Merc 3.7 hard start and carb backfire

[bogie418]

I need alot of gas to get the engine to finally turnover (three full pumps, and throttle on 3/4).<br />There is usually a backfire in the carb. Sometime the backfire will cause a stall, but it will fire up ok after this happens. Other times Ill get two or three backfire and then everything is ok. The motor runs fine once its started. It idles at 750rpm comfortably. But taks a long time before she'll turn over. Any ideas?<br /><br />Thanks Dave

 

[lowshovel1]

Re: Merc 3.7 hard start and carb backfire

when cold try 1 full pump to set the choke,give it 1/4 throtle. let us know how this works for ya. sounds like your flooding it.

 

[SeaSkwurrel]

Re: Merc 3.7 hard start and carb backfire

I thought backfires indicate too lean of a mixture.

 

[lowshovel1]

Re: Merc 3.7 hard start and carb backfire

you need to make sure choke is operating properly

 

[MrBill]

Re: Merc 3.7 hard start and carb backfire

Check inside carb to determine if there is raw fuel inside before you "pump", float valve may be worn and too much raw fuel may be causing the backfire. This will be exagerated if the choke is out of adjustment. On mine, I open it to one-half (no pump) and it starts first time, every-time after a carb rebuild and change over to electronic ignition.

 

[Don S]

Re: Merc 3.7 hard start and carb backfire

When was the last time you had a full tuneup. Points, condenser, cap, rotor, spark plugs, setting the dwell, adjusting the timing, checking advance timing, adjusting the carb mixture and idle speed, adjusting the choke.<br />Also do a compression test. If you have leaky valves you could have some popping.

 

[bogie418]

Re: Merc 3.7 hard start and carb backfire

Thank you all....<br />Ive decided to do a complete tune up and carb rebuild. I think this will be money well spent.<br />thanks again