Merc 165 again.

[jam39vw995]

Ok, we're ready to scuttle this damn thing!<br /><br />The engine runs and revs fine with no load.<br />Once you put it in gear and give it gas there is no power, none, and it pops back through the carb.<br />Here's what we;ve done so far.<br /><br />changed leg oil<br />New plugs<br />new wires<br />new cap<br />new points<br />had carb rebuilt by a marine mechanic<br />new fuel filter<br />Checked timing, dead on 6 btdc and it does advance when engine revs<br /><br />I'm thinking now that the timing chain jumped since the ignition timing is right on but it sounds like timing.<br />vacuum at idle is 16 which indicates late timing, then it drops down quite low (6) to where the gauge says late valve timing.<br /><br />Any suggestions would be greatly appreciated.<br /><br />thanks

 

[Trent]

Re: Merc 165 again.

Have the carb done "Again" This the six cylinder or four cylinder?? Popping is a lean condition most of the time.

 

[jam39vw995]

Re: Merc 165 again.

ok, thanks Trent.<br /><br />Yes, this is the inline 6. We were a little skeptical of the carb since the mixture screws don't seem to do much and I don't see and accel. pump into the carb, unless that's normal.

 

[LubeDude]

Re: Merc 165 again.

Did you actually set the dwell with a dwell meter , or just guess at the point gap! I hate points, put in a Pertronix unit and be done with them! About $80.00!!

 

[rodbolt]

Re: Merc 165 again.

hello<br /> the 2bbl rochester has an accelerator pump. with the wingine off and the flame arrestor off have some one work the throttle while you are looking down the venturi cluster. you should see 2 strong streams of gas every time the throttle is advanced.<br />if it is weak or non existant that will cause a lean out and a backfire on acceleration."popping" can be caused by numerous things. but not a jumped timing chain on that engine. because that engine has a timing gear arrangement. it either works or its all the way broke. I love points. if points are kept up they go and go and go with no worries and they will not leave you stranded waiting on a module.carefully test compression or better yet do a cylinder leak down. make sure you dont have any sticking valves. stuck valves and or a restricted exhaust will cause minor popping at speed and a low vacum as well. I dont think timing is an issue. when was the last time the engine was known to run well and what has been done since?<br /><br /> good luck and keep posting

 

[Bondo]

Re: Merc 165 again.

I Agree with All Here......<br />Sure Sounds like a Fuel Issue to me....

 

[mercrewser]

Re: Merc 165 again.

Had it all the time with my 250 I6. Carb jets get clogged. Run it up to 2500 Rpm and choke it. Alpo can over the carb worked for me. Just make sure you have the blower runnin and a buddy with a fire extingisher nearby. This is dangerous. Install a good water fuel seperator. Your tank is old and is corrupting your fuel system.

 

[jam39vw995]

Re: Merc 165 again.

Excellent posts.<br /><br />Yes, points were set with dwell.<br /><br />No to the squirting gas. I knew it wasn't right.<br /><br />We can try the alpo can, but after spending $140 to have the carb rebuilt can you guess where it's going? <br /><br />Excellent forums, highly recommended for any boat owner.<br /><br />Thanks.

 

[ithrowgirls]

Re: Merc 165 again.

Howdy,<br /><br />I had almost the exact same problem with my 155 horse OMC. Turned out the carb was not squirting, just like you've found. There's a little spring inside the carb with a rod going through it. Down at the bottom, should be a rubber (think it's rubber) seal, which forces the fuel to spray into your intake. Mine was deteriorated into almost nothing, so make sure this gets checked out. Also, a simpler thing to check first is to verify that you have the carb connected properly. IF it's not hooked up on the outside, well, you'll have no spray! Good luck!

 

[LubeDude]

Re: Merc 165 again.

Looks like you found the problem! Id still change over to electronic, but carry the points with you in case you have a failure on the water!

 

[mercrewser]

Re: Merc 165 again.

