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Discussion Starter #1
I need some help here. My daily driver is a 94 4x4 Suburban with a TBI 454. I changed the fuel pump and filter the week before christmas(old pump died) and ever since, the thing runs rich at idle and stumbles. The problem is especially bad when it's warmed up and you shut it off and restart it. It'll surge when in gear and stopped too. It seems to be worse at night when there's more electrical load with lights and all.
 

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Friend of mines did the same thing 3-4 months ago. Get the code for the malfunction, it is stored in the trucks computer. Use a piece of wire to jump the plug in ports located on the drivers side by your knees when sitting in the drivers seat, under the steering column. Look it up online or use your Chiltons manual once it blinks the code (it uses the check engine light to blink the malfunction at you and repeats it, over and over) for the malfunction and look it up in the manual. My friends problem was the knock sensor. Get the code and look up what your engine is TELLING YOU is wrong. It can tell you better than anyone else can.
 

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Discussion Starter #4 (Edited)
put a fuel pressure gauge on it and go from there
That won't be too easy. There's no fuel rail on these. just 2 lines that go into the back of the throttle body. I don't think it even has a regulator on it. I know the TBI runs at low pressure.


I'll try the code thing
 

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That won't be too easy. There's no fuel rail on these. just 2 lines that go into the back of the throttle body. I don't think it even has a regulator on it. I know the TBI runs at low pressure.


I'll try the code thing

There is no valve to put the gauge on but they make an adapter that goes in place of the fuel filter which has a valve on it for the gauge. In your case, that is probably the first thing you need to do to establish what is going on. Besides a scan tool or at least checking codes, provided the check engine light even came on or not?
 

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Did you check for vacum leaks ?
 

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That won't be too easy. There's no fuel rail on these. just 2 lines that go into the back of the throttle body. I don't think it even has a regulator on it. I know the TBI runs at low pressure.


I'll try the code thing
The regulator sits under the bracket that holds the two injectors , remove the two line adapters after removing the lines. Remove the 4 Torx 15 bolts that hold the injector bracket to the throttle body remove the injector wires . Pull the bracket up and out of the throttle body and the regulator is there.

Its not adjustable but they sell the bladder in the TBI master kit
 

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x2 on all suggestions. Get a scanner and check coolant sensor when engine is cold, make sure it reads close to ambient temp. Check MAP voltage, especially at idle. Should be .90-1.1v. Check fuel pressure, 9-13 psi. When you do a fuel pump you should take a good look at the wiring connections at the top of the sending unit and at the pump. A loose terminal will do funny things.
 

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Make sure you put the right fuel pump in it, the 94 and newer are high pressure, not the typical 9-13. They are 26-32 psi then in 96 they went to over 50psi. Most likely you put a old style pump and they dead head at around 15-18 which is way too low.
 
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