Old Evenrude 115 cuts out at high speeds

[IWAHAY]

I have a 1969 Evenrude 115 electric shift that starts great and runs great at low speeds. At middle to high speeds it cuts out badly. The higher the speed the worse it is. All 4 cylinders are firing. I have redone carbs, new plugs, wires. Compression is good. Any advise from anyone what I should try next? Thanks.

 

[Joe Reeves]

Re: Old Evenrude 115 cuts out at high speeds

If by cutting out, you're saying that the engine wants to dies out, the following pertains:<br /><br />If you have good compression (100+ psi and even on all cylinders), and proper spark (Jumps a 1/4" gap with a strong blue flame on all cylinders), you are overlooking something in the carburetors. The most likely area being the brass fixed high speed jets and/or the adjustment of the slow speed adjustable needle valves. For those that are not aware of it, the fixed h/s jets are near the center bottom of the float chamber, behind that 7/16" hex bolt on the float chamber lower side area.<br /><br />However, on the other hand, if by cutting out, you're saying that, at the higher speeds, the engine breaks up with a rapid sharp on/off type condition, that would pertain to an ignition problem. That could be caused by a frayed wire leading to the timer base, improper s/plugs.... many things. Which problem do you have?

 

[IWAHAY]

Re: Old Evenrude 115 cuts out at high speeds

Joe,<br /><br />The cutout is a missing in the engine. It runs very smooth at low rpm, but whether it has a load on it or not, at higher rpms it misses badly and vibrates. It does not try to die. When I pull back on the throttle it smooths out. I should have said "miss" instead of "cutout". I replaced the gas tank hose and fittings thinking that it might be sucking air but that didnt help.

 

[cowfarmer250]

Re: Old Evenrude 115 cuts out at high speeds

i had a similar problem, found that the plug caps had lost their tension on the spring inside and where slipping off the plugs ,didn't notice it until i went to check the plugs and tthe caps where just hanging on the ends of the plugs.<br /> i pulled the rubber boots off and wound up the stainless spring till it was a tight fit on the plug end, this fixed my miss.<br /> this may or may not be your prob?

 

[Joe Reeves]

Re: Old Evenrude 115 cuts out at high speeds

Iwahay.... What make, type spark plugs are you using, and if a gap peratins, what gap setting?

 

[IWAHAY]

Re: Old Evenrude 115 cuts out at high speeds

Joe,<br /><br />I checked the plugs. Three plugs are Denso and one is ND. They have the same numbers: w27fs-U10. Gap is .030. If you have advise for a different brand and gap I'll sure give it a try. Much appreciated.<br /><br />Jerry

 

[Joe Reeves]

Re: Old Evenrude 115 cuts out at high speeds

It's quite possible that your only problem is those s/plugs. Frankly, I've never heard of them. Try Champion L77JC4 spark plugs. Set the gap at .030 . Let me know the results.

 

[Franki]

Re: Old Evenrude 115 cuts out at high speeds

ND is Nippon Denso..<br /><br />thats why they have the same number..<br /><br />I'd take Joe's advice and change to the champions.. I have a similiar motor, (72 100HP Johnson) and it ran like a pig on anything but the Champions.. (which in my case don't even have ground terminals.)<br /><br />I think the Champions have a supressor built into the plugs to limit RF.. that might be your problem.<br /><br />regards<br /><br />Frank

 

[IWAHAY]

Re: Old Evenrude 115 cuts out at high speeds

I'll get some Champions today and let you know how it goes. Thanks.

 

[IWAHAY]

Re: Old Evenrude 115 cuts out at high speeds

Well I put the new plugs in and apparently developed another problem. No spark to the plugs. Just in case I put the old plugs back and still no spark. I guess another problem has developed since it was starting yesterday. I am going to try to run down the spark problem and will let you know how the plugs are doing if/when I can get the old girl to fire. <br /><br />Jerry

 

[IWAHAY]

Re: Old Evenrude 115 cuts out at high speeds

I got her fired up again. Put the new plugs in and gapped to .030. Plug wires appear good and tight. No change. I was trying to find those high speed adjustments on the carbs. I don't see any adjustment screws on the bottom of the float chambers. There are four brass adjustments sticking out the front with cover off. I took those to be slow speed adjustments but tried messing with them anyway with no help, then put them back to specs (7/8 back). I looked into the carb throats with the throttle high and can see the spray in each chambler but the spray appears to be erratic (sputtering). It does not have an even spray in any of the chambers. I'm not sure what it is supposed to look like but I thought I would mention it. Any more suggestions from anyone would be appreciated. The Wabash River is calling my name! FYI the boat is in the water so immediate testing is easy.

 

[IWAHAY]

Re: Old Evenrude 115 cuts out at high speeds

I just found those high speed adjustments. They are a stinker to get too so I'm going to fashion a special screwdriver and try that. I'll give you an update.

 

[IWAHAY]

Re: Old Evenrude 115 cuts out at high speeds

Well I feel like I'm being a pain in the butt, but I have more questions. Those high speed adjustments are very difficult to reach but I can get it done. I don't see how anyone can adjust those while the engine is running. When the cap screw is off to get to the needle adjustment it drains the fuel out of the float chambers. All the needles appear to be drawn down very tight. Should I back off each one, put it back together and try it? If so, how much is recomended?

 

[Joe Reeves]

Re: Old Evenrude 115 cuts out at high speeds

IWAHAY..... Apparently you misread my reply that mentioned the high speed jets. They are not adjustable jets. They are brass fixed high speed jets (orifices). The only think one can do with them is to remove and clean them.<br /><br />However, from what you've said lately (no spark, then spark), it sounds like the problem is indeed ignition rather than carburetion.