replaced my fuel pump, now gas pouring out of carburetor

possum2082

Petty Officer 3rd Class
Joined
Aug 29, 2010
Messages
98
hello everyone, i'm having a heck of a time trying to get the boat running this season and i need your help.

background: the boat ran perfect last year and was winterized properly.

when i tried to start up the boat this spring it sounded like it was starving for fuel. it would run rough and die at idle if i let the throttle get that low. i disconnected the fuel line going into the carb and very little fuel was coming out of the line when i cranked the engine.

i suspected a lack of fuel and i saw several possible sources: gas tank pick up screen, fuel filter, and fuel pump. i bypassed the fuel filter and eliminated that variable--same results. unfortunately, i can't get the pickup tube out of my gas tank as there is not enough room without ripping out the floor of my aft cabin. the fuel pump is the original volvo red mechanical fuel pump with only an inlet and an outlet.

i know people will go nuts...i replaced it with a gm automotive mechanical fuel pump with just an inlet and outlet--EXACT SAME SET UP AS MY VOLVO ORIGINAL! after i did this and fired it up, gas started pouring out of the carburetor. i didn't get to see where it was coming from as i was looking over my shoulder and couldn't pin point it.

This leaves me with 2 possibilities that i can think of:

the automotive fuel pump pumps too hard or fast?

my carb float or float valve is defective?


i haven't asked any questions here in awhile and could really use your help. please give me some wisdom. you can flame me for the auto part, too
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,092
Re: replaced my fuel pump, now gas pouring out of carburetor

there is also a vent to that fuel pump. The vent hole is what make the pump work. Marine pumps have a fitting with a hose.
This hose is called a "tell-tale" ,its lest you know the diaphragm has ruptured. Without it the gas from the ruptured diaphragm
goes into the bilge and we read about your death in the newspaper.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Re: replaced my fuel pump, now gas pouring out of carburetor

there is also a vent to that fuel pump. The vent hole is what make the pump work. Marine pumps have a fitting with a hose.
This hose is called a "tell-tale" ,its lest you know the diaphragm has ruptured. Without it the gas from the ruptured diaphragm
goes into the bilge and we read about your death in the newspaper
.

Ayuh,..... Agreed,..... A new fuel pump, 'n rebuild the carb,....
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
Re: replaced my fuel pump, now gas pouring out of carburetor

This leaves me with 2 possibilities that i can think of:

the automotive fuel pump pumps too hard or fast?

my carb float or float valve is defective?


i haven't asked any questions here in awhile and could really use your help. please give me some wisdom. you can flame me for the auto part, too

+1 with Bondo and will add, the automotive pump will pump no more volume or pressure then the marine. the marine pump just has the safety vent tube to flood the carb instead of where we might read about you in the paper as Bt Doc mentioned.
 

possum2082

Petty Officer 3rd Class
Joined
Aug 29, 2010
Messages
98
Re: replaced my fuel pump, now gas pouring out of carburetor

there is also a vent to that fuel pump. The vent hole is what make the pump work. Marine pumps have a fitting with a hose.
This hose is called a "tell-tale" ,its lest you know the diaphragm has ruptured. Without it the gas from the ruptured diaphragm
goes into the bilge and we read about your death in the newspaper.

i am totally good with getting a marine fuel pump. however, before i do, please tell me what's up with my old and possibly defective red volvo pump. it doesn't have the tell tale, just a weep hole it looks like. in the pic, the nipple is inlet, the block is outlet and there's a little hole and that's it. all can be seen in the pic.10336635_10202600181659112_8390327397571687254_n.jpg

did the previous owner buy an auto and paint it red? what the heck...or is it just that old.

btw, thanks everyone for helping me out.
 

MikDee

Banned
Joined
Jun 6, 2007
Messages
4,745
Re: replaced my fuel pump, now gas pouring out of carburetor

Looks like an automotive pump to me!
 

possum2082

Petty Officer 3rd Class
Joined
Aug 29, 2010
Messages
98
Re: replaced my fuel pump, now gas pouring out of carburetor

Looks like an automotive pump to me!

that's what i was thinking.

so, earlier when i went to the auto store to get my new one...the guy gave me one with a "tell-tale," from an 86 gm, i told him i needed 2 ports only and so we went back to 75 and found one that matched.

can i use an fuel pump replacement auto from an 86 as long as it has the "tell tale" for safety (clear line plumbed to my carburetor of course?
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
Re: replaced my fuel pump, now gas pouring out of carburetor

that's what i was thinking.

so, earlier when i went to the auto store to get my new one...the guy gave me one with a "tell-tale," from an 86 gm, i told him i needed 2 ports only and so we went back to 75 and found one that matched.

can i use an fuel pump replacement auto from an 86 as long as it has the "tell tale" for safety (clear line plumbed to my carburetor of course?

You can use a fuel pump so long as it has the diaphragm overflow fitting for the clear line which goes to the carburetor, like this Airtex model

Carter M61073 Fuel Pump Marine Mechanical Chevy Small Block 5 0 5 7L Each | eBay
 
Last edited:

possum2082

Petty Officer 3rd Class
Joined
Aug 29, 2010
Messages
98
Re: replaced my fuel pump, now gas pouring out of carburetor

thank you all for your help!

I took apart the top of my Rochester carb last night to find 2 things:

1. it was filled with crap (good news since I know what was causing my bad running even with the new pump).
2. previous owner definitely put in an auto carb along with his auto fuel pump and auto starter :(

we've been running this set up for 4 years and i'm done pushing my luck. i'll be putting on marine parts before I dip it in.

thanks again.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
Re: replaced my fuel pump, now gas pouring out of carburetor

You can use an auto carb so long as you can run the clear tube from the marine pump to the top of it. This way if the fuel pump diaphragm leaks the fuel goes down the carb and not in the bilge.

Getting a rebuilt one isn't a bad idea though
 

possum2082

Petty Officer 3rd Class
Joined
Aug 29, 2010
Messages
98
Re: replaced my fuel pump, now gas pouring out of carburetor

You can use an auto carb so long as you can run the clear tube from the marine pump to the top of it. This way if the fuel pump diaphragm leaks the fuel goes down the carb and not in the bilge.

Getting a rebuilt one isn't a bad idea though

doesn't my carb need a j tube to direct the flow of extra gas down the throttle?
 
Top