Crank no start

[steveo1]

I may have posted this in wrong location..

I am at witts end...2001 Tahoe 5.3 crank no start...I've replaced fuel pump three times in last week...It has a delpi pump with new filter ....replaced crank sensor repalces fuel regulator....I have injector pulse...I have spark at the plugs ....ive tried eliminating nuetral safety switch by moving thru the gears and trying in neutral to start...by way of cranking the motor sounds as if it has good compression..and it will run on starting fluid. I know I'm missing something that I've tried...I've also checked my grounds and ran a few temp grounds to be certain with new battery.....ANYONE HAVE ANY SUGGESTIONS

 

[rockola1971]

If neutral safety switch was bad then engine would NOT crank in neutral. You need to verify fuel pressure at the fuel rails. You have done alot of needed checks but in the wrong order. Replacing crank sensor likely will need a crank position relearn procedure done now. Your symptoms do fit fuel system or bad crank sensor problem. Having injector pulse BUT no fuel pressure will cause your symptom. Need to verify that fuel pressure and my bet is that you dont have it. Bad fuel pump, regulator or crammed full of sediment fuel filter which is mounted on drivers side chassis under driver door. You can goto most auto parts stores and "rent out" a fuel pressure test kit just for a deposit which you get back when you return the tool. Autozone, Advance Auto Parts and most other names loan out the tools. Just goto the counter and tell them what you need for test equipment.

 

[steveo1]

If neutral safety switch was bad then engine would NOT crank in neutral. You need to verify fuel pressure at the fuel rails. You have done alot of needed checks but in the wrong order. Replacing crank sensor likely will need a crank position relearn procedure done now. Your symptoms do fit fuel system or bad crank sensor problem. Having injector pulse BUT no fuel pressure will cause your symptom. Need to verify that fuel pressure and my bet is that you dont have it. Bad fuel pump, regulator or crammed full of sediment fuel filter which is mounted on drivers side chassis under driver door. You can goto most auto parts stores and "rent out" a fuel pressure test kit just for a deposit which you get back when you return the tool. Autozone, Advance Auto Parts and most other names loan out the tools. Just goto the counter and tell them what you need for test equipment.

Well I would agree but as mentioned I'm in my third pump this week...first started with the cheap knock off house brands but ended up with a Delphi pump today... And fuel pressure is there ...which is why I had moved onto the crank sensor after the previous pump replacements... I replaced a pump in this couple years ago and it worked fine simce so when this originally happened it was mentioned mimicks NO FUEL sysmotoms so I like a dummy just went ahead and changed out the first of the three pumps I've installed in the last three weeks....the last one tonight with the delpi pump...but oddly enough al three pumps were within spec....I Can rule out bad fuel pump....and can rule out alot of the ignition as it will run on starting fluid briefly..

 

[steveo1]

And yes I will need to relearn crank sensor but I'm assuming I'll have to do that after I get it going...not sure I can do that any other way..I'm definitely open to any suggestions and feel it's gonna come down to something stupid overlooked once I figure it. Anything can be fixed just need a new direction to travel

 

[rockola1971]

So you got compression, spark and fuel.....what about air? Is your air filter plugged up? Check for a plastic walmart bag sucked up into the system on the inlet side of the air filter snorkel. What color is your spark? Should be a pretty bright blue. Anything like white or orange aint gonna fly. Any chance it has jumped time? Stretched out timing chain.

 

[steveo1]

So you got compression, spark and fuel.....what about air? Is your air filter plugged up? Check for a plastic walmart bag sucked up into the system on the inlet side of the air filter snorkel. What color is your spark? Should be a pretty bright blue. Anything like white or orange aint gonna fly. Any chance it has jumped time? Stretched out timing chain.

It runs on start fluid... Does that eliminate the questions bout spark compression and air filter..

 

[B-train]

You say it has the correct fuel pressure. What did you read? Did you replace the fuel filter when doing the pump like stated above? Have you tried to see how much fuel flow you have at the rail? Pressure doesn't mean anything if there isn't fuel to push in. Do any of the spark plugs smell like raw fuel after crank-no-start?

 

[MassHoe04]

The fact you can get some reaction from starter fluid, indicates fuel issue. But seems more like an all or nothing situation, where you are getting nothing for some reason...

Is it possible the computer thinks the engine is already flooded and not telling injectors it is OK to send fuel?
Could try the process that clears flooded engine... Press and hold the gas pedal to the floor while cranking and try starting. Then try to start with no gas pedal.

Did you disconnect both battery cables from the battery terminals and touch the disconnected cable ends together for 5 minutes or more to reset the computer?

