rob v Posted March 19, 2009 Report Share Posted March 19, 2009 (edited) I'm still trying to get the motor I bought (1985/6 vintage) running properly. Apparently the engine has been sitting in someone's basement (i bought it at an auction) for some time. It seems to start okay (not great but okay) but I can't get any RPM's or power out of it - it really seems to bog down. At first I thought the engine was starving for fuel but pumping the bulb didn't help. Then I noticed that the exhaust was a terrible smell (smelled of gasoline) and the water it was running in (I had the motor in a barrel) gets very dirty and had a very distinct film of blackish oil on the surface. Plugs (which are new) get very black also. This led me to believe the engine is running far too rich. When I disconnect the fuel line and let it run - just as it begins to run out of gas the rpm's increase signficantly and it seems to run much better for a few seconds - then naturally it dies when it runs out of fuel. This makes me think the engine is getting too much fuel - and I'm wondering if this is due to the float valve not seating properly and the fuel supply is not shutting off. I've had the carb completely apart 3 or 4 times - soaked in cleaner and all jets appear open/clean. I've had the main nozzel removed and all the holes in it are open/clean also. I can't see anything in the float seat that would cause a problem so I'm thinking I may need to replace the float valve. It has what appears to be a small rubber tip on the seated end. Do you small engine experts think that the float valve is the problem and should be replaced ? The float seems okay - no holes and it's not flooded and it seems to move freely as well. I appreciate your input/suggestions. thx. Edited March 23, 2009 by Rob V Link to comment Share on other sites More sharing options...
GeorgeJ Posted March 19, 2009 Report Share Posted March 19, 2009 I think your on the right track, there is also a float adjustment you may want to do which determines how much fuel is allowed into the bowl before the needle and seat do their job and shut the fuel off. Usually the tab that contacts the needle from the float is bent to accomplish the proper level setting. I would also make sure the fuel is fresh, check the fuel pump diaphragm and it never hurts to do a compression test. Checking the valve adjustment might also be a good idea, they could also be sticking in the guides. Link to comment Share on other sites More sharing options...
2 tone z71 Posted March 19, 2009 Report Share Posted March 19, 2009 I would get a carb rebuild kit ,new needle @ seat will be included in kit ,if it will idle let it warm up and run the can of engine tuner or seafoam thru it to loosen up grunge carbon varnish off the valve train and piston Link to comment Share on other sites More sharing options...
Bernie Posted March 19, 2009 Report Share Posted March 19, 2009 Check the timing belt. It may be loose and has slipped a tooth or two. Few other things it could be too but being as old as it is it would be one of the first things to look at. Don't forget to replace the water pump too. Link to comment Share on other sites More sharing options...
Sinker Posted March 19, 2009 Report Share Posted March 19, 2009 I would get a carb rebuild kit ,new needle @ seat will be included in kit ,if it will idle let it warm up and run the can of engine tuner or seafoam thru it to loosen up grunge carbon varnish off the valve train and piston Have you decarbed the engine yet?? That would be the first thing I'd have done. Then play with the carb.....seafoam or power tuner. Sinker Link to comment Share on other sites More sharing options...
camillj Posted March 19, 2009 Report Share Posted March 19, 2009 Could be as simple as bit of bad gas ... or too much oil in the mix ... try on a fresh tank of 100:1 mix ... also try with a different tank/line ... its amazing how often the gas line is the problem (I have a particular tank that works on every one elses moter except my own ... probably just enough of pressure issue to starve the system ... also try fiddling with the choke ... sometime the adjustment knobs are way out of whack Could also be a compression issue ... which could mean a blown seal or a cracked head ... $$$ Hey Big Cliff where are you ??? Link to comment Share on other sites More sharing options...
2 tone z71 Posted March 19, 2009 Report Share Posted March 19, 2009 Could be as simple as bit of bad gas ... or too much oil in the mix ... try on a fresh tank of 100:1 mix ... also try with a different tank/line ... its amazing how often the gas line is the problem (I have a particular tank that works on every one elses moter except my own ... probably just enough of pressure issue to starve the system ... also try fiddling with the choke ... sometime the adjustment knobs are way out of whack Could also be a compression issue ... which could mean a blown seal or a cracked head ... $$$ Hey Big Cliff where are you ??? shes 4 stroke no oil in the mix,its bad fuel ,fuel cant sit that long without turning to varnish Link to comment Share on other sites More sharing options...
