GLH

My mech is looking into that with Merc Racing but from my research it looks like the pump for 800&900sc's run off a pushrod mines are off a cam so I wonder if it is compatible.

More motivation...

Lmarth

GLH- Good catch! I really don't know. You're right, my 800SC's have the pushrod. The Merc website doesn't show a pushrod with the 600SC. Let us know what Merc says. This has gotta be right. Funny how we gravitated from 'motivation' to 'pushrods!'

JIMG

I have seen many fuel pumps that are fine but wrongly accused.
Check the fuel pickup screen for debri, & make sure the rest of the fuel lines are of sufficient diameter and no restrictions. The restricted fuel pickup is almost always the reason for a pressure drop after a long run. Try putting a vacuum gauge at the suction side of the pump, high vacuum & you have restriction that no pump will overcome.

GLH

Thanks Jim checking for restriction was done everytime we changed the pumps and the cam.
My mech will again go thru the whole line next week before we head down to FL with the rig.

GLH

I checked the pics of the parts at Bam Marine's website.

More motivation...

GLH

I will check this when I go up to the boat today I know they are hard lines passed the pump and rubber lines prior to the pump.

This is the merc stock rigging.

I've played with the contrast in order to see but here is how it is plumbed standard from Merc

Click on the pics for the big versions

Pic #1
You see the rooting from the tank to the electrical priming pump at the bottom right from there thru the fuel filter, from there along the center transom over the strainer to the mechnical pumps, the other rubber hose is the return from the mechanical pump.

Pic#2
Stainless hard pipe routing from mech pump up to the fuel rail feeding the two 700cfm Holley's, notice the electrical pressure sensor is at the end of the rail.

This set up is similar between the two engines and one works fine the other is driving me nuts

GLH

Keep the conversation coming....

rbtnt

I use the CV Products billet mechanical pumps on 650 hp motors. I changed the bases with the Mercury sea pump bases. This required drilling the treads out so they would screw together. I tapped the holes as BenPerfected did for the overflow line.

This made for a clean install, but was a little pricey. If you're paying someone to do your work, this would be cheaper than electric pumps with all the plumbing, wiring, safety switches, etc.

The only drawback I have is if I take the fuel bowls off put them back on, I have to fill them manually through the side plugs.