Yamaha Sterndrive Mechanical Fuel Pump Replace

[castrolina]

Hi all, I have a 1993 Cobalt 185 with a Yamaha sterndrive v8 5.0. I had a crack in the original mechanical fuel pump and needed a replacement but they are no longer available. I bought an omc fuel pump because the plumbing was the closest match to mine. I have read numerous posts about installing a mechanical fuel pump, pretty straight forward. In all posts and videos I have seen, the pump rocker arm goes under the pushrod, correct? That's how installed it, but I had a no fuel situation, so I checked the Clymer and it says to make sure the rocker arm rides on the pushrod. Am I reading this correctly? Also, can you hear the mechanical fuel pump when the key is turned? Any input appreciated.

 

[Scott Danforth]

ignore the plumbing side

you got to match up the lever side first, and you have to make sure the pushrod is still riding on the cam

no, you wont hear a mechanical fuel pump when the key is turned. it is a mechanical device that is driven off a cam lobe in the motor. it needs the motor to turn to actuate the pump arm.

 

[castrolina]

Copy that sir, I will look at it again today and see if the pushrod is riding on the cam, I will pull the rod and measure for specs, says should be 145.7 mm (5.47 in). Thanks for the quick response.

 

[castrolina]

Update: I believe you are correct, the pushrod is not long enough or the pump lever is too short. Can I get a longer pushrod or should I look for another pump? There are a few originals out there, but I hate replacing a 25 year old part with a 25 year old part. Any suggestions appreciated, thanks.

 

[castrolina]

After further review, I read that big block fuel pumps have a longer rocker arm. Also, I found a 6" pushrod online. Not sure if I should try a longer rod or another fuel pump. Has anyone tried a 60" pushrod before?

 

[GA_Boater]

Post a photo of the two pumps side by side. There may be easy ways to make the new one work without buying more new pumps willy-nilly.

 

[castrolina]

Here are some pics of both pumps. I did order a 5.90" pushrod in case that is an option, seems the cheapest route to start.

 

[castrolina]

Problem Solved! Instead of buying fuel pumps willy-nilly, I went with a Carter electric fuel pump, p4389, with relay and oil pressure switch. Boat starts and runs now, Thanks for the Input and hundreds of posts I have read. just 2 questions:
1) Do I just cap off the hole where the clear sight tube went into the carb? That's what I did.
2) Hope this doesn't sound dumb, but how do I know if the shut off is working?
Thanks.

 

[Bt Doctur]

With the motor off ,and ign off you should not hear the pump running.
Next, start the motor for a second or two, and shut it off, then turn key to on, ,listen for the pump to shut down when the oil pressure bleeds off