How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Gary Your Own Question
Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15697
Experience:  15 years GM master tech
19513769
Type Your Chevy Question Here...
Gary is online now
A new question is answered every 9 seconds

Engine starts and runs for about 20 seconds thenbfuel shuts

This answer was rated:

Engine starts and runs for about 20 seconds thenbfuel shuts off ? If you crank it without shutting key off won't restart. But if you turnbkey off andbrecrank starts right up and runsbfor 20 seconds. Watching injectors ( van ) they shut off after 20 secs.

Welcome! My name is ***** ***** I will do my best to assist you with this problem.Ask me about added features such as phone contact anytime if you wish !

can you find the fuel pump relay as seen here bolted to the fire wall under the hood ?

Customer: replied 1 month ago.

Yes there is two right next to each other

the fuel pump relay should have

orange

green/white

black/white

tan/white

red

can you find those wires ?

we need to see if the green/white is showing 12 volts all the time when its running and the injectors stop spraying fuel

Customer: replied 1 month ago.

Shows full voltage until 5 secs after injectors shut off

unplug the relay and jump the orange wire terminal to the tan/white terminal in the connector with those 2 terminals jumped will it still do this ?

if so then when it dies and you did not turn the key off where it will not start if you unplug both fuel injectors will one wire on each injector show 12 volts ?

Customer: replied 1 month ago.

Still stalls after 20 sec with orange and white /tan jumped. All injector wires show .30 v while running and after it stalls.

30 volts ?

at one wire at each injector ?

Customer: replied 1 month ago.

.30V AT ALL 4 WIRES WHILE RUNNING AND AFTER IT STALLS > POINT THREE ZERO ?

Customer: replied 1 month ago.

HEY SOORY GARY ONE OF MY LEADS WENT bad mid testing all 4 wires have full voltage when running and after stalling

unplug the connectors and does just one terminal in each connector show 12 volts ?

and using a injector noide light or a test light with the test light clip connected to a good 12 volts when cranking it over when it will not start does the OTHER non 12 volts terminals blink your test light bulb ?

Customer: replied 1 month ago.

with connectors unplugged one wire shows batt voltage at each inj. and when it will not start both inj harness connectors blink noid light.

so there is 100 % an injector pulse when it will not run cranking it over ?

if so can you connect a fuel pressure gauge into a T fitting on the fuel line into the fuel filter and see what the fuel pressure is when it will not run ?

Customer: replied 1 month ago.

7lbs

ok so it has fuel pressure and a confirmed injector pulse and powers on the other terminals at the injector connector but no f**k comes out of the injectors ?

Customer: replied 1 month ago.

7lbs pressure 12volts at 1 wire of each injector and noid light flashes on both injectors when it wont spit fuel. its just like you shut the key off. did jumping relay bypass fuel injection module ? alldata shows one in the wiring diag it also shows the oil pressure switch in the loop ?

Customer: replied 1 month ago.

and yes no f**k comes out of injectors when it wont start lol ! ( see your post )

sorry about that typo

the oil switch will not stop fuel injection or the fuel pump from running with 7 psi the pump is making enough pressure and with 12 volts and an injector pulse it shows the ignition module is triggering the computer and the computer is telling the injectors to inject fuel

with the testing you did the only thing left to not allow fuel to come out is the injectors themselves being bad or the throttle body

dont forget to rate us here

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer

Customer: replied 1 month ago.

alldata shows fuel inj module overides ecm and makes pump run for 20 sec to eliminate a vapor lock problem. shows it to be on the seat riser ? there is a cover under seat on riser that says computer ?

Customer: replied 1 month ago.

just found it a little to coinicidental that it shows the mod will make pump run for 20 sec and that is exactly how long it runs before it stalls. and if tbody was the problem why would it not throw fuel if you dont cycle key but if you cycle key to off it starts right up and runs for 20 sec. just trying to sort this out if i put a throttlebody on this and it still stalls my cust will have a big fat cow lol ?

the ECM tells the fuel pump relay to turn on and off since you have 7 psi the fuel pump is relay is not the problem

the module does not operate the fuel pump the relay does

again with 7 psi fuel pressure is NOT the issue

Customer: replied 1 month ago.

if u think tbody ill put one on it and pray lol.

you confirmed everything for an injector pulse and 12 volts

you confirmed 7 psi

that is all that the throttle body needs to send fuel down it

please double check what you tested again if it tests the same the only thing left is the throttle body or the injectors

dont forget to rate us here

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer

Customer: replied 1 month ago.

this filter is clogged not the point of plugged but im afraid the 7 pounds isnt getting to tbody will install new filter and recheck everything in am. if it checks the same its tbody time inc prayers. thanks gary will let u know how it goes.

sounds good

dont forget to rate us here

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

Customer: replied 1 month ago.

what is specs for pump minimum pressure im still nervous because it does not stall like rns ut of gas its like u shut the key off.

