My engine will not start up and run

This sounds like the crankshaft angle sensor or the fuel pump has gone out, when you turn the key to the on position without cranking the engine over can you hear the fuel pump run in the tank for 5 seconds? These guides should help us fix it.

https://youtu.be/dCjmRL3p4Cs

and

https://www.2carpros.com/articles/car-cranks-but-wont-start

Also, lets run the codes to see what come up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down these guides and report back.

Changed out suspected bad fuel pump. now the car will not start? Do I have to do anything special with the new pump?

You may need to bleed the fuel system.
Open the air bleed valve on the fuel manager/filter.
Connect a hose to the air bleed valve and place the other of the hose in a suitable container.
The diesel/water mixture is flammable and may be hot. To avoid personal injury or property damage, do not allow the diesel/water mixture to come in contact with skin, open flame or a hot engine. Do not overfill the container holding the fuel mixture as heat from a warm engine or any another heat source may cause the fuel to expand and leak from the container that may lead to a fire.
Remove the F/SOL fuse from the fuse panel.
Crank the engine in short intervals of 10-to-15 seconds until clear fuel is observed at the air bleed hose (wait for 1 minute between cranking intervals)
Remove the hose and close the air bleed valve.
Install the F/SOL fuse and start the vehicle. Allow the vehicle to run at idle for 5 minutes.
Check for fuel leaks, and clear any Diagnostic Trouble Code's (DTCs)

My factory amp was bypassed by the previous owner. well, I have an electrical problem somewhere. so I hooked the factory amp back up to its original state and it will crank but not start! The factory radio harness gaff been cut out for some reason and they had a touch screen radio hard wired directly! Please help.

Good morning,

Can you hear the fuel pump run when you turn on the key?

Did you check for spark? When you crank the engine, does the tachometer move up a little?

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Does the check engine light on with the key on?

Trying to see if the engine systems are working.

https://www.2carpros.com/articles/car-cranks-but-wont-start

Roy

Changed crank shaft position sensor on my 03 chevy tahoe and now the truck won't start. It has fuel and spark I just drove it and changed the sensor now it won't start. How can I get this vehicle running again.

We need to check a couple things first. You said the vehicle has fuel and spark but will not start? If all you did is change the crank sensor then I am not sure we have fuel and spark because this is all that would effect. The PCM uses the crank to determine when to fire the plugs and injectors along with engine speed but if you have spark and fuel then we need to clarify how you confirmed this.

We need to make sure the injectors are firing and not that you just have fuel pressure. Here is a guide on how to check for injectors firing:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Then we need to check for spark by pulling a plug and holding it against the block and crank the engine to see if it fires.

Here is a guide that will help with these things in general but let us know about this info and we can go from there:

https://youtu.be/dCjmRL3p4Cs

Put old CSPS back in it runs but rough idle at lights. And stalls some days very sluggish going up hills.

So clearly you got a faulty CKP sensor. This unfortunately is not uncommon so I would take it back and have them exchange it for you.

I did it twice from two different stores it randomly stalls or gets sluggish up hill.

I am not sure I understand. Your not starting issue started after you replaced the sensor, you put the old one back in and it now it starts but it stalls sometimes and is sluggish? Then you put two other sensors in from two different stores and it still stalls randomly and is sluggish? Or it only stalls and is sluggish with the old sensor in it?

2003 Tahoe 5.3 Flex fuel with 90000 miles. Car would not start 2 months ago, was told it was the fuel pump, replaced it with an Airtex and it ran for a couple weeks, then would not start again. No fuel pressure at intake. Replaced fuel pump with a GM pump, car started and ran fine for a couple weeks, was out driving around, turned it off and it would not start. wiggled fuel pump relay with the key on, got fuel pressure and it started. Replaced fuel pump relay, checked connector for any signs of corrosion, used dielctric grease on new relay. Ran fine for a few days then the same no start condition. I wiggled the relay, swithced it out with another, and nothing happened.
Was told on another answer forum to replace ignition switch, I did, ran fine for a few days and now wont start.
One time when it did not start I held the key on and moved the gear selector rapidly from P to 1 and fuel pump kicked on.
Here is what happens when the no start condition is happening. I turn the key on and the fuel gauge stays on E, when I try and crank the starter it will turn over just fine, but only one time, if I want to turn the motor over again I must take the key out, wait, put it back in to get the motor to turn over again.
If the fuel gauge comes up when I turn the key on it will start righjt up, when it runs it is perfect, never skip a beat, no check engine lights or any such thing.
The car will not start now, I banged wiggled rattled everthing I ccould think of with the key on and the fuel pump will not kick on. I read the service bulliten about the fuel pump module connector, but I have the Flex Fuel model and it excludes that model, although mine does have the square connector.
This is driving me out of my mind. Please advise if you are able to help

Your statement that you need to remove the key to get the engine to crank leads me to think it could be the security system, which disables the starter and injectors, try a passkey relearn: GM PASS LOCK RELEARN- Ignition to "run" position, try to start and let key return to "run" position
Approx ten minutes security light will go off
Turn key "off" and wait 5 seconds
Repeat 2 more times for a total of 3 relearns.
Turn key off, then start it.

