Scott

I have the Merc Water/Fuel belt driven pumps on HP500 carb motors.
The one is showing some fuel in the site tube that runs to the flame arrester. The other has a tad bit of oil in the tube down close to the pump. I have searched and see there are some replacement choices that will replace the actual pump and maintain the Merc belt drive.

So what size fuel lines fittings do I have and will the Holley replacement bolt right up and still have the proper fuel pressure or will I have a lot of mods involved? I know there may be a problem with some of these having the correct pressure with the Merc drive unit.

I will not consider electrics at this time and this far into the season so any input on a good replacement that won't have the Merc $$$'s attached would be appreciated.

BTW I did a board search and did find some info but I am not too sure about the advice because most cases involved blower motors and high fuel volume I'm guessing I need 5 to 7lbs.

Wobble

The only pump that will bolt up is a merc unit. Try Bam for a discounted price.

Carter hi-perf BBC chevy pumps are similar in that you can use the valve body as a replacement for the top half of the merc pump and get more flow however the lines wont match what you have.

You best choice would be 2 replacement merc pumps unless you want to get into replaceing lines fitting etc.

Make sure there is gear oil in the sump where the pump lever bolts in.

The one with fuel in the vent tube has a bad diaphram and should not be used.

I think the discount price for the merc pumps is about $100 on a $180 or so list price.

Iggy

Why replace the pumps ???
Can't they be rebuilt with new diaphragms ?

Wobble

Merc designed it so that is very difficult to get pin out. I have done it, but it's a pain.

Dont think you can buy diaphragm unless you but similar Carter pump. Min $70.00

When all is considered. New pumps are best result for stock type motors. The lever arm wears if sump oil level gets low
(and nobody checks this), the 2 springs on lever are getting old, ditto the valve body springs and seals. Finaly this is on a boat.

BTW I have rescued two buddies on the water with my spare holley electric pump in the last month. One was no oil in sump causing lever to wear out. Other was failed check valve in valve body.

Scott

$100.00 or so is fine I just thought they were closer to $500.00 each and did not want to spend that much on a "stock" pump.

Is the Merc pump the whole assembly or just the top part? I was trying to find them on Bam's site and could only find a pump that had the lever type drive that rides on the cam on a Gen IV or does it still have that stile lever and run off the Sea Pump drive. Sorry I'm confused and can't find a decent diagram.

Wobble

Their online price is $125. Call Bam, it may get better, you will need engine info to make sure of exact part number. Good time to replace both IMO

Bad Girl

scott , they do cost $495. i can get you one for 287$ send me the cash and I will get right on it. better get 2! no need to look through "DOGS PICK -A-PART" ??

Scott

Dog,
Get of the computer and find me my free pump fom the Pick-A-Part!
I think Wobble found the right one and I have Stu checking on a price. You should call him he's having a bad hangover type day

Wobble,
Thanks that is the same one I saw but the ride on the cam type lever in front through me off. I do agree about replacing both since the other is showing signs of wear.

Scott