120 hp mercruiser fuel pump.

[jerrfaz]

I have a 1968 120hp mercruiser and have to replace the fuel pump. The new pump (carter) is exactly the same as the old one except for one thing. There is a second port under the port that runs to the carburator. What is this for? Now my old fuel pump had a restrictor line that by passed the fuel pump. Could this be what this is for? hope somone can help. Thanks

 

[Rhadley]

Re: 120 hp mercruiser fuel pump.

There should be a yellow tube going from the pump to the carb, which is there in case the diaphram leaks in the fuel pump.

 

[jerrfaz]

Re: 120 hp mercruiser fuel pump.

Thanks for your responce. It is much appreciated. Unfortunatly, There is no other line running from the carb to the pump. Only the fuel line. As I had stated, my old fuel pump only had one outlet to the carb. I also looked and there is no other port on the carb to run a barbed fitting off of. Its a Rochester if thats any help. So... my stupid question of the day is. Since the second port is a saftey feature and my old pump didn't have this couldn't I just plug this port??? Or, can I attach a tee fitting off of the carb and hook both lines to it? Again, thanks for your help. Jerry

 

[SamJ]

Re: 120 hp mercruiser fuel pump.

I just did the same repair to my '64 Penn Yan. I went with the Carter and used a tee fitting.

 

[ron7000]

Re: 120 hp mercruiser fuel pump.

Originally posted by jerrfazz:<br /> help. So... my stupid question of the day is. Since the second port is a saftey feature and my old pump didn't have this couldn't I just plug this port??? Or, can I attach a tee fitting off of the carb and hook both lines to it? Jerry

Yes, just plug the port. It's on the bottom side of the diaphram, when the diaphram goes bad and ruptures, what fuel is in the pump and lines leaks out. On newer motors, like my 2002 3.0L, there's a yellow tube running up to the carb for this. And you can always here it puffing air which bothers me. On the old motors, there was a little glass bowl off this port with a little sign in it that said "if there's fuel here, replace fuel pump". If you could fine one of these, you'd be stylin.<br /><br />No, don't attach a t-fitting to the main fuel line running from the pump to the carb, and link that to the port to the underside of the diaphram. The pump won't pump!

 

[jerrfaz]

Re: 120 hp mercruiser fuel pump.

Thanks much for the very usefull info. I did in fact roll the dice and plugged the port and all is well.

 

[Bt Doctur]

Re: 120 hp mercruiser fuel pump.

Heres the real reason for the vent. It allows the diaphram to move freely and pump fuel.secondary function it to allow a defective fuel diaphram to be seen by seeing fuel in the plastic line going to the carb.