why wont my truck start ?

[still2smokin]

Please help as I am at my wits end with this truck . 

 

What started as an intermittent crank but no start has progressed in to no start at all . 

Some days it would start fine and run great the next day no start , a day after that it would fire up

and run perfect for a week then not again . But now it will not fire up at all .
 

It's a 96 Yukon 5.7l with 150K.

 

Good Battery , Fuel pressure is 55-60lbs , compression is good and level on all 8 cyl ,  spark tests good on the 2 cyls that I have tested , just dropped $500 on the new spider injector assy with the upgraded MPFI unit and still no start ! Sometimes when letting go of the starter the motor will diesel a few times .  Spaying ether into the intake does nothing . No check engine light on and my OBD code scanner says it is communicating with the comp and no trouble codes are present ........ARGH !   

 

Any ideas whats next to replace besides the truck ?

Edited January 25, 2016 by still2smokin

[inthedirtagain]

Try another starter. Had intermittent no-start issues on my Dodge. Pulled the starter and it tested good at 2 different shops. Bought a reman thinking if it fixed the problem, great. If not, Im not out the full price ofca brand new unit. That reman was still in the truck when I sold it 3yrs later.

[still2smokin]

Engine cranks fine , turns the motor at normal speed till the battery gives up .

[yzmxer12]

My truck recently has the EXACT same problem... Illuminati

[yzmxer12]

Ive heard rumors about a crankshaft position sensor or valve timing sensor, but im not sure.

Edited January 25, 2016 by JohnRatkinson

[uuhhhh]

Replace the coil wire just for the hell of it. They tend to go bad on those engines. Might as well check the coil while you're at it. 

[xxsnaponxx]

Clean and tighten all body grounds and check ign switch, make sure you are not losing signal from when you have key in the crank position and releases to the run position.

[topaz250]

similar symptoms to my brothers 97.
his turned out to be the fuel pump.

sensor issues usually throw a code.

 

have you checked out gmt400.com?
lots of guru's.

[ac717]

I owned a lot of Chevys and still do. When I had this happen it was either crank sensor,MAF sensor (after air filter) or the ground wires. There is one or 2 grounds behind the cylinder head. The other one I had was a bad distributor it looked good but replaced whole distributor and it fixed it.

[still2smokin]

It's running !

Picked up a crank position sensor on the way home today and just for shits and giggles a new cap and rotor .

I wouldn't believe it if I didn't see it myself but just changing what looked like a good cap and rotor out and the bitch fired right up ! The cap is only a year and a half old but the spark must have been just jumping around in there for the last few months . It never ran bad just wouldn't start sometimes . I dumped 600 bucks into shit I didn't need but at least it's running .

Expensive lesson I guess .

[gots_a_sol]

Just look at it as preventative maintenance  ?

 

 

 

My truck was missing/blowing white smoke/overheating so I did a headgasket only to find out it was a bad fuel injector after the problem persisted 

Edited January 26, 2016 by gots_a_sol

[yzmxer12]

Glad to hear you got yours running 2smokin. I decided to wait for warmer weather to work on mine. Instead of starting a new thread I'm going to continue on this one.

 

Here's what mines doing: A few months before it stopped starting up, every now and then it would idle low and want to die when I would start it. It wouldn't come out of it until the truck was turned off and back on again. No lights on the dash.

 

Now for the most part it wont start. It will crank over at normal speed, and if I give it WOT while cranking it will cough and sputter.

If it decides to start, It runs and idles perfectly fine and has no trouble starting. I can't Imagine it would be fuel pump or fuel filter since it runs fine when it does start, and the fuel pressure is reading good.

 

I replaced the crankshaft position sensor with no luck, and I also hooked a fuel pressure test gauge to it. Its showing 53psi, dropping down to about 47 in 20 minutes.

 

I don't think it would be any sensors or anything since shes coughing when I have the truck WOT. It'd be fuel/air related, right?  I'm about to go out and check spark, grounds, clean battery connections, and spray some starting fluid in the throttle body. Ill let yall know how it goes.

Edited March 14, 2016 by yzmxer12