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I have a 1995 Chevy S10 and it usually will not start unless I use starting fluid. Once it starts it runs perfectly at all rpm's, under load or not, etc. I can hear fuel pump run when I turn key, I can hear the fuel pump relay click after a few seconds when it "thinks" fuel pressure is right, if I turn key off at this point and turn it back on, the fuel pump doesn't run, indicating to me that the fuel system is holding pressure. My question is: would the motor run perfectly at ALL rpm's, on the highway for as many miles as I care to drive, with low enough fuel pressure as to cause it not to start? Could I be running in part off intake manifold vacuum and in part the weak fuel pressure the pump is still delivering? The check engine light is NOT on but could a sensor or something in computer be failing to let fuel into manifold? I really don't want start replacing things one at a time until I hit the culprit because it's so expensive!

Your Chevy engine is called a Vortec engine. This fuel system needs 60 PSI to start! Anything less will cause the exact same problem you are describing. To verify this problem a fuel pressure test must me performed. You may find you have around 50 to 55 PSI. So have your tech VERIFY what I think the problem is. Make sure that you buy the very best fuel pump you can buy. (If your fuel pump is faulty, don’t forget to replace the fuel filter and fuel pump relay.) Another cause could be the injector unit may be leaking. The fuel pressure test along with the static pressure test will verify if you have these problems. Go to my web site www.masterautotech.com and click on "technician training" You will see how to test for a faulty fuel pump using the 4 tests I have described. Of course you will need to find a shop to do these test because the test equipment needed to do these tests is not inexpensive. Most shops charge around 1 hour to perform all these tests and perform a diagnosis to what your problem may be.

 

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