johnkot

Just installed a new mechanical fuel pump on a 454 (1986 vintage). With it was a new fuel filter (screw-on water separator) so the fuel line is empty. The engine just cranks so I disconnected the fuel-line at the carb and cranked it again and no fuel. Do these things have to be primed somehow or did I mess up when installing it? There is a rod that runs off a cam and rides on a lever in the pump. Before I take it apart just wanted to know if it s/b primed.

Also, a Mercathode question:
My 86 Formula 357 has a Mercathode system. Can anyone tell me what this does and how can it be checked for function? Is it checked with the boat in or out of the water? When I bought the boat I found it to be disconnected. I have reconnected it but want to ensure that it does not do more harm then good regarding any galvanic action/electrolysis or what not. Does it draw much from the battery?


Thank you

JK

38KV

Make sure you didn't mixed up the in/outlets.
The mechanical fuel pumps don't need to be primed.

Danny_Ocean

Are you sure you have the cam-driven pushrod in place? It's a little tricky getting it in position (for us amateurs).

Remove the fuel lines (inlet & outlet) and crank the motor (taking precautions to prevent ignition/spark) with your finger over the fuel-pump inlet port. You should fee it sucking on your finger. Then switch to the outlet. It should blow air past your finger.

D. Ocean
Pompano Beach, FLA

Danny_Ocean

Then...if the pump is sucking and blowing properly, I'd start checking "upstream". Correct water-seperator filter (looks like an oil filter, but it ain't)? Kinked fuel supply line? Gas tank full? Gas shut-off valve in the on position?

Some of these suggestions may sound simplistic, but I've left the dock more than once with my fuel valve in the "off" position!

D. Ocean
Pompano Beach, FLA

Griff

Filling the the filter with fuel will also reduce the amount of cranking needed to get fuel up to the carb.

johnkot

I started to disconnect the fuel outlet and fuel dribbled out. Does that suggest that the pump is working or would engine vacuum as it's cranking over be enough to get the fuel through the new filter and through the new pump.

Background: My old pump was working but I had a strong fuel smell in the oil and the oil would thin.

Danny_Ocean

It may be getting fuel, but perhaps not enough to feed the engine. Do the above tests and work your way backward.

D. Ocean
Pompano Beach, FLA

Griff

Dump a couple ounces of fuel into the carb. It should fire and run for 5-10 seconds and pump enough fuel through the system. If it doesn't fire, I would suspect that you have a diferent issue.
Even with replacing the fuel pump, you should have still had plenty of fuel in the carb bowls to fire the engine.