Very low power from 1968 evirude 18 hp

[james__12345]

The drama with this motor continues. I finally got to take it out on the water today after doing a ton of work on it. One of the things I did was rebuild the fuel pump because it was fouling plugs really bad due to extra gas getting into the motor from a bad diaphragm. The crazy part is, now after all that work, despite idling extremely well in a barrel, I have even less power and lower speed out on the water than I did before when it was running worse.

I have good spark, that jumps well over a quarter inch gap on a tester (I already replaced coils points plugs and plug wires), good compression, I rebuilt the carb, and it was spotless inside when I took it apart (and yes, I pulled the welch plug and the holes under it were clean too). Before rebuilding the ignition, fuel pump, and carb, I was able to get about 16 mph out of it, even with the trim way too far in. Now with all of that rebuilt, and the trim adjusted right I'm doing good to get 10 mph, and its very weak and slow taking off. While on the water I tried pulling the plug wires one at a time to be sure both cylinders were running, and they were. I also checked for a spun prop, and the prop is fine. I dont know what the rpm is running, because my tiny tac that I've only had for about two months died out of no where yesterday while I was getting the idle somewhat adjusted before taking it out today, so I've got to send it back. I really don't think by how it sounds that its getting anywhere near what the wide open rpm should be.

The only conclusion I can come up with at this point, is that the carb is not the right one for this motor and isn't giving it enough gas. I think the reason it ran faster before, was due to the extra gas the bad fuel pump was giving it. To get this carb out, I had to pull the air silencer plate off the front, which I've never heard of anyone saying they had to do, so that makes me think the carb is longer than the one thats supposed to be on this motor. The low speed needle is also not set up the way the parts diagram shows. Instead of this carb having the knob at the bottom of the front of the motor, with a linkage running to the needle, the needle has been ran straight out the front through a hole drilled in the housing and quite frankly, I dont think there is room between the housing of the motor and the front of the carb for those parts to be there which also makes me think the carb is longer than it should be. I am also having a problem getting the throttle timing to adjust right. The cam plate is bottomed out, but the butterfly is still opening too early. I was told there should be a set screw that will adjust the linkage between the arm on the roller, and the arm that moves the butterfly, but there is not a screw there that can be adjusted. Also, that linkage looks like its something someone may have made their self. It just doesn't look like a factory made piece so it seems like it may have been a patch to try to make this carb work on this motor.

What would be great is if someone had some good close up pictures of the carb on one of these motors so I could compare and see if it's the right one or not.

Here is the one picture I have of it right now (its too dark out to get another one now, but I can tomorrow)


I'm starting to get really frustrated with this motor, because I've got a 9.5 that runs great for it, and I only got the 18 to be able to run faster, and even after all the work I've done on this motor, it still doesn't run any faster than the 9.5.

 

[AlTn]

Re: Very low power from 1968 evirude 18 hp

if you'll go marineengine.com and find the diagram for your carb it looks like you'll need #10, 11, and 79...I guess you could just bend the link from the roller shaft to the throttle shaft until you achieved something close to the the correct link and sync. I'd ask around at any of the marine repair shops around Cookeville for the parts availability from some old donor motors. Many packrats in our state.

I have a 72 18 hp. now and it has a setup very similar to yours with regards to the idle mixture needle,; the extension, spring, etc. it works and the correct parts can be "pricey" when you locate them.

Keep pluggin', you're getting closer.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

There are still much bigger problems going on here than just that linkage. I'm still only getting about half of the speed I should out of this motor. I'm still only getting 10 mph when I was getting 16 mph while the fuel pump was leaking. The link and sync is really the least of my concerns at this point. I was just including that as one of the many things that make me suspect this is the wrong carb. I also forgot to add that I know for sure the lower unit is not from a 68 (i'm pretty sure its a 71) and my pull starter is off a different motor, because its a different shade of blue than the rest of the motor is. Having other parts frankenstiened together makes me think the carb may be too.

As far as spare parts at a repair shop, I was almost laughed out of most of them for looking for a pull handle for the starter for a motor that old, so that's not going to happen I dont think.

 

[F_R]

Re: Very low power from 1968 evirude 18 hp

As far as looks are concerned, your carburetor looks like the correct one. Yes, somebody has dinked with the linkages though. And yes, you do have to tilt the silencer forward to remove the carburetor. That's the way they were.

I don't think not getting enough gas is the problem. It probably would quit if that were the case. But it could be getting too much gas. Perhaps some genius changed the high speed orifice plug or drilled out the original one in a futile effort to make a go-faster motor out of it.

Beyond that, is the throttle butterfly opening completely at wide open throttle? Is the magneto armature plate going fully against the stop (interlock lever / last step) at wide open throttle?

Now we gotta get back to basics. You said you removed the plug wires one at a time and it proved to be running on both cylinders. But were those two cylinders equal? Have you checked compression? Let's face it, the motor could be sick.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

As far as looks are concerned, your carburetor looks like the correct one. Yes, somebody has dinked with the linkages though. And yes, you do have to tilt the silencer forward to remove the carburetor. That's the way they were.

