[Apparently in reference to a 2005 Mercury 90-HP FOURSTROKE outboard motor with] carburetor problems: I found a replacement jet kit mentioned. Has anyone seen [a replacement carburetor jet kit for a 2005 Mercury 90-HP FOURSTROKE outboard] or tried [to remedy carburetor problems in a 2005 Mercury 90-HP FOURSTROKE by using a replacement carburetor jet kit]? Dealer, of course, did not mention it. Has anyone found any other fixes for the [problems with carburetors on a 2005 Mercury 90-HP FOURSTROKE]? Thank You.
bdawg5219 posted 03-24-2010 05:18 PM ET (US)
Go through, clean everything, making sure to get in all pasageways. Synchronize carburetors with vacuum gauges. I wouldn't change jets unless you live in high altitudes.
bdawg5219 posted 03-24-2010 06:09 PM ET (US)
Im not sure. I assumed it was carbureted because of wezie's refrence to carburetor's. You may be correct
wezie posted 03-24-2010 07:25 PM ET (US)
The model year is stated to be 2005. It does have carbs.
Thank you for your interest.
Yamaha uses different carbs than the merc. version.
I just wondered if anyone had found a fix or change for these engine, that would make them a bit less difficult. Even changing out to Yamaha carbs might be a thought.
We cleaned everything we can get to. Not the insides of the carbs. but the gas looks great, with no water or debris in the bowls.
We did determine today that the primer/enrichment circuit is dead.
We do not know what else might be caused by that.
Thanks again!
jimh posted 03-24-2010 07:39 PM ET (US)
The announcement that Mercury uses different carburetors in the 90-HP motor than Yamaha, even though Yamaha makes most of the parts in both motors, is quite interesting. The Mercury carburetor 90-HP motors have a very bad reputation for problems with carburetors, while the Yamaha motors have no problems reported--at least none that I can recall. It has not been mentioned before that the two motors use different carburetors. That would explain the difference in reported problems.
L H G posted 03-25-2010 12:50 AM ET (US)
This link seems to indicate the 2005 90's had EFI. Yamaha 90 HP versions of the engine got the same EFI in 2005.
http://continuouswave.com/ubb/Forum2/HTML/018264.html
I have always read, here on CW, that Mercury bought the Yamaha engines lock, stock and barrel, and that both used a Japanese brand of carb. It seems that when the engines get praised, Yamaha gets the benefit, with Mercury unable to produce a mid-range engine of it's own. But when they have problems, it's Mercury's fault and Yamaha skates, even though the engines were identical.
Wezie's engine must be a 2004 MODEL year.
wezie posted 03-25-2010 09:05 AM ET (US)
The mercury uses a carb that sounds like Chinese. ?Kaishun?
That would tie in with their Chinese mfg. links.
Yamaha uses a well known and much liked carb.," mikuni".
So it is a decision by Mercury that seems to have complicated this situation.
The question is has anyone solved this problem (other than EFI) either by fixing the existing carbs or replacing them???
This problem will be worse with the alcohol junk fuel.
Thank You All.
bdawg5219 posted 03-25-2010 03:30 PM ET (US)
Take carbs apart & spray carb cleaner into passageways with the nozzle-straw. Make sure fuel/system is clean & synchronize with vacuum gauges. I had an 01' 100hp Yamaha that was carbureted & every time i ran into a problem i would take carbs apart & then synchronize the carbs with vacuum gauges.
L H G posted 03-25-2010 04:30 PM ET (US)
It sounds like the Yamaha Mikuni carbs had the same problem.
All of Mercury's 40-60HP engines manufactured in China use ONLY EFI systems. They never had carbs, so it's not likely they had a source in China. I always thought the ENTIRE powerhead was manufactured in Japan.
My Mercury-Yamaha dealership, who works on both brands of 75-100HP versions, said both had the same problems. And the problem is not the carb manufacturer, but the tiny jet passages required in the idle circuits because of the extremely low fuel consumption. They all are susceptible to clogging and varnishing with non-use.
Have a complete carb job done, and then use QuickClean every 4th tank, and always use Startron or Marine Stabil.
jimh posted 03-25-2010 05:34 PM ET (US)

quote:
"The mercury uses a carb that sounds like Chinese. ?Kaishun?"
