Fuel supply issue

[Mxdude91]

1998 225 3.0L carb (0g607475)
I have read many post and the stickies for fuel concerns, I have a few questions, I squeeze the new mercury primer and it gets tight I start the engine it runs fine and I run down the river and anchor I go to start the engine and the engine starts and stutters/sneezes and dies,squeezing the bulb tight again fixes it until I anchor again. I know it has been suggested in other post that the primer be squeezed every start up but never in the countless trips would i ever have to do this even on a cold start WHY?.


I have already installed new mercury (silver and blue) line from the tank to the primer to the pulse pump.and plan to replace the anti siphon valve and the fuel lines from the pulse pump to the carbs this evening.im using fuel injection hose clamps.

With the pulse diaphragm pump I read that the rubber seals should not be installed on the check valves inside the pump and only the plastic ones...I tried that and it seem to not feed fuel as well??? What was reason for not using the rubber washer seals any more?

I removed the on boat canister fuel-water separator mounted in the hull,I had read that they can cause a restriction...it was on there when I bought the boat and I have been changing the filter quite often...I use this boat very often and never seen an issue.when I bought the boat the primer never got tight but it never starved for fuel..until I replaced the fuel line from the tank to the pulse pump as a maintenance and I had used poor quality hose that kinked.

[Savage]

You are likely sucking air in one of the many worm drive hose clamps.....Replace the worm drive clamps with the proper radius head zip ties made for fuel lines.

[Mxdude91]

I will post back results

[Mxdude91]

Ohkay so I have another new mercury primer bulb because the bulb started leaking on me Friday and I have replaced all the fuel lines with mercury (blue letter) fuel line all used the special zip ties, also replaced the anti-siphon valve, engine runs great once primed at each start up but it completely looses its prime each time after anchoring.could a gasket in the fuel pump or carbs be leaking air? Pick up tube is good and tank vent is good because it still does it if I leave the fuel cap off.

[Savage]

What is the fuel pressure coming out of the pulse pump?

[Mxdude91]

Tested the fuel pressure between the pump and carbs and the needle flutters like crazy but it is I’d say between 0-4psi at idle on the muffs

[Savage]

Better go over the pulse pump and check the pressure at cruising speed.

[Mxdude91]

Now I read on a post where don had stated to not install the rubber part of the check valve is that true???thanks

[EuropeanAM]

Now I read on a post where don had stated to not install the rubber part of the check valve is that true???thanks

Yes- the instructions in the OEM Mercury Kit also state this (and provide some instruction).

If you bought a kit with rubber check valve parts it's either ANCIENT or it's AFTERMARKET.

Note: As has been stated and explained HUNDREDS of times in the past: Pump the primer bulb firm before EVERY engine start. That's why the engine has a primer bulb- and it is simply a necessity with today's "fuels" (term used loosely).

[Mxdude91]

I have been out on the water twice after rebuilding fuel pump with oem mercury kit and the engine starts and runs fine since.thanks

[Savage]

Glad you fixed the pulse pump.