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John
John, Master A.S.E Automotive technician
Category: Chevy
Satisfied Customers: 9176
Experience:  A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
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1989 chevy k2500 4x4: with a 5.7 v8..idles fine..accelerate it dies

Resolved Question:

i have a 1989 chevy k2500 4x4 pickup with a 5.7 v8. It starts and idles fine but when you put in drive and start to accelerate it dies.
Submitted: 8 years ago.
Category: Chevy
Expert:  John replied 8 years ago.

HelloCustomer

There is a good possibility that you have a fuel pump going out(low flow or pressure).You can check this by installing a fuel pressure gage at the filter connection & cycle the key a couple of times.Pressure should be around 12-15 psi & holding for at least 4 minutes.The flow can be checked by running an open fuel pressure line into a containers.It should pump a pint in less than 12 seconds.

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Customer: replied 8 years ago.
if i run a pressure test an everything checks out to 12-15 psi and holds then what?
Expert:  John replied 8 years ago.

Use a scan tool to inspect the ECM for failure codes & data.The throttle position sensor should be at .50 mv(at idle) & near 5.0 volts at wide open throttle.The manifold absolute pressure sensor should be 4.89 volts with key on/engine off-1.5 v to 2.2 at idle & voltage decreasing on acceleration.These 2 sensor are critical for an engine rpm response.

If this looks good pull a plug wire & install a spark tester in the plug wire(start the engine) end to make sure you are not losing spark.

Customer: replied 8 years ago.
one more thing , if it is the fuel pump do i have to drop the tank to change it, any tips on this would be helpfull
Expert:  John replied 8 years ago.
The tank must be pulled down for access.Since you do have some pressure,use the pump & drain the tank.You will find the wiring along the left frame rail(underneath).If you have access to a lift,The way I do it is raise the bed.Put the truck all the way up ,unbolt 8 bed mount bolts from underside,place 2 jack stands at the front of the bed & lower the vehicle until enough area is open to access the tank.