These may not do anything for you, but we won't know unless you try. Neither procedure will cost anything. See what happens.

 

[Doubeleive]

stubbornness will get you no where, if you want assistance online then we need accurate data, we can only "guess" what your issue is otherwise. I would imagine if you have replaced the fuel pump 3 times already then that alone is probably pretty frustrating. As already mentioned the 01 indeed has a fuel filter right under the drivers seat area on the inside edge of the frame, later models do not have a exterior fuel filter.
so that being said. 1st things 1st.
1. what is the Fuel pressure on the fuel rail at the schrader valve? it needs to be in the range of 50-65 with key-on only (engine not running)

 

[mattbta]

Will it start at all?

Mine (04 flex) was doing this -

after a shop put in a non-OEM camshaft position sensor while doing my rear main. Failing sensors also exhibit the same random crank no start. I fired a parts cannon of new FPR and fuel pump with no change. Flood clear method didn't do anything. Later put in an OEM camshaft sensor and good to go.

Just something to think about.

I've also seen a post recently about a fella that forgot to plug one of the fuel pump connectors back in...tech2 would help here.

 

[steveo1]

You say it has the correct fuel pressure. What did you read? Did you replace the fuel filter when doing the pump like stated above? Have you tried to see how much fuel flow you have at the rail? Pressure doesn't mean anything if there isn't fuel to push in. Do any of the spark plugs smell like raw fuel after crank-no-start?

58 psi on crank. After key is let go n returns to on position it settles to 50/51 psi... And holds

 

[steveo1]

stubbornness will get you no where, if you want assistance online then we need accurate data, we can only "guess" what your issue is otherwise. I would imagine if you have replaced the fuel pump 3 times already then that alone is probably pretty frustrating. As already mentioned the 01 indeed has a fuel filter right under the drivers seat area on the inside edge of the frame, later models do not have a exterior fuel filter.
so that being said. 1st things 1st.
1. what is the Fuel pressure on the fuel rail at the schrader valve? it needs to be in the range of 50-65 with key-on only (engine not running)

I by no means am being stubborn....I was stubborn before resomring to a forum for help...I have secum to this vehicle and decided it was beyond my current knowledge and decided reaching out for help was best route .so stubborn is complete opposite I am currently...willing to try anything...if ya told me to dig a whole in back yard and fill it in then try starting I'd be digging within minutes of the response..

 

[Doubeleive]

I by no means am being stubborn....I was stubborn before resomring to a forum for help...I have secum to this vehicle and decided it was beyond my current knowledge and decided reaching out for help was best route .so stubborn is complete opposite I am currently...willing to try anything...if ya told me to dig a whole in back yard and fill it in then try starting I'd be digging within minutes of the response..

Will it start and idle or do anything different if the maf is unplugged?
at this point I would start looking at air data, do you have a obd/scanner tool capable of reading live data?
also what is the temp sensor reading

 

[Fless]

58 psi on crank. After key is let go n returns to on position it settles to 50/51 psi... And holds

Without cranking or starting, what does the fuel pressure read when they key is first turned to "run"? Key on, engine off.

 

[steveo1]

Will it start and idle or do anything different if the maf is unplugged?
at this point I would start looking at air data, do you have a obd/scanner tool capable of reading live data?
also what is the temp sensor reading

I have a cheap obd ll reader...but oddly it isn't showing any codes but that could be from the previous battery going dead..I went at this six months ago and got frustrated and let it sit recently revisiting it and doing the things mentioned and unplugging maf was done with no change.. I even ran an alternate battery to block ground trying to eliminate a ground issue..I heavily want to lean on the ignition switch or pass lock but I don't have a security light so I've opted to not replace but I almost feel like it's one of only things left...question I was researching and watched a video that states the oil pressure switch could be faulty interrupting the fuel pump circuit and a backup source of power in event there was a failure with the relay for fuel pump....what's your thoughts

 

[steveo1]

Without cranking or starting, what does the fuel pressure read when they key is first turned to "run"? Key on, engine off.

58 psi

 

[steveo1]

58 psi

On the prime ignition in on position

 

[steveo1]

Give me a call 937 509-7104. Would be easier the exchange thoughts

 

[steveo1]

Without cranking or starting, what does the fuel pressure read when they key is first turned to "run"? Key on, engine off.

58 psi ..then after prime is complete it.falls off to 50/51

 

[Fless]

58 psi ..then after prime is complete it.falls off to 50/51

Non-Flex Fuel spec is 55-62 psi KOEO. If it drops to low 50s before cranking that could be an issue.

I don't recall -- has the fuel pressure regulator been checked and/or replaced?