7 to 13 psi is spec

try a new fuel filter

is still does this test with another gauge if below the pump is bad

Customer: replied 1 month ago.

new fuel pump and strainer and filter 13lbs pressure. Still runs 20 seconds. Replaced throttle body still runs 20 seconds. If i hook up noid light injector pulse is present. something has got to shutting pump down.

jumping the orange to the tan wire it will still do this ?

if the pump was shutting down the fuel pressure would be 0

Customer: replied 1 month ago.

alldata shows an oil pressure sensor and an oilpressure switch for the fuel pump im betting its not sensing oil pressure and shutting punmp off ? got switch ordered be here in am. it looks baked /melted. your thoughts !

the pump will still run with the relay the oil pressure is an override if the relay fails it will still run the pump once it gets oil pressure

its a redundant system

if you jump the 12 volts from the orange to the tan that goes to the tank and it holds 13 PSI the pump is NOT shutting off as it would NOT have fuel pressure

Customer: replied 1 month ago.

i checked fuel pressure at the filter line coming off pump . dont have an inline guage. so your saying that if i jump the orange to the to the tan that bypasses eveything and powers the pump directly ?so if i do that and i have injector pulse why does it still stall ? replacing relay in am. also. #^#%@%!$@%#%#^&@&&@^^!!%@ no what i mean lol

yes that is what i am saying jumping that bypasses all the stuff even the computer

if it stalls and you do NOT see fuel coming out of the injectors there is a chance the injectors are loosing the pulse or something else is just causing the stall if it starts right back up

Customer: replied 1 month ago.

gary i unplugged the fuel pump relay and the oil switch it still starts and runs fro 20 sec what is powering the pump ?

Customer: replied 1 month ago.

relay has all the right color wires and a small diam red test lead ? right above the air intake kinda oval shaped has another twin relay right next to it.

if the relay is unplugged then nothing is

but if you jump the orange to tan which the tan shows 12 volts that should send 12 volts to the pump does the pump show 12 volts all the time at it when jumped ?

is the big black a confirmed good ground ? if unsure run a new good one from the frame to the black wire

Customer: replied 1 month ago.

im saying that with the relay unplugged and nothing jumped it still starts runs and stalls in 20 sec. how ?

i do not know

with the relay unplugged does the tan show 12 volts at the fuel pump when its running ?

it should not be able two run with the relay unplugged and oil pressure switch unplugged

Customer: replied 1 month ago.

just noticed orange wire has no voltage to untill you turn key on then has voltage for 20 secs. then nothing

Customer: replied 1 month ago.

with relay and switch unplugged tan wh swows 9.5 v for 20 secs then nothing

are you sure ?

if so run a wire from the positive battery cable to the tan wire will the pump run all the time and will it stop stalling ?

Customer: replied 1 month ago.

orange wire shows .32 v when you turn key on for 20 secs ? this killing me ! wtf how could the pump work for 20 secs with evrything unplugged and all voltages are weird and they dissappear after 20 secs untill you cycle key. ??????

try to run a new orange wire right to battery positive cable..will it still stall ?

Customer: replied 1 month ago.

does not stall with tan/wh jumped let me try orange.

what did you run the tan wire too for it to not stall ?

Customer: replied 1 month ago.

ran the tan direct to pos batt ! jumped pos batt to orange and runs fine ! can i cut the orange and run it direct to battery with inline fuse. ?

yes that is exactly how your going to fix this

run a 30 amp inline fuse and a new wire and it should be fine

dont forget to rate us here

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer

Customer: replied 1 month ago.

#@$$%@%#^&^&!^@%@%#$$!!%!^!^@^&&&^!^!%%$#@$#$ lol thanks g

anytime

dont forget to rate us here

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

let me know how it goes

dont forget to rate us here

Gary and 4 other Chevy Specialists are ready to help you
Customer: replied 1 month ago.

can i run that new orange off pos on battery without creating a draw that will run battery down. thats what i did ?

yes you can