Young Performance

I didn't think so. If they did, then it's news to me. I'm no expert in Merc engines but I have only known them to have either 42 or 43#'s.
Eddie

Alex

I think you're refering to injectors on the 7.4 MPI Vortec which used Keihin (spelling?) injectors.

JasonSmith

Nope. 454/502 Mag MPI motors. The little short ones are 42 or 44's. The latest sets I bought were made by Magneti Marelli. Who lows who else makes them. This was the least expensive source I could find. ~$750 for 16.

Raylar

Let's back up and get one given on the table here. How many pounds per hour an injector will flow is also determined by what pressure it is operating at.

For purposes of clarifying here all Merc HP500efi engine and fuel systems are set to run at about 43-45psi and that's where most are measured at with the standard Merc Cool/Fuel system and stock fuel program tables and pulse widths..
At 43psi fuel pressure our injector house reports on their printouts that they flow just about 42lbs/hr of fuel with Mercury's maximum programmed pulse width.

That would mean for purposes of a stock HP500efi and any other Merc engine using that same injector and fuel pressure from its Cool/Fuel system the flow rate of that injector would be the same as long as its pressure and max pulse widths have not been changed.

Use an aftermarket fuel pump and pressure regulator or a modified Merc cool/fuel system operating at different fuel pressures , modified the fuel mapping -pulse widths and the flow rate of the injector will change accordingly up to a reasonable and sustainable pulse width and pressures below lets say 65psi.

So we can assume that stock HP500efi injectors at Mercury's stock fuel pressure and and stock programming flow a max of about 42lbs/hr of fuel.

Now wasn't that easy!

Best Regards,
Ray @ Raylar

JaayTeee

$ 750 will buy you 2 500 EFI injectors from merc

JasonSmith

Here is where I found the injectors:
http://stores.ebay.com/AutoMods-llc/...=p4634.c0.m322

tunertech

the early version MPI's using the VST utilized the Japanese KEHIN 48# injector B8, don't have my notes right in front of me. You can find these at the auto parts store... a Subaru injector... But they are pricey. Typically retail is about 135.00 each. This injector is very rebuild/recondition friendly

The later Cool fuel 454/502/6.2 systems used what was classified as a 43# Marelli/Weber Style injector. Typical retail is about 48.00 to 56.00 per injector. Not so rebuild and recondition friendly.

Trash

KEIHIN injectors are actually Honda style injectors. RC Injection out of Torrance, CA has Keihin style aftermarket injectors if that's what you need. (I'm not affiliated). Not cheap, but WAAAAAYYY less than the Merc priced Keihin.

As Tunertech said the Keihin style is recondition friendly. Plus you can get the O-rings and grommets from any local Honda dealer for pennies. Merc wanted nearly $200 a pop for a replacement 24 lb Keihin injector. I paid around $78 or so a piece for some 42 lbrs.

LiveFREEorDIE

I have a 94 454 mag efi gen v with vst. The injectors are keihin. Can anyone verify what pound injectors these are? Is tunertech correct at 48#? I have also heard others say they are 36# injectors and others say 38# and 42#. These are the older style longer injectors (pre 1999 cool fuel). What is the max HP they are able to power? One has been replaced and has a shorter black tip on the spray nozzle instead of the normal yellow tip. I plan to get them bench tested and cleaned but if they are too low of psi for my applicatuion I will just buy new larger ones. Part # is 805225a1 and also cross referenced a mallory # 9-3310 and still can't find the flow rate on any site.

Trash

36# injector is good to approximately 450 hp at 80% duty cycle.