1959 35hp big twin hard to start

[60stiletto]

I have been working on my 1959 35hp Big Twin, and when I can get it started it runs good. It has new plugs, coils, points, condensers, fuel lines, vacuum lines, carburetor kit installed, water pump, it has 91 and 94 lbs. of compression, and I have serviced the lower unit. The problem is it does not seem to be getting enough fuel into the cylinders, if I spray premix into the cylinders it fires up right away, which is strange because it actually just by looking appears to be flooding ( gas comes out of the front of the carb). Could I have missed some gunk in the carb? Do I need to rebuild the fuel pump? I also did not replace the float, but it appeared to be dry, and have good varnish on it. Like I said this motor runs really good for the most part. I still need to get it fine tuned, which may be part of the problem as it seems I am only getting about half throttle even though the butterflys are opening fully and I have done a link and synch. Sorry if I am rambling, but this thing is driving me crazy. Thanks in advance for any help.

 

[DJ]

Re: 1959 35hp big twin hard to start

The fuel pump is a great place to start. If the diaphragm is torn, it will flood the engine with raw unmixed (fuel/air)fuel.

 

[Paul Moir]

Re: 1959 35hp big twin hard to start

You have a fuel pump? You're not on the pressure tank system? The fuel pump is out of action when you start up, since you use the primer to fill the carb. It can (generally) only be responsible for running problems rather than starting problems. Unless you fill up the whole engine through a torn diaphram like DJ says.

Cure that flooding problem first. That's the needle/seat/float affair. It's simple and easy to diagnose, and could be responsible for your half-power issue. I'm assuming it's flooding when you pump the primer, not only while it's running. Is that the case?

Do your spark plug firing ends appear the same? What do they look like?

 

[DJ]

Re: 1959 35hp big twin hard to start

Paul,

I thought the same thing. I just assumed that it had been converted somewhere along the line.

60stilletto,

Paul is correct. If you have the two hose system, you have a carb issue.

 

[BoatBuoy]

Re: 1959 35hp big twin hard to start

Even though the experts have weighed in, I would presume to ask a couple of questions.

You say the plugs are new. Exactly what plugs have you put in? Gapped at .030?

Even though you put a carb kit in, did you soak it after dis-assembly and/or spray good with carb cleaner? Did you remove the welch plugs and make sure all tiny passages are clean?

Points gapped at .020?

How many turns out are the jets?

Sometimes the devil is in the details.

 

[60stiletto]

Re: 1959 35hp big twin hard to start

This motor has a fuel pump, it is the one with the strainer basket attached. I believe 1959 was the first year these motors came with them. It does not flood when running only when I pump the primer bulb to start it. I soaked the carb and blew out the passages with carb cleaner, but I did not replace the welch plugs (the kit I got did not come with replacements). The plugs are champion J6J's gaped at .030, and my points are at .020. When I look pull out the spark plugs the ends are dry with a black coloring, but not oily or covered with too much carbon. I adjusted my carb using Joe Reeve's post in the engine faqs.

 

[60stiletto]

Re: 1959 35hp big twin hard to start

Actually the plugs are J6C's.

 

[Paul Moir]

Re: 1959 35hp big twin hard to start

J6C is fine for now. If you run at full throttle then you should switch over to J4C.

The fact that the J6C plug is black suggests you're running rich, which isn't surprising considering the carburetor is flooding on you. It really shouldn't ever do that. When you replaced the needle and seat, did the gasket go on the seat? Float adjusted correctly? I've never had much trouble with the rubber tipped needles themselves.

Since you're short a welsh plug, failing picking one up from your local Johnson/Evinrude dealer you can try removing the carburetor and manually cleaning out the narrowest parts of the passages with a wire bent at 90 degrees via the carb's throat. They're clustered around the top of the throttle plate. I usually try to use copper wire to prevent damaging the aluminium. Of course, that won't help at all if there's something durable like an old piece of packing floating around in the chamber.

Sorry about the fuel pump business: you're right, '59 was the first year for them in the 40hp. The rest (18hp-5.5) didn't get them until 1960 which is what I was thinking of.

