No power in engine, and a clanking noise from the bottom of the truck. I changed the plugs, Fuel pressure regulator, and air filter. Coils are good.

Check fuel filter and lin3s to make shure they have not been pinched by some one jacking car up in wrong spot

Could be a bad coolant temp sensor, making the ECU think the engine is a different temp than it is. However, smelling fuel makes me think you might have a bad fuel pressure regulator. Instead of just bolting on parts, use a fuel pressure gauge to test the system, and look for leaks too. Also insure you have spark to the plugs, but BE CAREFUL! If you have fuel fumes present and create a spark things could go BOOM!

hi, I use to have the same problem I had to change engine electrical wires, then I had to change the crank sensor and the module ( destributer ) first let him check the complete wires installation then if they are good let him change the crank sensor

There is no test

You replace every 3 or 4 years,then if you want
to know if that is the right time frame, you cut the old
one open & check for dirt

You put a fuel pressure gauge on the engines fuel rail to
check for pressure.

What you get is fuel regulator pressure
Then you remove the regulator vacuum hose to see
fuel pump pressure
If that is low, then you change the filter & cut open

If you have vehicle problems explain in detail

A fuel filter is preventative maintenance just like trans
fluid,power steering fluid,brake fluid,coolant,air filter,
spark plugs.

air filter really dirty, injectors stuck open. fuel pressure regulator is bad.

usually caused by busted diaphram in fuel pressure regulator allowing fuel to be drawn thru regulator directly to intake manifold. Pull vacuum line off regulator, plug line with golf tee, start car and watch to see if gas comes out of regulator. If yes, turn off car, replace regulator. The regulator sits near the fuel rail on the top of the engine as shown below. I will paste replacement instructions below from autozone.com in case you need to replace the regulator. Please let me know if you have any questions.

Removal & Installation

4.2L Engine

1. Relieve the fuel system pressure.
2. Remove the air cleaner outlet resonator.
3. Disconnect the engine wiring harness from the retaining clips at the front of the engine.
4. Disconnect the fuel pressure regulator vacuum line.
5. Clean any dirt from the fuel pressure regulator and the surrounding area.
6. Disconnect the fuel return pipe.
7. Remove the fuel return pipe retainer.
8. Remove the fuel pressure regulator retainer.
9. Remove the fuel pressure regulator.
10. Inspect the regulator filter screen for contamination. If contaminated, replace the fuel pressure regulator.

To install:

1. Install the regulator filter.
2. Install the new O-ring on the fuel pressure regulator.
3. Lubricate the fuel pressure regulator O-ring with clean engine oil.
4. Push the fuel pressure regulator into the regulator housing on the fuel rail.
5. Install the fuel pressure regulator retainer. Tighten the regulator retainer screw to 71 inch lbs. (8 Nm).
6. Install the fuel return pipe retainer. Tighten the return pipe retainer screw to 71 inch lbs. (8 Nm).
7. Connect the fuel return pipe.
8. Connect the fuel pressure regulator vacuum line.
9. Connect the negative battery cable.
10. Inspect for leaks:
    1. Turn ON the ignition for 2 seconds.
    2. Turn OFF the ignition for 10 seconds.
    3. Turn ON the ignition.
    4. Inspect for fuel leaks.
    
    
11. Install the engine wiring harness into the retaining clips at the front of the engine.
12. Install the air intake resonator.

Removal & Installation of fuel Regulators on
4.8L, 5.3L & 6.0L Engine To Remove:
CAUTION
Three styles of fuel pressure regulators and fuel rails will be used in this model year. Each regulator has a different "footprint" that consequently changes the size of the receiving port in the fuel rail. The regulator retaining clips are specific to each rail-regulator design and cannot be interchanged.

1. Remove the engine sight shield.
2. Relieve the fuel system pressure. Refer to Fuel Pressure Relief Procedure.
3. Clean the fuel pressure regulator retainer and the surrounding area.
4. Remove or disconnect the following:
   • Fuel pressure regulator vacuum line.
   • Fuel pressure regulator retainer.
   • Fuel pressure regulator.
5. Remove the following parts from the fuel rail:
   • Backup ring (10)
   • Regulator Seal O-ring (11)
   • Regulator filter (12)
   • Regulator seal O-ring (13)

To Install:

1. Make sure the NEW fuel pressure regulator retainer is the right one.
2. The tabs (1) are used on the straight vacuum port retainer (2), and the E85-straight vacuum port retainer (3).
3. The angle vacuum port retainer (4) has no tabs.
   
