MorganM Posted November 18, 2004 Share Posted November 18, 2004 Black smoke huh.... lots of unburnt fuel or oil I would say. What does the smoke smell like.... raw fuel or burnt oil? Quote Link to comment Share on other sites More sharing options...
Mudboat Posted November 19, 2004 Author Share Posted November 19, 2004 Smells like it's burning rich. The plugs soot over pretty quick. It was not doing that before the intake and carb swap. Quote Link to comment Share on other sites More sharing options...
MorganM Posted November 19, 2004 Share Posted November 19, 2004 WAY too much fuel in the hole then. Not much tere in the intake manifold that would cuase this. Gotta be the carb man. I'm not a carb guy though so I can't really say what but sounds like she's just pushing fuel by unexpectidly. These little engins really run off little fuel so it doesnt take much to start running rich, foul plugs and cuase bad missfires and/or smoke! Maybe even the wrong jets in that rebuild kit would do it? Quote Link to comment Share on other sites More sharing options...
Mudboat Posted November 19, 2004 Author Share Posted November 19, 2004 That's pretty much the conclusion I came to. As much as I hate to pull the carb off again and send it out to a carb shop, that looks like where I stand right now. Quote Link to comment Share on other sites More sharing options...
Petersubaru Posted November 19, 2004 Share Posted November 19, 2004 your vacuum advance, working or not, would not cause this much grief unless things are seized up inside of the dist...3 sooty plugs ,not 4??...I take it that we are short on tools here...so check each plug "visually"to see if each "seems" to fire with the same intensity..if so then I would think the ignitor in the dist.is good and if they don't fire evenly across the board,check the wires, gap etc...)I am sure you know this; so I am not trying to be insultive here)......since not knowing the complete history of the motor and if I was a gambling man I would bet either the timing belt is off by one tooth or the spark plug wires not hooked-up correctly...not everyone knows it, but subarus turn counterclockwise and thus can be confusing when hooking up the plug wires correctly...I did this a while back ago and spent hours trying to figure it out...lets hope it is not the valves...good-luck and keep us posted Ok... I set everything today, cranked it up and did a quick timing check. Launched the boat and starting running. Boat started sputtering like it was running on 3 cyls. Black smoke from exhaust. I pulled all 4 plugs and they were black and sooty. I cleaned them, re-installed and cranked it up. It ran fine for a few minutes then it started doing the same thing. I pulled a plug back out and it was getting black and sooty again. I took a wild guess at vacuum hoses when I installed them, but there is basically a hose from the manifold that tees off. One to the vacuum advance and one to the carb. Everything else is plugged. ????? Can anyone tell me what may be happening now? Quote Link to comment Share on other sites More sharing options...
Partsman Posted November 19, 2004 Share Posted November 19, 2004 I'm leaning toward the fuel pump from everything I've read in this post. Facet (the rattler pump manufacturer that makes them for NAPA and probably for Purolater too) makes one that does 2 1/2-4 1/2 lbs. If your 4-7 lb. pump is running on the high side, it's probably pushing fuel right past the needles in that carb. Quote Link to comment Share on other sites More sharing options...
Mudboat Posted November 19, 2004 Author Share Posted November 19, 2004 The Hitachi carb I have on right now has a sight glass on the left side. I can visually see the level maintaining in the bowl at 1/2 of the glass. I spoke to a mechanic this eveing and he was more interested in the way I had vacuum hoses routed. His theory is as follows: I have a single vacuum hose tandem happening. The hose is hooked directly to the intake manifold (which runs at 22" of vacuum). The hose Tees, and one end runs to the carb and the other end to the disty vacuum advance. He is telling me that the intake vacuum is too strong for the disty advance and is robbing vacuum from the top half of the carb. His suggested solution is to plug the vacuum port on the intake, and run the vacuum hose directly from the carb to the disty vac advance port. He claims that the distributer vacuum should see progressive, or intermittent vacuum from the top half of the carb and not continuous vacuum from the intake. He also claims that by having the intake vacuum hooked directly to the carb is robbing upper vacuum the carb and causing it to dump excessive fuel into the intake???????? Oh well?? Tomorrow I will clean the plugs again. I will also disconnect the vacuum hose from the intake manifold altogether. I will basically have a single vacuum hose from the top half of the carb to the vacuum advance... Every other vacuum port on the engine will be plugged. Remember... this is a boat engine.. There are no environmental or emmissions standards that need to be followed (in Louisiana) for this application. Not yet anyway.... So.... Any theories on the vacuum issue besides the one I heard tonight??? Quote Link to comment Share on other sites More sharing options...
MorganM Posted November 19, 2004 Share Posted November 19, 2004 The Hitachi carb I have on right now has a sight glass on the left side. I can visually see the level maintaining in the bowl at 1/2 of the glass. I spoke to a mechanic this eveing and he was more interested in the way I had vacuum hoses routed. His theory is as follows: I have a single vacuum hose tandem happening. The hose is hooked directly to the intake manifold (which runs at 22" of vacuum). The hose Tees, and one end runs to the carb and the other end to the disty vacuum advance. He is telling me that the intake vacuum is too strong for the disty advance and is robbing vacuum from the top half of the carb. His suggested solution is to plug the vacuum port on the intake, and run the vacuum hose directly from the carb to the disty vac advance port. He claims that the distributer vacuum should see progressive, or intermittent vacuum from the top half of the carb and not continuous vacuum from the intake. He also claims that by having the intake vacuum hooked directly to the carb is robbing upper vacuum the carb and causing it to dump excessive fuel into the intake???????? Oh well?? Tomorrow I will clean the plugs again. I will also disconnect the vacuum hose from the intake manifold altogether. I will basically have a single vacuum hose from the top half of the carb to the vacuum advance... Every other vacuum port on the engine will be plugged. Remember... this is a boat engine.. There are no environmental or emmissions standards that need to be followed (in Louisiana) for this application. Not yet anyway.... So.... Any theories on the vacuum issue besides the one I heard tonight??? SOunds like a good idea. Reroute those vacume lines properly as he suggested. Could also go to a junkyard and look at how vacume lines are hooked up on a Subaru with the hitatchi. Quote Link to comment Share on other sites More sharing options...
