1985 johnson 140 need some carb. help

[hydraulicane]

I finished my fuel tank installation a few months ago. everything went rather well.
I've been using the boat no problems.
went out of black point marina Saturday, got to the marina the boat started right up as usual.
but, on the way out I could tell something was a miss. at first I thought it was missing, I checked for spark,
all cylinders were sparking just fine. I took off the air breather in front of the carbs, (also the boat would not plane off)
after removeing the breather, I noticed as I powered the engine up, the jets were shooting way to much fuel into the carbs,
kinda like it was drowing itself out. ran fine at idle, but would not plane. I know its carb problems.
but I would appreciate some feed back, so maybe I could narrow it down some.



p.s. my mechanic came over sat. and took all 4 carbs with him. thanks guys!!!!!!!! have a good day!!

[flounderpounder225]

I finished my fuel tank installation a few months ago. everything went rather well.
I've been using the boat no problems.
went out of black point marina Saturday, got to the marina the boat started right up as usual.
but, on the way out I could tell something was a miss. at first I thought it was missing, I checked for spark,
all cylinders were sparking just fine. I took off the air breather in front of the carbs, (also the boat would not plane off)
after removeing the breather, I noticed as I powered the engine up, the jets were shooting way to much fuel into the carbs,
kinda like it was drowing itself out. ran fine at idle, but would not plane. I know its carb problems.
but I would appreciate some feed back, so maybe I could narrow it down some.



p.s. my mechanic came over sat. and took all 4 carbs with him. thanks guys!!!!!!!! have a good day!!

When you say "way too much fuel in the carbs" if it looked like fuel spitting everywhere in the throats of the carbs, it could also be a reed valve issue... interesting to see what the mech sees when he pulls the carbs apart.. because it happened so suddenly adds to the mystery.

[hydraulicane]

Thanks for the response flounderpounder, I'm definitely going to wait to see
what my mechanic says.
I did think about the reed issue also, don't want to get to far ahead of myself.
hopefully it's just going to be a jet adjustment!!!!

we will see, as soon as I find out what the problem is i'll post it.

[Georgie]

HC-

Looks like you have first generation looper?  FYI - the carbs in these OMC engines used fixed diameter orifice plugs (jets) to meter the fuel flow.  They wouldn't "go bad or lose adjustment" pre to post fuel tank replacement project.  If your float/needle assembly is stuck or fouled, then they could be free-flowing fuel if the fuel pump is pushing the fuel through real strong, but otherwise the problem may not be from your carbs.  A much more common symptom would be a partial clog or lean running condition caused by gum buildup or particulates, and that's obviously NOT what you're seeing (unless some gunk is preventing your float needle(s) from seating properly.  Check out Rhojo's recent post showing the bad reed and try to do the same inspection for yourself while the carbs are off.  Let us know what your mechanic says after opening it up.  If you can, tell him you want pictures or drive over to see how the insides look once he opens them up.

[hydraulicane]

Georgie,
I do have a first generation looper. so there is no jet adjustment on these carbs?
well then I'm willing to think the float or needle assembly may indeed be stuck
or fouled.
georgie, when you say a much more common symptom would be a partial clog
or lean running conditions caused by gum build up your talking about the carbs. correct?

I will definitely post the findings as my mechanic only lives about 1 mile from me.

thank you very much.

[futch13]

Also make sure the fuel lines inside the motor are good.  I don't know how many of the formed lines I've replaced due to deterioration.
And ck the reed plate gaskets while you have the carbs off.  Common problem was them pooching out and causing a "broken reed" like effect.

[Georgie]

so there is no jet adjustment on these carbs?

Nope.  You'd need to buy different size orifice plugs and swap out the existing ones, and there are at least two different jets per carb in your looper.  They're made of pretty tough brass alloy (I think) so they don't really "break" or "go bad" unless you destroy them with a screwdriver trying to remove them.

when you say a much more common symptom would be a partial clog
or lean running conditions caused by gum build up your talking about the carbs. correct?

 Yessir.  There are a lot of narrow passages inside the carb that transport the fuel from the bowl through the jets and out the venturi.  Any one of them can build up varnish/gum/particulates which will screw up fuel distribution. (think cholesterol in the veins   )  Generally this only happens if you run the engine without fuel filters or if you allow it to sit for an extended amount of time, especially w/crappy ethanol fuel, but there are always exceptions.