boatman Posted March 20, 2009 Report Share Posted March 20, 2009 I've never worked on a 4 stroke outboard so I can't give you any model specific advise. I will assume the carb is completely clean as you have cleaned it 3 times. The rubber tipped float needle is the bain of the old outboarder's existance as it as they often stick. However, that shoudn't be the problem if you are getting lots of fuel. They stick closed not open. The float must be level in the bowl when the bowl is full. Set too high and fuel will flow past the needle. Too low and it prematurely shuts off the fuel flow. You can try a new carb kit and actually rebuild the carb. Compression may be an issue. You need good compression to start and run. A tired motor may run, but not have much umph. The rings could also be stuck from sitting causing low compression. Removing the spark plugs and spraying with pentrating oil and then doing a decarb may help unstick the rings if they are stuck. The last possibility is spark. Have you checked for spark? Do you have it on all cylinders? Frequently multi-cylinder outboards will run on one cylinder. Everything appears fine except you have no power. I have no idea what the Honda ignition is so I can't help much here. So to recap; check for spark in all cylinders, check compression with a gauge and recheck the float level. If you were closer I'd tell you to bring it over and I'd help you check it out. Link to comment Share on other sites More sharing options...
boatman Posted March 20, 2009 Report Share Posted March 20, 2009 At first I thought the engine was starving for fuel but pumping the bulb didn't help. Then I noticed that the exhaust was a terrible smell (smelled of gasoline) and the water it was running in (I had the motor in a barrel) gets very dirty and had a very distinct film of blackish oil on the surface. Plugs (which are new) get very black also. This led me to believe the engine is running far too rich. When I disconnect the fuel line and let it run - just as it begins to run out of gas the rpm's increase signficantly and it seems to run much better for a few seconds - then naturally it dies when it runs out of fuel. I forgot to mention that all this stuff is normal. Except the exhaust smell, which sounds like a bad gas issue. Link to comment Share on other sites More sharing options...
POLLIWOGG Posted March 20, 2009 Report Share Posted March 20, 2009 Take the bowl off the carb ,hook it up to a fuel line and check the fuel level. Link to comment Share on other sites More sharing options...
Fisherman Posted March 20, 2009 Report Share Posted March 20, 2009 Take the bowl off the carb ,hook it up to a fuel line and check the fuel level. You better explain that a bit more...please enlighten me on how you would hook "it"(the bowl?) up to a fuel line and check "what" fuel level. Link to comment Share on other sites More sharing options...
POLLIWOGG Posted March 21, 2009 Report Share Posted March 21, 2009 I had the same motor but can't remember ever having the carb apart , you might not be able to do it. On my bikes the float and valve are in the fuel bowl so I just take it off the carb and turn the gas on to watch it fill up to check the level.. Something else you might check is the choke linkage and make sure its working. Link to comment Share on other sites More sharing options...
Big Cliff Posted March 22, 2009 Report Share Posted March 22, 2009 (edited) The fact that the engine runs well for the few seconds just as it is running out of gas leads me to believe that your problem is fuel related. As it is running out, it is running lean. Too rich and/or stale fuel would cause all of the things you have mentioned. First and most important: Make sure the fuel you are using is fresh clean fuel, not something that has been sitting in a can for the last 3-4 months. Stale fuel would cause the symptoms you mentioned. Make sure you are using high test, that motor is desigined to run on 91+ octaine. With the proper prop on that motor it should run at 5000 RPM +/-200 at WOT (wide open throttle), do you have a tachometer? Let's start with the easy things first and see what that does then we can go from there. Can you get me the serial no. as there are 4 different service manuals for that engine depending on the sn. Edited March 22, 2009 by Big Cliff Link to comment Share on other sites More sharing options...
POLLIWOGG Posted March 22, 2009 Report Share Posted March 22, 2009 If the motor was fogged that might be whats fouling the plugs or the coil might be weak, thats what happened to mine. Check the spark and maybe a compression test?. Link to comment Share on other sites More sharing options...
