[AllanC]

Vehicle is a 2007 Chevy Silverado 1500 Classic model, regular cab truck with short bed. Engine is 4.3 liter V6. Odometer reading is about 160,000 miles. Truck was cruising just fine, went to accelerate and it quit running. Starter spins engine but no attempt to fire and run on its own.

You can hear the electric fuel pump run when first turning ignition key switch to ON / RUN position. After engaging starter and releasing key switch to ON / RUN position the fuel pump runs 1 - 2 seconds and then stops. That tells me that electrical power to the pump is good.

Removed the air intake plenum on the throttle body. Opened the throttle plate and gave the throttle body a 5 second squirt of starting fluid. Cranked engine, it started, ran 2 seconds and then died. That tells me the engine is getting proper spark and timed properly.

Problem is with fuel delivery. Attached fuel pressure gauge to test port on intake fuel line at throttle body. Cycled ignition key switch to activate electric fuel pump. No pressure at all. Remove the pressure gauge hose and depressed the schrader valve insert at the test port with a screwdriver tip and cycled the ignition key to ON / RUN and activate fuel pump. Still no fuel at the test port.

Instrument panel fuel gauge indicates about 1/4 level so I do not think the tank is empty. Fuel gauge sending unit was replaced 2 years ago because the original failed and would not register. Replacement sending unit has functioned as expected.

So I am ready to make the recommendation to neighbor friend that electric fuel pump needs to be replaced. What bothers me is that I would expect at least a dribble of fuel from the test port but I get nothing. Do electric fuel pumps fail in such a way that you get absolutely no pressure? Could a plugged fuel filter / fuel line restriction act like a failed pump?

 

[chuzz]

Stupid question, I'm sure, but is there a fuel pressure regulator on the truck, Alan? If not that, then I'd suspect the fuel pump has failed completely. If there IS an actual fuel filter in line somewhere that you can check? To replace the fuel pump, I've found it easier to raise the bed of the truck rather than drop the tank.

 

[Bob Lincoln]

When you found no fuel, and no pressure, did you hear the pump run that time? On most cars, turning it only to ON lets the pump run 2 seconds, then shuts off. It will do this typically twice, then the 3rd try, it won't let the pump turn on until you crank the engine and get a crank signal.
It's possible that a check valve at the pump has failed, so that the pump can't build pressure. Or that a filter is clogged, wherever that may be located.

 

[bguy]

Check crank sensor.

 

[AllanC]

. . . but is there a fuel pressure regulator on the truck, Alan? If not that, then I'd suspect the fuel pump has failed completely. If there IS an actual fuel filter in line somewhere that you can check?. . .

From information that I have gathered on the web and from Y T videos GM used a spider type fuel injection arrangement on these engines. There is no fuel rail that runs outside the intake manifold and provides pressurized fuel to an individual injector at each intake runner port to its respective cylinder. It is centralized at the throttle body with a pressure regulator.

I checked the pressure upstream at the fuel line test port at the throttle body both with a gauge connected and without the gauge connected. In the latter I just depressed the schrader valve insert at the test point with a screwdriver tip, turned the ignition key to the ON / RUN position, heard the electric fuel pump run but no liquid fuel spray at the test port. Even if the pressure regulator had failed I should still get some fuel at the test port if the pump is good and can pressurize??? I need to look on the inside of the frame rail to see if there is an inline fuel filter. If YES then disconnect and see if pressurized fuel is found at that point. But like Chrysler vehicles the fuel filter may be incorporated into the fuel pump module and is not serviceable as a separate item.

. . . .To replace the fuel pump, I've found it easier to raise the bed of the truck rather than drop the tank.. . . .

I would agree but we got "slid" several years ago on this procedure. When the fuel sending unit failed and needed replacement, we attempted to loosen all of the bolts attaching the bed to the truck. There are round, threaded fasteners spot welded to the bed channels and then bolts go through the frame and attach. One broke loose and turns freely so you cannot get this one lone bolt removed to lift the bed. It is in the vicinity of the fuel tank so I did NOT want to apply heat / flame to try and get the stuck bolt removed. So alas to get to the fuel pump you have to drop the tank. UGH!

