does anybody know the fuel injectors size and fuel pressure of the 4.3l marine intake manifold. i found 28.4 ish and 58-60psi like ours but i want to be sure.

 

I have a 5.7 mercruiser marine intake on my truck right now. I am using the marine MULTEC 2 EV6 connector injectors. I had them flow tested and they flow around 24 #/hr at 43.5psi 3 BAR of fuel pressure.

The marine FPR regulates teh rail pressure to 58 psi or 4BAR of fuel pressure. At this pressure they flow 27.2 lb/hr according to the Weiss fuel injetor calculator.(or 28.2 lb/hr at 60 psi)

peace
Hog

 

thank you, i finally found some info online, and this helps to confirm what i found.

 

So far how is this intake working out for you? I just ordered mine today, I will be installing it in a few week, probably early Febuary.

 

not so good truck runs like ***. but its not caused by the intake. but maybe the injectors it came with. most new injectors come encased in oil. these were dry and already installed for no telling how long. so i think some may be faulty. not sure just yet if its spark or fuel but there is a multiple misfire somewhere.

 

I have found that the marine intake regulator works quite a bit differently than teh stock L31/35 poppets spider regulator.
The stock FPR would have fuel pressure up around 66 psi, with a low of around 56 psi, of course depending on vacuum.
the marine FPR has a high of 58 psi and a low of 50 psi.

When I did my V8 marine intake swap I had the injector harness swapped bank to bank causing split BLM's, I diagnosed it with an injector balance test.
A simple balance test should tell you if your injectors are good.
You cycle the fuel pump with the key, then the scan tool cycles 1 single injector, then you record just how much the fuel rail pressure drops. Then you recycle teh key, bringing the rail pressure up, then you do the enext injector, then record the fuel rail pressure drop.
the cylinder with the least pressure drop, or no pressure drop is a weak/clogged injector.
This test told me that I was energizing injectors 2,4,6,8, when I was commanding 1,3,5,7.

I hope you get it figured out.
peace
Hog

 

which scan tool? the orange ones like auto zone has or the tech II? i tore the old manifold apart to see which injector went where. but i could be wrong I'll see if i can find a write up with wiring to make sure its right. i tried to use hp tuners balance injector thing but its only good for v8's it seems. i can get a fuel pressure gauge from a buddy.

right now after idling for a few minutes you can touch the manifold right where it comes off the head. some ports are hot as hell a couple are just warm to the touch.

here is a question. if i pull the plugs on the cold ports, what would they look like if no fuel but good spark good fuel no spark?

 

Not meaning to be nit-picky, but it they flow 27.2 at 58psi, they'd flow 27.7 at 60psi (sqrt(60/58) x 27.2)

 

well i had 27.8 in there anyway.

 

No, no, thats cool, you kinda have to be picky with IFR's.

I was simply using Stan Weiss's online IFR calc.
OLD pressure=43.5
new press=58
injector size 24 pph
I get 27.7

old press 43.5
new press. 60
injector size 24pph
28.1pph

Sorry, I musta entered an incorrect digit. Thanks Justin.

peace
Hog