I plan on getting the Sniper 4500 but was contemplating just getting rid of all the old ignition setup. The engines are 1990 so figured might be good to replace ignition components along with all the fuel upgrades needed.

Holy smokes! way beyond my skill level with a welder. Guess I will just stick with carbs

Not that hard at all for someone familiar with TIG welding. And Eddie has the process down perfect.

I’m going to run FAST’s dual channel AFR meter. It’s a little over $500 with 20-foot cables. Being able to see what the engines are doing in the boat is important to me. Next year, maybe FI so the bungs will already be there and ready.

It can only “control” the HS ignition. And even with that it’s not doing active management. It accepts your inputs and adjusts timing based on the RPM/advance settings you created. Similar to MEFI but it has no way to retard timing if it detects an issue (no knock sensor input). That’s my understanding as it was explained to me last week.

There are some workarounds but they’re not supported by Holley.

LOL
I took mine to welder and picked it up a few days later , but if you can`t handle that then yes stick with carbs.

Just the Holley hyperspark ignition ?

You have a link for the documentation ? Thanks.

Here's a link to the installation manual:

https://documents.holley.com/199r11031r.pdf

A quick look shows that it can control a MSD magnetic pickup distributor with CD box after locking out the advance (duh) and installing an adjustable rotor.

That was not what the EFI System Pro told me.

Probably just a sales-related comment because I had mentioned that I wanted to stick with my distributor. He mentioned the plug and play Hyperspark system though the documentation only shows Dual-Sync.

The installation manual does not really go into deep timing control.

More info and resources here:

https://www.holley.com/support/resou...Fuel_Injection

I appreciate all you more knowledgeable people discussing this so i can try & follow along. :)

Okay , it says you can use sny magnetic pick up dist. Which the small cap hei/EST/voyager GM/Mercruiser distributor is.

Also says other (than Holley’s) hall effect distributors may be able to. So, possible the Merc IV:V dist could to. Obviously timing module eould not be used. Proof would be in someone trying.

I found a local welder, sent him the video, and he gave it back to me a couple days later. He even already had the bungs in stock.

That’s what I did. I still have the wideband in the port side bank with the EFI in the SB bank and I can keep an eye on them both. On occasion there’s about .5 difference in the AFRs and it’s a redundant way to keep an eye on things.

I had my carb “dialed” in running perfectly, but installed the wideband and in the window of about 500rpms where I cruise the most it leaned out to the high 14s and occasionally the 15s. Would’ve likely toasted the engine. So even with carbs I highly recommend a wideband. I know a lot of the vendors will install them if you send the exhaust bits back to them.

Maybe next year if I make changes.

I’ve read on the forums that you have to do some trial and error stuff to get them to work. A concern was that Holley wouldn’t support these configurations I think it was scaring off some from attempting to get them working. Could very well be the target audience. I don’t think that would be an issues for folks around here.

I’ve got too much invested in these engines to have them burn up and that’s exactly my biggest worry... lean cruise and creeping up on peak torque where real damage can happen without even realizing it. AFR monitoring is cheap insurance in my eyes.

New to the efi world but have bought a Holley sniper system to install on a single engine fountain, the problem we are having is where to run the return fuel line back into the fuel system . What is the best way to get it back in the loop ?

Best way is back to tank. 2nd way is back to an inlet to the fuel filter/water separator.

Is the fuel fill hose nearby ?
See for two fill hose size options:
https://www.cpperformance.com/vsearc...Tank%20Adapter


https://cimg9.ibsrv.net/gimg/www.off...55b542222.jpeg

If you route back to the separator, you could run into heating/vapor lock issues. Merc used the cool fuel system to combat this.

SB’s suggestion of running it back to the fill hose is best. The tank then ends up being the heat sink.

You may have just sold me on it. Gonna contact CMI about some new tail pipes this week.

Love the fill neck adapter, would have been easier than welding a bung to my tank. I run tank to separator, to pump, to carb, back side of carb inlet line to regulator, regulator to tank. Constant circulation of fresh , cool fuel, zero chance of vapor lock or pressure build up. Next time I have the tank out, I would love to go with a set of the in tank pumps and push fuel through the separator/filters. The pumps I have are mounted low (stringers) and thanks to the constant circulation of fuel they dont get warm, but they, like most pumps are better at pushing than pulling.

I'm planning this myself on my 454 mag.... my plan was to pump fuel from the stock pump/filter into to a surge tank setup with built in high pressure pump, then run that to the sniper setup.

Sidebar question.... I currently only run premium mostly to avoid ethanol in the carb and risk it gumming it up over winter. This engine does not need the high octane fuel, especially as cool as they run with only around 8:1-8.5:1 compression.
So, one of the fringe benefits I expect with EFI is to be able to run standard fuel without the problems the carb has with it... 87octane which around here has 10% ethanol. Is that a realistic expectation, or do I still want to stick with premium (over $4 a gallon now into my 88 gallon tank)?

you can run the return to the water separator filter head if you have a port available without issue if done correctly

You don't need premium MT. Ethanol won't be a problem unless your fuel lines can't handle it, or you have a fiberglass tank.

Return line
 

Have any pictures of how this is plumbed in ?

The return goes in the top of the filter bracket, these are TCM units, this is per Whipples install guide
https://cimg0.ibsrv.net/gimg/www.off...8baab6bab5.jpg