80 hp 1966 Evinrude V4 only runs 11mph

[watchman926]

My 80 hp older Evinrude 66 model runs great for a few minutes while pressure is in the tank from heat of the sun. I know that I am supose to open the cap to vent setting but when the pressure is off released it only runs slow but idles good and never dies. Also starts up ealily. It has a new fuel pump and lines with no leaks. I did have the wrong size fuel line connector at first but put the right one on. Why won't my engine run up to proper rpms and mph?

 

[BonairII]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

Check spark. You're probably only running on 2 cyls.

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

Check spark. You're probably only running on 2 cyls.

I have new points, coil, condinsor and plugs. It has checked out good in the past for spark. I will check it again though. I thought it was odd that it started up and ran good for a few minutes with the pressure in the tank and then only ran slow. Any suggestions as to why?

 

[BonairII]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

I had the same motor last year. And had issues with only 2 cyls firing(despite changing points, plugs , wires etc).

Check your compression first
Then check spark with an adjustable spark tester. Spark must jump a 7/16ths air gap.

Make sure all fuel connections are tight and that fuel tank vent is open. Have carbs been cleaned lately.

Search for my threads regarding my '67 80hp...some of it may help you.

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

I had the same motor last year. And had issues with only 2 cyls firing(despite changing points, plugs , wires etc).

Check your compression first
Then check spark with an adjustable spark tester. Spark must jump a 7/16ths air gap.

Make sure all fuel connections are tight and that fuel tank vent is open. Have carbs been cleaned lately.

Search for my threads regarding my '67 80hp...some of it may help you.

I will do that. I really thought it was fuel related but can't be. Everything is working perfect in that dept. New fuel lines, cleaned carbs and a new fuel pump. It has to be the spark. I am off work in in a couple of days and will check out the spark. It must be that is fired good while cold and after it heated up is changed something. The compression is the same on all cylinders and is good. Will run great at times or not fast at all. I know it is a simple issue now. Thanks for the help.

 

[BonairII]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

It's common for ignition parts to seem ok.....then act up(fail) they got warm. What condition is your coil in? They are hard to find...and can be expensive. I mentioned a seller in one of my threads...that may still have some new "old stock" coils for sale.


You'll need to check your timing also. That distributor needs to advance the spark at the correct time or you won't make much power.

 

[BonairII]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

Deleted*****double post

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

It's common for ignition parts to seem ok.....then act up(fail) they got warm. What condition is your coil in? They are hard to find...and can be expensive. I mentioned a seller in one of my threads...that may still have some new "old stock" coils for sale.


You'll need to check your timing also. That distributor needs to advance the spark at the correct time or you won't make much power.

I put a new coil in it along with condinsors and points a few months ago. I assumed that since it ran so good that the timing must be okay. It does sound like it could be the coil heating up. Always ran good when cold, for a few minutes then acted up. I will be off today and plan to check it out. Now that is does it all the time, I may be able to find the problem. Would the conection at the engine being one size too big, make it suck air and therefore not pull fuel in properly? I did have the wrong size on it at first. I also took off the original fuel pump and replaced it with a new style, that may be part of it as well. I plan on putting back the original part today. thank you for the help.

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

It's common for ignition parts to seem ok.....then act up(fail) they got warm. What condition is your coil in? They are hard to find...and can be expensive. I mentioned a seller in one of my threads...that may still have some new "old stock" coils for sale.


You'll need to check your timing also. That distributor needs to advance the spark at the correct time or you won't make much power.

Okay, here is the update. I checked the spark and found that the two cylinders on the right were not firing because the plugs had melted. One was completely melted and the other just enough to fuse the gap on that plug. Now I need to know what is causing this to happen. It is harder to start now that it has new plugs on that side but runs with a more full sound to the motor. The starter is part of that. It needs replaced. It bends and allows the teeth to climb on top of the flywheel. I don't know if it was timing or the advance adjustment was off. It has a flat two-piece rod that attaches to the magneto. How do I know were to put it? It has a slot where the screws can slide one half inch back and forth. Since this is only one side of the motor, what could that signify?

 

[nwcove]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

the spark plugs melted???? you sure its not aluminum fused to the plugs??? ( not good) id do another compression test before doing anything else.

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

the spark plugs melted???? you sure its not aluminum fused to the plugs??? ( not good) id do another compression test before doing anything else.

It did look like aluminum on the plug but the electrode was completely missing on the one. The other just had a slight bridge welding the two parts of the electrode together. I take it that the engine got really hot in the one cylinder. I think the one carb must be adjusted too lean? I will recheck the compression. There is two hand knobs on the top of the carbs to adjust the fuel mixture or air, not sure but the one must be adjusted wrong.

 

[nwcove]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

jmo.... aluminum on the plugs is not good, and adjusting the carbs at this point is not going to cure the damage done.

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

jmo.... aluminum on the plugs is not good, and adjusting the carbs at this point is not going to cure the damage done.

What it the chance that the aluminum was just a small amount and the cylinder is okay? I believe the problem was the carb on the affected side had the fuel adjustment turned out only half as much as the other side.

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

What it the chance that the aluminum was just a small amount and the cylinder is okay? I believe the problem was the carb on the affected side had the fuel adjustment turned out only half as much as the other side.

I did the compression test and that cylinder was slightly lower but my starter was binding. I had equal compression on the other three and with proper adjustment of carbs and two new plugs it starts and runs pretty good. I haven't had a chance to get it out on the water yet but I can tell that it sounds more powerful now running on all 4 cylinders. Before it ran too smooth and quiet. it does seem that the fuel adjustment screw was closed up too much on the affected side and now it is adjusted properly. Thanks for the help.

 

[nwcove]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

if it were me, i wouldnt go to far from the ramp for the first hour!! but you may have dodged a bullet!

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

I have finally been able to get the boat out on the Ohio river. The one cylinder that was a little low was making it run a little rough but was going faster than it did when it ran good but had the one carb running too lean. It only ran for a hundred yards of so then started to bog down again. I guess I will have to pull that head and see how much damage was done. Can anyone tell me what they think I will find? The last one that did this to me had gotten hot from the water pump loosing suction and the pistons were scored and the rings were pulled off of them somewhat and the cylinders damaged. The engine is still reliable to start right up and even pull started in gear once. It got me back to the docks. Should I get another motor or fix this one?

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

Is there any chance that the particle that fused onto the plugs the first time were just foweling the plugs and that it was not the head or cylinders?

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

What I mean is; could the remaining particles have just foweled the new plugs and that is why it ran so poorly?

 

[BonairII]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

If compression is good on all cyls...then a little more work to get her running well won't cost you much(if any) money. Be forewarned.....these motors suck fuel like crazy.

IIWM, I'd always be watching Craigslist etc for a 3-cyl "looper" (i.e. Johnson/Evinrude 70 or75hp).

The difference in fuel consumption between my old '67 V-4 Johnson(crossflow)....and my '78 75hp(looper) is amazing.

 

[watchman926]

Re: 80 hp 1966 Evinrude V4 only runs 11mph

I found a three cylinder last night on CL. The compression was lower on the one cylinder by 30 pounds. I have not checked the plugs yet. They could be my problem. Thanks for the help.