Can a fuel pump cause a no start condition?

CASE 1: If your fuel pressure gauge read 50 PSI or more as the engine cranked. This means that the fuel pump on your 4.3L, 5.0L, or 5.7L is OK and not the cause of your No Start Condition. The next step is to observe the fuel pressure gauge’s needle (after your helper stopped cranking the engine).

Why is my fuel pump relay not working?

I have replaced the fuel pump relay oil pressure switch and computer. If you’re not getting a signal for fuel, then you either have a faulty crank sensor, or bad ignition module. But the truck runs great until you cut it off. If you poor a little gas in the intake to get it started would that only effect the starting ? Ok.

Is there a way to turn on the fuel pump?

There’s no way you have no signal, but then starting the truck by adding fuel will then turn on the injectors and pump. That’s just crazy. Good luck with that one. Once the truck starts and is running you can remove the jumper to the fuel pump and it will continue to run.

How to check no fuel condition on GM 4.3L?

I’ve also included how to check a no fuel condition with starting fluid (although this is not the most effective way to test the fuel pump). It’s been my experience that misdiagnosing a bad fuel pump is a common occurrence on the 4.3L, 5.0L, 5.7L GM vehicles with the ‘Spider’ fuel injector assembly.

When was the last time my Chevy fuel pump failed?

The technical service bulletin that explains the cause of the repeat failure of the Chevy fuel pump replacement unit covers all years from 1996 to 2003 and includes all of the pickup trucks. Also included is the Tahoe and suburban and their GMC counterparts such as the Sierra and Envoy. Oh and don’t forget the Cadillac Escalade is also included.

Can a bad fuel pump start a truck?

Yes and have nothing. Well getting to start by adding fuel to the throttle body is not going to turn on some special switch that will send a signal to the pump and injectors. I’m sure you probably just have a bad fuel pump that doesn’t have enough pressure or volume to start the truck, but at running speed can keep up.

Why does my GMC Sierra have a bad fuel pump?

If you get P0420 or P0430 trouble codes with a scanner, it very well may be the catalytic converter causing these symptoms. One of the best indicators of a clogged fuel pump is going to be that the your Sierra is difficult to start. This because there’s not enough fuel pressure to properly atomize the fuel as it enters the combustion chamber.

How much psi does a fuel pump need to start?

The fuel pump produces much more than just 50 PSI of course.. but the bare minimum the engine needs to start is 50 PSI… so anything less and it will crank for ever before it starts or not start at all.

What should fuel pressure be on GM 4.3L Vortec?

You can find this tutorial in Spanish here: Cómo Probar La Bomba de Combustible (GM 4.3L, 5.0L, 5.7L) (at: autotecnico-online.com ). The fuel system in your 4.3L, 5.0L, or 5.7L Vortec engine needs at least 50 PSI of fuel pressure to start.

How to test a GM 4.3L fuel pump?

More GM 4.3L, 5.0L, and 5.7L Tutorials. It’s very important that you start off your fuel pump relay diagnostic by first testing the fuel pump pressure with a fuel pressure test gauge. If the fuel pump relay IS NOT activating the fuel pump, the fuel pressure test gauge will register 0 PSI when cranking the engine.

How to test a GMC fuel pump relay?

TEST 1: Swapping Out The Fuel Pump Relay. TEST 2: Making Sure The Fuel Pump Relay Has Power. TEST 3: Bypassing The Fuel Pump Relay. TEST 4: Bench Testing The Fuel Pump Relay. Fuel Pump Circuit Diagram. Where To Buy The Fuel Pump Relay. More GM 4.3L, 5.0L, and 5.7L Tutorials.

What does it mean when your fuel pump is losing pressure?

Losing Fuel Pressure. If the system keeps pressure you know that injectors are ok and the problem may be down stream (fuel pump or fpr). On the flip side, if it didn’t hold pressure then it could be an injector or an fpr leaking into the vacuum line. To check the fuel pump, presurize the fuel system and only block off only the return line.

Why is the fuel pump and relay not working?

The ignition circuit, which includes the ignition switch, controls power to many components, including the fuel pump and relay. If there is an issue with the switch or the circuit, perhaps a wiring problem, then power to the fuel system may be cut off.

Can a bad FPR cause a fuel pump misfire?

If yes, bad fpr, injector leaky and fuel pump check valve could be culprit. P1406 is for the EGR valve. Different issue from fuel pressure drop. EGR or passages could be blocked by carbon buildup. Intake leak, injector and fpr leak can cause P0300 multiple misfire though.

What causes low fuel pressure in an engine?

1 Clogged Fuel Filter The fuel filter cleans the fuel entering the engine. 2 Bad Fuel Pump A bad fuel pump is probably the most common cause of low fuel pressure. 3 Bad Fuel Pressure Regulator The fuel pressure regulator controls the fuel pressure in the fuel rail.

Can a fuel pump crank while the engine is cranking?

So, the very first thing you need to do is to verify that the fuel pump is delivering at least 50 PSI of fuel pressure while the engine is cranking. Yes… while the engine is cranking. Locate the Schrader valve on the fuel line that connects to the ‘Spider’ assembly.

What should the fuel pump pressure be to start the engine?

The fuel pump produces much more than just 50 PSI of course but the bare minimum the engine needs to start is 50 PSI. Anything less and it will crank for ever before it starts or not start at all. So, the very first thing you need to do is to verify that the fuel pump is delivering at least 50 PSI of fuel pressure while the engine is cranking.

How can I tell if my fuel pump is leaking?

Once the fuel pressure gauge registers pressure, check for fuel leaks around the Schrader valve. It’s very important that NO fuel leaks are present for the accuracy of the test. Once you have verified no fuel leaks, continue to the next step.

How to troubleshoot fuel pump in GM 4.3L?

Once the intake air duct is back on the throttle body, have your assistant, inside the vehicle, crank the engine. 1.) The engine will start momentarily and after a few seconds will die. 2.) The engine will only crank but not start at all. 3.) The engine will start and stay running. OK, let’s find out what your results mean:

When did I change the fuel pump on my GMC Sierra?

I changed the fuel pump on my 1996 GMC Sierra earlier in the year. I cut through my truck bed right above the fuel pump so I would have easier access to it. For the most part my truck has been fine but I have had problems with the ground wire coming from the fuel pump. At first I thought it was just the old rusty bolt that grounds the fuel pump

How do you start a GM fuel pump?

Open the throttle plate, manually, and spray starting fluid down the bore. When you have sprayed a good squirt of starting fluid, quickly reconnect the air duct to the throttle body (you don’t have to tighten the fastener).

When do you need to replace the fuel pump relay?

If the engine is stalling or not starting, or the fuel pump is not making any noise when the key is on, you may need to replace the fuel pump relay. 1. Engine stalls 2. Engine does not start 3. No noise from the fuel pump

What’s the difference between CPI and CSFI fuel injection?

If you don’t know whether you have a CPI or CSFI system, you can find out the difference between them by checking out the info in this subheading: ‘Spider Fuel Injection Basics’ found in this tutorial: How To Test The ‘Spider’ Fuel Injector Assembly (4.3L, 5.0L, 5.7L). Connect your fuel pressure gauge to the Schrader valve.

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