rob v Posted March 23, 2009 Author Report Share Posted March 23, 2009 Thanks for all the good information guys, but most of what you've mentioned I've tried or ruled out. I did some additional research on line and found out a bit more info. There's a small screw on the side of the carb (not the idle screw/needle). I've had it open up several times so far but couldn't really figure out why it was there. Ends up there's a small jet ( that I had made sure was clean) that leads into what I thought was a dead end chamber underneath of this screw. On a different forum I found out that there's a really (and I mean really) small jet that leads back into the carb perpendicular to the jet coming into the side of the chamber. I got some compressed air into it and a single strand of copper wire (hair thin) to open the jet. Put it all back together and it ran better, but still quite a ways from perfect. On that same forum I figured out how to check the timing settings - there's a small dot on the to of the cam that's supposed to line up with a T on the flywheel. I checked that and it didn't look lined up very well to me (but the belt tension felt good to me). I was a bit hesitant to take the timing belt off cause I don't have a timing light and I didn't want to make things worse. Bottom line I slipped the timing belt off and after eye-ball lining up the dot and the T, put the belt back on. One pull and she was running like a top. After spending about 5 or 6 hours trying to figure this darn thing out I finally got it running really well. So Bernie the timing definetly needed adjustment and all the carb cleaning, de-carbing & seafoam (thanks sinker) I'm sure helped also. Big Cliff - the serial # is BF 75L 1700986- now I think I should change the impeller. There's a pretty good stream coming out of it, but since I have no idea how old the one that's in it is I don't want to take a chance. If you've got a manual and could give me some direction on how to go about it That would really be great. thanks. Bottom line she's running great - I can't really believe how nice a 4 stroke this size sounds when it's running well. Quite a difference from the old two stroke ! Rob V Link to comment Share on other sites More sharing options...
Bernie Posted March 23, 2009 Report Share Posted March 23, 2009 The carb rich could have been the issue quite easily there Rob but the hard start and lack of power is what made me think of timing. When the belt (or chain on some) on a 4 stroke is off by even a tooth you get those exact symptoms you described (I learned this lesson many years ago on Dodge 2.2 engines). A camshaft and its moving parts take power to operate, especially as the RPM's increase. So a loose belt can slip. Timing belts should be quite snug, but not too tight as it can be hard on bearings. Good job on fixing her up. Real nice little engines. Link to comment Share on other sites More sharing options...
Big Cliff Posted March 23, 2009 Report Share Posted March 23, 2009 Sorry, owners manual doesn't cover changing the impeller and I don't have access to the service manual for that engine. To the best of my knowledge the hardest part is reconnecting the shift rod when re assembling. Link to comment Share on other sites More sharing options...
Fisherman Posted March 23, 2009 Report Share Posted March 23, 2009 Not that hard at all. Remove engine cover, look where the shift lever goes into the side of the casing, move the shift lever up and down, F-N-R and see where the linkage is held together with a short pin and cotter pin. Remove cotter pin, pull out the small pin. Tilt motor up, remove the four bolts under the cavitation plate. Now with a bit of luck, the lower unit should slide down, it may be persuaded with a rubber hammer. Once the lower unit is off, you'll see two long shafts, where they enter the lower unit, theres a cover with 2-3 small bolts, remove the, lift off the cover and the impeller is underneath. STOP, look which way it's in there, some have a little flat spot on the shaft. Get out the new impeller, apply a bit of vaseline to the wings or fingers and a bit inside the housing, replace the impeller, replace cover, replace bolts. Now at the top of the splined shaft, clean it with a steel brush, apply anti seize. Now comes the fun part. When you slide the lower unit back in, you must aline the shifter rod, the splined shaft and the tube that goes up for the water cooling for the engine. Replace lower unit bolts. Replace the small rod and cotter pin for the shift linkage. Now if all was lined up correctly, place the shifter in F or R, slowly pull the motor over, the prop should turn either forward or back, In N, it should free spin. Get out your big garbage can, fill with enough water to get about 1/2 way up the leg of the motor and give it a start, water should start peeing out within a couple seconds. Done. Good luck. Bolts are metric, most likely 12mm, the impellor cover bolts might be 7-8mm. Link to comment Share on other sites More sharing options...
rob v Posted March 23, 2009 Author Report Share Posted March 23, 2009 Hey thanks Fisherman - sounds simple enough - I'll probably give'er a go in the next couple of weeks. I assume if things aren't lined up properly than it's take things apart again and try re-aligngin. If I run into trouble I may have to contact you. thanks for the input. Link to comment Share on other sites More sharing options...
Fisherman Posted March 23, 2009 Report Share Posted March 23, 2009 Ya, the realignment part is probably the most frustrating, something I forgot, some lower units slide off without a hitch, don't drop it! Link to comment Share on other sites More sharing options...
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