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Ask Chad Farhat Your Own Question
Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: Chevy
Satisfied Customers: 1219
Experience:  Owner at Carolina Auto Service & Sales , 20 years Experience in Foreign & Domestic vehicles A6 - Electrical / Electronic systems A7 Heating / Air Conditioning systems
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All was fine, lost power exelerating from a stop light.

Customer Question

all was fine, lost power exelerating from a stop light. Limped to gas station, then would not restart. Fuel pressure gauge says no fuel pressure, but fuel pump is definitely working. pulled a plug wire, I have spark. Full tank of gas. Brand new fuel filter. Swapped out relay with known working one, nothing. Still won't start
JA: Is the power loss consistent, or does it fluctuate?
Customer: Won't start now, or turns over and dies. No resistance in gas pedal
JA: What year is your Station?
Customer: 03 Chevy Tahoe 5.3
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes, I listed what I have tried above
JA: Anything else you think the mechanic should know?
Customer: not that I know of
Submitted: 1 month ago.
Category: Chevy
Expert:  Chad Farhat replied 1 month ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Customer: replied 1 month ago.
great, I'm beatin my head over here...
Expert:  Chad Farhat replied 1 month ago.

1-the fuel pressure needs to be (55-62 psi )

2-do you have spark ?

3- is there a check engine light on & did you scan it for fault codes?

4- what is the mileage on it?

5- fuel pump relay checked ?

6- you said you do hear the fuel pump prime for few secs from igntion switch off to on ?

please let me know

Thank You *****
ASE Certified Technician

2003 Chevy Truck K Tahoe 4WD V8-5.3L VIN T

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Fuel pressure ......................................... 385-425 kPa (55-62 psi)

Expert:  Chad Farhat replied 1 month ago.

also the CKP(crank shaft position sensor or sensor or the wiring to it is common fault , if no spark exist ?

Customer: replied 1 month ago.
test gauge says little to no pressure. I have spark. No check engine light. OBDII says no codes. 150,000 miles. Relay swapped with known working one, still no start. Fuel pump IS bringing fuel to the rail
Expert:  Chad Farhat replied 1 month ago.

The Fuel Pump Relay is located in the Underhood Fuse Block. The Underhood Fuse Block is located in the left side of the engine compartment to the rear of the battery.

have you swapped or checked fuel pump relay , I sent you location at diagram, there is also a fuse for it in that box 15 amp

1- we need to confirm 2 things , I know fuel pump is running but are you getting 55 to 62 psi ?

2- are you getting good spark , how did you test for spark, ?

you need these 2 things to run ,you are either missing one or both , or one of those is weak ?


Expert:  Chad Farhat replied 1 month ago.

if no pressure on gauge but fuel pump is running ,and you have a new fuel filter , that leaves a weak pump , unless fuel pressure is good to the rail but the injectors are not opening and you have pcm ground issue ?

Customer: replied 1 month ago.
tried again, not reading any pressure on test gauge. Definitely fuel at the rail. It actually started after 4 tries, but was super rough, and when I pumped the gas it felt like I was doing nothing. Like no resistance in the gas pedal. Also, When I try to start it, it doesnt just keep turning over. I put the key in and turn it all the way over and it starts and dies, starts and dies. No continued sound of turning over with key turned. Tried for spark by pulling a plug wire and sticking a screw driver in the wire and arcing to engine block
Expert:  Chad Farhat replied 1 month ago.

unplug the mass air flow sensor and cranked it up ,will it make a difference?

Expert:  Chad Farhat replied 1 month ago.

fuel at the rail is good, but we need to have enough pressuer to open up the injectors ?

Spray starting fluid in the Throttle body ,does is fire right away if you did that ,have you tried ?

Customer: replied 1 month ago.
Pulled MAF, nothing. Sprayed starter fluid and it definitely started for longer, then died. Gas pedal didn't feel like it was doing anything
Expert:  Chad Farhat replied 1 month ago.

do you have a scanner ,did you retrieve any codes ?

Customer: replied 1 month ago.
scanner said no new or saved codes
Customer: replied 1 month ago.
I am a novice, at best. How can there be fuel at the rail and the test gauge reads nothing?
Expert:  Chad Farhat replied 1 month ago.

If the Throttle body or tps sensor is an issue ,it would have showed it in the pending codes, as long as you did not disconnect battery since the failure and erased the codes :)

The gas pedal not feeling right ,i m not sure i cant feel what it is doing , i m assuming since it is not getting enough gas it is doing that ?

there can be fuel at the rail but just not enough ,because of a weak fuel pump, pump lost its pressuer , especially when you sprayed it ,it started quicker, the fuel pump assembly is common failure on these tahoe

Change the fuel pump assembly in the tank

Please let me know if you need anything else on it, just reply back & we can continue trouble shooting the problem

If you are good , kindly rate me.

A Positive rating is much appreciated

This post will stay open for you even after you rate me, for you to come back and ask any follow up question you may have on this issue

Thanks You
Chad Farhat
ASE Certified Technician

Customer: replied 1 month ago.
Tank is FULL of gas, and pump is less than 2 yrs old. I hesitate to go to all the trouble and expense if this is not 100% the problem
Expert:  Chad Farhat replied 1 month ago.

you have to see pressuer on the gauge for it to be working correctly should see 55 to 62 on key on and hear it run,for fews secs at the turn of the switch

if you getting power to it and you already swapped the relay , and you hear priming and still no pressuer , it tells me it went bad again , usually it has a lifetime warranty if you bought from like advance auto or auto zone .

Expert:  Chad Farhat replied 1 month ago.

but the trouble codes are necessary , in case we have electrical issue or tps or pcm problem ?

so if you can get it scanned , I would do it, another area is the fuel pump electrical connector ,inspected it for back out pins

, if go to auto zone, if you have one where you at , they will run the scan for free and give you a print out at least the one around here does it

that if you can make it there with it running rough when it runs

Customer: replied 1 month ago.
I released the pressure to the system when I swapped the fuel filter yesterday. At this time I hooked up the test gauge to the test port. And tried to start it. Forgetting that I had repressurized the system, I went to detach the test gauge from the test port and got sprayed a bit. So fuel is there. I can hear pump, no problem. I used a jumper wire in place of relay and pump stayed on, no problem. I had the battery out for a few hours before I got it towed to the house, so any codes would have been reset, right? How can I get codes if I cant run truck to get them to show up again?
Expert:  Chad Farhat replied 1 month ago.

unfortunately you cant on the codes , after you keep cycling the switch it might or might not throw a code , problem with a weak fuel pump it will not throw a code

unless it runs and the pcm picks up other sensors like injectors and set an injector code as an example

so at this time you can only rely on the pressure tester, why cant you now , hook up the tester ,turn key from off to on and tell me what you get ?

i understand you hear it running and you swapped the fuel filter, sorry you got sprayed :),if it goes in the eye it will burn bad, but we still dont know how much fuel pressure we have ,can you do that & let me know

and you jumping relay that is cool that confirms the circuit to it is good and the pump runs , but dont confirm if relay is good ?

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

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