When you found no fuel, and no pressure, did you hear the pump run that time? . . . .

YES. And the fuel pump continues to run for 1 - 2 seconds after disengaging the starter.

. . . On most cars, turning it only to ON lets the pump run 2 seconds, then shuts off. It will do this typically twice, then the 3rd try, it won't let the pump turn on until you crank the engine and get a crank signal. . . .

I understand what you are saying about this. My 1988 Dodge Caravan with 3.0 liter V6 and port type fuel injection behaved in this manner. After turning the ignition key switch to ON / RUN several times without engaging the starter, you had to crank the engine to get the fuel pump to energize again. I have never encountered another Chrysler electronic fuel injection system that behaved in that manner. And on this Chevy you hear the pump energize every time the ignition key switch is turned to ON / RUN position.

. . .It's possible that a check valve at the pump has failed, so that the pump can't build pressure. Or that a filter is clogged, wherever that may be located. . . .

Good point about check valve failure. That makes sense.

. . . Check crank sensor. . . .

I sprayed starting fluid into throttle body, engaged starter, engine started and it ran 2 seconds and then died. So sensors that control spark and timing are functioning properly, otherwise engine would NOT have ran at all.

I am doing this diagnosis as a favor to a former neighbor so I would like to be 100% sure on making the call for a failed fuel pump. I do not like to fire the "parts cannon" and hope that I made the correct assessment.

Some good thoughts presented and I need to search and see if an in-line fuel filter is present. A plugged, external filter could be the culprit.

 

[Bob Lincoln]

After turning the ignition key switch to ON / RUN several times without engaging the starter, you had to crank the engine to get the fuel pump to energize again. I have never encountered another Chrysler electronic fuel injection system that behaved in that manner.

Every EFI Chrysler product I've owned or worked on behaves this way - 84, 85, 92, 93 Daytonas, and 89 Acclaim. Both TBI and multi-port.

 

[85lebaront2]

I was hoping it was like the older Chevy trucks I have worked on, many had a fuel pump priming wire that can be used to "hot wire" the pump in order to make it run for test purposes. This does not, but if you pull the fuel pump relay in the underhood power distribution box and jump relay socket 30 to 87 the pump will run. Unfortunately, unlike Chrysler or Ford, the computer provides the 12V to the relay and the other side of the coil is grounded. I would do that first and see if you get any fuel. I would definitely check for a clogged filter with what we get for fuel these days.

It also looks like the fuel level sender goes through the PCM and then to the gauges, so there could be an issue there. I would go thump the tank to be sure there actually is gas in the tank especially since GM has had a lot of gauge cluster issues on later trucks.

 

[Bob Lincoln]

Good point, the tank might really be empty. Throw in 2-3 gallons and see what happens.

 

[chuzz]

^^^ Bob, have you been watching Slingblade? LOL

 

[Bob Lincoln]

I don't know what that is.

 

[AllanC]

. . . the tank might really be empty. Throw in 2-3 gallons and see what happens. . . . .

I revisited the problem truck today. I looked inside the frame rail at the fuel lines. On this model there is no external, inline fuel filter so the filter has to be integrated into the fuel pump module.

I had the owner purchase a few gallons of fuel and added that to the tank. Primed the electric fuel pump at the relay, engaged the starter and the engine fired and ran immediately. So the fuel tank was empty though the gauge was over the 1/4 mark on its scale. So the solution was to NOT overlook the obvious and assume you have gasoline. A fuel gauge can mislead you.

So the truck is running and no need to expend a lot of labor to remove the tank and replace the fuel pump module. However it still has a problem with a fuel gauge that gives bogus values. Fuel sending unit or instrument panel gauge has gone wonky. So a challenge for another day!

Thanks for the tips!

 

[chuzz]

I don't know what that is.

It's a movie with Billy Bob Thornton in it. He plays a guy that's mentally challenged and has been in a mental hospital for year for killing some people. He gets out and starts working as a small engine mechanic at a local shop in his hometown. Dwight Yokum is also in it. Good movie.

