1976 Evinrude 15hp dies

[Stumpalump]

I'm resurrecting a 1976 (15604r) 15hp Evinrude that sat for 9 years. New pull rope, water pump, upper cylinder coil and clean carb. It starts and runs good for two minutes and then dies. Primer stays hard and pumping it does not help. I'm running it off of a known clean tank and hose. Thinking ignition, I filed and gapped points. No change. It starts right up, runs for two minuets and dies. It fires right back up and runs one minute and dies. Starts up and runs a minute or less and dies then it won't start. I ordered condensers since the rubber top of the old ones looks old but IDK....

 

[Johnny]

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Edit: what color is your fuel hose ?? how old is it ?

if it starts and runs - then dies I would suspect a fuel delivery issue (in my very personal opinion).

have you used the fuel tank, hose with primer bulb on any other motor successfully ?
if the answer is "yes" that would eliminate the tank and hoses to the motor.
I would check the fuel pump innards. perhaps the diaphragm has a small hole in it.
spring is crusted and stuck - trash clogging the holes.
carb issue the same: trash may prevent the float from operating properly or it is not set to specs.
fuel delivery issues will drive you NUTS before you get it to run properly.

https://www.tinboats.net/primer-bulb-primer/
https://www.forum.tinboats.net/viewtopic.php?f=4&t=42597&p=430268&hilit=silver+fuel+hose#p430268



.

 

[Outbdnut]

Hi - I'm new to the forum here, but I'm a regular at Antique Outboard club's forums where I'm known as outbdnut2 and have been active in the old outboard hobby for a lot of years.

When your motor won't start, have you checked for spark? If you have spark, look to the carb for flooding. You cleaned out the carb, but after sitting 9 years, there could be crud from old decaying fuel lines or crud caught in the fuel pump that has found its way to the carb. I've seen this happen on the 9.9 version of your 15 that sat for years (same motor, different carb) where there was a small piece of dirt I could hardly see keeping the float valve from shutting completely, and after running awhile, the carb flooded and the motor quit. You wouldn't believe the gritty stuff I found that was past the filter in the fuel pump that had crystalized from the old gas sitting in it.

The carb could also be running out of gas due to a small piece of dirt you can hardly see sitting at the input side of the float valve seat - take the seat out and look at the underside of it. A small piece of dirt maybe restricting gas flow into the carb and it runs dry - after a minute or so being off, the primer bulb pressure and/or fuel pump residual pressure fills it again enough to get it started.
Good Luck!
Dave

 

[KMixson]

I would also suspect fuel delivery issues. When you rebuilt the carb. did the float and needle valve move freely and not in a sticky fashion? If the float or needle valve is sticking it can cause the motor to burn just the fuel in the float bowl and then die to fuel starvation. You say it runs for two minutes and dies. That burned the fuel in the bowl. Immediately after that it runs one minute then dies. That burned the little fuel that managed to get into the bowl after it died the first time. After pumping the primer bulb a few times it should get hard due to the float rising and closing off the bowl with the needle valve. As the engine runs the float should fall with the fuel level decreasing in the bowl opening the needle valve to let more fuel in from the tank. If the float is stuck it may not let fuel into the bowl fast enough to keep it running.

 

[Stumpalump]

I pulled the float and needle. The needle looked good and I blew carb spray and compressed air thru the holes. It did not look bad at all inside and the float looked like it hung corectly. The line going from the pump to the carb was shot but that got replaced prior testing it. The tank and hose run great on other motors I have. If the pump is bad could the bulb stay hard? I could swap pumps with a 6hp I have. Same pump.

 

[Johnny]

Stump - I had a '79 Johnson 25 that gave me fits with fuel issues.
I disassembled, inspected and reassembled everything fuel related
several times . . . I don't know why, but I held the fuel pump diaphragm
up to the sun and I could see a very tiny pin hole in it . impossible to see
just by looking at it on the table. if the fuel pump is leaking or sucking air, that is a problem.
I ordered a new fuel pump gasket kit and everything went back to running normal.
it is amazing how easy it is to keep these vintage motors running but
on the other hand, the simplest things will eat your lunch.

good luck in your endeavors !!!