I tried the relearn, it did not work. The security light goes off 5 seconds after I try and start the car. I did the relearn exactly as you outlined, and then tried it again as soon as the security light went off. Still no fuel pressure. Gauge stays on E with the low gas light on. I have also tried the other set of keys and door lock fob in the past and it made no differance, I tried disconnecting the battery once before also and it did not help. Everything else on the dash functions normally. I had the cluster replaced through GM at about 50000. Any other suggestions? Thanks, Robert

There is a Tech bulliten about the ignition switch indexing be off, read it below! Diagnostic Information for Intermittent Vehicle No Crank/Dead Battery TECHNICAL SERVICE BULLETIN Reference Number(s): 04-06-03-002, Date of Issue:  February 05, 2004 Related Ref Number(s): 04-06-03-002 ARTICLE BEGINNING SERVICE INFORMATION When diagnosing a concern regarding an intermittent vehicle no crank or dead battery, technicians should remove and reinstall the ignition switch using the Ignition Switch Replacement procedure in the Steering Wheel and Column section of SI. The ignition switch may have been misindexed in the steering column during a previous replacement . If the ignition switch is misindexed in one direction, the ignition switch circuits will not be completely open when the ignition switch is in the OFF position with the key removed. This may result in lights remaining on or instrument panel lights illuminating, which will drain the battery. If the ignition switch is misindexed in the opposite direction, the ignition circuits will open correctly but the ignition switch may not close the crank circuit properly when the ignition key is turned to the crank position. This will result in a no crank concern. Press Ctrl+F to find exact text Affected Model(s): 2004 Buick Rainier; 2000-2004 Cadillac Escalade; 2002-2004 Cadillac Escalade EXT; 2003-2004 Cadillac Escalade ESV; 1998-2004 Chevrolet Blazer, S-10 Pickup; 1999-2004 Chevrolet Silverado; 2000-2004 Chevrolet Suburban, Tahoe; 2002-2004 Chevrolet Avalanche, TrailBlazer, TrailBlazer EXT; 2003-2004 Chevrolet Express; 1998-2004 GMC Jimmy/Envoy, Sonoma; 1999-2004 GMC Sierra; 2000-2004 GMC Yukon, Yukon XL; 2002-2004 GMC Envoy, Envoy XL; 2003-2004 GMC Savana; 2004 GMC Envoy XUV; 1998-2004 Oldsmobile Bravada; 2003-2004 HUMMER H2 Page 1 of 1 2/19/2010 http://www.ondemand5.com/mric/common/asp/Article.aspx?MOD=TSBART&YEAR=20 ...
Check email for the proceedure.

I don't understand how this could be the problem. I installed a factory switch and it worked fine after I put it in.

Your cranking problem fits the description of a mis indexed switch. You might want Chevy to check it for you.

Removed ignition switch, it was correct. This is the same no fuel problem I had with the factory switch, and after I replaced the switch. Everything else on the vehicle works correctly. I am not getting fuel, the fuel pump does not kick on.

There is another tech bulliten on the driver's seat wiring harness chaffing on the seat rail, have a look there, it also can cause a no start.. Here's the TSB: INTERMITTENT NO START, SERVICE STABILITY MESSAGE, ABS LIGHT ILLUMINATED, MULTIPLE DTCS, DIC SHOWS UNKNOWN DRIVER, VARIOUS ELECTRICAL RELATED CONDITIONS (REPAIR AND/OR REROUTE SEAT WIRING HARNESS) TECHNICAL SERVICE BULLETIN Reference Number(s): 03-08-50-014,  Date of Issue:   August 20, 2003 CADILLAC: 2003 Escalade, Escalade ESV, Escalade EXT CHEVROLET: 2003 Avalanche, Silverado, Suburban, Tahoe GMC: 2003 Sierra, Yukon, Yukon XL SECTION: 08 - Body and Accessories Related Ref Number(s): 03-08-50-014 ARTICLE BEGINNING CONDITION Some customers may comment on any of the following conditions: Vehicle intermittent no-start "¢ Service Stability Message "¢ ABS light illuminated "¢ Multiple DTCs set "¢ Driver Information Center (DIC) shows unknown driver "¢ Various electrical related conditions "¢ CAUSE A chafed or pinched seat wiring harness under the driver seat may be a cause of this condition. Because of the routing, a portion of the seat wiring harness may rest on the inboard edge of the seat track or frame. Over time, the harness may be pinched or chafed because of the seat movement. Refer to the illustration below ( Fig. 1 ). The illustration shows the inverted position of the seat bottom. The arrow shows the primary location of the possible harness chafing/pinching. CORRECTION Inspect the routing of the seat wiring harness. Reroute the seat wiring harness and attaching harness fastener (1 in Fig. 1 ) to the opposite side of the seat module bracket. Repair the harness as necessary. Refer to Wiring Repairs in the Wiring Systems sub-section of SI. The seat may have to be removed for ease of access and proper repair of the wiring harness. Fig. 1: Sear Wiring Harness If any of the above conditions still remain after this repair, refer to SI for further diagnostic information. Page 1 of 2 INTERMITTENT NO START, SERVICE STABILITY MESSAGE, ABS LIGHT ILLU...2/21/2010

