See gas in throat of carb?

[bergsofafeather]

I have a 85 hp 1975 (s/n: 4722152)Merc that won't stay running. With full choke at start up it seems to be ok, but ease off and it dies. Also, should I be able to see gas spraying into the throats of the two carbs? I don't see any. And who makes a better manual, Clymer or Seloc? Thanks in advance, and sorry for the lengthy previous post.

 

[corm]

Re: See gas in throat of carb?

Hi,<br />Turn the silver screw (idle) out 1/4 turn more.<br />All inline Mercs run much better in the real world that way. Real world being the water not the dealers' test tank. You may need to up the idle speed a bit to compensate for the richness of the carbs. I would get a merc book, if you can't get that then it is a toss-up between the other two for my money. You will only see gas at speed in the carbs, not at idle. 1/2 speed and higher.<br />BTW,that is 1.75 turns out from a lightly seated position on the idle.

 

[bergsofafeather]

Re: See gas in throat of carb?

First and foremost, thanks for replying to my post, you are the only one and I was getting disappointed. I apologize for my ignorance, and lack of a manual also. I backed my idle screws (silver ones) out 1/2 turn when I had no responses, do you think that is too far? It runs better now, but at initial startup, boy is she runnin! And should I have only done that to the top or bottom carb, and not both as I did? Also, you said that I may need to up the idle speed to compensate for the richness....I don't understand (I'm sorry again for the manual/ignorance bit) didn't I just up the idle speed by backing out the idle screws? Should I be adjusting something else?

 

[corm]

Re: See gas in throat of carb?

Hi,<br />Is your motor idlling to fast so it clunks hard when you Shift it? <br />By turning both screws out 1/2 turn and it runs much better makes me think you have carb butterflies that are not syncroized, or you have a crankcase air leak.Because it idles faster. It may be as simple as lowering the idle speed down.<br />You will need a manual for this as it is easy, but hard for me to explain tonight. <br />Do you have a fax machine? If so email me your fax number and I'll fax you some pages to explain it.

 

[bergsofafeather]

Re: See gas in throat of carb?

Corm (and anyone else too), Just got back from the water, started nice with cold start lever full up, let it warm for a few minutes and slowly brought the arm back down. Idled much quieter (slower) in the water than it did on the muffs. Decided to take her out and we did ok in the no wake zone, top speed about 5 mph, nice tell tale, no hard jolt when put into gear. Out of the zone, though, we had problems. Everytime I tried to give her more gas and go, she would start to slow and die unless I eased back on the throttle quickly? I guess it is getting too much gas? I HAD to get a line in the water, the humminbird was just a singin', so we actually trolled for a little bit, sounded pretty good. The wife popped off the downrigger, so I killed the motor, and when I went to start up again, the worst sound in the world..nothing! and I mean NOTHING! Not a click, whirl, zip. I immediately thought battery and did a voltage diagnostic on the humminbird, it read 12.9 so I chesked the battery connections, looked good and tight. I figured it was something in the side mount control, so I took the first screw out just below the choke button, and I thought, if I take this apart, I have no idea what I am doing and I'll lose or break something, so I put it back in, tried to start it again and it turned over just fine. Isn't that weird? Loose connection inside maybe? Anyways, we decided to go back to the dock, if we could. One time on the way back when I eased back it sped up a little like it had caught up to the flow or something, and another time it just started to speed up all on her own like it had blown enough of the excess out, of course I thought this was good so I gave her a little more, she responded, a little more, she responded, we were up to 21mph (1/2 speed) and then she slowed all on her own again (pretty quickly)and died. Needless to say we limped back to the dock and came home before we got stranded. ANY help much appreciated. I'm going to the library in a little bit to see if they have a manual, and will try to get a neighbors fax number for you also. I know setting up on muffs is not the same as in the lake, but how about putting a big old garbage can around her, will that be more real world?

 

[mellowyellow]

Re: See gas in throat of carb?

sounds like it's flooding to me. I reccomend<br />getting carb kits and rebuilding them.<br />good luck,<br />M.Y.

 

[bergsofafeather]

Re: See gas in throat of carb?

Also, just checked the new plugs: 1 & 2 looked great, light gas residue on them, but 3 & 4 had some oil on them to be sure, I cleaned them off and stuffed them back in for now, before I did that though I took a flashlight and looked into the #1 cylinder and could see black and bronze (oil and varnish) streaks on the cylinder head, I need to decarb I think, and will probably later today. But I am curious, is it possible that the #1 & 2 cylinders run the low rpm stuff and the plugs looked good because it idled fairly well, where as #3 & 4 run the high end rpm's and they looked bad because it wouldn't run worth a crap? I don't know if this is how a Merc works, but when it wouldn't idle worth a crap I backed out both carbs' needles out 1/2 a turn each, a full 2 turns from gently seated, and maybe I should have only done that to the top carb?

 

[bergsofafeather]

Re: See gas in throat of carb?

Man, you are the best! I, and my wife, are really impressed with your willingness to help a rookie. A big thank-you. Update for you....I think I took care of the water in the carbs possibility-I ran sea foam deep creep (1 bottle) through the carbs today, slow at first then more til it almost stalled, then shut her down, removed the plugs and sprayed some in there too, let it soak for 2+ hours, and then flushed it all out with sea foam mixed in my fuel mix. I then put in new plugs, greased all my zerks, changed the lower unit gear lube and the washers on the plugs. I also set the idle mixture screws back to 1-1/2 turns out from lightly seated again. She sounded the best she has yet this year after all that, and I am going to take her to the lake tomorrow afternoon to see if it made any difference. I'll stay closer to the ramp this time though Oh- I ordered a Seloc manual on-line, and made it to the library, copied everything I could find in their reference books (I wish I had written down the name of the book, Energec or something?), I also checked out their Clymer Mercury 3.9-135 HP, 1964-1971 shop manual, I know it's not the right year (1975), but I thought anything would be better than nothing at this point. I have learned that I have two Mercarb carburetors equipped with enrichment valves? in place of choke plates, since my serial number is 4722152, I can ignore about 10 pages of ignition stuff before I get to my Thunderbolt Without Distributor section, and apparently I will either kill myself or the switch box if I disconnect anything! by the way "turn flywheel clockwise until piston is .464 inch BTDC." what is BTDC? and I found a section on diaphragm type fuel pumps..that's my next chore I guess. Anyway, this turned into a book, and your time is valuable, I will keep plugging on this end, and any comments you may have are always appreciated. Almost forgot to ask, referring to your comment on spraying oil on the crankcase halves, as soon as I locate the proper joint, will WD-40 work for this?

 

[EE1812]

Re: See gas in throat of carb?

BTDC=Before Top Dead Center

 

[bergsofafeather]

Re: See gas in throat of carb?

I'm going in deep now I sprayed WD-40 all over like you said, and low and behold a small line (13.5 inches long and an inside diameter of .1) was either blowing fuel or WD-40 (if it's an air line?) out of a real nice couple of cracks at the top. I haven't been able to find a picture of it in the books, so I don't know yet what it is, but it appears to run from the top back side of the crankcase all the way to the bottom back side of it. I am going to the shop now to see if they have replacement hose. Could this have been my problem or is it just another thing I found wrong? By the way, this line was behind the switch box, so I removed all 5 thousand wires to it, then the box itself, then the three bolts holding the switch box mounting plate onto the block/case before I could access it. Hope I have done no wrong. I did think it wise to take the key out of the ignition, disconnect the spark plug wires, and disconnect the battery before I started (the electrical on this Thunderbolt scares me, specially since the book had so many warnings about frying it one way or the other).