1977 175HP Black Max - poor accelleration and sometimes loosing prime

[keviwe]

Had the same poor accelleration issue last year. Replaced fuel pump kit and all carb gaskets in 2014. Then motor sat for 4 years. Fuel pump kit has maybe 2 hours of use since replaced in 2014. Starts fine, idles fine, accellerates sluggishly, but runs fine once it revs-up. Sometimes will stall during throttle-up. Must then squeeze primer bulb, then it will run and accellerate (but accellerate poorly - takes maybe a minute to finally get up to full rpm). I replaced the suction side of the gas hose (from bulb to tank barb fitting). two 6 gallon fuel tanks have vents open. Ran motor for for 3 hours off and on. Loaded onto trailer, tilted motor up, drove home 30 minutes. Pulled gas hoses off fuel pump pressure side (3-hose barb fitting which goes to 3 carbs) - no gas ran out. Pulled gas hose off fuel pump suction side - no gas ran out. Gas did run out of main gas hose when I lowered it toward ground (I guess gas siphoned out?)
Could primer bulb check valve be allowing "leak down" letting gas to run backwards back into tank? Could BOTH 6 gallon tanks have bad O-rings in the barb-to-socket connection (I put some grease on the tank barb to see if it would "seal" a possible air leak at the tank barb fitting - no improvement was noticed).
should I put a new fuel pump kit in (anyone know that fuel pump part number?)
Also read that float levels are critical for good accelleration. I wouldn't think float level chanced mby itself but I will pull all carbs and check them if you think it's a good idea. (If I do what is the float level measurement (and measure from where to where?)
Thnaks for your advice!!!

[boats.net]

Ethanol gas will deteriorate fuel pump diaphragms and rubber fuel hoses even if engine has not been run so I would probably check them first. If you see any black or plastic looking debris in fuel filters then there is bad fuel hose, primer bulb or rubber components bad.

[keviwe]

I have only used 100% pure gas (which happens to be Premium grade). I used pure-gas.org to locate ethanol free gasoline.
I will replace the primer bulb and put in a fuel pump kit and check strainer.
What fuel pump kit part number do I use for my 1977 Mercury 175HP serial 04733877
Also please recommend a high quality primer bulb with 5/16" barbed ends

[boats.net]

On the longer fuel pumps then use kit number 89031A2.
On the square fuel pumps use kit number 42990A10
Use Mercury primer bulb, 8M0061876

[keviwe]

I ordered fuel pump kit 89031A2. Also ordered Mercury primer bulb 8M0061876 and new alcohol tolerant fuel line.
Can someone send me a link that shows the sequence of gaskets and diaphragm in the fuel pump. Thanks!!

[boats.net]

The parts catalog is a good source for that, https://www.boats.net/catalog/mercur...-inline-filter

[keviwe]

Thanks for all your help!!!
Does the Fuel Pump Kit 89031A2 include the check valve assembly #24 on exploded view (image 18887) Part# 30430A2. If not should I replace that as well?

[keviwe]

One last question (hopefully)
Mounted on the gas tank, the "socket" (housing) that accepts the fuel line male barb adapter. This could be something like Mercury Part 83618M. There is a seal #92037 inside the housing "socket" that seals the tapered barb adapter as it twist locks onto the gas tank. I have the genuine Mercury 6-gallon tank and this SEAL #92037 is no longer available. Is this something I should replace too? Any suggestions on where to find this seal. I hate to have to throw away a genuine Mercury gas tank.
PS I have two other aftermarket 6 gal gas tanks with an aftermarket female adapter and If necessary I can replace the whole female adapter BUT I have the same fuel starving issue no matter which gas tank I use.