   
4. Install the following parts onto the fuel pressure regulator (9).
   • Backup ring (10)
   • Regulator seal O-ring (11)
   • Regulator filter (12)
   • Regulator seal O-ring (13)
5. Lubricate the fuel pressure regulator O-rings with clean oil.
6. Install the fuel pressure regulator and retainer. CAUTION
   Whenever the fuel pressure regulator is removed from the fuel rail NEW O-rings and a NEW retaining clip should be used on reinstallation.
   
7. Connect the vacuum line.
8. Tighten the fuel filler cap.
9. Use the following to inspect for leaks:
   • Turn ON the ignition, with the engine OFF, for 2 seconds.
   • Turn OFF the ignition for 10 seconds.
   • Turn ON the ignition, with the engine OFF.
   • Install the engine sight shield.

8.1L Engine To Remove:
Fuel pressure regulator vacuum line

1. Before servicing the vehicle refer to the precautions at the beginning of thjs section
2. Remove the fuel injector sight shield as needed
3. Relieve fuel system pressure (See: Fuel Pressure Relieving)
4. Disconnect the fuel pressure regulator vacuum line (A) 8.1L Fuel pressure regulator retainers
   
   
5. Clean any dirt from the fuel pressure regulator retainer and the surrounding area
6. Remove the fuel pressure regulator retainer (I)
7. Remove the fuel pressure regulator (H) from the fuel pressure regulator housing

To Install:
8.1L Fuel pressure regulator retainers

1. Install or connect the following:
   • Backup ring (J) on the fuel pressure regulator (H)
   • New large O-Ring (K) on the fuel pressure regulator
   • Regulator filter (L) on the fuel pressure regulator
   • New small O-Ring (M) on the fuel pressure regulator
2. Lubricate the fuel pressure regulator large O-Ring and the small O-Ring with clean engine oil
3. Push the fuel pressure regulator onto the regulator housing on the fuel rail
4. Install a new fuel pressure regulator retainer (I)
5. Install or connect the following:
   • Fuel pressure regulator vacuum line
   • Negative battery cable
6. Tighten the fuel filler cap
7. Inspect for leaks using the following procedure:
   • Turn on the ignition with the engine off for two seconds
   • Turn off the ignition for 10 seconds
   • Turn on the ignition with the engine off
   • Inspect for fuel leaks
8. Install the fuel injector sight shield
9. Road test the vehicle to check performance

I would change the fuel pressure regulator first, if no change in pressure the fuel pump is on the way out.I have a 01 silverado 4.8 and my fuel pressure is between 55and60 psi.

HI. There are some areas that will need to be checked for faults, in this case. Check the following:

1. Fuel filter- If this device is clogged, or faulty, it will decrease the flow of fuel to the injector assembly. If the filter hasn't been changed recently, this will be a good place to start.

2. Fuel pump- This device may be weak, or grounded poorly. check the ground, and all wires the link the pump to the power source. replace any corroded contacts and connectors. wires,as well, if needed.

3. Fuel pressure regulator- The fuel pressure regulator is used to keep the fuel pressure in the fuel rail consistent and change the fuel pressure depending on the throttle position. The fuel rail is in a fuel loop between the fuel pump feed and return lines. Because the fuel delivery requirements change depending on the engine's throttle position and engine loads, the fuel injection system must be able to adapt to meet the fuel requirements of the engine's operating conditions during idle, acceleration and steady cruising.The fuel pressure regulator has a small vacuum line attached to it that allows the pressure regulator to change the fuel pressure in the fuel loop depending upon the intake manifold pressure which changes as the throttle position changes. When the throttle is opened, the manifold vacuum pressure drops off, causing the pressure regulator to increase the fuel pressure in the fuel loop, which increases the amount of fuel delivery at the injectors to provide for the additional fuel needed for the engine to operate properly.At idle, the manifold vacuum increases and the demands for the rate of fuel delivery are decreased so the pressure regulator decreases the fuel pressure in the fuel loop.

1. Look for visible evidence of fuel leaks.
2. A pressure regulator can become defective due to foreign material or a ruined diaphragm.

The result will be hard starting, poor idle quality, and lack or power. Burned spark plugs can result from operating with a lean air/fuel mixture, as well. replace this device if faults exist.

It is possible that your fuel regulator is leaking.

On the throttle assembly, there should be a few vacuum hoses attached. Pull those off and shake it a bit to see if there is any fuel coming out of it.

If it is...there should be an updated fuel pressure regulator.

Also you should replace the Idle Air Control Valve which is located near the front to bottom side of the throttle assembly.

When the fuel pressure regulator leaks, it causes a rich mixture and also damages the Idle Air Control Valve.

Both of which I have seen cause a hard start, lack of power, and blue smoke.

One more thing to look into are a set of coils, wires and plugs.

I've seen the coils get hairline cracks which causes the electricity to fire the spark plugs to arc out and not fire off the plugs efficiently, which ultimately causes lack of power and blue smoke.