Mudboat

My EA 81 has a recent, shop rebuilt Hitachi 2bbl carb (rebuilt in November). I am starting to get a sputter and hesitation when I accelerate from idle and low rpms. Can the accelerator pump go bad that quick? Any other components will give the same symptoms?

What type of carb do you have? Hitachi or Carter/Weber? You also mentioned the timing belt. Are you positive that everything was lined up correctly when you put the new belt on? If it was running ok, maybe not 100% before you did everything, then I suspect something else like the timing belt or a bad plug, especially with 3 different carbs...

A 1.25 thread pitch is quite common on metric bolts, which is what the drain cocks should have. Get a bolt with that pitch that fits the hole, wrap it with teflon tape and screw it in and go...

Ah..... Sounds like your crankcase vent tubes from the valve covers. One side connects to the pipe on the intake, which uses intake vacuum to open and close the ball valve, while the other side vents to atmosphere. The crankcase must be vented, but should also operate under a slight vacuum (thus the reason for one side going into the intake). I think you need to leave these as they are. Positive pressure on your crankcase is not a good thing....

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.

I just did this same swap over last week. I had to change the intake which I paid $40 from a guy who has spare parts all over. I also bought a used Hitachi for $50 and put a rebuild kit from NAPA in it before installing. Took about 3-1/2 hours and $140 in parts and gaskets...

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.

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!!!!

Right now the engine in my mud boat (83 EA-81) is running extremely rich and fouls plugs in matter of minutes following a carb and intake manifold swap from a Carter/Weber 1bbl to a Hitachi 2bbl. The intake I now have installed is set up a little different as compared to the one I removed. Not knowing a thing about how to properly run the new vacuum hoses, I took a wild guess. Speaking over the phone with a mechanic last night, he gives me the impression that I have the hoses installed incorrectly and that this is probably causing my present problem. The engine has no emmissions stuff on it at all. The EGR is removed and the intake EGR ports are covered with a piece of 1/4" aluminum plate. There is no PCV valve either. This mechanic tells me that the simplest way to route the vacuum hoses is to plug everything on the intake manifold, and run a single vacuum hose from the carburetor to the disty advance unit. Right now he feels that by having the intake vacuum tied in to this hose that the intake is sucking fuel from the carb directly to the intake through the hose (yes, there is a hose connecting the intake and carb)???? Before I run outside and try this simple setup and spend another 2 hours toting the boat to and from the launch to run it, does anyone else have an idea on the simplest way to hook up my vacuum lines?

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???

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.

Smells like it's burning rich. The plugs soot over pretty quick. It was not doing that before the intake and carb swap.

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?

I suspect the filter. You might want to get another one...

Rebuilt carb installed. It took me all evening (6hrs) to cut out and mill the throttle and choke cable brackets, but everything is in place. Hooked up the fuel line, vacuum hoses and filled the reservoir with anti-freeze. Turned the key and it came back to life immediately!! The Hitachi carb seems to be super responsive as compared to the Carter. I'll know more tomorrow when I launch the beast and take it out for a test run. All indications are that I should get 3-5 mph faster, but speed is not a factor in a mud boat. It's power that counts.. I'll post the results after the test run... Again, thanks for the tips and info on this problem. If it is indeed solved, the total for the fix will be under $100 and roughly 10 hours labor. Of course most of the labor went in to fabricating custom brackets to accomodate the new carb..

That's the truth brotha... These guys are great!!!

Yep... Been there and done it. Swap the points disty for an electronic disty and add a single 12v power supply. About a 1/2 hour job with everything on hand..

Just make sure you use studs and not bolts. I've tried both. Bolts tend to come loose for some reason even with lock washers. Studs, lock wahers and nuts hold tight.

Well, the intake was swapped out this evening and the carb looks in great shape. I still bought a rebuild kit from NAPA and my mechanic is going through it tonight. I will have to re-route the throttle cable and install a manual choke cable since the Carter was an auto-choke. The Hitachi is manual. No biggie though. That's life when dealing with a car engine in a boat.... The new intake is a whole lot cleaner and less cluttered than the intake for the carter. I think this was a good move. Thanks for the suggestions and ideas. I will let you know how it runs on Thursday.... If anyone is interested, Boats by Kirk in Des Allemands Louisiana has stacks of low milage EA-81 and 82 engines. He sells them for $700... I think he paid $500 each from a dealer overseas.... I'm thinking about buying a spare just to keep on hand.

Now that is another good idea that would have never crossed my mind. I have some 1/2" aluminum plate that would work nicely and access to a machine shop. Maybe I'll make the wedge and keep the carter and intake as a spare to try in the future. I've already picked up the new intake and Hitachi, so I'm going with it starting this evening..

Change seals at a minumum. Pull the plugs and see if you can turn it over with a wrench. If it turns over freely, you're in good shape. If not, pour 1/2 oz Marvel in each cylinder and work it slowly with the wrench until it frees up. With only 4000 miles, chances are you will not need to do much as long as the engine was stored indoors or covered and that nothing was taken off of the engine to expose internals to the elements. After it's in the car, turn it over without the plugs until you're positive that the oil pump is still primed. Oh, new oil and filter is a must... (Duh).. Pull the disty cap and spray a good electrical contact cleaner and thoroughly wipe it clean with a lint-free cloth. Make sure all fuel delivery linkages operate freely and are lubricated. Other than that, it sould be good to go. Oh, and $500 for an engine with 4000 miles is a very good deal..

I never noticed an A or B. I have it lined up with the big "O" on the flywheel. Hmmmm... Maybe I'll try wiping it or something... (Ok, so I don't know much about soobs, but I'm learning more with each reply). You guys are great. I just got off the phone with the guy that builds and rigs mudboats with Subaru engines. He tells me he has 40 something used engines in stock plus piles of parts. He does not recommend the Carter carb in a boat because they are too hard to get set right with the engine at an angle. Looks like my plans to replace the Carter have changed. Anyway, he said he has an intake for a hitachi carb and also has a used carb that can be rebuilt for about $100 for both. He also carries the gaskets. Looks like I'll be changing over to the Hitachi tomorrow evening. I'll pull the plugs this evening and let you know what they look like. They have about 1 to 1-1/2 hour run time on them right now.

Already have new cap, rotor, wires and plugs. A level float bowl is not an option because of how it is mounted in the boat (slanted with shaft through the bottom), but there are hundreds of boats with engines like this in my area, and no one else seems to have problems. You have me confused on the timing check. How can you tell where BTDC is in relation to ATDC? I hooked up the timing light to the #1 plug and lined up the mark with the little hole... Compression was checked 1st, that was when I noticed the bad rings in one cylinder (40 psi). The rest were fine. Compression is good in all 4 now. Like I mentioned in my original post, it runs great for a little under a minute before it sputters out and nearly kills. I naturally assume it's either a fuel or ignition related problem. I'm working through it from cheapest to most expensive. Right now everything is new except for the carb and the distributor. ?????

The fuel pump is an off the shelf Purolator rated at 4-7 psi. It maintains about 5 psi when I checked it after installing. The one I took off was pumping about 3 psi, but I didn't notice any difference between the two.

Thanks. Too much fuel is something I never considered. Being the engine is situated at about 15 degrees in the boat, I guess it's possible that the float bowl level is higher than it should be. I'll adjust the float a bit and try it again. Fuel pressure at the carb inlet is 5 psi. One other thing. All of the vacuum ports on the carb and intake are plugged off with the exception of the hose to the distributer vacuum. Is there anything wrong with having everything plugged? It's been like that since I've had it and never had a problem.