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Ron, ASE Certified Technician
Category: Chevy
Satisfied Customers: 34744
Experience:  35 years experience with ASE Certs
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I have a 1998 1500 Silverado that sat up a year because the

Customer Question

I have a 1998 1500 Silverado that sat up for over a year because the prior owner's father ran the truck in the middle of an oil change without verifying that the oil was added during an oil change. I changed the motor, fuel sending unit, fuel pump and screen, ignition system components. The engine would run fine sometimes at an idle, sometimes it would start rough, and sometimes the engine would run smooth to idle or idle to rough. When driving, the engine would run rough, backfire, launch, and then it would run smooth. I had a scan done at Auto Zone and their computer stated that the cam position sensor, MAP sensor and the knock sensor were bad. A map sensor was used from another engine. Upon inspection of the distributor, it was discovered that the gear was bad. I replaced the distributor and now the truck runs fine at an idle, but now the truck will not accelerate at an idle or under a load.
JA: How many miles are on the car? Have you checked the spark plugs?
Customer: I don't know how many miles are on the replacement engine. Possibly 150-200,000 miles. I took it out of a truck that I wrecked. I have new plugs, wires, pick up coil.
JA: What is the model of your '98 Chevy?
Customer: It is a 2wd Silverado with a 5.7 litre engine.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I have a mechanic working on it now and he is baffled. I have only tried the above mentioned steps.
JA: Anything else you think the mechanic should know?
Customer: I think the mechanic should know of any possible solutions to the problem.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Chevy Mechanic about your situation and then connect you two.
Submitted: 9 months ago.
Category: Chevy
Expert:  Ron replied 9 months ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

With everything you have already replaced I would start with having him check the fuel pressure while the problem is occurring. Normal fuel pressure on your 5.7 needs to be right at 60 to 66 PSI. Anything less then 60 would indicate you have a failing fuel pump. Have him check this and post back with the results and we can work from there.