Do any of these (116) companies sound like it?
http://www.made-in-china.com/companysearch.do?subaction=hunt&mode=and& style=b&word=Carburetor&comProvince=nolimit&code=0
wezie posted 03-30-2010 11:15 PM ET (US)
Jim, KEIHIN is the mfg. of the Merc 90/Yamaha carbs.
It is a Japanese company, and therefore may have been OEM for the Yamaha power heads Mercury purchased from them.
I was wrong about the Chinese connection at that point.
The discussion about 2005 Carb. and EFI overlooked the tendency of Mfg. to introduce new items and charge extra for them during the introduction period.
No one has heard of any after market "fix" for this problem? That was the real question?
Good Luck.
jimh posted 03-30-2010 11:24 PM ET (US)
The best remedy for the chronic carburetor problems with the Mercury 90-HP FOURSTROKE motors seems to be to have the dealer take them back, give you credit for nearly the full purchase price, and buy a different motor, perhaps a 90-HP motor with electronic fuel injection.
Thanks for the clarification on the carburetor manufacturer as KEIHIN for the carburetors on the Mercury 90-HP FOURSTROKE motor. If I understand your representation above, you say the carburetors used on the Yamaha 90-HP four-cycle outboard--which is otherwise very similar to the Mercury 90-HP FOURSTROKE--are made by Mikuni.
Your representation is that there are chronic problems with the KEIHIN carburetors on the Mercury 90-HP motor, but on the Yamaha 90-HP motor the carburetors are made by Mikuni. The Mikuni carburetors are not prone to the same problems. Is that correct?
bdawg5219 posted 03-31-2010 08:13 AM ET (US)
As the owner of a 2001 100hp Yamaha 4-stroke i ran into running problems a couple of times. Make sure the fuel/system is clean. Install of a fuel/water separator is recommended if you dont already have one. Take carbs completly apart & clean. I would take a can of carbcleaner with the sprayer/nozzle inserted in the can & spray into all ports and passageways. Be very careful of your eyes when spraying because you spray the cleaner in one port & it shoots out another port. After reinstalling, synchronize carburetors with vacuum gauges. Carb-tune makes a nice set of gauges for fairly cheap
wezie posted 04-01-2010 07:41 AM ET (US)
Jim, I do not know there is any difference between the carburetors [used on the Mercury model of the 90-HP four-cycle engine and the carburetors used on almost the identical engine sold as a Yamaha 90-HP]. After paying for "carb. rebuild" last fall and finding the engine would not start this winter, I was a bit angry at the whole system. These engines do run well. It seems , from a lot of input, and the manuals, that the passages are very small and they stop up more easily than they should.
There is another problem with this one. The primers (enricher) are not working, even after that expensive trip to the Dealer. I will sort that out also.
The two items and the junk alcohol fuel, means that it is difficult to get the engine to begin to start. Worked through all this without making another deposit to the dealer. Now to the primer circuit. I appreciate all of the positive suggestions. As to taking apart the carbs. I doubt that I will do this. I did drain all of them and flushed them.
Thank you for trying to sort this out.
jimh posted 04-01-2010 08:26 AM ET (US)
Well, I am afraid I am now completely confused about the carburetors used on these two 90-HP motors, one a Mercury and one a Yamaha. In the course of this discussion they've gone from being different, one being made in Japan, one made in China, and now we're not sure about them at all. I think it would be extremely useful to get some accurate information about the carburetors. Both Mikuni and Keihin are mentioned as manufacturers--which is it?
What we need to resolve this is to find two motors of the same model year, one a Mercury 90-HP and one a Yamaha 90-HP, get them together, take off the cowlings, and have a look. It ought to be simple to compare the arrangement of carburetors and fuel enrichment circuits, and we could finally see if there is any difference. Perhaps someone who has worked on both brands of this motor can help out.
95Outrage17 posted 04-01-2010 08:42 AM ET (US)
Jimh,
I have a 2004 and 2003 Mercury 90-HP Fourstroke and a 1999 Yamaha F80 here right now. I can't take the cowl off the 2003 right now (the boat is shrink wrapped), but I can get pictures of the carbs on the 2004 and 1999. I'll see if I can do so later today. I believe all the carbs are from the same manufacturer.
