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Old 05-07-2003, 11:02 PM
cnred
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Default won\'t start unless you pour gas down the throttle

I have a 1987 chevy 3/4 ton 4x4 350 5.7 lt. It wont start unless you pour gas down the throttle body brand new fuel pump and throttle body also there is a humming sound coming from my ecm at idle any help will be usefull thanks
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Old 05-08-2003, 02:26 PM
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Default Re: won\'t start unless you pour gas down the throttle

bad fuel pump relay, clogged filter, clogged or pinched fuel line.
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Old 05-08-2003, 03:09 PM
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Default Re: won\'t start unless you pour gas down the throttle

I've replaced the relay,filter and checked all my lines.
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Old 05-09-2003, 12:50 PM
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Default Re: won\'t start unless you pour gas down the throttle

maybe bad fuel pressure regulator?
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Old 05-09-2003, 03:36 PM
cnred
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Default Re: won\'t start unless you pour gas down the throttle

I put a new throttle body (fuel pressure regulator's are part of the main body)on it. Thanks.
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Old 05-09-2003, 06:18 PM
87sm465np208
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Default Re: won\'t start unless you pour gas down the throttle

did you put the filter on backwards?, perhapes take off the incomeing gas line on the filter and have someone turn on the key, see if gas comes out, did you make sure to plug the pump back in? and put gas in it. [img]images/graemlins/RockOn.gif[/img]
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Old 05-09-2003, 08:44 PM
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Default Re: won\'t start unless you pour gas down the throttle

You weren't specific, but we can assume it is a TBI?
And - after you pour gas down it starts and runs fine?

1. The ECM should not be making any noise - ever.
Smells burned? History.
Does it make the noise only during cranking or all the time?

2. Have a listen right at the fuel pump itself. Have someone turn the key on but not start it - the pump should run a few seconds to pressurize the system, then shut off. It won't run again until the engine starts and the ECM sees distributor reference pulses. See if it runs that first few seconds.

3. If it does run a moment, don't crank it, turn the key off, then open the inlet fuel line quickly to verify pressure is there. If not, it's leaked down through that new pressure regulator on the TB - replace again.

The ECM noise - try disconnecting the connectors to the throttle body injectors, see if the noise still happens.
Try disconnecting the connectors to the throttle positioners.
Try disconnecting each sensor, one at a time till it stops making the noise.

I have a feeling you got the wrong throttle body on there, the resistances of the injectors are wrong, creating too much load on the ECM. You can measure the resistance of the injectors to make sure all's well. And - measure to ground, the injectors should not be grounded at all, the ECM does that.

Let us know -
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Old 05-10-2003, 02:49 PM
cnred
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Default Re: won\'t start unless you pour gas down the throttle

Thanks for the list of things to try R.Rich as soon as it the tornados pass i'll try them.
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