Efi 1998 5.0 mercruiser flooding from over flow tube on tbi carb


New Member
Oct 20, 2023
Boat Info
21.5 2k express cruiser
305(5.0) mercruiser efi raw water pickup
Guys I'm flabbergasted have replaced every sensor fuel pump and regulator filter hoses the injectors spray perfectly fuel pressure at 40 psi and keep getting a huge amount of fuel come out through the overflow tube on the bowl of the carbs regulator I have a screw in there temporarily and it runs fine. Albeit injectors sounds louder.. but it's obviously not soposed to be closed for a reason I also of course serviced the cool fuel. What can this be? It's Def not the ecm it's running the injectors perfectly can it be something with the spring and gasket in the carbs regulator /float bowl! Super frustrating thanks in advance


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Yes I believe that's correct the manual says from 30 to 40 is okay I believe don't think this much gas should be pouring out of the overflow with a little higher psi? Tomorrow I'll post a short vid maybe someone could help me sense of this
What are your symptoms? I have a similar issue with my TBI injected big blocks and the overflow tube drips after I shut down from a run, and then is hard starting
When I put it in Ac the Injectors spray a nice pattern but when I fuel pump primes it shoots alot of gas into the Barrel enough to fill it up completely if it's closed then even while injectors are spraying it's odd the regulater on the bowl seems to be working I'm getting a more or less normal psi. I mean So much fuel that it ends up flooding the oistons then filling the pan with fuel that gets through the rings
I've looked everywhere for info on it and nada
Replace the fuel pressure regulator. Def. shouldn't be 40
Dang that's two of them I replace lol I will give it a go anyways thanks bud
Yea it is I think I just figured it out Logically the overflow tube it has there is just to tell you that the Diaphragm is bad and leaking to the bottom of the bowl I don't see any reason fuel should even be in there unless there's a hole or crack that it's getting through does that make sense

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