- Chris

95Outrage17 posted 04-06-2010 08:44 PM ET (US)
Hi guys,
Ok, a few days late, but here are the pictures: http://s9.photobucket.com/albums/a84/95Outrage17/ 1999%20F80%20and%202004%20Merc%2090/
The Yamaha and Mercury both have Keihin carbs.
- Chris
lefty93 posted 04-06-2010 09:41 PM ET (US)
My solution to my frustrating 2002 Merc 90hp fourstroke carburetor problems was to get an ETEC 115. Worked(s) like a charm!
bdawg5219 posted 04-07-2010 09:18 AM ET (US)
Bwahahaa. E-tec, thats funny.
jimh posted 04-07-2010 10:18 AM ET (US)
Many thanks to Chris for taking the photographs of the Mercury and Yamaha four-cycle engines to permit comparison of the carburetors, and for finding them to both use Keihin carburetors. This discover seems to conflict with some prior reports of a difference between the Mercury and Yamaha motors regarding the carburetors used, as well as a difference in the brand of carburetor mentioned. Based on Chris's observation, it appears that these four-cycle carburetor motors from Mercury and Yamaha use the same arrangement of carburetors and the same (Keihin) brand of carburetors.
Reports of difference in the operation of the motors by brand are not likely to be attributable to differences in the carburetors, inasmuch as there appears to be no difference.
95Outrage17 posted 04-08-2010 10:06 AM ET (US)
No problem Jim, glad I could help. I've worked on and serviced several of these engines now (I own the 2004), so I've learned a fair amount about them. I think they're great engines if serviced properly. Mine has given many hours of reliable service on the back of my Outrage. The F80 in the picture has been pushing our sailing club's Carolina Skiff work boat for the past two years without carburetor problems (although it's had a couple other problems). I think the newer EFI engines are nicer, but I'm not sure the carbed versions deserve the poor reputation they've been given by some.
- Chris
pcrussell50 posted 08-16-2012 02:06 AM ET (US)
[Revived two-year-old thread to ask about ultimate resolution.]

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Author	Topic: 2005 Mercury 90-HP FOURSTROKE
wezie	posted 03-23-2010 03:20 PM ET (US) [Apparently in reference to a 2005 Mercury 90-HP FOURSTROKE outboard motor with] carburetor problems: I found a replacement jet kit mentioned. Has anyone seen [a replacement carburetor jet kit for a 2005 Mercury 90-HP FOURSTROKE outboard] or tried [to remedy carburetor problems in a 2005 Mercury 90-HP FOURSTROKE by using a replacement carburetor jet kit]? Dealer, of course, did not mention it. Has anyone found any other fixes for the [problems with carburetors on a 2005 Mercury 90-HP FOURSTROKE]? Thank You.
bdawg5219	posted 03-24-2010 05:18 PM ET (US) Go through, clean everything, making sure to get in all pasageways. Synchronize carburetors with vacuum gauges. I wouldn't change jets unless you live in high altitudes.
bdawg5219	posted 03-24-2010 06:09 PM ET (US) Im not sure. I assumed it was carbureted because of wezie's refrence to carburetor's. You may be correct
wezie	posted 03-24-2010 07:25 PM ET (US) The model year is stated to be 2005. It does have carbs. Thank you for your interest. Yamaha uses different carbs than the merc. version. I just wondered if anyone had found a fix or change for these engine, that would make them a bit less difficult. Even changing out to Yamaha carbs might be a thought. We cleaned everything we can get to. Not the insides of the carbs. but the gas looks great, with no water or debris in the bowls. We did determine today that the primer/enrichment circuit is dead. We do not know what else might be caused by that. Thanks again!
jimh	posted 03-24-2010 07:39 PM ET (US) The announcement that Mercury uses different carburetors in the 90-HP motor than Yamaha, even though Yamaha makes most of the parts in both motors, is quite interesting. The Mercury carburetor 90-HP motors have a very bad reputation for problems with carburetors, while the Yamaha motors have no problems reported--at least none that I can recall. It has not been mentioned before that the two motors use different carburetors. That would explain the difference in reported problems.