That's a start atleast. I really didn't think taking the silencer off was right, but I didn't know one way or the other, atleast now I know that's how it should be.

I don't think not getting enough gas is the problem. It probably would quit if that were the case. But it could be getting too much gas. Perhaps some genius changed the high speed orifice plug or drilled out the original one in a futile effort to make a go-faster motor out of it.

I wouldn't have thought that, had it not been running faster before when the fuel pump was leaking more gas into the motor before the rebuild, but that's the only thing I'm basing it on, so I could very well be way off with that thought. The orifice plug being different was a thought I had also had about it. I was thinking that I read somewhere that some of the carbs for the different sized motors were the same except for that, and that's also part of what I was thinking about with it being the wrong carb. I thought someone may have found one that looked the same and fit, but didnt realize some of the internals were different. Is there any way to check the size of the plug to see if its right?

Beyond that, is the throttle butterfly opening completely at wide open throttle? Is the magneto armature plate going fully against the stop (interlock lever / last step) at wide open throttle?

Yes, the butterfly opens completely. There is a bit of a problem with the interlock lever. The lever doesn't go back far enough toward the armature plate to actually stop it, but the plate does turn far enough to be at the point that it would stop it.

Now we gotta get back to basics. You said you removed the plug wires one at a time and it proved to be running on both cylinders. But were those two cylinders equal? Have you checked compression? Let's face it, the motor could be sick.

Yes, both cylinders ran equal. I have checked the compression (it was back before rebuilding the fuel pump, ignition, and carb and resealing the low end) , and I don't remember now exactly what it was, but it was a little over 100, and with in a pound or two of each other. I can check it again but nothing I've done should have had any effect on compression I wouldn't think.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

I checked the compression again, it's right at 100-105 on both cylinders. I pulled the jet and found out it is the right one. It doesn't look to me like it has been drilled out, but I don't have a bit that fits it right (naturally the couple of bits missing from the box were the ones I needed to size it). I adjusted the length of the throttle linkage by putting a bend in the middle of it to make the link and sync work out right.

After doing some more reading on setting the timing (as a result of my neighbor suggesting the timing being an issue) I found out I may not have had the timing set exactly right. I was using a what I thought was a mark next to the word "top" and then setting it at .02. From what I've read now, it seems that may just be an indicator to make sure the cam isn't put on upside down, and its not actually a set mark like some of the cams have. If anyone can verify that on this particular motor for me I would greatly appreciate it. Anyway, I had got the timing jig from Frank, but I couldn't get my electrical tester to work out when I tried to use it last time (cheap digital meter). This time I tried it with the buzzer on our older analog meter and after setting it that way, it wouldn't even start. I went back to the "mark" I was using before, and it starts again. But I still wonder if that might be part of the problem.

I also replaced the fuel lines between carb and the fuel pump, and the fuel pump and the connection at motor, and I took the inline fuel filter out of the line to eliminate that and its connections as an issue.

I haven't had a chance to get it to the lake yet but hopefully I will in a couple of days to see if the fuel line replacements, removing the filter, and fixing the link and sync helped anything. If not, I may try tinkering with the timing a little more by setting somewhere between where it is now, and where the jig sets it.

 

[samo_ott]

Re: Very low power from 1968 evirude 18 hp

How did you verify that the prop was not spun? And what kind of boat do you have? How heavy? How's it loaded?

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

How did you verify that the prop was not spun? And what kind of boat do you have? How heavy? How's it loaded?

I took the prop off, made a mark across the back of it, put it back on, ran the boat, pulled it off again, and made sure the marks were still lined up.

I have a 16 foot mod v lonestar aluminum boat. I have no idea what it weighs, but I know that this motor is pushing me slightly slower than my 9.5 horse johnson. As far as the load, I had me, a 6 gallon gas tank a trolling motor, and two batteries in it (the same load I had with the 9.5 and I was running about a half a mile an hour faster than the 18).

 

[Watermann]

Re: Very low power from 1968 evirude 18 hp

Post the diameter and pitch of your prop, maybe a PO put a wrong prop on with too high a pitch. That would definitely make for a lower rpm slow ride. Maybe one of the guys here who have the same engine that runs max rpm at WOT can let you know what their pitch is.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

It's a 9x10

 

[emckelvy]

Re: Very low power from 1968 evirude 18 hp

OK, I may be seeing things, but what I noticed is that the throttle actuating arm/roller, has some sort of botched-up linkage attaching it to the bellcrank of the throttle shaft.

There is no way that arm could ever move the throttle bellcrank to fully open the throttle butterfly.

Take a look at this carburetor breakdown for a '68 18hp:

Evinrude Carburetor Group Parts for 1968 18hp 18802A Outboard Motor

You'll see how the throttle cam follower is constructed (part #19). Note that the follower arm assy (pieces 10 & 11) are supposed to be attached to the other end of the cam follower.

