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Rangerj
User
Nov 25, 2010, 6:26 PM
Post #1 of 12
(1354 views)
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1999 Chevrolet Malibu 3.0 auto.Ran great this a/m went to drive this p/m won't crank spins good etc.so I am thinking the fuel pump.If it checks out bad can I access it from under the back seat?
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 25, 2010, 6:35 PM
Post #2 of 12
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That would be a "no" on the seat access and I wouldn't be so quick to jump to that conclusion that the pump is the problem.
Here the diagnostic sequence
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.
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.
(This post was edited by Hammer Time on Nov 25, 2010, 6:35 PM)
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Rangerj
User
Nov 25, 2010, 6:51 PM
Post #3 of 12
(1343 views)
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Thank you Hammer for your response I was just kicking ideas around. I would not buy any part unless it was needed.I do not have the tools or knowledge for all the test needed. But will have to have it towed for the test. Just looking for ideas.Thanks
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 25, 2010, 6:53 PM
Post #4 of 12
(1340 views)
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The spark tester and noid light can be purchased for under $10 and many parts stores will rent fuel pressure gauges. There are no ideas until you have some test results.
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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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Rangerj
User
Nov 25, 2010, 6:54 PM
Post #5 of 12
(1336 views)
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Thanks again Hammer I will look into that.
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Sidom
Veteran
/ Moderator
Nov 25, 2010, 7:03 PM
Post #6 of 12
(1331 views)
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Spark and fuel should be confirmed with the right tools so there is no confusion as HT posted...
Something to get you in the ballpark would be to crank it for a bit and then depressed the schrader valve on the fuel rail if no fuel comes out pound on the gas tank with some thing heavy that isn't going to damage the tank. If it starts then you are in the 70% area of a bad fuel pump.... It would also be a good idea to make sure there is spark while it isn't starting....
True story: A co worker got lazy and didn't verify no fuel or no spark. Went out pounded on the tank, car starts, replaces fuel pump. Only problem was the car had a bad control module which just happened to start working again while the tank was being pounded on...........ooooops
(This post was edited by Sidom on Nov 25, 2010, 7:04 PM)
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Rangerj
User
Nov 25, 2010, 7:09 PM
Post #7 of 12
(1325 views)
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Thank you sir,I have a big rubber hammer I will give it a tap or two.Will post back results Tommorow.
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Rangerj
User
Nov 25, 2010, 7:55 PM
Post #8 of 12
(1319 views)
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Just went out and car started right up runs fine. Now what? Thanks
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 25, 2010, 8:09 PM
Post #9 of 12
(1316 views)
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Now your screwed until it happens again. You can't fix what isn't broken.
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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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Rangerj
User
Nov 25, 2010, 8:48 PM
Post #10 of 12
(1309 views)
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Yep,just my luck.
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Sidom
Veteran
/ Moderator
Nov 25, 2010, 9:06 PM
Post #11 of 12
(1307 views)
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Yup......without knowing what you were missing it would be a total guess....
What you can do is get a fuel pressure gauge and check your pressure, get the codes pulled and see if anything was set
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Rangerj
User
Nov 25, 2010, 9:16 PM
Post #12 of 12
(1301 views)
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Yep,gonna have to do that.Thanks
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