L H G	posted 03-25-2010 12:50 AM ET (US) This link seems to indicate the 2005 90's had EFI. Yamaha 90 HP versions of the engine got the same EFI in 2005. http://continuouswave.com/ubb/Forum2/HTML/018264.html I have always read, here on CW, that Mercury bought the Yamaha engines lock, stock and barrel, and that both used a Japanese brand of carb. It seems that when the engines get praised, Yamaha gets the benefit, with Mercury unable to produce a mid-range engine of it's own. But when they have problems, it's Mercury's fault and Yamaha skates, even though the engines were identical. Wezie's engine must be a 2004 MODEL year.
wezie	posted 03-25-2010 09:05 AM ET (US) The mercury uses a carb that sounds like Chinese. ?Kaishun? That would tie in with their Chinese mfg. links. Yamaha uses a well known and much liked carb.," mikuni". So it is a decision by Mercury that seems to have complicated this situation. The question is has anyone solved this problem (other than EFI) either by fixing the existing carbs or replacing them??? This problem will be worse with the alcohol junk fuel. Thank You All.
bdawg5219	posted 03-25-2010 03:30 PM ET (US) Take carbs apart & spray carb cleaner into passageways with the nozzle-straw. Make sure fuel/system is clean & synchronize with vacuum gauges. I had an 01' 100hp Yamaha that was carbureted & every time i ran into a problem i would take carbs apart & then synchronize the carbs with vacuum gauges.
L H G	posted 03-25-2010 04:30 PM ET (US) It sounds like the Yamaha Mikuni carbs had the same problem. All of Mercury's 40-60HP engines manufactured in China use ONLY EFI systems. They never had carbs, so it's not likely they had a source in China. I always thought the ENTIRE powerhead was manufactured in Japan. My Mercury-Yamaha dealership, who works on both brands of 75-100HP versions, said both had the same problems. And the problem is not the carb manufacturer, but the tiny jet passages required in the idle circuits because of the extremely low fuel consumption. They all are susceptible to clogging and varnishing with non-use. Have a complete carb job done, and then use QuickClean every 4th tank, and always use Startron or Marine Stabil.
jimh	posted 03-25-2010 05:34 PM ET (US) quote: "The mercury uses a carb that sounds like Chinese. ?Kaishun?" Do any of these (116) companies sound like it? http://www.made-in-china.com/companysearch.do?subaction=hunt&mode=and& style=b&word=Carburetor&comProvince=nolimit&code=0
wezie	posted 03-30-2010 11:15 PM ET (US) Jim, KEIHIN is the mfg. of the Merc 90/Yamaha carbs. It is a Japanese company, and therefore may have been OEM for the Yamaha power heads Mercury purchased from them. I was wrong about the Chinese connection at that point. The discussion about 2005 Carb. and EFI overlooked the tendency of Mfg. to introduce new items and charge extra for them during the introduction period. No one has heard of any after market "fix" for this problem? That was the real question? Good Luck.
jimh	posted 03-30-2010 11:24 PM ET (US) The best remedy for the chronic carburetor problems with the Mercury 90-HP FOURSTROKE motors seems to be to have the dealer take them back, give you credit for nearly the full purchase price, and buy a different motor, perhaps a 90-HP motor with electronic fuel injection. Thanks for the clarification on the carburetor manufacturer as KEIHIN for the carburetors on the Mercury 90-HP FOURSTROKE motor. If I understand your representation above, you say the carburetors used on the Yamaha 90-HP four-cycle outboard--which is otherwise very similar to the Mercury 90-HP FOURSTROKE--are made by Mikuni. Your representation is that there are chronic problems with the KEIHIN carburetors on the Mercury 90-HP motor, but on the Yamaha 90-HP motor the carburetors are made by Mikuni. The Mikuni carburetors are not prone to the same problems. Is that correct?