Petersubaru Posted November 19, 2004 Share Posted November 19, 2004 your mechanic is correct (this is not theory, but basic knowledge for anybody that understands carbs) when he says that the vacuum to the distr. needs to be progressive and this can only be accomplished when the distr. is hooked up to the proper carb port DESIGNED for the vacuum advance... and yes if the vac lines are not hooked up properly on the carb, it can pull to much gas thru the carb.. it is hard over the internet to tell which carb inlets to plug up, but talk to your mechanic again and have him use a vacuum gauge to find the correct port for the distrutor...and plug up any other ports that don't make any difference The Hitachi carb I have on right now has a sight glass on the left side. I can visually see the level maintaining in the bowl at 1/2 of the glass. I spoke to a mechanic this eveing and he was more interested in the way I had vacuum hoses routed. His theory is as follows: I have a single vacuum hose tandem happening. The hose is hooked directly to the intake manifold (which runs at 22" of vacuum). The hose Tees, and one end runs to the carb and the other end to the disty vacuum advance. He is telling me that the intake vacuum is too strong for the disty advance and is robbing vacuum from the top half of the carb. His suggested solution is to plug the vacuum port on the intake, and run the vacuum hose directly from the carb to the disty vac advance port. He claims that the distributer vacuum should see progressive, or intermittent vacuum from the top half of the carb and not continuous vacuum from the intake. He also claims that by having the intake vacuum hooked directly to the carb is robbing upper vacuum the carb and causing it to dump excessive fuel into the intake???????? Oh well?? Tomorrow I will clean the plugs again. I will also disconnect the vacuum hose from the intake manifold altogether. I will basically have a single vacuum hose from the top half of the carb to the vacuum advance... Every other vacuum port on the engine will be plugged. Remember... this is a boat engine.. There are no environmental or emmissions standards that need to be followed (in Louisiana) for this application. Not yet anyway.... So.... Any theories on the vacuum issue besides the one I heard tonight??? Quote Link to comment Share on other sites More sharing options...
Mudboat Posted November 19, 2004 Author Share Posted November 19, 2004 I found a guy this morning who had the identical engine/carb combination in his boat. I ran my vacuum identical to his. Although it ran a little longer before blowing smoke and fouling plugs, the same thing happened... Being hunting season opens tomorrow, I gave up on it. I hooked up the boat and brought it to the shop. This guy works on everyone's mud boats with Subaru engines and pretty much knows them inside out. He thinks that the float is the problem after initially running it at his shop. As much as I hate to pay someone to work on my stuff, I didn't have anymore time or energy left to mess with it. I have a loaner mud boat for the weekend, but hopefully my mechanic will have mine going by the time I get out of the swamp on Monday. I will definitely post what he does to fix the problem... Once again, you guys are the best!! I've been on many message boards looking for answers to different things, but the response from the people in here are by far the best I have ever seen.... Have a great weekend and wish me luck hunting!!!! Quote Link to comment Share on other sites More sharing options...
Mudboat Posted November 21, 2004 Author Share Posted November 21, 2004 Back from hunting earlier than I wanted. My loaner mud boat damper plate, which is a special marine plate replacing the clutch pressure plate and couples the transmission to the flywheel, desintegrated after about 1/2 hour of running. Springs and pieces of metal went everywhere... My buddy said that he did notice a strange new rattle coming from the flywheel about a month ago, so we'll be changing it out tomorrow.... Oh, well.... I guess someone is telling me not to spend so much time in the swamp this year????? Anyway, I hope to get my boat out of the shop tomorrow or Tuesday at the latest. Quote Link to comment Share on other sites More sharing options...
Mudboat Posted November 30, 2004 Author Share Posted November 30, 2004 Final update on this issue...... My mechanic worked on the carb for 2 hours and called to tell me that even with the the NAPA carb kit installed, it was pretty much shot and needed to go out for a full fledge rebuild. He had a fully rebuilt Hitachi on the shelf which he installed for $175 and my old carb core. The boat now runs great. Only some slight hesitation when hitting the throttle, but that is more than tolerable. My mechanic suggested checking to make sure that all of the valves were properly adjusted, but I'm not doing anything until after hunting season. I did notice some vibration from the drive train and found the shaft cutless bearing to be severely worn, causing the shaft to wobble close to the propellor. Another $30 and 3 hours work, but I think that it is FINALLY done. Thanks again to everyone that contributed to the thread offering advice and help. Quote Link to comment Share on other sites More sharing options...
Nug Posted November 30, 2004 Share Posted November 30, 2004 I'm glad it finally worked out. I find that when I'm on a deadline, something always goes wrong and I miss it. Quote Link to comment Share on other sites More sharing options...
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