Fuel Feed Issue

If the yellow tube was clogged then that is not good!!

That is designed to direct fuel to the carb if the pump diaphragm ruptures......... also this is a tell tale sign the pump is bad!!!!!!!!


I think you have found your problem.

When removing the pump from the block there should be NO fuel anywhere but in the pump and the steel lines. If fuel was in the pump cavity where the lever goes into the block then it was leaking past the diaphragm (s) and past the lever assembly because the plastic tube was blocked......

In an automotive setting there is no tube, there is a weep hole where the pump barbed fitting is for marine and the fuel would simply leak to the ground........Not the best idea but that is how it was done.
For marine, obviously they could not allow that to happen so they installed barbed fittings and a tube to the carb.



Do not waist anymore time. Purchase a brand new Mercruiser MARINE replacement fuel pump!!

Thanks for all your help ..thats my plan

Just reading through this thread and might add a note:

I had to warranty return two, yes two in a row...bad Merc OEM pumps due to output over pressures (12-15 psi) causing carb flooding problems.
Apparently poor quality control from Mexican factories...the third pump was good thankfully! Once again ...pump pressure is important.

Welcome to the 2017 boating season. I'm just now getting my boat out and back to my fuel problem from last year. The fuel pump was toasted and I installed a new pump today but I noticed the cam wheel on the drive shaft for the water pump that the fuel pump's pump lever rides on just spins freely on the shaft. I'm thinking that's not right and it can't possibly actuate the pump. If so the water pump assembly is probably bad. Any feed back out there?

Thanks

kghost said:

First check anti siphon valve at gas tank. Small check valve/ball inside......make sure it is free/rattles air blows in one direction only.

when you change/empty a water separating filter you really need to fill with gas to prime, a typical fuel pump cannot pull enough fuel to fill it.

Only way to properly tell if pump has failed to to put a pressure gauge between pump and carb......

Click to expand...

Yup I had my anti siphon valve get clogged, it had a spring and ball bearing inside, and algae clogged it. So I replaced it. Mine was Aluminum.

I have two on my boat, both are on the fuel tank, one goes to the water/fuel separator, and the other is for the fuel flow back into the fuel tank.

Easy fix, good luck.
Sam

Thanks for the reply. I put in a new anti siphon valve last year and it was running before I crashed out and I determined the fuel pump was toasted so that's not the problem. I'll take your advice and fill the water separator today to see if that helps . Baring that I'll try the pressure gauge.

ehlien said:

Thanks for the reply. I put in a new anti siphon valve last year and it was running before I crashed out and I determined the fuel pump was toasted so that's not the problem. I'll take your advice and fill the water separator today to see if that helps . Baring that I'll try the pressure gauge.

Click to expand...

Every year I change my Water Separator / Fuel filter AND my engine fuel filter, if the micron does not have proper flow, it will give problems.

Actual I have never been able to locate the engine/carb fuel filter.