Injector question.
#1
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Joined: Mar 2010
Posts: 251
Likes: 17
Question: will MEFI 3 work with the fat injectors pictured below? Will it communicate properly with the injector?
Back story:
I have a 99 502 MPI with a MEFI 3. My intake went bad and I bought what I thought was a intake that fit. Come to find out it was a intake for a 1998. Now that intake won't work with my current fuel rail and injectors, it just doesn't sit right. I could not find the right intake at all. So I bought a new fuel rail and injectors that fit that intake, thinking it should work cause now it all fits.
Well I am questioning my injectors. I have recently read that the injectors I have (pictured) are for MEFI 1 and not MEFI3. My question is, will these injectors work with a MEFI 3 system? Everything is stock, I am not building power or anything, just want reliability and run it long term.
Also note:
I know the intake, fuel rail and injectors are not made for a 1999 motor. I know this was used with VST system and also cool fuel (which I have). I can rig the fuel to work with my cool fuel system. I am just questioning the computer talking to the injectors.
I can not find a good condition intake that is why I went this route. I had talked to 20 people who “had what I need” and bought / wasted time because it wasn’t for a 1999.

Back story:
I have a 99 502 MPI with a MEFI 3. My intake went bad and I bought what I thought was a intake that fit. Come to find out it was a intake for a 1998. Now that intake won't work with my current fuel rail and injectors, it just doesn't sit right. I could not find the right intake at all. So I bought a new fuel rail and injectors that fit that intake, thinking it should work cause now it all fits.
Well I am questioning my injectors. I have recently read that the injectors I have (pictured) are for MEFI 1 and not MEFI3. My question is, will these injectors work with a MEFI 3 system? Everything is stock, I am not building power or anything, just want reliability and run it long term.
Also note:
I know the intake, fuel rail and injectors are not made for a 1999 motor. I know this was used with VST system and also cool fuel (which I have). I can rig the fuel to work with my cool fuel system. I am just questioning the computer talking to the injectors.
I can not find a good condition intake that is why I went this route. I had talked to 20 people who “had what I need” and bought / wasted time because it wasn’t for a 1999.

Last edited by srdrago; 09-08-2023 at 09:34 AM. Reason: Added picture
#3
I have the proper intake manifold and fuel rail for the later 98-99 MPI. The intake has some corrosion and probably needs a little aluminum welding and resurfacing to make it perfect. It never leaked on my 502s using the Merc gasket set. I'll throw in the hose, too as well as the original injectors (all sixteen - should be able to make a working set).
PM me if you're interested in going that route.
PM me if you're interested in going that route.
#4
Thread Starter
Registered

Joined: Mar 2010
Posts: 251
Likes: 17
I have the proper intake manifold and fuel rail for the later 98-99 MPI. The intake has some corrosion and probably needs a little aluminum welding and resurfacing to make it perfect. It never leaked on my 502s using the Merc gasket set. I'll throw in the hose, too as well as the original injectors (all sixteen - should be able to make a working set).
PM me if you're interested in going that route.
PM me if you're interested in going that route.
#5
THE 454/502 MAGS regardless of Mefi1 or Mefi3 both use "high impedance" injectors, ie, the amount of resistance the injector coil has/current it takes to open so electrically . They also both use Ev-1 style connector plugs so the harness will physically plug in.
As far as their flow rates and tune, assuming stock, working injectors, they are considered a 48 lb injector although the mefi3 /gen 6 shorter ones are sometimes called a 46.5 lb/47 lb. So switching to the early honda keihan /mercruiser injectors with stock mefi 3, at most it could be 1, 2% rich
As far as their flow rates and tune, assuming stock, working injectors, they are considered a 48 lb injector although the mefi3 /gen 6 shorter ones are sometimes called a 46.5 lb/47 lb. So switching to the early honda keihan /mercruiser injectors with stock mefi 3, at most it could be 1, 2% rich







