Fuel Pump
 

Guys,
Is there anyone that sells a rebuild kit for the Merc 500hp fuel pump (raw water pump mount)? I need a diaphragm kit (only getting 3 1/2 psi)!!!! If not, where would you recommend getting one, or does anyone have a good one I can get before FRI???
I've got to finish dialing in the carb jets and without fuel pressure, the engine runs LEAN in upper RPM's


Thanks
Zack:confused: :confused: :(

The Carter HV automotive pump will bolt to the top of your pump. Same thing CP performance sells as a HV marine pump. Did you check your sea water pump they also wear out.

I saw the one in CP - the only thing is it doesn't have the provision for a fuel dump if the diaphragm ruptures, does it????

Raw water pump is brand new, looks good....

Use the bottom of the Carter and the diaphram and bolt it the the top of the merc fuel pump. You can pick up the Carter at most auto parts stores for around $50.00.

man I need to get out of this cushy job... suggestions like yours used to be second nature (great one by the way). I'll pick one up later this eve


Thanks,
Z

K-BOAT,

You wouldn't happen to have a part number on that would you???

No I don't. I went to a automotive speed shop to get mine. I am sure if you ask for a Carter HV for a big block you will be fine.

Re: Fuel Pump
 

Old thread, new solution...

I found an outfit that sells a rebuild kit that works on the Merc water pump-mounted mechanical Carter fuel pump. It cost 42 bucks and works like a dream. I didn't use all the parts, just the diaphragm. the gasket and the pin for the arm. Beats the heck out of 150 or so for a new pump.

The website is www.dscmotorsport.com

It's sold as a rebuild kit for the Carter X pump found on early 428 CJ's.

Jim

I recently purchased the same kit for my MC HP525SCs. The diaphragm is somewaht different:

The diaphragm in the kit has a black spring with 8-1/4 turns of 0.100" wire.

The original diaphragm in the pump has a green spring with 7-1/4 turns of 0.125" wire. The number stamped is 223.

Did you diaphragms differ?

What is effected by the difference in the springs?

Not sure on the difference... I'm guessung just a different manufacturer. Mine worked like a champ...

Thanks so much for the reply.

Was the spring on the diaphragm in the kit you bought different then what was originally in your pump?

fuel pump
 

did anyone find this ?? i tried all my parts places and the ford dealer with no luck.

Find what?

the rebuild kit. no one in my area has one or can get one

I got one from www.dscmotorsport.com this past September. Cost about $45 or so.

See my comments about the diaphragm spring earlier in this thread. Dennis at www.dscmotorsport.com was not familiar with marine application...he sells it for rebuilding pumps for older muscle cars.

I'd love to know what effect the difference in diaphragm springs has.

Joel

My fuel pump seems fine but isnt there supposed to be some oil to change in the sea pump? If so how do you go about this... I was changing impellers and noticed a ton of oil everywhere

Yes, there is oil in the raw motor pump (I use outdrive lube). Some pumps have a drain plug and fill plug...others like mine only have a fill plug (what a PIA!). I remove the pump to drain...maybe it can be sucked out thruogh the fill plug or from were the fuel pump attaches?

There is oil in the chamber where the fuel pump arm rides on the cam inside the water pump housing. The easiest way to change it is remove the fuel pump and drain, then refill to the bottom of the check plug in the side. You can use straight 30w oil in there although some people use gear lube.

Oops! ...raw WATER pump...

Did you use your old spring or the new?

I haven't rebuilt the pump yet.

rebuilt my fuel pump with the kit from dsc motorsports and it worked great. shot to 8 lbs of presure and didnt budge at 2000 rpms will try in water this weekend hope it holds at full throttle. :grinser010: :drink:

Mansfield Mustangs has the kit for $37

http://mansfieldmustang.com/EngineFuelCarbp2.html

Thanks for the update. We'll be interested in how it does at WOT. I'd bet you'll be fine.

I have yet to source the rebuild kit part number C7AZ-9349-A but I did find a very helpful website that has a step by step rebuild with pics here http://www.428cobrajet.org/how-to-fuel-pump.html

that is the same site i used for refrence. and works great. wot holds 6 lbs nickersons said dont go under 5 lbs . so i orderd a 2nd one to rebuild the other pump and have 2 new ones. ps i did see a difference in psi at idle one time its at 6 lbs and next time its just under 9 lbs. other than that they run great.

well bad news guys. pump didnt keep up at wot. lost rpm looked at gauge and at 3lbs. backed off and went to 6lbs after 2ndaries shut. well time for electrics. good luck :picard1:

Sorry to hear the pumps don't deliver enough fuel. What do you have for motors?

540s between 625 - 650 hp

Definitely needs more fuel than my HP525SC motors. The mechanical pump seems to be fine for my application. Currently my fuel pumps are as they came from Mercury. I haven't tried the rebuild kit yet. (I found that the erratic pressure reading I was getting on one of the motors was cuased by vibration. I had a mechanical test guage connected to the hard fuel lines at the carb. One cylinder was not firing!)

Clearly from what you describe there is not enough fuel flow at WOT.

I'd be surprised if the stock pump, rebuilt or not could support 650 hp.