1983 johnson V-4 140hp

I have a l983 Johnson 140hp V-4. It is fairly fresh with 128 in one cyl and 130 to 135 in other three. It runs out of gal on top in. I run a 19 pitch OMC stainless prop. Reaches 5000 rpm for about 4-5 seconds then falls on it's face. Frankly, I think it hit that rpm with a 21 pitch. It also will sneeze and surge(about 2-300 rpm idling in gear) then sometimes die. I have Boyson reeds and read in a forum that you should rework the idle jets with them. What does that mean? Enrichen or lean them? Also, what kind of timing can I put in it? The cover says 28 Deg. My engine rebuilder said he retarded that about 4-5 Deg for the break-in. I now have about 25 or 30 hours on it and have long ago gone to 50 to 1 oil. The boat (1983 17ft Glastron-Carlson) has tons of low end but not top. Can trim the 19 prop out and get 5400-5600 rpms but only 41 mph (GPS). I guess because of the small prop. The motor is on a 8inch mechanical set back all the way down. I also put a new fuel pump on it, the box said it was for a 20-30hp outboard. The mechanic said they are all the same. That doesn't sound right to me but, as I said I'm new at outboards. Any suggestions?

Re: 1983 johnson V-4 140hp

If you do your own work I suggest buying a Johnnyrude manual and parts catalog for you particular engine. I cannot say if you fuel pump is correct, but the parts manual can. If the engine gets up to speed then dies, I would at least check to see if your fuel bulb is collapsing indicating a restriction in the line.
I put a clear gas filter up towards the engine. You can see bubbles (indicating line leak), fuel movement, fuel condition (water/contaminants) and lack of fuel. It is cheap and has saved me a lot of trouble.

Re: 1983 johnson V-4 140hp

Your engine has great compression. Agree with Ebry. Your engine may be running out of fuel at top end. It may be consuming more fuel than the pump can supply. My concern with the pump you have is that it may not have the right size inlets/outlets to flow the fuel you need. Get the right pump. The original was 388268 and probably supercedes to a newer number. That engine should be a high port block and when setup properly should be getting 5800 to 6000 rpm. You have not reached it's potential yet. I'd be inclined to time it at 26 and run premium gas all the time. (timing needs to be set at over 4500 rpm) The sneeze at idle indicates it is running lean or has too much idle timing. The Boyesens may have contributed to the sneeze problem. Make sure both the carb butterflys are closed all the way at idle. Did you completely disassemble the carbs and jets, then blow out all passages with carb cleaner during the overhaul? If you have replaced either of the power packs with new, the newer ones are marked rev limited to 5850 rpm. Look for a set of original unlimited packs for it.

Re: 1983 johnson V-4 140hp

I don't know if my answer to you was sent. Anyway that's a good idea. Never thought about the clear in line. Right now I have a spin on filter. It isn't the problem as I by passed it today with same results. Tomorrow I'm going to by pass the built in tank with a portable 6 gallon tank and try to eliminate my built in.

Re: 1983 johnson V-4 140hp

The answer on the jets is Boyeson recommends enrichening the idle jets 3 to 5 sizes. Yours should have air jets, which means you should go 3 to 5 sizes SMALLER.

Re: 1983 johnson V-4 140hp

Thanks, I'm going to try a few more things tomorrow to try to find the fuel blockage. Don't want to change the timing until I have the fuel problem solved. The powerpacks are not rev limited, plus, before this happened I have seen 5600 rpms even without the engine not running right. I'll check the butterflys tomorrow. If it still falls on it's face with a different tank, Then the carbs are coming off. The engine builder said he did that but who knows. He could very well had the block bored, new pistons and rings, and put it back together without doing all the other stuff he said he did.

Re: 1983 johnson V-4 140hp

I am a simple man when it comes to repair. It seems that these marine engines are designed to take a lot without going out of adjustment. That is why I look for things like air leaks, restrictions, water in the line, sediment in the carburetor bowl and other problems before I adjust a carburetor or replace a pump. It has save me a lot of time. That and greasing everything.

Re: 1983 johnson V-4 140hp

Why are we putting a 20 to 30 hp rated fuel pump on a 140 hp outboard ??
Your mechanic said they are all the same ???? I do not know for sure but I am certain we have many people out here that do. However I seriously doubt that the same pump would be used for a motor several times the size of a 20 to 30 hp. !!! Fuel flow for one thing. 2 to 3 GPH at WOT to 14 GPH at WOT.

Re: 1983 johnson V-4 140hp

I agree with emdsapmgr. Did some checking and the fuel pump that you need is used on the 90 to 140hp engines that year. That means that you are on the upper end of the fuel pump that is used. The 150 hp uses a different pump. They are not all the same. There are at least a half dozen different fuel pumps for that year depending on the hp. I know that it is about another $100.00 but I would start there. It sounds like what is happening, is that you hit WOT the fuel pump won't keep up and when the bowls emptys it "falls on it's face". I would be careful, this would be creating a lean condition also and could ruin that new rebuild. The clear fuel filter is a great idea, I have used them for years, but I don't think it will tell you anything about the fuel pump sizing on the suction side of the fuel pump.

Re: 1983 johnson V-4 140hp

My feeling is that using a single lift pump is at best marginal for the 1983 140HP motors when operating in the full throttle range.

The 150 V6 motors used two pumps for many years before that and continued to use two pumps on the commercial models that did not have VRO.

One factor is the fact that ethanol is a less efficient fuel that places greater demand on the supply.

You can follow the two pump setup easily by checking the 1983 V6 fuel pump diagrams.

When the motors are running at cruising speed, the single pump seems to be adequate.

Re: 1983 johnson V-4 140hp

Ran it yesterday with a seperate 6 gal outboard tank. Idled perfectly, but still fell on its face. That tells me that it is at the fuel pump or beyond. I have ordered the exact fuel pump that is for that engine from i.boats. along with it the proper carb kits and a manual. They will all be here next tue. I don't like fixing two things at the same time ( I won't know which one hopefully fixed the problem) but, I don't feel good about running wide open every check just to see if it works. Too many high speed lean outs. I do like the idea of two fuel pumps (it was only 48.00). But I would have to see how they got the vacuum for the extra one. Mine get it directly from the block. In any case, I'm pretty sure it's the pump or the carbs. And they will be done by Wed.

Re: 1983 johnson V-4 140hp

I will be watching the outcome with interest !!!

Re: 1983 johnson V-4 140hp

I finally got everything together. New fuel pump, carb kits. Engine turned 5600 rpm"s trimmed and did not run out of fuel. Put on a new Viper 19 pitch ss prop. Dropped 300 rpm's but it never broke loose and picked up 4 mph on gps. I can now start playing with engine height as it is all the way down on the 8" setback. Unfortunatly, I forgot to check the low speed jets as it still idles lean and sometimes dies. I'm 99 % sure it is because of the Boyeson reeds. They are type 2 carbs. Does anyone know if the low speed jets are air jets(need to go smaller) or fuel jets (need to go larger)? And would you happen to know what size idle jets they are so that I can order new one's before I take the carbs apart? In any case, I'm smiling now.









5

Re: 1983 johnson V-4 140hp

If they're in the carb throat and not the float bowl they're air jets. Pull 'em out there should be a number stamped someplace.

You'll need four, and on some engines the jets are different across the cylinders. So, pay attention to that too.