bdawg5219	posted 03-31-2010 08:13 AM ET (US) As the owner of a 2001 100hp Yamaha 4-stroke i ran into running problems a couple of times. Make sure the fuel/system is clean. Install of a fuel/water separator is recommended if you dont already have one. Take carbs completly apart & clean. I would take a can of carbcleaner with the sprayer/nozzle inserted in the can & spray into all ports and passageways. Be very careful of your eyes when spraying because you spray the cleaner in one port & it shoots out another port. After reinstalling, synchronize carburetors with vacuum gauges. Carb-tune makes a nice set of gauges for fairly cheap
wezie	posted 04-01-2010 07:41 AM ET (US) Jim, I do not know there is any difference between the carburetors [used on the Mercury model of the 90-HP four-cycle engine and the carburetors used on almost the identical engine sold as a Yamaha 90-HP]. After paying for "carb. rebuild" last fall and finding the engine would not start this winter, I was a bit angry at the whole system. These engines do run well. It seems , from a lot of input, and the manuals, that the passages are very small and they stop up more easily than they should. There is another problem with this one. The primers (enricher) are not working, even after that expensive trip to the Dealer. I will sort that out also. The two items and the junk alcohol fuel, means that it is difficult to get the engine to begin to start. Worked through all this without making another deposit to the dealer. Now to the primer circuit. I appreciate all of the positive suggestions. As to taking apart the carbs. I doubt that I will do this. I did drain all of them and flushed them. Thank you for trying to sort this out.
jimh	posted 04-01-2010 08:26 AM ET (US) Well, I am afraid I am now completely confused about the carburetors used on these two 90-HP motors, one a Mercury and one a Yamaha. In the course of this discussion they've gone from being different, one being made in Japan, one made in China, and now we're not sure about them at all. I think it would be extremely useful to get some accurate information about the carburetors. Both Mikuni and Keihin are mentioned as manufacturers--which is it? What we need to resolve this is to find two motors of the same model year, one a Mercury 90-HP and one a Yamaha 90-HP, get them together, take off the cowlings, and have a look. It ought to be simple to compare the arrangement of carburetors and fuel enrichment circuits, and we could finally see if there is any difference. Perhaps someone who has worked on both brands of this motor can help out.
95Outrage17	posted 04-01-2010 08:42 AM ET (US) Jimh, I have a 2004 and 2003 Mercury 90-HP Fourstroke and a 1999 Yamaha F80 here right now. I can't take the cowl off the 2003 right now (the boat is shrink wrapped), but I can get pictures of the carbs on the 2004 and 1999. I'll see if I can do so later today. I believe all the carbs are from the same manufacturer. - Chris
95Outrage17	posted 04-06-2010 08:44 PM ET (US) Hi guys, Ok, a few days late, but here are the pictures: http://s9.photobucket.com/albums/a84/95Outrage17/ 1999%20F80%20and%202004%20Merc%2090/ The Yamaha and Mercury both have Keihin carbs. - Chris
lefty93	posted 04-06-2010 09:41 PM ET (US) My solution to my frustrating 2002 Merc 90hp fourstroke carburetor problems was to get an ETEC 115. Worked(s) like a charm!
bdawg5219	posted 04-07-2010 09:18 AM ET (US) Bwahahaa. E-tec, thats funny.
jimh	posted 04-07-2010 10:18 AM ET (US) Many thanks to Chris for taking the photographs of the Mercury and Yamaha four-cycle engines to permit comparison of the carburetors, and for finding them to both use Keihin carburetors. This discover seems to conflict with some prior reports of a difference between the Mercury and Yamaha motors regarding the carburetors used, as well as a difference in the brand of carburetor mentioned. Based on Chris's observation, it appears that these four-cycle carburetor motors from Mercury and Yamaha use the same arrangement of carburetors and the same (Keihin) brand of carburetors. Reports of difference in the operation of the motors by brand are not likely to be attributable to differences in the carburetors, inasmuch as there appears to be no difference.
95Outrage17	posted 04-08-2010 10:06 AM ET (US) No problem Jim, glad I could help. I've worked on and serviced several of these engines now (I own the 2004), so I've learned a fair amount about them. I think they're great engines if serviced properly. Mine has given many hours of reliable service on the back of my Outrage. The F80 in the picture has been pushing our sailing club's Carolina Skiff work boat for the past two years without carburetor problems (although it's had a couple other problems). I think the newer EFI engines are nicer, but I'm not sure the carbed versions deserve the poor reputation they've been given by some. - Chris
pcrussell50	posted 08-16-2012 02:06 AM ET (US) [Revived two-year-old thread to ask about ultimate resolution.]