1973 Evinrude 25 sneezing

[breakerbryo]

Hi All, I'm under a bit of pressure to get a boat from our dock to the public launch and having a few issues.
Motor ran fine in May, sat all summer with no fuel in it inside a shed. Compression is over 150 psi, new OEM head gasket, new impeller and the coils look nice and new.
I went to run it with a new primer hose from Amazon and had a terrible time starting it and ultimately had to put brake clean down a plug and it started.
It sputtered and I thought sneezed, stalled etc. I installed a new fuel pump, hoses with clamps and tried turning out the the jet and squeezing the primer and it seemed to be slightly better. The carb which was spotless inside is currently in my ultrasonic doing it's magic, I tried switching plugs yesterday to no avail. I remembered on my way home that it has points and will clean them next. Any thoughts or suggestions greatly appreciated. We can't get parts here so everything is a huge PITA so I need to think in advance and have parts on hand. I'm going to look for a timing light today.....can't remember the last time I used one. Likely next to my GM turn signal cancel springs lol. I do have a parts motor here. Thanks in advance!

 

[breakerbryo]

The fuel hose is 3/8" and the plugs are J4C's I was thinking of switching to QL77's... looking for reliability so I don't mind spending money.

 

[racerone]

Does spark jump a gap of at least 1/4" ( 6 mm ) or more , yes or no?-----Sounds like throttle plate is opening too early.-----Thermostat installed and working properly ?-----J4C is the correct plug.

 

[breakerbryo]

Thanks racerone. I'll have a look tomorrow. I found a timing light today so I'll let you know.

 

[oldboat1]

I think your carb has a slow speed needle valve at the top of the carb -- adjusts air/fuel mix. Try enriching the mix by rotating the needle slightly counter clockwise.

 

[brodmann]

In the attached diagram of your carburetor, items 4, 5, 35 are all part of your idle circuit. The plugs need to be removed so you can thoroughly clean the passages beneath those plugs. In order to do this, you'll need to order a carb kit which will contain the replacement plugs. If you don't have access to carb kits, remove the idle mixture screw (#42), and spray carb cleaner and compressed air if you have a compressor. That should clear out idle passages. If you're having to spray something in plug holes to get it to run, I think you have a fuel delivery problem.

 

[breakerbryo]

I think your carb has a slow speed needle valve at the top of the carb -- adjusts air/fuel mix. Try enriching the mix by rotating the needle slightly counter clockwise.

I tried that the other day as well as squeezing the fuel hose. Going back out today with the carb that was spotless inside that is now cleaned in ultrasonic. I didn't have a kit handy or I would have removed the welch plug but I am sure it is not the carb however I wouldn't mind being wrong...

 

[racerone]

See post #3

 

[Crosbyman]

I tried that the other day as well as squeezing the fuel hose. Going back out today with the carb that was spotless inside that is now cleaned in ultrasonic. I didn't have a kit handy or I would have removed the welch plug but I am sure it is not the carb however I wouldn't mind being wrong...

actually... at idle ....the fuel is extracted from the upper section of the carb so the welch plug cavity is a critical path to check out.

the top half of the carb's side channel leading to the upper cavity & idle screw is a very narrow passage and also needs a close inspection .

Blow out the side channel and confirm the cleaner exits the top half via the small needle hole into the top idle chamber under the welch plug. REMOVE the idles screw and plug the screw hole with a finger to force the carb cleaner towards the idle chamber .

 

[breakerbryo]

I may want to slap myself in the head....but won't know till tomorrow how stupid I am.
Compression 135/135. Spark tester shows steady spark, gap tester shows 1'4"
Can't get it to run properly to use timing light. personally, all I have ever done is the impeller and head gasket, maybe plugs.
Carb is back on, needle at 1 turn out and I adjusted the throttle plate linkage.
I pulled the rope starter which had a stripped bolt -fixed with Time-Sert, found a chunk missing where it had jammed or something - put on my spare,
the bolts for the flywheel were 1/4" course. I thought they should have been fine thread but whatever. Cleaned the points -did not look disgusting but one was at 0.014" and the other at 0.020". I don't have the OEM tool but the cam lobe is marked "set". Wires all looked like new. Runs like crap. Pulled the plugs, installed new J4C, gapped. Ran like turd. Changed a coil out even though I had spark indicated on all testers. Motor ran then stalled and would not restart. Starts on brake kleen in #1 then dies. By this time I have played with the idle jet, primer and have even had it to the point I thought it was fixed. Then it dies.
I decided I was running the brake cleaner in the top hole too often when I found the top plug covered in soot but dry and the bottom plug clean and wet. I installed 2 more plugs then switched coils top to bottom. I now have the head off and there is raw gas in the lower ports on the exhaust side #2 (no water). I swapped the head off my spare motor to rectify spark plug thread issues in #2 as my Time Serts were going to be too deep. I didn't restart the motor bc I sprayed the copper stuff on my new gasket and reused it since I can't get one for a week or 2. Going to go back tomorrow and do final torque.
The motor is near level on this stand, I normally run 85-90 hp motors and don't do anything under 50hp. Is it possible the carb is flooding???? The 90hp motors hang a little differently on this test stand. Had a 40hp Selectric on it a month ago no issues but I do recall years ago having to put a brick under the front for something.....this motor is near level though.
At one point we could almost count 1,2, 3 pop, 1,2,3 pop and so on.
I do have a spare carb but it is for electric choke, I didn't look really close at it yet to see if it would fit.
Thanks again! I'm going to learn a bit this week.

 

[OldOMC31]

Did you get it running?