.

 

[Stumpalump]

Stump - I had a '79 Johnson 25 that gave me fits with fuel issues.
I disassembled, inspected and reassembled everything fuel related
several times . . . I don't know why, but I held the fuel pump diaphragm
up to the sun and I could see a very tiny pin hole in it . impossible to see
just by looking at it on the table. if the fuel pump is leaking or sucking air, that is a problem.
I ordered a new fuel pump gasket kit and everything went back to running normal.
it is amazing how easy it is to keep these vintage motors running but
on the other hand, the simplest things will eat your lunch.

good luck in your endeavors !!!



.

I'll try the pump. I'll pull the carb again only after the pump and condensers because of the one nut. It's easy to get off with an ignition wrench and magnet but ya gotta dangle it with a wire over the shift shaft hole to get it back on. Sure I use a rag down there but it's a real stress fest until you get it started. I can't wait to run it!

 

[ProduceMan]

Also check the hose between the crankcase and fuel pump. Often overlooked.

 

[Pappy]

That engine is widely known for a funky ignition system. Part points ignition and part electronic.
There is an ignition module in the 1976 engines that controls spark. Chances are this is failing. Have seen it do exactly what yours is doing on several occasions.
All of your symptoms point toward an ignition component that is heating up and failing.
By the way....once you have the primer bulb firm the bulb should not remain firm once the engine starts. The bulb will be on the suction side of the pump.

 

[Stumpalump]

Funky is not what you want to see when working on old electrical things.

 

[Pappy]

Stump.....trust me when I tell you that was not my first choice of a descriptive term!

 

[Outbdnut]

You can pull the gas line off the output of the fuel pump, and with the throttle closed so it won't start, pull the starter rope and see if gas comes pulsing out of the fuel pump. SInce you replaced that gasline already, I would be suspect that some tiny rubber pieces flaked off the inside of the old line and got into the carb's gas input nipple - these could be blocking the inlet underside of the float valve seat, or, as I mentioned before, dirt, etc from the fuel pump could also be lodged there.

To get that pesky carb nut started, first I place a rag or paper towel under the carb to catch the nut if you drop it, next I get the nut "sort of over the threaded stud" with two fingers or a longnose pliers, and then, with my other hand, I place the end of a small to medium screwdriver on/in the hole in the nut to hold it there while I turn it with one finger until it starts to thread itself onto the stud - sounds complex, but after you've done it once or twice, it works pretty slick.
Dave

 

[Stumpalump]

.


Edit: what color is your fuel hose ?? how old is it ?

if it starts and runs - then dies I would suspect a fuel delivery issue (in my very personal opinion).

have you used the fuel tank, hose with primer bulb on any other motor successfully ?
if the answer is "yes" that would eliminate the tank and hoses to the motor.
I would check the fuel pump innards. perhaps the diaphragm has a small hole in it.
spring is crusted and stuck - trash clogging the holes.
carb issue the same: trash may prevent the float from operating properly or it is not se to specs.
fuel delivery issues will drive you NUTS before you get it to run properly.

https://www.tinboats.net/primer-bulb-primer/
https://www.forum.tinboats.net/viewtopic.php?f=4&t=42597&p=430268&hilit=silver+fuel+hose#p430268



.

Fuel pump inop. I missed it because the bulb hardly squeezed. Unfortunately my eBay pump never arrived which seems to be the case with about 10% of the stuff I order from them. I pulled the old one apart and learned why they don't sell rebuild kits for them. Very touchy in there with the springs and diaphragms. The old ones do not even have alignment marks but you can do it if your careful.No holes but the diaphragms are hard and bagged out. I thought I could get it pumping by cleaning but no.
These are the caps that I did replace this morning. You can see why they were a suspect.

With the clean carb and ignition tune all I have to do is look at the starter rope and it pops right to life! I'm gonna love this motor when the new pump comes in.

I love the smell of a two stroke outboard in the morning!