Wow. Who would have thought to look under the seat!! I spent 3 hours yesterday looking for wiring problems, took the fuse block out, took the dash apart, looked for any king of loose or chafed wires, but silly me did not look under the seat. Well I looked under the seat today, moved the wire from where it was caught on the seat frame, moved the seat all the way back, and what happened? The fuel pump kicked on and it started right up. Thank you!!! I hope that is really the problem this time. I guess I will know in a few weeks if it keeps on starting. Everytime I have replaced something else it always started right up so it is hard to say if this was the culprit, but I sure hope so.

It is wierd how they route wires sometimes!

We have driven the vehicle about 5 times, less than 100 miles, started up and ran fine all week until this afternoon when it wouldn't start again. I examined the wiring harness and everything is nice and tight, no chaffing, everything looks and fits like it should, but I'm having the same problem with the fuel pump not kicking on. What else do you recommend I try? Thanks, Robert.

I dont know who linzsmith is...not a big help..did you remove the plastic conduit under the seat and inspect the wiring inside it? That would be my next step, then test for power at the pump connector. Something in the wiring or the pump needs a look...

While driving home from work going sixty on freeway my gas pedal suddenly stopped working. I pressed down on it twice and did not feel or hear motor rev up or the car speed up. However, on the third time I stepped on the gas pedal it felt like engine started back up and the car sped up. Then it happened again same scenario, I exited freeway made right turn and my SUV turns off. So I turned off key then on and started back up and then it turned off again. So I pulled over and tried starting it again and it would start up again but for only three to five seconds then turned off.
I changed throttle body and still the engine turns but no start. There is no check engine light turning on. Please help. I hope I explained myself.

Hello, I am Danny.

Well since there is no check engine light on I would suggest first to check your Fuel Pressure. There is a Schrader valve located on the fuel rail to check. Most auto part stores have a tool loaner program (AutoZone, Pep Boys, O'Reillys) that can rent you one. Your fuel pump is an in-tank unit and they wear out after time.The fuel pressure should be 48-52 PSI if your engine is 5.3L VIN code Z. All others should be 55-62 PSI. I have included a link as a tutorial to give you an idea as to what is involved. Hope this helps and feel free to ask any questions as needed.
Danny-

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Hi Danny, thanks for the fast reply.
About checking the fuel pressure I have not checked it with actual gauge, but a friend that used to be a mechanic took off the cap and looked at it and said that it is good. That it is spitting out the right amount off pressure but I will double check it with a gauge. And what if pressure Is good since I replaced the throttle body (but I got it from junk yard from 2003 Silverado) and someone told me that it needed to be reprogrammed or program it to my cars computer. What are your thoughts on that? Thank you.

Hello again.
Yes, You definitely need to test the fuel pump with a gauge (directions in last my last post). In my last post I also gave you the fuel pressure specifications. When you installed the throttle body did it give you a code? Check engine light? Happy 4th! Danny-

We have replaced the starter, and also the ignition switch, and can’t get SUV to start. It will start every once in awhile, but then you turn it off, and it just cranks and won’t fire up. Please help.

Hello,

This sounds like it could be a problem with your Crankshaft Position Sensor (CKP). The CKP sensor tells the Power-train Control Module(PCM) AKA, "computer" where the engine is in its cycle. When the PCM loses track of where the engine is in its four stroke cycle, it will not know when to fire the spark plugs or when to send the duty cycle to the fuel injectors.
I have included a few links down below for you to go to:

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works
https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor
https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

Please go through these links and get back to us with what you find out.

Thanks,
Alex
2CarPros

I also wanted to add now it’s not even cranking. Could it still be the crank shaft position sensor out even though it’s not cranking at all now? Like I said, we have tried the ignition switch and the starter. I initially thought it was the ignition cylinder, but we haven’t replaced that yet. Should we start with the crank shaft positioning sensor or the ignition cylinder? I forgot to add the security light will blink sometimes too. Just started doing this.

