1981 90 hp fuel pump problems

[fishon2]

I just rebuilt the fuel pump on my '81 90 hp merc and I'm still not getting it to work. I can get a strong flow from the line coming out of the fuel pump when I squeeze the primer bulb but only a tiny trickle when I try to start the motor. Compression is good on the cylinders. I do have some residue on the filter screen. Will a clogged line allow a healthy flow when primed but completely stop the fuel pump?

 

[Chris1956]

Re: 1981 90 hp fuel pump problems

That fuel pump works on pressure and vacuum pulses of the crankcase. Make sure hte hoses to the crankcase are clamped and in good shape. The behaviour you describe sounds reasonable. I would expect the fuel pump to provide a few squirts on each rev of the motor.

 

[fishon2]

Re: 1981 90 hp fuel pump problems

Thanks for the response. Should a squirt from the fuel pump be about the same volume as one from the primer bulb?

 

[Chris1956]

Re: 1981 90 hp fuel pump problems

I would think the fuel pump would spirt less volume than a primer bulb.

 

[fishon2]

Re: 1981 90 hp fuel pump problems

That's what I would expect as well but I would also expect a noticeable spurt which I'm not getting. I will check the hoses and, given the amount of sediment I'm seeing on the filter screen, change the line going to the pump to see if that works. I probably won't be able to get it all done until this weekend and will report back. Thanks!