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kobe1234
New User
Dec 9, 2012, 12:46 PM
Post #1 of 6
(2049 views)
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fuel system problems
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2002 chevy 3500 express van 5.7L not bi-fuel. parked truck to repair a/c system,new coil, dryer, orifice tube, etc. finished it and wanted to start truck to take and get a/c charged, truck doesn't start. has approx 280,000 miles, this is the 3rd fuel pump i''ve installed, installed a new wiring harness, but this time truck wouldn'd fire up. checked relay by switching the a/c relay with the fuel pump relay, still doesn't work, opened up inside engine cover and checked shrader valve for gas line pressure no gas squirted out hence no pressure( i did have the ignition key on). when i dropped the tank to install the new pump a lot of fuel back drained from having to disconnect the fuel filter. could the fuel filter really be the problem or is there a electrical problem. my brother told me that there might be a switch of some sort to shut off the pump in case of an accident. your help would be appreciated thankyou in advance.
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Hammer Time
Ultimate Carjunky
/ Moderator
Dec 9, 2012, 1:36 PM
Post #2 of 6
(2027 views)
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Re: fuel system problems
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You need to use a fuel pressure gauge to know exactly what the fuel system is or isn't doing. The pump only powers for 2 seconds when the key is first turned on.
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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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kobe1234
New User
Dec 9, 2012, 2:52 PM
Post #3 of 6
(2001 views)
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Re: fuel system problems
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thanks for the quick reply, i went and changed the fuel filter, now i get plenty of gas out of the schrader valve, i also changed the cap and rotor as i saw spark coming from the outside of the cap. but this still hasn't done the job. any other suggestions ? control module ? coil? or is this something i have to take to a dealer to have them put it on their analyser.
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Hammer Time
Ultimate Carjunky
/ Moderator
Dec 9, 2012, 2:54 PM
Post #4 of 6
(1995 views)
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Re: fuel system problems
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There won't be any other suggestions since you have done what I instructed in the first suggestion.
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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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kobe1234
New User
Dec 9, 2012, 5:20 PM
Post #5 of 6
(1972 views)
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Re: fuel system problems
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sorry for not doing what you suggested but i didn't have a pressure tester,. i'm trying not to buy tools i probably won't use again . but i did buy a tester. the tester reads 64 psi when the key is turned on then drops to 56-58 when the pump stops pumping. it stays there . i hope that you will still share some of your knowledge and experience , i'm just trying to get this fixed as inexpensively as i can. again sorry! thanks
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Hammer Time
Ultimate Carjunky
/ Moderator
Dec 9, 2012, 5:24 PM
Post #6 of 6
(1963 views)
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Re: fuel system problems
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If you have 60PSI of pressure, then it's time to look elsewhere.
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off. (already done)
4) If all of these things check good, then you would need to do a complete compression test.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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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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