IROC4U

using a universal holley external pump http://www.summitracing.com/parts/HLY-12-920/
26 pound accel injectors 45 psi set on the regulater works fine till the engine warms up about 20 mins in i floor the pedal and itll sputter and my fp gauge dropps dramatically down to 20 psi or so give or take 5 pounds its enough to keep it running i have heard these 2 pop up alot amperage overload or possible vapor lock any suggestions crummy fuel pump?

Orr89RocZ

iTrader: (20)

whats your motor setup, it may not be enough pump to support your goals but it should be as its a 255lph/67 gph setup. Is it a return system I'm assuming? what kind of regulator? factory hsr regulator is known to fail

IROC4U

using a painless tpi map sensor harness holley regulator 7730 computer chiped by motovation ......the motor is a 383 blueprintengine it doesnt happen often and i have changed pumps cause i thought that was the problem and i bought the suggested parts for amp overload put the pump on a seperate relay with a circuit breaker it only happens when i get on it when the engine gets warmed up other then that for easy driving its fine all the time
Critical Specs:
Stroke:
3.75

Rod Length:
5.7

Camshaft:
.487Int / .508 Exh & 234 Int / 244 Exh duration @ .050 - 110 degree lobe sep.

Horsepower:
405

Torque:
440

Compression Ratio:
9.5 to 1

Ignition Timing:
13 to 16 Degree Initial / 34 Degree Total




Cylinder heads:
* New cast iron "Vortec" heads
* 1.25 in. diameter valve springs
* Hardened retainers and springs
* 2.02 in. swirl-polished intake valves
* 1.60 in. swirl-polished exhaust valves
* Hardened pushrods
* 9.5 to 1 compression

Orr89RocZ

iTrader: (20)

what injectors are you using and do you have the holley fuel regulator or something else? I bet its the regulator as they fail often.

tune probably could use work too.

IROC4U

26 pound accel injectors with holley regulater

IROC4U

yea i dont know how to get it re tuned i dont have access to a dyno or anything i couldnt send the chip back but i dont know what id ask for...who did your chip?

Orr89RocZ

iTrader: (20)

when i had my 383 I got a base bin file from pcmforless. I used that and started tuning it myself.

IROC4U

you hook it up to your laptop ? how do you burn your own chips always wanted to do that but never knew how to start it ...

ploegi

Have a look in the DIY PROM board, LOTS of good information there for getting started on chip burning.

IROC4U

its a wild shot but what about a bad battary and alternater im running a fuel pump 2 fans msd box fuel pressure gauge tach and shift light and the harness and computer on the battery is it possible its a crummy battery and weak alternator it is always charging and thank you for your help

vetteoz

iTrader: (13)

Need to check actual Voltage at pump next time it happens

articwhiteZ

iTrader: (56)

the GM stock in tank Pump works/worked for my 383
92 Z28 Lingenfelter stage 5 ENG
stock reg (Moded to adjsbl)
30lb injtrs
52PSI (never dropped below 50 @ WOT) 6400rpm
super ram
383 11.1
But thants mine

johnny89345

im having the same exact problem and pressure readings. i changed the regulator this morning and nothing. im going to try a new pump. 1 thing it can be on my first iroc the rubber hose that connects to the fuel pump was old and spongy and was pumping the fuel right back in to the tank.

IROC4U

when does it happen on yours when you get on it? when its warm ? im gonna change my regulater its been good lately so idk wtf is up the pressure at start up is 44 then drops down to 41 when its warm i mean on an adjustable regulater is that normal ?

johnny89345

mines about 40 idling and drops as low as 20-25 and it gets worse as it gets hot and only notice a drop under hard acceleration. it really isnt noticed i still have decent power but im changing the pump in about a week so ill let you know what happens

mrlipps

Hey Johnny

I have the exact same fuel pressure problem as you, only I have mine set to 50psi at cold start up and by the time the car is hot, it stops dropping at 34psi, did changing your fuel pump correct this problem?
Or does this problem have something to do with our headers and gas lines or even higher engine temps and fpr?

IROC4U

i put smaller injectors when i stomp on it ...it doesnt dropp dramaticlly also i put the fuel pump on a relay both helped it fixed my problem

johnny89345

i didnt fix mine yet those ****ers at summit had my msd distributor and pump on backorder since a few weeks before christmas

transam85dudeman

glad its working, also try opening the fuel cap and see if you can hear suction when you have that issue again.. If the check valve on the gas tank is clogged it wont allow air in the tank as the car uses fuel. i heard When the fuel level drops and the tank becomes a vacuum, hard on the pump--- all if the check valve isnt working.

IROC4U

yes i have that issue to i leave the cap open now just for the time being