 

[85lebaront2]

I had the owner purchase a few gallons of fuel and added that to the tank. Primed the electric fuel pump at the relay, engaged the starter and the engine fired and ran immediately. So the fuel tank was empty though the gauge was over the 1/4 mark on its scale. So the solution was to NOT overlook the obvious and assume you have gasoline. A fuel gauge can mislead you.

This is exactly why I mentioned the gauge issues on these trucks, and the exact test you performed was suggested and at least solved the no run issue. Good luck with it. probably too old for there to be an active recall on it.

 

[AllanC]

. . . This is exactly why I mentioned the gauge issues on these trucks, and the exact test you performed was suggested and at least solved the no run issue. Good luck with it. probably too old for there to be an active recall on it.. . . .

I checked my notes and found that I assisted with replacement of the fuel sending unit in summer of 2017. At that time the OEM sending unit failed and replacement fixed the issue. Instrument panel fuel gauge was NOT the problem. So this latest issue is more allusive. When the OEM unit failed there was no response at the fuel gauge.

Has the replacement fuel sending unit failed but only when fuel level is below 1/2? I do not know the origin of the replacement fuel sending unit that we installed. If it was an Airtex assembly then it would be no surprise if it failed at 1+ year.

One can move the sending unit arm and measure the resistance change across the terminals of the fuel sending unit. I do not know if there is a way to test the accuracy and proper functioning of the instrument panel fuel gauge.

 

[1999 White C5 Coupe]

I revisited the problem truck today. I looked inside the frame rail at the fuel lines. On this model there is no external, inline fuel filter so the filter has to be integrated into the fuel pump module.

I had the owner purchase a few gallons of fuel and added that to the tank. Primed the electric fuel pump at the relay, engaged the starter and the engine fired and ran immediately. So the fuel tank was empty though the gauge was over the 1/4 mark on its scale. So the solution was to NOT overlook the obvious and assume you have gasoline. A fuel gauge can mislead you.

So the truck is running and no need to expend a lot of labor to remove the tank and replace the fuel pump module. However it still has a problem with a fuel gauge that gives bogus values. Fuel sending unit or instrument panel gauge has gone wonky. So a challenge for another day!

Thanks for the tips!

I have owned numerous GM vehicles (and many Dodge vehicles......). In the 1990’s and 2000+ model years, GM had a significant problem with the fuel gauges reading inaccurately. At one point, GM issued a TSB instructing the dealers to first try a bottle of GM fuel system cleaner (which was made under license by Chevron, makers of Techron). I have used Techron Fuel System Cleaner PLUS (now just Fuel System Cleaner) in my GM vehicles to improve the accuracy of the fuel gauge. At one point, the bottle even stated it helped clean sulfur deposits on the fuel sensors.

You may want to have the owner use the Techron cleaner according to bottle directions, twice.

 

[AllanC]

. . . . At one point, GM issued a TSB instructing the dealers to first try a bottle of GM fuel system cleaner (which was made under license by Chevron, makers of Techron). I have used Techron Fuel System Cleaner PLUS (now just Fuel System Cleaner) in my GM vehicles to improve the accuracy of the fuel gauge. At one point, the bottle even stated it helped clean sulfur deposits on the fuel sensors. . . .

Interesting that a major automotive manufacturer would resort to a "snake oil" fix to correct problems with a fuel sending unit. I checked notes and find that the OEM sending unit was replaced in June 2017 on this truck. Original had broken fingers on the arm that traverses the resistance strip on the sending unit. So it is too soon to have a replacement sending unit fail.

The owner found a replacement on the internet and purchased it. It probably was a "no name, Chinesium" product with poor quality contacts. I will mention the fuel system cleaner to the owner but I have my doubts that it will solve the problem.

 

[ka9yhd]

Good point, the tank might really be empty. Throw in 2-3 gallons and see what happens.

This happened to my friend's mother. The fuel gauge was showing a half of tank of gas, and the car died on her. My friend was diagnosing the problem when he noticed the pump sounded very loud. So he poured some gas into the tank and the pump got quieter, and the engine started...... Ran out of gas because of a stuck sending unit.