I think I have a fuel leak in one of my fuel pumps on my Merc 420's. I have two sets of Holly mechanical fuel pumps that I could swap the stock ones out with. The 420's have the Holly carbs. When I first got these pumps I put them on my 330's and they over powered the floats so I had to put a regulator on them with a guage to get the fuel preasure down. Will I have the same issue if I put them on my 420's or are the Holly carbs able to handle the higher fuel preasure?

Thanks
Jon

Holley makes 7 psi fuel pumps for use without a regulator, they also make higher pressure pumps (15psi) for use with a regulator. A 7 psi pump should work with a Qjet, Weber, Holley, etc carb fine.

I used one on with a dominator and had no issues.

Any idea how you can tell what pumps I have?

Mechanical right? I think I have 2 holley regulators laying around that I could send you if your interested. (free)

Thanks Rookie for the offer that is very nice. I Have regulators just wanted to not use them if I do not have to.... I guess I have all the lines made up so it would not be that big of a deal if I have to use the "new" lines. Would they be the same going from a Q-jet to a Holly?

Bolt on the pump, hook up a fuel pressure gauge, see if it reads 7 psi or significantly more than that.
All carbs are set up for about 7psi.

Is there any number on them? Could you post a pic?

I will try and get some tomorrow.