HELP.. Mercury 850 (85 HP) Issues

[bktheking]

Re: HELP.. Mercury 850 (85 HP) Issues

High speed jet is under the brass nut coming out the front (looking at the carbs from the front) of the carb bottom. Issue with the motor i'm working on, as soon as I go past idle it bogs out and dies. i cleaned the carbs, verified timing, verified fuel, did it all.

Hard to say if it's a dirty jet, usually if a jet is dirty it doesn't come and go, they get plugged and stay plugged, that's why I think it's electrical.

 

[bktheking]

Re: HELP.. Mercury 850 (85 HP) Issues

Here is the choke setup as promised.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

Shove it back in, it's magnetic, it should stay in the choke solenoid assembly. The manual choke rod should be enough to hold the choke rod up unless it's bouncing too.

I tried shoving the thing back in and it will not stay. I think its only magnetic when its working. I assume the solenoid is garbage.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

Here is the choke setup as promised.

Thanks for the pic. This is exactly like mine, except my plunger refuses to stay in there. I never choke the engine, so I am not sure I actually need this.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

High speed jet is under the brass nut coming out the front (looking at the carbs from the front) of the carb bottom. Issue with the motor i'm working on, as soon as I go past idle it bogs out and dies. i cleaned the carbs, verified timing, verified fuel, did it all.

Hard to say if it's a dirty jet, usually if a jet is dirty it doesn't come and go, they get plugged and stay plugged, that's why I think it's electrical.

In that case, fuel was not coming out of the high speed jet at all. It was coming from the jet vent bowl (what ever that is).

 

[bktheking]

Re: HELP.. Mercury 850 (85 HP) Issues

Then that's a float height issue or needle and seat. I wish I could fix it and you could fix what i'm fixing, oracle 8 system at work from 1999, went down 2 days ago, I got it back up, been working all night blind, I don't know screw all about oracle 8.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

Update: I got back from vacation and began working on the motor. I removed the top carburetor from the motor. I have to work the next four days (twelve hour shifts) so I won't continue working on it until Sunday. I plan on cleaning out the carbs really well and slapping them back on. Any suggestions on how to clean the carbs? Do I soak them?

 

[Chris1956]

Re: HELP.. Mercury 850 (85 HP) Issues

Sure, strip them down and soak them. Remove adjustment needles, carb covers, floats, inlet needles and seats and main jet cover (brass plug in base of carbs). Jets may not want to come out. Don't force or strip them or they may break. Blow every passage out with compressed air, or carb cleaner (protect eyes). Now reassemble with new gasket sets, inlet needles and seats and new floats if necesary.

 

[pujols5]

Re: HELP.. Mercury 850 (85 HP) Issues

i had the same problem pumped the ball up for fuel started up and ran for a short time bogged out come to find out my ball had a leak in it and would not stay primed hope this helps 5.00 part roger

 

[swamp-fox]

Re: HELP.. Mercury 850 (85 HP) Issues

If the plunger is not in the selenoid, then it chokeing while running isn't the problem. Don't know about that exact motor but mine has a tension spring that keeps the long black arm that the plunger connects to down. Keeping it not choked. If the spring is bad then it may be flopping around. Causing it to choke while running.
It's not magnetic until you press the choke button, then makes a electro magnet that sucks it up.(that's my take on it anyway)

However, if I pumped the primer bulb I watched fuel come out of a little hole to the side of the carburetor.

Mine did this after I cleaned and replaced parts in my carb.

Then that's a float height issue or needle and seat.

Yes this is what mine was. I used a non merc carb kit, put the old needle and seat back in and then worked fine..

P.S. if you can start the motor without choking it that a great motor keep with it.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

i had the same problem pumped the ball up for fuel started up and ran for a short time bogged out come to find out my ball had a leak in it and would not stay primed hope this helps 5.00 part roger

I replaced the bulb and it is still doing the same thing. Thanks.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

If the plunger is not in the selenoid, then it chokeing while running isn't the problem. Don't know about that exact motor but mine has a tension spring that keeps the long black arm that the plunger connects to down. Keeping it not choked. If the spring is bad then it may be flopping around. Causing it to choke while running.
It's not magnetic until you press the choke button, then makes a electro magnet that sucks it up.(that's my take on it anyway)

Mine did this after I cleaned and replaced parts in my carb.

