Popping sound on 2t 75HP outboard

[onemanorthree]

All, just service 75HP 2T Mariner and it's running fine. Took a little to get it started after 6 months off, but once it got going it was fine.

One thing I noticed there is a small pop ever 5 or so seconds and it spits more water adn some smoke from the prop.

Is this anything to be worried about? I'm selling this so just want to make sure it's in good shape.

 

[KevinV]

Did you replace the plugs like-for-like? Some engines can be very sensitive to supposedly compatible varieties

 

[onemanorthree]

I actually was given different plugs by my Marine supplier. Then didn't have the ones I wanted in stock but said that
the ones I got were the same. The looks identical to the ones I replaced though. I'm not 100% sure what the actual difference was though.

I kept the olds ones so I can take photos of both, plus part numbers.

Do you think the engine sounds ok?

 

[KevinV]

I actually was given different plugs by my Marine supplier. Then didn't have the ones I wanted in stock but said that
the ones I got were the same. The looks identical to the ones I replaced though. I'm not 100% sure what the actual difference was though.

I kept the olds ones so I can take photos of both, plus part numbers.

Do you think the engine sounds ok?

Try the old ones back in it - I have a strimmer that runs remarkably better on champion rather than the equivalent ngk, and one of my bikes is the other way round - there are obviously slight differences.

I don't know enough about outboards to comment on how yours sounds, so won't. My only query would be about the hosepipe - you're sure you aren't forcing water in? Also, with the prop out of the water, are you missing back pressure? A wheelie bin is traditional for test running.

 

[onemanorthree]

Yes, I am feeding through a hose, I do have a bin somewhere around, I'll use that tomorrow when I go down to finish work.
Might try putting back sparks in, but apart from that popping it sounds fine.

 

[onemanorthree]

I've put the engine in a bucket now it was running well the first time, Friday, for about 20 mins.
Tried again today and it's popping again. You can see at at the X second mark, it pops and then blows smoke.

Engine Troubleshooting: Popping and Starting Issues

I've been experiencing some trouble with my engine and could use some advice. Here are the details:

Initial Success​

• Day: Friday
• Duration: Ran well for about 20 minutes.
• Issues: Was very hard to start, took easy start in carbs to get going.

Current Issues​

• Day: Today
• Symptoms:
  • The engine is popping and blowing smoke. You can see this happen at the 10-second mark and at the end in the below video.
  • It's hard to start. I turn the key and push it in to release some petrol into the carbs, but it doesn't start.
  • The engine only starts when I spray Easy Start into it.
  • The engine idles at 20,000 RPM, but it usually idles at 10,000 RPM. The RPM fluctuates when the popping happens. (second video)

Possible Causes​

• Fuel Delivery: It seems like there might be an issue with the engine getting petrol.
• Spark Plugs: There might be a problem with the spark plugs, although I haven't changed back to the old ones yet as I wanted to give the new ones another shot.

Any insights or suggestions would be greatly appreciated!

Thoughts?

Here is the rev counter:

 

[BruceK]

The first vid your engine has a through hub exhaust. Running in a tub will do that, try it with the boat in the water.

The second video you are leaning out. You have a fuel blockage, duff pump or some other fuel delivery restriction.

 

[onemanorthree]

@BruceK - ok thanks, makes sense re popping.

Re' the fuel issue, when pumping the fuel in, the bulb never goes hard, so I think there is air getting in from the connection.
I bought a new connector to the engine, and tank, plus new line and bulb, but still the same issue. I notice the connector at the tank
end is not very tight (see vid) . I was hoping not to have to get new tanks as I'm selling. Are there any other options for me. I dont think
this is the correct connector but it's what the supplier had, they said it matched.