volvo penta 90, only runs on choke

[xluke]

Hello,
I am trying to repair a volvo penta 90. After a thorough carb cleaning I got it to run on choke but it stalls out of the choke is completely closed. If the choke is even open a few mm it will still run. It produces a ton of smoke and if I run it like this for a while fuel starts dripping out of the back of the carb throat.
I noticed today that if I disconnect the fuel line and let it stall itself out, before it stalls it all of a sudden works perfectly with the choke closed (good throttle response, etc.). This lasts for maybe ten seconds and then it dies. This made me suspect the float but I have adjusted it a thousand times... (though maybe the needle is bad or the seating is bad, though it looks fine). I also pressure tested the seat with a syringe and with light pressure on the float it sealed to a fair amount of pressure.

Any ideas? I am considering retrofitting a different carb to it (I would have to buy one though) as I can not find a replacement carb nor rebuild kit for this one...

Thanks!

 

[JasonAych]

Re: volvo penta 90, only runs on choke

Does it have a "bing" brand carburetor?

 

[xluke]

Re: volvo penta 90, only runs on choke

You guessed it! Its a Bing 62 / 15 / 102 ("Type 62")

Does it have a "bing" brand carburetor?

 

[JasonAych]

Re: volvo penta 90, only runs on choke

Currently I have a 5 hp Zundapp that has a similar problem which also has a Bing carb. Mine stalled the last time I used it. After finding a very dry spark plug and good spark I checked for fuel flow, bowl was full, pulled the jets, which seemed clear. I will be investigating tomorrow. If I figure something out, I will keep you posted. Please do the same.

 

[JasonAych]

Re: volvo penta 90, only runs on choke

Prior to going through the carb yesterday, my spark plug was dry now it is wet. Now I am having ignition issues so I can't tell you if what I did worked all I can say now is that I wasn't getting fuel to the plug and now I am.

Here is what I did with my BING carburetor. Replaced all my fuel lines since I had a full bowl which had turned to varnish. The main jet and slow jet are fed at the bottom of the bowl by the tapered brass bolt which has a metering orifice and 2 feed holes. Obviously make sure this is all clear. The slow speed circuit is a metered tube that runs down the center of the main jet which is threaded in from the top of the carburetor. Make sure this is all clear. This tube reaches from the bowl to the top of the venturi. There is a metering screw just before this idle tube. This screw meters/baffles air draw. The more you close it, the more fuel is drawn into the idle circuit and less air. So turning the screw in richens and out leans at idle. This is opposite most. The high speed is fixed. I made sure the idle circuit was clear by putting the plastic tube from the carb cleaner up the the main jet from the bottom into the top where the idle tube comes through. I then covered the bosses where the idle tube threads in and the idle screw threads in with my fingers and sprayed the cleaner through observing until I saw cleaner spraying from the jet in the front of the venturi and back of the venturi. Finally I made sure the fuel feed circuit was clear. I like to run copper strans of wire through everything, spray carb cleaner through them and compressed air as a final measure. I take time to study the carburetor and understand all the circuits and passages. I rarely have to take a carburetor off again and usually get in the first time using these methods.

You may also have a week fuel pump. See if you can keep it running by continually pumping the bulb. Don't over due it, just pump the bulb to keep it moderately firm.

Now onto my ignition issue. Hope that helped.

 

[JasonAych]

Re: volvo penta 90, only runs on choke

Also, I noticed and repaired something with the idle tube. Just under the threaded part of the idle tube at the top there are holes that feed the idle circuit. Just below these holes is a collar. If you look into the hole this threads into there is what appears to be a packing material to make a seal. This seals the circuit from the venturi at this point. If you think about it this would make sense. If the seal doesn't do it's job, it would lean out the idle circuit. I was missing half the seal. I made a new seal by using a punch about the size of the hole the tube treads into and drilling a small hole in the center of a piece of PVC rubber material I have. PVC is supposedly OK with ethanol. I got the PVC from a plumbing supply store. Used for tubs are something like that. It seemed to be about the same thickness as the remains of the old seal. Gotta do what you gotta due when things are made of "unobtainium".