marine intake injector size

[4.8t]

what size injectors are in the marine intake? i need to know for the tune. and does anybody know what the fuel pressure is for that set up?

[jpalmer]

have you talked to UR50SLOW, he knows all about this.

[4.8t]

i'll do that thanks.

[UR50SLO]

Hey.. how's it going...

The Marine stock injectors are 24lb/hrs... (your stock intake injectors are 23.1lbhr.

The fuel pressure is higher on the Marine intake FPR.

If your not planning on using HPTuners to program the ECM for those or larger injectors then plan on

Getting a AFPR and dropping the Fuel Pressure till your regular scan tool reads with in 3-5 on the

STFT and LTFT's you'd be in the ball park for no programming. (Long/Short term fuel trims)

Send me a e-mail anytime.. be glad to help,
Scott.
UR50SLO@aol.com

[UR50SLO]

http://www.ecklers.com/product.asp?p...LL-_-35855-_-X

There is a AFPR for the Marine intake fuel rail.

~Scott

[4.8t]

thanks for the help. i'm tuning with hptuners. from what i have found so far is the marine intake fuel pressure is 58-60 like the stock pressure on his truck. but his 23.1 lbhr rating is actually at 58-60psi where as the marine injector rating is at 43.5psi. so with alittle math (hptuners conversion tool) i set it to 28.19.

motor still won't start. i think when the guy put in the dizzy he may have had the crank on the exhaust stroke instead of the compression stroke. i'm gonna go now and try going 180 out on it. it was making the boing sound they make when the spark fires at bottom dead center instead of tdc.

Thanks again,
Mike

[UR50SLO]

It'll run with the stock perameter's in it... that's not a huge worry.

Sounds like your on the right track why it won't start.

Got the injectors wired up right? I've got the schematic for that if you need it.

When you do the first fire up... let it go into closed loop. You'll see the the HPTuners scanner

where your LTFT/STFT's are and then you can go back in and adjust your fuel injector size accordingly

to where the trims are.

If it's subtracting fuel.... (Negitive fuel trim) Increase your injector size (shorten your pulse width)
If it's adding fuel (Positive fuel trim) Decrease your injector size (longer fuel pulse)

Till your in the 1-4 range.

Let me know if you need that injector wire schematic.
~Scott

[4.8t]

well i got it to fire. it was 180 out. i'm pretty sure i got the right fuel numbers in there now. but i have to figure out why it is running like crap. it stumbles really bad when you rev it and it responds real slow to throttle. when at idle it has a bad stumble also. i got a crank position sensor code. i unpluged it and plug it back in and it ran great. then i finished putting everything back together and fired it up and it ran like crap again. i messed with the sensor again and it did nothing for it. my buddy said his cam position sensor caused the same thing.

i know the throttle position sensor is good as it would register perfectly with hptuners.

any ideas?

[UR50SLO]

What are the LTFT and STFT?

Any other codes?

I know there is a tab on the dist. that keeps you from putting it in the wrong position (timing wise)

But you could still be 1 tooth off and it'd run.

Tap the engine over with the #1 plug out. Finger over hole. To find TDC. (Line up timing mark on ballancer to cover) by hand once close.

Take the dist. cap back off and verify that it's actually on #1. With a crank sensor code and

the poor running... I'll bet your close on the dist. but one tooh off causing it to be very retarded in timing.

Remember that cap is the spider one... Follow the hump on the top to get to the actuall #1 post.

Once that is solved you can do the LTFT/STFT and your driving!

Call me if you need to.
(Phone number in vendors section) Scott's paint and Performance.

[4.8t]

the trims are alittle off but it can't be assumed its just the injectors. we installed a nice cam also. i'm going to try the crank sensor and cam sensor. i checked the dizzy 3 times last night. the rotor bug tab points directly over the rotor tab. if i go one tooth either way it goes way off.

[UR50SLO]

Sound good if you've got the rotor in the right spot...

Did that 3 bump crank wheel get re-installed?

Are you sure you got the timing chain on right? Depending on the brand and how many key ways it has I've seen a ton of guys install it wrong by accident.

Local guy had it 3 teeth off and the GN still ran... (17.80's) ... But ran and drove.
I tracked it down to a improper ground cam or installed wrong.. The cam had one lobe starting to wear so I put a new cam in with the timing chain right and it went 12.60's next pass. DOH!

Anyway... How much is the long/short term fuel adding or subracting?
Get the codes cleared up... and let us know how it go's!
Check for vaccume leaks too!
~Scott.

[blk00z28]

Have any pictures of this build 4.8?

[supersports10]

Originally Posted by 4.8t

the trims are alittle off but it can't be assumed its just the injectors. we installed a nice cam also. i'm going to try the crank sensor and cam sensor. i checked the dizzy 3 times last night. the rotor bug tab points directly over the rotor tab. if i go one tooth either way it goes way off.

what cam brand, and part# did you install??

i put the biggest cam comp cams makes in one and chased my tail forever, finally advanced the cam timing 4 degrees, and BAM!!!! whole different truck!!!

[4.8t]

224/224 525/525 on a 110lsa CCA-56-430-8 http://store.summitracing.com/partde...8&autoview=sku


http://videos.streetfire.net/video/4...t-2_206778.htm here is a vid. you can hear it deisel when it shuts off.

[UR50SLO]

How are the valves adjusted? Did you put in a set of real screw in studs that you can adust the rocer arms or did you run the stock studs/rockers and bottom them out?

If you left the stock rockers/studs in there I have a feeling the adjustment depth with that lift of camshaft would keep the valves open.
I can't tell much from that video... I heard it kind of knock when shutting off.

Where are you from?