 

[60stiletto]

Re: 1959 35hp big twin hard to start

I am still stumped with this thing. I went ahead and rebuilt the fuel pump just in case that was the problem, and it couldn't have been helping the motor run any better. One of the diaphram supports was off of the spring, and somebody had put one of the valves in behind the gasket, and the diaphram was just about petrified. Fixing this did not help any so I decided to get an OMC rebuild kit with a new float and welch plugs. I cleaned the carb again really good and put in all the new pieces, in doing so I may have fixed my problem with this motor getting only about half throttle. the other kit that I had put in this carb before did not have the seal that goes around the high speed nozzle, and I have heard that if you leave this out it is almost impossible to adjust the high speed needle. So now the motor seems to be running a little smoother, but it is still almost impossible to start without spraying fuel or starting fluid into the throat of the carburetor (I know you should never use starting fluid, but I do have some that is supposedly safe for two stroke engines as it has a lubricant in it.) I still need to take it out and try to adjust the carb with the motor under load, but I do know that I have the slow speed needle adjusted as per Joe Reeves instructions. I also have checked and I have hot blue spark on both plugs. I do not know if I can get this thing to start any easier or if I just need to go get a motor with electric start so my arm doesn't fall off after having to pull this thing twenty or more times to get it started. Sorry if I have to vent a little but I am getting very frustrated, I mean I have an 18hp fastwin that I rescued from under a pile of leaves that starts with two pulls, and all I did was put new plugs in that motor.

 

[F_R]

Re: 1959 35hp big twin hard to start

You are hand starting this thing?? OK, I never was very fond of those compression reliefs. In my opinion they only made it easier to pull, but harder to start. Try disconnecting it by removing the stainless steel bar between the valves and recoil starter. The compression relief also gives you false readings on your compresion guage. BTW, OMC discontinued use of the compression reliefs altogether on the 40hp.

 

[60stiletto]

Re: 1959 35hp big twin hard to start

I will give that a try when I get home tonight. I did disconect the steel bar when I did my compression test. I will let you know if there is any difference. Thanks

 

[60stiletto]

Re: 1959 35hp big twin hard to start

Well it looks like you guys were right about this being a carburetor issue. After putting in the new kit and getting this thing adjusted properly it starts with three pulls when cold, and one after it has been started one time. I will let you guys know about the WOT problem when I get it out of the no wake zone tomorrow. Thanks again for the help!!!d

 

[60stiletto]

Re: 1959 35hp big twin hard to start

So, just when I thought I had this thing beat. I took my boat down to the boat ramp and launched it, and nothing after pulling on the starter for about a half an hour it only tried to start a couple of times. At one point I had thought that maybe it was flooded so I closed the throttle down, and it tried to start but would not. My fiance finally made me stop pulling and put the boat back on the trailer. I was wondering if anybody could think of anything else that I could check. I was able to start this thing in the driveway in a garbage can all week, so I thought it was OK to take out. I am running out of summer, and I do not trust this motor anymore, it will not run when it needs to.

 

[F_R]

Re: 1959 35hp big twin hard to start

This topic comes up over and over again around here. Running half speed generally means it is running on one cylinder. I see by you first post that you've changed coils, points and condensers. You need to back track and check out that job. Will it spark across a 1/4" gap? Don't assume, check it. Jumping the .030" spark plug gap laying on the head is not a valid test. Did you clean and dry the shaft and flywheel tapers and torque the flywheel nut to 60-65 ft/lbs with a torque wrench? If not, you may have sheared the key. Finally, if and when you can get it to run, short out one spark plug wire and then the other to see which one is not doing anything. That is the one where you need to look for a problem. Oh, and by the way, even a new spark plug can be bad. They do that at the factory to drive you nuts (just kidding).

 

[60stiletto]

Re: 1959 35hp big twin hard to start

Today I decided I would give another look at my motor, and check my spark again. I noticed that the spark seemed to be intermittent and not consistent with the distance of gap that it would jump, and I still could not get the motor started. I took another look at my plug wires ( the one thing that I haven't replaced on this motor), and I hadn't noticed before but they look a little worn where they are attached to the powerhead with a metal strap. So I took them out of the strap and the motor fired up with the first pull. Do you guys think that I have bad plug wires, and should replace them, or is this just a coincidence? I also pulled one plug boot off when it was running, and it is definetly running on both cylinders.

 

[tashasdaddy]

Re: 1959 35hp big twin hard to start

sounds like they are shorting out, or a loose connection, and moving them stopped it.