I may have forgot to tell you something very important. Before all this happened, we replaced the oil pan gasket, and rear main seal. She had one of those DUI blower things and it started acting crazy and would start to reset itself and wouldn't let her start her truck for thirty minutes sometimes. so then she took it to the place thinking it was the blower, and they took the blower off, and still having problems. There’s no wires or anything I could have accidentally hit when fixing the rear main or oil pan gasket right? I know kinda stupid question because there shouldn’t be anything electrical, but everything started happening after we did the work on the rear main and oil pan gasket. I may should have told you that from the get go. I do apologize. I do want to add, my grandpa fixed a toggle switch that you can crank it right up with, but you take the toggle switch out, it does nothing. No crank, the lights on the dashboard do light up, though. I hope this is more helpful for you to diagnose.

Hello again,

Okay, are you guys trying to replace the toggle switch? I am not sure what is going on? Please get back to us with what you guys are trying to do please.

Thanks,
Alex
2CarPros

Sorry no, I shouldn’t have mentioned the toggle switch. Okay, here’s what we did first: First off, my girlfriend has a Interlock system in her car. We did the rear main seal and the oil pan gasket, put that back together, and then the interlock started acting weird after that and would make you wait thirty minutes after blowing to start, and then wouldn’t start at all after, would just crank over. We thought maybe it was the interlock messing up, but we took it to the place, and they took the interlock out, and the car is still just cranking. Almost like it’s not getting fire to the starter, but we have replaced the starter and the ignition switch. Could it be the cylinder itself that needs to replaced, or could it be the crank shaft positioning sensor like you mentioned? Sorry for the misunderstanding.

When you turn the key to the on position without cranking the engine over can you hear the fuel pump run in the tank for five seconds? It sounds like they may have bumped the connector for the crankshaft angle sensor as well. here is a guide that can help. See if the engine will run on starting fluid.

https://www.2carpros.com/articles/car-cranks-but-wont-start

Please run down this guide and report back.

2002 tahoe 5.3 ,48 psi fuel pump pressure , spark at plug wire , installed crank positioning sensor won't start , cranks a little faster and sounds as though it wants to start , but won't . battery is up and there is plenty of fuel . I don't want to start putting any more sensors on at random . Audley

You're computer needs to see both a crank speed reading and cam position reading for it to tell the coils to fire a spark to the plug.

Since you've checked spark and fuel pressure, use an automotive stethoscope to listen for your injectors firing. You'll hear a distinct clicking sound. If your injectors are firing, the valve timing may be off (bad timing chain). You can verify this by doing a compression test.

If your timing chain has slipped, just replacing the timing chain wouldn't be economically sound, as that would be like putting a band aid on a gunshot wound. The rest of the motor will be just as worn as the timing chain. However, I do not recommend rebuilding this motor unless you want to keep this truck for 10 more years. There are too many low-mile used engines for dirt cheap.

It isn't your ignition switch. If that were the case, you wouldn't be getting spark at the plugs. Your ignition timing is controlled by the computer. If that's out of wack, your computer would be bad. Sometimes an intermittent fault with your sensors will fail to set a code. Depending on which sensor is faulty, the computer will have to determine it has been faulty for a certain amount of drive cycles or time. If the sensor acts good, the computer will shut off the light by itself.

If a scan doesn't produce anything, you'll need to continue your diagnoses on the systems components the computer can't always read. These would be the mechanical components of the engine.

If the crank sensor was bad and to replaced it the sensor will sometimes need to be programmed to the car a shop can do this for about $130.00.

Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers

I pushed truck to the pump and put gas in it. After I got gas tried to start the car but it wouldn't start, and it said I had low fuel even though I just put gas in it. I'm not sure if it's the fuel filter or the fuel pump. I also wanted to know where the reset switch is located if this module has one. I've recently had the alternator replaced as well as an oil change/tire rotation. And just put in transmission fluid.

Hi,

The fuel pump relay is under the hood in the power distribution box. There is no reset on it. I attached a pic below (picture 1) and circled the relay. If there is a relay with the same part number, switch them. If not, here is a link that explains how to test it:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Here is a link that explains the most common causes of a crank no start. Take a look through it to see if it helps.

https://www.2carpros.com/articles/car-cranks-but-wont-start

Next, check fuse 30 also (under hood). It powers the fuel pump relay. (see picture 2 and 3)

Now, the first thing I would be checking is if there is fuel pressure at the engine. I can provide the manufacturer's specs, but I need to know which engine is in your vehicle. There are 4 different V8 engines.

Here is a link that explains how to test fuel pressure in general:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Next, if fuel pressure is good, then we need to determine if the ignition system is working. Here is a link that explains how to test for ignition spark:

https://www.2carpros.com/articles/how-to-change-spark-plugs

________________________________________

Here are a few links you may find helpful when testing.

https://www.2carpros.com/articles/how-a-car-fuse-works

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

________________________________________

Let me know what you find. I will watch for your reply.

Take care,
Joe