OMC 351W fuel delivery problem

[danthern]

77 OMC 351W I/O not getting gas to the carb. I've disconnected the line at the carb and when I crank the motor, no fuel....The line is clear from the tank all the way to the carb. Got a mouthful of gas making sure the pick up wasn't clogged. I disconnected the line from the tank and put it in a 2 gal. can of gas just to be sure. I ran a little gas into the line from the tank end and blew on it and it comes out at the carb...Put another USED fuel pump on (mechanical) with same results. There is no fuel coming from the little port on top of the pump, which i think would indicate a ruptured diaphram. I am doubtful that both pumps could be bad. Could it possibly be anything else but the pump??? Thanks for any help.<br />Dan

 

[McKenzie]

Re: OMC 351W fuel delivery problem

Is the cam pushing the pump arm like it should?

 

[danthern]

Re: OMC 351W fuel delivery problem

How can you tell? I wondered about that....

 

[Dunaruna]

Re: OMC 351W fuel delivery problem

You can test the pump out of boat. Operate the arm manually and fell (or listen) for suction & pressure - it makes a distinctive sound. The second pump you fitted was used, maybe it was removed for a reason. If the pump tests o/k, stick your finger inside the block and feel for the cam lob that drives the pump arm (egg shape)if your bilge is big enough you can get down low enough to look inside. Good luck.

 

[danthern]

Re: OMC 351W fuel delivery problem

The pump does seem to be working, I did work the arm manually, you hear the pumping sound that you describe. How do I make sure that the arm is seated correctly? thanks for the advice.<br />Dan

 

[danthern]

Re: OMC 351W fuel delivery problem

BTW, the pump does mount flush to the block, slips right in.

 

[McKenzie]

Re: OMC 351W fuel delivery problem

Did you try to crank the engine over by hand (or tap the starter quickly) so the cam's pump lobe is in a position that allows the most clearance for the pump arm?

 

[danthern]

Re: OMC 351W fuel delivery problem

Didn't do that...can you elaborate a bit? Much thanks,<br />Dan

 

[McKenzie]

Re: OMC 351W fuel delivery problem

use a mirror or put your finger into the fuel pumps hole and see where the cam lobe is. You want the lobe to be out of the way to allow the most clearance for the pump arm. Keep tapping the starter until you don't feel the lobe anymore. Just in case you don't already know this, don't turn the engine over with your finger in it. (I witnessed a "lesser" mechanic do this once) Then slide the fuel pump in. You wanna slide it around a little to make sure the pump arm is under the cam lobe. Then bolt it up and it should work.

 

[danthern]

Re: OMC 351W fuel delivery problem

Thanks alot for the instructions....I'll give it a whirl. I believe that is the problem. However, I've learned quickly that what seems to be (with a boat) is usually not the case! Thanks again for your help. I'll let you know.<br />Dan

 

[Crazy]

Re: OMC 351W fuel delivery problem

You have a Holley 4BL 600cfm carb ???? Did you change the fuel filter in the carb ? Or take the fuel line off the carb and try cranking , did fuel come out of the line , What's the chance that you have 2 BAD pumps ... Change your filters ... Or hook up a portable fuel tank ... maybe your pick up line broke off in your maine fuel tank ... anyways ... good luck .