You can put a brand new carb on that engine, turn the key and clog it with junk. The stock filter MerCruiser put on that engine is inferior. You dont have a propeller problem. Just be careful with the alpo can. Try to choke it with the linkage first. This is a temporary solution. It will clog again right away. Put a better filtering system on it right away. I drill a hole in the alpo can to let the fuel that gets sucked in run back into the engine (releases vacuum)

 

[rodbolt]

Re: Merc 165 again.

better to fix it than alpo it.<br /> take the carb someplace else. if you had so much trash in it that the large passages of the accelerator pump circuit clogged it should be flooding and all kinds of other nasties.<br />most of the inline engines had a very nice filter on the fuel pump that is more than adequate for debris but not at all for water. the problem with that filter especially the later 120/140 was its impossible to change and if you break off the steel screw that holds it altogether you have to buy a new pump. I read a post awile back about never junking a carb. if I open one up and its full of the white corrosion nasties I toss it in the trash. some carbs that have been exposed to water and corroded internally are just junk.<br /> I would ask the mechanic to open it up and let me see what it looks like inside. if its all pitted and nasty, chunk it and buy a reman.<br /> if you play with it to much you will damage something else or cause a fire or worse possibly hurt someone. but first a compression and/or leakdown will tell you if the engine is mechanically sound.<br /> a new carb with a stuck exhaust or intake valve wont work either.<br /><br /> good luck and keep posting<br />suck,squeeze,bang and blow. all the right amounts at the right times and its a purring kitten

 

[mercrewser]

Re: Merc 165 again.

I was implying that the carb is fine. I think the jets keep getting clogged from junk in the tank. My alpo method is very dangerous and on second thought you should find a safer way to choke it.

 

[Bhamil]

Re: Merc 165 again.

Rodbolt; suck,squeeze,bang and blow. all the right amounts at the right times and its a purring kitten? For shame, rodbolt. I thought this was a family forum. You should have written commercials for the Superbowl or lyrics for Janet Jackson! Tsk, Tsk.

 

[Trent]

Re: Merc 165 again.

Ben. What did Rodbolt say that was so bad??

 

[rodbolt]

Re: Merc 165 again.

wow some dirty minded folks. its a simple way to remember Intake, compression,ignition and exhaust. from what I see on this board most posters either forget the basics or dont know them. it does not matter who or where the motor was built it has to perform all the basic functions at the right time with the correct air/fuel ratio and it will run perfect. if any are out the performance degrades rapidly. sorry I didnt watch the bowl game. sounds more like a toilet bowl game.<br /> yall have a nyce day now ya heah

 

[donzi5]

Re: Merc 165 again.

Try simply replaceing the condenser. Can't tell you how many I have had bad from the supplier. If you have a spare coil laying around try that also. Donzi5

 

[Bhamil]

Re: Merc 165 again.

To Rodbolt and Trent; He said nothing bad, I was teasing. I thought it was pretty neat and just threw a tease at him. The bit about the Superbowl was a shot at some of the lyrics in a few of the "tunes" (I use the phrase loosely) but I found nothing offensive in what was posted here. Sorry if I led anyone to believe otherwise.

 

[jam39vw995]

Re: Merc 165 again.

Here's an update.<br /><br />My friend decided to pull the exhaust manifold and head against my advice. I was sure it was the carb and after much slapping around he finally took it back to the mechanic. There was something wrong with it for sure. plugged main jets and no accel pumping.<br />He then took the head to a machine shop where they estimated a 600 repair for new guides, seats, and valves plus shaving it a little to deal with warpage. I guess it was beat up pretty good.<br />Maybe this was a good thing anyway. Turns out the head was not a marine head, smaller valves and steel frost plugs. He paniced and was almost going to spend the $ to get it fixed or to buy a new head.<br />I talked him out of it, and he found a good used marine head that needed no work for $200 and the mechanic fixed the carb.<br />Early indications are that it's running great, he was in a hurry to get home last night so I haven't heard it run yet.<br />whew!<br />I hope nothing else happens.

 

[mercrewser]

Re: Merc 165 again.

Something bad is gonna happen if you dont address that dirty tank and lousy filter. Those jets are gonna clog again.