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Carb issue on 1985 Mercruiser 170 - Wellcraft American 192

M

Mark1960

New member
HI, need some advice and what I am pretty sure is a carb problem..But I have been wrong before. My 170 starts ok...After running for a while, it starts to run rough, sputter then stalls. Then its hard starting,...If I pump the throttle and put in full position it will start. I bring throttle back to faster than idle position and it will start to stall..I can pump it but it bogs and stalls. It actually ran at fast idle for 20 mins this way after a 2 week sit. I broke down this way in the middle of Cape Cod bay a few weeks ago...All the cranking actually killed the started. When I got back I took out the little filter in the carb and it was all black..Figured this was the problem. I just replaced the starter cleaned out the filter but it still does this stalling thing after running. I pumped the fuel out of the bottom of the tank and its clean and water free. I use treatment religiously when I fuel up.

DO I need to rebuild the carb? Any ideas? Fuel pump, accelerator pump? I am disppointed as I had wanted to get her out this weekend..Supposed to be near 80....
 
My first suspision is the Choke is staying closed when it is warm.

Do you understand enough to determine if the choke is functioning properly?
 
Your conditions you report

""After running for a while, it starts to run rough, sputter then stalls. Then its hard starting,""

could be choke, feul pump. Also check gas vent on side of boat, blow into it carefully and it should be free and air should pass into gas tank. Not too much air as it will have no where to go but back out at you..............


""If I pump the throttle and put in full position it will start.""

Sounds more like choke if it restarts and runs for a while.

""It actually ran at fast idle for 20 mins this way after a 2 week sit.""

This makes no sense as there is NO high idle for marine carbs..........operator controls throttle position thus rpms..........
 
Thanks.. ANyway..just to reiterate the problem. I replaced the starter this week. It fried the day the boat died...Go figure...Got the starter in and the boat cranked..very happy. Started it up and let it run for a while at a about 1000RPM. It ran fine for at least 20 mins. Then I cut it back a little to normal idle...It started running real rough..Then it sputtered and died. Had to put in full throttle position to get it started..It started, cut it back so I would not blow it up but it almost dies immediately. Cannot save it..Try giving it gas and it just moans and dies. Then I can repeat the whole thing again...Just wont run.. But I did check the choke at the time and it was working.
 
It could be a ignition problem.........when was it tuned? do you still have points or electronic conversion?

Due to the distributor being on an angle it is possible if the motor has high hours the point gap is no longer staying constant or it just may be off enough not to allow it to idle. The point gap directly affects timing which would also give you the symptoms you are reporting......
 
Now thats interesting...I had my boat mechanic do tune up in June. Replaced points, condensor, plugs...It an great at the end of July and Early August. Took her out 2nd week of Sept and thats when she took this turn.. I will have to check the timing... If its not timing then what?
 
Sounds like it could be a plugged low speed jet, if the ignition checks out OK.
That will require a carb service job.

Rod
 
That motor should have a fuel pump with a screen / filter inside it. It should be a bell type. Open it and don't loose the spring. Clean or replace the filter.
The return hose to the carb.- does it have fuel in it ? If yes the pump went. There is a screen on the bottom of the fuel pickup tube. And the one way valve that is the fitting that enters the fuel tank that is connected to the fuel pickup tube could be clogged.
What i would do if it were my boat is rebuild the carb. Make sure there is no fuel in the return line to the carb. and run the motor on a external tank, with fresh clean fuel.

Good luck !
 
Thanks...I will check that...I did not know there was a filter inside the bell type fuel pump.. There is no fuel in the return line. Also, where is the screen on the bottom of the fuel pickup hose...I pulled the hose off the top of the fuel tank to pump out from the bottom to check for water and junk but saw no screen....Where do I look to find that....Previous post suggested timing...Could it be off when the boat gets warmed up? Why does it run ok initially then die....Just curious...Also, I was planning on ordering a rebuild kit and rebuilding the carb. My mechanic friend also suggested it...I just dont want to rebuild the carb and then find I still have the problem...

thanks
 
kghost said:
It could be a ignition problem.........when was it tuned? do you still have points or electronic conversion?

Due to the distributor being on an angle it is possible if the motor has high hours the point gap is no longer staying constant or it just may be off enough not to allow it to idle. The point gap directly affects timing which would also give you the symptoms you are reporting......
Click to expand...

reread for ignition concerns. To check this remove dist cap and see how much side to side play in distributor shaft. If any replace distributor.
 
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