Mercruiser 3.7 Quadrajet Flooding Out - Help I am 11 months into this!

[rozicrc]

Terry I read and checked all of that when I was troubleshooting the float level and fuel pressure. I have a fuel pressure regulator installed and have confirmed 4 psi as well as the needle and seat hold at 7 psi with fuel in the bowl.

 

[stonyloam]

I have looked for the thread where the person finally wound up using the Airtex pump, but I have not been able to locate it. You are right it does not make sense that with the regulator in line it still floods. Unless it has something to do with the positive displacement pump. You know the Airtex pumps are only about $32, it might be worth a try to see if it works. If it did you would only have to add a fuel pump relay and a oil pressure switch for a permamant instillation. Better than driving yourself crazy!

 

[stonyloam]

did find this: https://www.youtube.com/watch?v=lQVlnK1g59s

 

[NHGuy]

If you flip the carb over will it hold vacuum at the inlet? That's the test my carb book has. And I am not home but I recall 15/64 as correct float height on my qjet. Which is not for the same engine so, who knows.
Were both carbs old rebuilds? Were both spec'd for your engine, jets, etc? I will be able to help you later. If you want to talk we can phone when I get home. I feel pretty confident on marine qjets. Send me a PM if you'd like.

 

[rozicrc]

It is close so at least it should fire. I am going to replace the coil and plugs as well as they are fouled from the incorrect float usage. I am getting a bit more orange than I woul like and this will rule it out. The carb needle and seat hold vacuum and pressure with fuel in the bowl up to seven Psig so this is really messing with my head. Between the fuel pump saga and the wrong float maybe I am looking in the wrong place so I will work over the ignition to make sure it is not causing me secondary pain...otherwise I will be looking to send my carb to someone to run on their boat.

 

[rozicrc]

Nhguy both carbs are the correct art number and internal specs for this boat engine. Both are rebuilds by me, if I am making a consistent mistake I would love to know what it is but do not think this is the case. I am an engineer and ex machinist so I am confident in the measurements and setup...that being said the boat is still not running...

 

[Willyclay]

Disclaimer: I have never rebuilt a Quadrajet but found the link below that may be of some help although all references are automotive.

http://www.thecarburetorshop.com/Troubleshooting.htm

I am old enough that I owned cars with Quadrajet carbs. They were notorious for developing leaks via the welch plugs in the bottom. I have a repair kit on my workshop shelf for that exact problem. Your situation sure reminds me of this classic issue. Try PM'ing forum member Bondo who recently posted that he epoxied the holes on one of his. Good luck!

 

[NHGuy]

By any chance did you do the trick with the accelerator pump check ball. You use the old ball in there and give it a tap with a flat punch to reshape the check ball seat. Then you put the spring back in.
Also since you are getting too much fuel could there be low manifold vacuum? That would allow the primary rods to rise and feed too much gas.

 

[SDSeville]

How about some pics of the fuel pressure gauge setup? I don't know how to the pics smaller on your phone but it is easy when emailing a picture to yourself.

 

[ematz22]

I have a quadrajet also that had the same issue. After taking it apart several times couldn't get it right. I actually live near Rochester where the were manufactured. I found a man that worked for them for 30 years as an engineer. He rebuilds carbs on the side now for $200. I know many people at my marina used him with zero complaints. If you are interested I can give you his contact number.

 

[rozicrc]

Changed the plugs and tried - nothing still died after a few seconds. Changed the coil back to stock and it ran well. Ignitor ii coil went bad with maybe 8 hours on it. I figured it was still flooding out as it would run and die like it did with the bad float/new fuel pump, but it was just what shook into the carb brought the primaries when it would start to run rough and stall. At least I know quadrajet tear downs that o could literally do blindfolded now!

Thanks to all who helped, this was a pain but I am glad we were able to resolve

 

[biggjimm]

Another thought, you said you checked the needle & seat with water & air pressure. Gasoline is a lot thinner & lighter than water & may seep past the needle & seat valve where water won't??? Just an observation. Good luck & hang in there, these guys will help get you fixed up. Jim

 

[rozicrc]

It is running. No first did the test with water then with gasoline. Gasoline is 20 percent lighter Han water so what you are saying is correct

 

[biggjimm]

Ok good, for some reason only the first page loaded when I first read your post. Now I see that you have it resolved. Good job.