Merc 170/470 backfires, dies .. please HELP

[fone_man]

Re: Merc 170/470 backfires, dies .. please HELP

On the way........<br /><br />

<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[jbwilson]

Re: Merc 170/470 backfires, dies .. please HELP

Got it! After checking local dealer's price on accelerator pump ($32), decided to double check the basics ... and ... timing was off! Got it right and she's running like a dream. Still a little hesitation on full throttle starts, probably the acc pump now, but I can live with it. <br /><br />Thanks to all for your help!

 

[Fouled Plug]

Re: Merc 170/470 backfires, dies .. please HELP

Glad to hear you're running better. My bro has the same engine, and the best $ he ever spent was for a Pertronix igniter. Replaces points and condenser, then set the timing once and forget it. Was about $70 and took minutes to install. It now idles smoother, has better acceleration and economy. Trust me, it's the only way to go!

 

[fone_man]

Re: Merc 170/470 backfires, dies .. please HELP

Glad to hear you got some of it resolved... $32.00 for accelerator pump... someone is taking you for a ride, go to your local parts outlet and buy a marine carb kit... comes with accelerator pump & should be a lot less expensive...<br /><br />Thanks for the followup post... as we all like to hear about what has transpired!!!<br /><br />

 

[twollin]

Re: Merc 170/470 backfires, dies .. please HELP

Great information!<br /><br />Fone_man, would it be possible to get those Service Bulletins you mentioned (wollint@saic.com)? <br /><br />I'm having the exact same problem with my Merc 260 Quadrajet as jbwilson - under hard accelaration the starboard engine pops from carb. If I ease into it, no popping.<br /><br />Just now starting to dig into the problem.<br /><br />Thanks.

 

[petryshyn]

Re: Merc 170/470 backfires, dies .. please HELP

Hi gents:<br /><br />Just a few worthless generic tips...<br /><br />>to reduce hesitation on hard acceleration...add 2 degrees advance (for every 1000' above sea level) to manufacturers spec for base timing. eg. if you altitude is 2000' above sea level, add 4 deg. to OEM specs.<br /><br />> quadrajet 4bbl and the 2bbl roch. both have a common failure leading to hesitation.<br />> The power-piston in the quad sticks in the lean position. (simple cleaning from a carb job usually rectifies this, and most people don't realize what they fixed)<br />> the power-piston in the 2bbl sticks in the lean position as well. Not because the bore and piston are dirty, but because the piston bore is worn. Cleaning and polishing improves for awhile, but a new air-horn housing is needed...<br /><br />Hope this helps some poor soal who pulled out as much hair as I have...LOL<br />