mercruiser 140 fuel pump replacement?

[jimmytee]

Tried to switch fuel pumps on my 1984 merc 140. It was running ok at idle but on accelerating would bog down; thought maybe the fuel pump was bad, Switched it with the one from my 140 with the cracked block; it was a good pump when switched engines. It wouldn't start at all, But the old pump back on, still wont start. Is there a wrong way to put one on? I tried taking it off and reinstalling it tonight and the pump seems to work as when I push it in to tighten the screws, it pumps gas. Everything was working; what could I have done wrong?

 

[JCWhiplash]

Re: mercruiser 140 fuel pump replacement?

Make sure that nothing else has happened (such as ignition problem and/or spark plugs) while switching pumps. The distributor is rather close to the fuel pumps on those motors, so make sure.

BTW ... How are you determining the pumping action of each pump? I disconnected my coil leads (so there's no spark to worry about) and disconnected the fuel line from the carb. I then loosened the fuel line down at the pump enough so it could pivot out toward the front of the motor. I then was able to catch any fuel with a bucket while cranking the motor with the starter.

Hope this helps. Sometimes the most obvious problems are the ones we miss.

 

[jimmytee]

Re: mercruiser 140 fuel pump replacement?

i should have said I did what you just suggested, I have the coil lead off, and the fuel line disconnected from the carb, trying to pump into a jug...nothing. Even tried disconnecting the fuel line, right at the pump. nothing...even tried a portable tank hooked up and nothing. It did all of these before, and I know both pumps worked. It's almost like the cam or whatever is not pushing the lever, but when the bolts are lose about halfway, the pump "springs" out and if I push it in by hand the pump works, so it must be something internal. I don't think there is a pushrod to activate the pump on a 4 cylinder, I think its just the cam, and it pumped before so ????? I didn't take the pump off the first time and my friend that did said just insert the lever end up in the block and then tighten it down...sounded simple enough....maybe I'm not simple enough?!?!?!?!

 

[roadking666]

Re: mercruiser 140 fuel pump replacement?

I seem to have this exact problem, I just rebuilt the entire floor and stringers so I had the tank out. the engine cranks but no gas to the carb, and no gas at the intake hose fore the tank. I thing this fitting from the tank has a special fiting cause I tried to siphon the tank fomr that ling and I could get any sution. I'm wondering if I should remove that fitting?

If someone could help, I appreciate it.

 

[chiefalen]

Re: mercruiser 140 fuel pump replacement?

i think u both have different problems.yes there is a special fitting its a anti shiphon valve on top of the tank turns 90 degrees.take it off and blow thru it it allows gas to flow one way only.if bad replace maybe dirty or just stuck.second check your vents make sure they are clear.there are 2 filters one in the fitting at the carb. u clean that one out?there is a filter in the fuel pump itself and there is a screen at the bottom of the fuel pickup tube in the gas tank itself u guys check those?post your results seperatly different posts please.