A.O.26

A little confused, appreciate some needed guidance,

So finishing up my refresh, cant decide if the OEM mercury fuel pump on the sea pump housing
is ok for my setup, or if its enough, OR if electric w/ regulator is needed, My engine is carbed w/ 1150 dominator
Just want to get it going, and later on dial it in as i go, wondering if any have experienced this and whats been done,
cant find anywhere that lists specs for the high performance mechanical pump on the mercury's 500, 525 efi, 575 sci's
Ive notice they have the same setup but w/ EFI. Ultimately my question is, does anyone know the GPH and Pressure, of the
oem pumps on those engines, and do they have additional components, for the setup!
It had a mechanical pump, but I cant find the same one anywhere, so hence my dilemma.

I'm est my engine @ approx 650HP +/-

any feedback, or help would be great, thanks much!

A.O.26

Ok Update: hopefully to narrow down, So i was looking at a 575sci fuel system diagram;
So I may have essentially a simpler answer:
Say, I have a 575SCI, ( which essentially I think is what I have-relatively) , AND I wanted to do away with the OEM fuel system,
what would be the best setup,( of course, hypothetically only) would the Holley Sniper (140gph), and a Holley sniper regulator
( to set fuel pressure for Dominator), work? or is that not compatible, if not, whats my best options?

appreciate any advise, thanks

Griff

Mechanical Fuel pump upgrade
https://www.hardin-marine.com/p-1246...6-engines.aspx

A.O.26

Any experience with it, or know of someone using it?
thanks

BBYSTWY

I had it for a little bit and honestly was not a fan. I read hundreds of posts of people saying they loved it but for me it did not work. Ultimately if I were you I would do either the sniper or terminator 2x4 efi setup with matching holley pump, regulator, and ignition. You will have fuel distribution problems eventually running a single on top of a 250 blower. Do and search on that subject and you will find several threads on it. I have a 540 built good with a 14-71 making 1000 and the sniper kit worked for me. I am pulling it all off and switching to either a terminator 2x4 or injector plate with throttle bodies and a HP computer setup. Only reason I am changing is I want to up my boost a little(currently only running 4-5 lbs) and the sniper is about at it's limits for my application. I want to add knock sensors and CNP ignition which the sniper won't support but other than that it's been a great system once I found a good tuner.

On the flip side, if you want to run your single carb for now to get you going, I would highly suggest an electric fuel pump and regulator. I did this before the switch to EFI and for me the peace of mind was well worth it. I believe I still have the pump I used which had about 5-10 hours on it if you would be interested at all. It has and internal bypass regulator so plumbing was a breeze and setting the regulator takes about 2 min and you're done. I will try to find a link for it so you have an idea.

Many have run the mechanical pump without issue but for me the swap to an electric pump even while carb'd was a big plus for me.

BBYSTWY

Quick Fuel 30-175QFT 175 GPH Bypass Billet Electric Fuel Pump (holley.com)

This is the one I ran which I believe I still have it on the shelf somewhere if interested?

A.O.26

Greatly appreciate all of your feedback, awesome stuff, I had considered both options, and I too am planning a nice 540, next go around, (slowly acquiring the necessary hardware) as yourself, and will most likely go the same route especially the Tbi, or injected blower, not sure yet) got time on that!
eventually, for now, being the age of the boat, “94” it only has 1 40gallon tank, ( eventually add tank(s) later) , unless I upgrade bo a 28/31 footer. so I’m just looking for the most economical way for now!
I just found out about mercury mech pump, that was on the older 662 sc ( odd , never heard of it) that supported 660HP, that might just work! Next step maybe add the Hardin upgrade! However, leaning more towards the electric pump and regulator, the electric internal regulated option (if I read correctly) sounds very interesting, have to research that a little more!
I will be firing it up on the eng run stand possibly next week, and monitor its performance, if it does not pan out, I will definitely look towards one of your offers!! so appreciate it very much guys. I’ll post results for entertainment/ feedback info

WR-1

I have al the parts needed to switch you over to dual carb setup on your 250 if you decide to go that route... 2x holley 750s, fuel lines, linkage, flame arrestor and plate to bolt to your 250.. you can take a look at my post in the swap shop.. would take your Dominator on trade if your interested

AO31

I ran my 250’s set up as Dean Nickerson suggested. Holley Black electric pump with regulator by carb set at 8 psi. Never an issue. Single carb also. 1/2” inner dia fuel line.

A.O.26

Thanks Griff! I decided to go with your Recommendation, Happy! Looks nice and performs great!