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fuel pressure


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ThGeneral1
Novice

Jun 30, 2010, 7:13 AM

Post #1 of 10 (1703 views)
fuel pressure Sign In

Hello all ....need some help guys I have 2002 Silverado 1500 4.3L with 95000 miles on it..it starting running poorly with a loss of power under load I replaced the plugs, wires, air filter, oil figuring it was time for a tune up... didnt help the problem only got worse I replaced the coil nothing..then it really got bad took a month to get down to this level now only going up to speeds of 30mph so I then checked the fuel pressure when you first turn the key it didnt read at all....it would crank and run at around 55psi when the key was turned off it would drop to zero..so it wasnt holding pressure. I replaced the fuel pressure regulator figuring that was the answer..that helped but didnt solve the prob..now when key was turned on pressure went to 65psi but would bleed down to 20psi in about 5 sec..would run at around 50psi and when key turned off would fall to zero in 10-12 sec. I plugged the return line and it held at 65psi and ran fine so what gives? my new regulator bad? isnt if the return is blocked the pressure should go on up to 75psi? oh im getting P0300 reading on my scan tool..multiple misfires..not enough fuel pressure across the board I imagine....what do I check next? what is causing it to lose pressure through the line? thanks for all replies


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 30, 2010, 7:31 AM

Post #2 of 10 (1699 views)
Re: fuel pressure Sign In

What are the fuel adaptives doing?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ThGeneral1
Novice

Jun 30, 2010, 8:25 AM

Post #3 of 10 (1694 views)
Re: fuel pressure Sign In

not sure what you are refering too...


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 30, 2010, 8:29 AM

Post #4 of 10 (1690 views)
Re: fuel pressure Sign In

You said you had a scan tool. Is the computer trying to make it more rich or more lean. It would be listed as long term fuel trim. Is that number moving positive or negative when the engine is running?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ThGeneral1
Novice

Jun 30, 2010, 8:42 AM

Post #5 of 10 (1686 views)
Re: fuel pressure Sign In

yes I have a OBD2 code reader but I dont think its advanced enough for that..I'm looking in the manual and see nothing about while the vehicle ruuning


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 30, 2010, 8:43 AM

Post #6 of 10 (1683 views)
Re: fuel pressure Sign In

Does it display sensor data or not?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ThGeneral1
Novice

Jun 30, 2010, 9:04 AM

Post #7 of 10 (1679 views)
Re: fuel pressure Sign In

it gives the 3 digit code and shows icons to eleven systems it monitors


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 30, 2010, 9:23 AM

Post #8 of 10 (1676 views)
Re: fuel pressure Sign In

Your going to have to get a professional scan tool to diagnose this. That thing you have is worthless.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ThGeneral1
Novice

Jun 30, 2010, 10:09 AM

Post #9 of 10 (1669 views)
Re: fuel pressure Sign In

ok thanks..I was hoping for something a little more constructive though..maybe someone else has an idea?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 30, 2010, 10:52 AM

Post #10 of 10 (1664 views)
Re: fuel pressure Sign In

We can't conclude things without some information and the equipment your trying to use isn't capable of giving any info.
I suspect you may have pinched off the feed instead of the return because the way you said you did it points right to a regulator which you said you already replaced.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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