Great additional info Futch!

[hydraulicane]

futch,
I did already replace all the fuel lines on the engine. but will double check the lines while my mech.
has the carbs.


flounderponnder, futch, georgie, thank you all very much for all the info. I'm defintly
going to check everything while the carb's are off. even the reed's. I'm kinda partial
to that '85 Johnson 140.
but one day i'll have to replace her with a new evinrude etec 150.


thanks guys, have a good day.

hey georgie, I did look into rhojo's post about the reed's very interesting, like I said
i'll also be checking the reed's.

[hydraulicane]

hey guys,
I forgot to say that I tried to control the fuel flow with my fingers by trying to slow down
the amount of fuel that was coming out the all 4 carbs.
the engine wanted to take off but it was very difficult to
try to control the fuel flow.

[fitz73222]

I read through the posts and one thing I've learned about OMC and Mercury loopers is that you can't take poor running quality for granted when doing this out of water on the flush. It should always be tested in the water with normal back pressure. Next,I have found that idle timing is very critical to running quality for these engines. 1 or 2 degrees off can actually make the engine act like it has carb issues so make sure the engine is set up and syncronized exactly as a factory manual dictates, including idle speed. Not an aftermarket generic manual. Typically, If the engine is backfiring through the exhaust it is a timing issue; through the carb a lean issue. I remember when your engine was new, we had brand new out of the box engines run like crap at idle, boggy and spit until we re-timed them. As mentioned, your engine has no adjustments for the low speed mixture which amazingly worked pretty well most of time. I'm not sure how OMC managed a 1 size fits all low speed jet without adjustment but again, it seemed to work. As far as the engine speeding up when you restricted fuel flow was probably the engine going lean which would increase speed at least for a moment before it would eventually start to spit and cough.

[hydraulicane]

fitz,
thanks for the response, everything I did was in the water out of black point marina.
I gotta tell ya it's been a while before I checked the timing. after my mech. rebuilds the carbs
can they be synchronized?
I might as well check the timing while I'm into it.

so, I'm rebuilding the carbs.
checking the reeds
checking the synchronization of engine including idle speed
and synchronizing the carbs.
am I missing anything?

guys, I can't thank ya'll enough!!

[futch13]

Farley is right on the money about the Sync.  Can't stress it enough!!!  Not only the idle timing and pickup, but the carb sync itself making sure all throttle plates are closed and move at the same time.

[fitz73222]

First off, if you can borrow a inductive shop tach and timing light from your mechanic, do so. I found that standard analog tachs are notorisly off at idle speeds; 50-75 rpms is enough to make a difference at idle. As futch said, make sure both throttle butterflies are closed at idle. You check by looking down the carb throats with the attenuater box removed and making sure that the advance throttle cam is not touching the roller attached to the throttle linkage. This may require disconnecting the throttle cable from the engine and backing of the idle stop screw until there is some clearance between the throttle cam and roller. Then make sure they are closed. If not, loosen the screw that connects the two vertical throttle links and let the return springs seat the butterflies against the venturie body then retighten the screw and check again. This is purely from memory so it should be validated that on older OMC's that you advance the throttle in neutral slightly as if you are cold starting the engine and check to see if the throttle roller is just making contact with the horizontal line that is cast in the throttle cam and the roller centerline that allows for a slight amount of butterfly opening for cold start, this basically syncs the amount of timing advance needed with correct amount of butterfly opening to start the engine cold. You're going to need a reference manual to get idle speed and timing advance pick up in order to do this right. I'm a MERCURY guy who just plays one on TV!; so Futch, Georgie or Deburr can walk you through the details of the correct set up process for this OMC. Everything I have stated assumes that this engine is healthy and is sealing well with respect to compression, intake gaskets and upper and lower crankshaft seals.

[Georgie]

If the engine was running OK prior to the fuel tank replacement, common sense would say that the carbs didn't all of a sudden go bad or develop problems.  Could your primer solenoid suddenly be free-flowing fuel?  Have you accidentally opened the red lever?  That could explain the excess.  

[fitz73222]

K.I.S.S. Georgie! Keep me reeled in!