When the cam follower is pushed forward by the ramp on the mag plate (advancing mag timing), the follower arm also moves forward (or down, depending on the style of linkage) and, via the throttle linkage (piece #79), moves the throttle butterfly in the open direction.

There's no way the existing linkage could fully open the throttle, period. So, you're getting lots of timing advance but no throttle, she ain't gonna run worth beans!

What you really need is the cam follower arm (piece 10), and the linkage (piece 79).

I found a couple of pics on eBay, maybe they'll help.

HTH.............ed

 

[samo_ott]

Re: Very low power from 1968 evirude 18 hp

He already said on an earlier post that he verified that the throttle butterfly opened up fully.

 

[HighTrim]

Re: Very low power from 1968 evirude 18 hp

Set the points to 020 when the rubbing block of the points is aligned with the flywheel key, not the word TOP. That simply shows the orientation of the cam. The ones that say SET are for setting timing however. Ill bet the key is the widest point of the cam, that is where you set it at 020.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

OK, I may be seeing things, but what I noticed is that the throttle actuating arm/roller, has some sort of botched-up linkage attaching it to the bellcrank of the throttle shaft.

You're not seeing things, it is a home made linkage (not my doing), and that has already been verified by other members.

There is no way that arm could ever move the throttle bellcrank to fully open the throttle butterfly.

However you are completely wrong about that. The butterfly was actually opening too far before I adjusted the length of the linkage. The picture was taken before the adjustment. It was also opening a bit too early, but after putting a bend in the middle of the linkage to shorten it, the butterfly opens right when it should based on the marks on the cam, and opens to perfectly horizontal at WOT.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

Set the points to 020 when the rubbing block of the points is aligned with the flywheel key, not the word TOP. That simply shows the orientation of the cam. The ones that say SET are for setting timing however. Ill bet the key is the widest point of the cam, that is where you set it at 020.

I tried setting at .02 with the rubbing block lined up with the key after I tried the jig. It wouldn't start at all that way either. Out of frustration I set it back with the "mark" I was using before and got it to run again. I'm going to the lake tomorrow morning as long as the weather holds out. I'm going to test out the few changes I've made with the new lines, inline filter removed, and the link and sync finally done right, and if I don't get the expected results, I'll try setting the timing somewhere between where it is now, and using the key and see if somewhere between the two works out better.

 

[HighTrim]

Re: Very low power from 1968 evirude 18 hp

If you have a timing fixture, you dont need any feeler gauges or to worry about where the rubbing block is. Use a meter to tell you when the points break.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

When I used the timing fixture and meter the motor wouldn't even start.

I went to the lake today with the motor, and the second I put it in gear the shear pin broke, and I didnt have an extra one with me. Because of that, I didnt get to test the motor at all, and ended up running the 9.5 that I also had with me just in case, so it will be a few days before I get to test it out now.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

I got to run the motor again today, and FINALLY its back up to a little over 16 mph. I ran around close to the dock for a while, stopped and restarted the motor a few times (it was still a little slow to start, takes a lot of pulling and the throttle turned up pretty high to get it going) and thought I may have finally been making some progress. A little later in the day, and three miles later, the starter housing broke. One of the three legs that holds the starter down to the motor had broke before I got the motor, and been welded, this time one of the other legs broke off. As thin as the broken area is, and as long as the break is I don't know if welding is gonna work and the part isn't available, so it looks like I may be getting in touch with a salvage yard to try to find a starter.

I had planned to go back for my screwdriver at the end of the day, and put the inline filter back in place and see if that had any effect on the motor but obviously with no starter that wasn't really an option. I have a feeling shortening the throttle linkage was probably the major determining factor on it, but honestly at this point I don't care what fixed it as long as its fixed.

 

[james__12345]

Re: Very low power from 1968 evirude 18 hp

I got the "new" starter but the rope was MUCH shorter than my old one, and I've read on here that they're supposed to be a touch over six foot, which my old rope was, so I put the old rope on the new starter, and tried it out. It started, eventually, with the throttle wide open, like it had been doing before, but then when I went to turn the throttle back up to start it a second time, it was stuck.

I ended up pulling the flywheel and one of the screws holding the coils in had backed out, and was getting against the fly wheel. I apparently had also tightened the armature plate up too much, and it had about locked up from some combination of being too tight, and the pressure that screw had put down against it. Anyway, I pulled the brass ring off, flattened the ding in it out a little, and put some fresh grease on it. I put the armature plate back back on, and knowing that having to start at full throttle wasn't right, I decided to adjust the timing again.

I checked first to see where the widest point of the cam was, and best I could tell, it was at the mark I had been using to set the points. The gap was larger there than it was with the rubbing blocks at the key. I decided to try setting the gap with the rubbing block half way between the mark I had been using, which would run but not start good, and the key, which is supposed to be where they set it but wouldn't start before. I put the flywheel and starter back on, and tried to start the motor. This time it started on about the second pull, with the throttle just barely opened, just like its supposed to. Before it was taking WOT and pulling 20 or 30 times or more. I think this motor is finally done. Hopefully this weekend I'll be able to take it out and see what it will do.