rochester quadrajet carburetor questions

[jcritt1]

I am having some issues with a 1986 mercruiser mcm230 gm 5.0 with the Rochester quadrajet carb. It starts okay when cold as choke plate is closed but as it warms up and the plate opens it seems to be sucking a lot of air. It has the manifold choke. Once running seems fine until you shut it down, then it won't restart without a lot of swearing and fiddling with the choke plate. I'm guessing that it is time to rebuild it but will that really affect the choke issue? If anyone has any ideas or has had a similar issue Please enlighten me as how to proceed. Believe it or not I am just getting around to getting on the water for the first time this year and would like to get this issue resolved as soon as possible. Due to money issues taking it to someone is out so if anyone can help me out I would really appreciate it.  Thanks Jcritt1

[Edspleefman]

Sounds like the carb is leaking down past the bowels. You need to rebuild or replace it. Sorry to be the bearer of bad news but I have been dealing that problem since 1985 . If you decide to rebuild it make sure to epoxy the lower bowls on the underside of lowest part of carb . Use a A@B mix epoxy like JB weld. also make sure to change the float ! Its a cheap fix if you do it yourself. A shop will charge ya about 3 hrs labor. (if they are nice) new carb is the way to go... 350.00 $ rebuild it yourself...50 bucks.  . Also make sure to add a new filter to the deal pal!

[Xxx]

When you shut it off and go to restart it, it won't restart, why because its choking it to much or it won't choke itself. Need a little more info. There are 3 screws on the choke, where the black Bakelite is you can adjust the choke plate buy turning that black round thing, there are marks on the aluminum part of the carb, mark where it was and with the motor hot turn this till the choke plate stands open then tighten the 3 screws up and try that. I personally hate auto choke plates, I turned mine open so it can't work. I pump the throttle 3 times and hit the key and she stays running, whether its 1 week or 1 month mine fires right up without the choke. Rebuilding the carb won't fix the choke issue.

[jcritt1]

Thanks for your response, I will look at the choke linkage as soon as it is light and try the adjustment. Although tonight when I was running with the muffs it seams like it is sucking to much air, it seems to smooth out when you manually close the choke plate some and the air sucking noise diminishes.it seems to restrict the air flow when you install the flame arrester,but if you shut it down it will not restart until it cools down and the choke plate is closed again.input from anyone is greatly appreciated as I am really anxious to be on the water!

[skipper19]

Sounds like from sitting and not running you might have some deposits formed by evaporated fuel in the idle bleed circuit but as mentioned check the automatic choke setting too. A quick and easy fix could be treating the air stream into the top of the carb while it's idling with some sea foam. Get it at Auto Zone or whatever automotive parts and accessories store you have nearby. A spray bottle will make it easier or you can sprinkle it in slowly from the can. It will clean bleeds that supply air at idle. They are small brass tube and one is in the body midpoint of the choke plate I believe. Been a while since working on one. You will get some blue smoke from the sea foam burning off but it's no worry. Snap the throttle a few times to create high vacuum in the manifold and draw air into those idle air bleeds along with the sea foam. It will clean the deposits out.

Just thought of one more thing. Make sure the carb bolts are tight to the manifold. No vacuum leaks anywhere. If your engine is warm and the choke plate needs to go closer to closed or you place your hand over the carb throat and it smooths out running at idle, the engine is not getting enough idle circuit air from the bleeds and trying to pull fuel and air from the venturi running circuit leading to your lean idle condition. If the sea foam doesn't clean up the problem then it needs internal cleaning and a kit. Hope this gets you going quick without a problem. I hate not being able to fish until the last hour of the season!

Mark

Cent frum my notso smart fone

[Reel Overtime]

I had this issue with my past boat, a 86, 350,  thought I would save some money and bought a carb off E-bay,    not.

after sending the first one back and the second one just burning fuel like no tomorrow and still stalling, I had a local marina do a rebuild and electric choke on the original. cost less and ran like it should.  good luck Rick

[longbow]

There is a fella in Ontario that works on carbs.  He invented the Quadra Jet for Delco.  Fella in our Marina took his to him and he said his boat has never run better.  I'll find his name.  He is an older gent but like I said if I am not mistaken this fella invented or holds pattens to the Quadra Jet.  

[borderline 350]

The gentlemen's name is Tom Toal in Ontario, NY. He is the man to do Q-Jets and any other Rochester Carbs. His Work is flawless. Sincerely,.....X-Jet Boat Bill

[longbow]

That is the man!