Yes this is what mine was. I used a non merc carb kit, put the old needle and seat back in and then worked fine..

P.S. if you can start the motor without choking it that a great motor keep with it.

Was your motor doing the same thing as mine?

 

[swamp-fox]

Re: HELP.. Mercury 850 (85 HP) Issues

No mine just wouldn't start. Gas wasn't getting into the carbs because the non merc needle seat was longer than the stock. Therefore the float was stopping fuel flow to early. I was told gas should never come out that overflow, that's how I new I had a problem.

It doesn't explain why that happened to you on the water, but I looks like a problem now.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

I forgot to mention, when I was taking apart the carbs I saw the ELBOW on the side of the carb was loose. The fuel line attached to the elbow piece (its a brass piece). The elbow was so loose that I could wiggle it. I started the engine and observe small air bubbles at the elbow threads. Could this be the perpetrator?

 

[swamp-fox]

Re: HELP.. Mercury 850 (85 HP) Issues

Absolutly!!

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

Well, as soon as I get new gaskets for the carb I will slap it back on, tighten the elbow, and take her back on the water.

 

[chum1]

Re: HELP.. Mercury 850 (85 HP) Issues

It seems like there is a lot of these 850's out there still floating around, there good engines, my old 77 salty dog had the same issues as yours and the main culprit was electrical, wiring was shot and switchbox was junk after testing under a water load and per cdi tests,

To make this engine perform like new again ( assuming compression is good) set aside some money and bring it up to todays electrical standards which is better then 70's am radio days, those parts are more then 30 years old...can you say snap, crackle, pop? (pep boy kids when they worked for kellog's)

This is what i did and ended up changing: trigger (wiring) ( hooked trigger by the way), stater from cdi ( wiring) (found used on ebay), switchbox from cdi (caused bogging because it dropped 2 cyl's), bridge rectifier (from rad shack per Martins threads)

If there are super clean plugs from water there is probably a lower seal or water jacket issue, if the plugs are good and dirty dont mess with the water covers.

changed all misc. carb and fuel pump parts as necessary and pulled finger screens out of carbs per manual( behind fuel elbow)

link and sync per instructions here on this forum

Remember you may have to undo 20 garage mechanics errors and BS and set things per manual to get this thing right, if its not to ate away from corrosion it should last you a good long time, good luck, its worth fix'n

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

Haven't taken it out on the water yet to test it, but I did replace the gaskets on the carbs today and tightened the brass elbow. When I removed the lower carb, I found that it did not have a gasket between the carb and the engine block. I believe that was the cause of the fuel getting into my engine. I cannot believe someone put a carb against the motor without a gasket. Maybe this will help my issue. Guess I won't know until I put her in the water. Hopefully, I can drop it in tomorrow.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

Took it out today and still bogging down at WOT. I am guessing, per post on this forum, that it maybe an electrical issue? I don't know? Very frustrating.

 

[jimmy120]

Re: HELP.. Mercury 850 (85 HP) Issues

It seems like there is a lot of these 850's out there still floating around, there good engines, my old 77 salty dog had the same issues as yours and the main culprit was electrical, wiring was shot and switchbox was junk after testing under a water load and per cdi tests,

To make this engine perform like new again ( assuming compression is good) set aside some money and bring it up to todays electrical standards which is better then 70's am radio days, those parts are more then 30 years old...can you say snap, crackle, pop? (pep boy kids when they worked for kellog's)

This is what i did and ended up changing: trigger (wiring) ( hooked trigger by the way), stater from cdi ( wiring) (found used on ebay), switchbox from cdi (caused bogging because it dropped 2 cyl's), bridge rectifier (from rad shack per Martins threads)

If there are super clean plugs from water there is probably a lower seal or water jacket issue, if the plugs are good and dirty dont mess with the water covers.

changed all misc. carb and fuel pump parts as necessary and pulled finger screens out of carbs per manual( behind fuel elbow)

link and sync per instructions here on this forum

Remember you may have to undo 20 garage mechanics errors and BS and set things per manual to get this thing right, if its not to ate away from corrosion it should last you a good long time, good luck, its worth fix'n

Can you post a list of parts that I need so I can start ordering them? There are a lot of wires that look mildly frayed. I am wondering if electrical is what is causing my problems.......