backfire through carb

[Davidmerc140]

I have a Merc cruiser 140 #3681706 and I'm getting

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back fire through my carb, I rebuild a carburetor , change the fuel pump change the spark plugs, and check the timing. I've determined I have a leak in my exhaust manifold which I sealed I sealed it to determine whether the leak was the problem. after reinstalling the exhaust manifold I still have the same problem of backfire the carb I'm stumped I'm not sure what the problem is I don't seem to have any intake leaks

 

[86 century]

Re: backfire through carb

Have you run a compression test on the eng.
Made sure the firing order is correct.

Does it backfire all the time or just under certain loads.

 

[Bondo]

Re: backfire through carb

I have a Merc cruiser 140 #3681706 and I'm getting

---

back fire through my carb, I rebuild a carburetor , change the fuel pump change the spark plugs, and check the timing. I've determined I have a leak in my exhaust manifold which I sealed I sealed it to determine whether the leak was the problem. after reinstalling the exhaust manifold I still have the same problem of backfire the carb I'm stumped I'm not sure what the problem is I don't seem to have any intake leaks

Ayuh,.... Welcome Aboard,... Generally speakin',... Backfires through the carb are caused by a Lean condition...

 

[81 Checkmate]

Re: backfire through carb

May i ask how the reseal was done?

 

[Davidmerc140]

Re: backfire through carb

Are you referring to the seals in the outdrive?

 

[Davidmerc140]

Re: backfire through carb

Well the carb seem to be in good condition and the adjustmests were pretty straight forward ....

 

[Oshkosh1]

Re: backfire through carb

When does it backfire?

Is it running?

Is it occuring at startup/shutdown/during operation/under load/acceleration?

Take a can of starting fluid and spray around...a little at a time so you can determine the spot if necessary...to look for possible leaks.

If it's running you might do a vaccuum check also.

 

[81 Checkmate]

Re: backfire through carb

Reseal on the the manifold?

 

[Davidmerc140]

Re: backfire through carb

Hey buddy braised it for me

 

[Lyle29464]

Re: backfire through carb

Don't get sidetracked. The manifold is not the problem. Check for air leaks, under carb, intake, fuel restriction.

 

[81 Checkmate]

Re: backfire through carb

The reason i asked how he fixed it is becouse he could be sucking air in on the intake side.........Thru a botched up repair.

Thats not a sidetrack in my book!

Good Luck David!

 

[Davidmerc140]

Re: backfire through carb

Well as i checked the compression in engine I realized I had had to disconect fuel and fire to plugs and decided to wait till the morning ,I decided i had time to turn distributer just a hair to line it up with first plug at tdc and i got it to run with no backfire . I still need to check the compression and timing adjust the carb and so i will keep you guys updated far from fixed thanks for the replys