1997 K1500 Wont Start

[aleebee156]

Hey guys, disclaimer Im just headed out to try and diagnose the truck further. Truck always starts right up, today it won't start. See you tube video for sound. Battery is good, starter seems fine its getting good crank and power. Wondering if anyone can help me direct my diagnosis process. Are there any common fuel problems? Unsure how to check if a relay is bad... fuel pump relay?? unsure how to check that. Any thoughts for me is appreciate, headed out to truck now, will report back what I find. Truck is in park and has 3/4 tank of fuel. has 211,000 miles on it. Only recent work done was brake rotors and pads and fluid (fluid did spill our of reservoir and get on fuse box cover, inside cover seemed protected). I replaced fuel filter probably 500-1,000 miles ago, crappy filter, maybe thats it?? Has run fine since i replaced fuel filter.

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[aleebee156]

Cap and rotor, wires and plugs all new 50,000 miles ago. Pulling plugs to see what I find


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[east302]

You need fuel, spark and air. Assuming there is no compression issue, it just leaves two things to check.

Grab a spark tester and see if you have spark at all plugs.

An auto parts store can rent you a fuel pressure gauge. Connect it to the schrader valve on the driver side, with ignition on see what your pressure is. Spec is 60-66 psi.


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[east302]

Here's a good write up on ignition system testing...

http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/ignition-misfire-diagnostic-tests-3


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[aleebee156]

You are able to get fuel pressure without vehicle running yea? So testing with the fuel pressure gauge tester I don't have to start the vehicle it should show pressure with the key in the ON position, shouldn't the fuel pump run then? just checking.

 

[east302]

Yes. You should hear the fuel pump come on for a few seconds when you turn the ignition on (the accessory position before the start position).

With the ignition off, hook up the gauge and then turn the ignition on without trying to crank it. That will pressurize the system. See what the pressure is after maybe 30 seconds and then turn the ignition off. Watch the gauge for a couple of minutes. It may drop a couple of psi, but if it goes down to zero then you have a leaking injector or bad regulator.

Edit: link to pressure test on a 350:

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[east302]

Just thought of something, turn the ignition on, wait a few seconds and then hold the pedal to the floor while cranking and see if it starts.

A bad coolant temperature sensor can sometimes cause flooding issues, holding the gas to the floor stops the injector pulses.

You are hearing the fuel pump come on, right?


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[aleebee156]

So its hard because I'm only one person right now, so i can't have my ear at the pump or fuel likes to listen for the pump or fuel flowing for those first couple seconds. But i've tried just listening from cab, and jumping under truck to gas tank super fast (i was pretty fast) and Im not hearing anything at all. Should I be checking fuel pump relay? are there other fuses i don't know about?


tried your method for bad coolant temp sensor, didn't change anything, still no start.

 

[aleebee156]

I've got this feeling it's fuel related. But starting with spark first making sure that's good. Gonna take me a minute, gotta walk to auto parts store. I'll report back


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[east302]

It can be hard to hear it from the cab when you first turn it on (it only runs for about two seconds and the ignition chime is loud) but when you turn it back off you should hear it then as well.

Do you have a test light or multimeter? You'll need that to check the pump relay. I'll post the diagnostics on that if you aren't hearing the pump at all.


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