Yet another crank no start...strange

[res02p35]

I have 99 Tahoe, won't start.
Was running last week now it just turns over but won't start.
Put on a new dist cap and rotor. New Crankshaft sensor.
When I turn the key on the relay click and it sounds like it is presureizing the system.
No security light on. Code reader will not connect to the Computer.
All fuses have been checked.
Any input would be greatly appreciated.

 

[strutaeng]

Fundamentals:

Have spark? Check multiple wires...if none, check at the coil.

Have fuel pressure? What is the fuel pressure with key on, engine off? Does it hold the pressure for about 10 minutes?

 

[res02p35]

Just checked for spark...yes
I dont have a fuel pressure gauge to check, however when I press the sharder valve it output fuel. I release the valve and it pressurize again.

Fundamentals:

Have spark? Check multiple wires...if none, check at the coil.

Have fuel pressure? What is the fuel pressure with key on, engine off? Does it hold the pressure for about 10 minutes?

 

[Doubeleive]

I would start at the battery and grounds, you could have spark but not a good ground.
or also check the ICM (ignition control module) that one is a classic problem, if that is bad everything else will be fine but it won't run and they tend to die out of the blue

 

[res02p35]

ICM ordered. Will update once received

 

[strutaeng]

I'm pretty sure you won't have spark if the ICM was bad.

Get yourself a cheap fuel pressure gauge. I'm shocked how many DIYers try to fix their vehicles with these symptoms without one! Having fuel squirt out of the Schrader valve is not a substitute.

I hate being a parts changer. Only time I'll do it is if I have another vehicle with the same engine, I'll swap something like a sensor since it's a known good and it doesn't costs me anything.

 

[res02p35]

ICM on order

 

[res02p35]

It's either I throw 25 at it or pay 45 for a gauge.
Pretty sure the pump is working as stated I drove it last week and wasn't an issue. Next I buy a gauge

 

[Eman85]

Buying parts is a BAD idea, many new parts are junk.
Code reader won't connect? You need a scan tool, cheaper than buying junk parts. Pressing on the schrader valve is good if you want gas on your finger, tells you nothing except what gas smells like, you need a fuel pressure gauge. Harbor Freight is your friend, instead of buying Chinese part buy some Chinese tools and diagnose what's wrong.

 

[Fless]

A fuel pressure gauge can be obtained through the loaner tool program at many auto parts stores. Essentially you pay for it with a credit card, use it for the alloted time, and return it for full credit.

 

[Doubeleive]

ya with spark it's probably not the icm, but.... if the spark is weak, could be it is not carrying enough current or a bad ground
you can test the system with a meter, probe or even with a couple wires and a 12v bulb

 

[Ibustbravo]

My no-start, no ecm communication issue was the main harness ground. I forgot to connect it.. heheh.. It goes on the engine btw.. so maybe put some eyes on the battery terminals and grounds.

 

[res02p35]

I got a fuel pressure gauge form Autozone loaner program.
Once I turn on the key gauge goes to 55, then slowly starts dropping to 44 psi. It stays there.
Is that enough PSI?

 

[res02p35]

I got a fuel pressure gauge form Autozone loaner program.
Once I turn on the key gauge goes to 55, then slowly starts dropping to 44 psi. It stays there.
Is that enough PSI?

BTW, I did get another code reader. It says 0 DTC codes

 

[res02p35]

BTW, I did get another code reader. It says 0 DTC codes

I will pick up a new Wix filter from NAPA in the morning.

 

[Hoesgottaeat2]

Clean up the battery terminals too with a wire brush. Especially the dual layer positive cable. Known culprit for giving only partial power.

 

[Doubeleive]

I got a fuel pressure gauge form Autozone loaner program.
Once I turn on the key gauge goes to 55, then slowly starts dropping to 44 psi. It stays there.
Is that enough PSI?

Should be fine on fuel pressure

 

[Doubeleive]

Double check all wiring and fuses under the hood

 

[Doubeleive]

Also not sure on the obs but obd communication on the 00+ is tied in with the cigarette power port, check the left side dash fuses

 

[strutaeng]

I got a fuel pressure gauge form Autozone loaner program.
Once I turn on the key gauge goes to 55, then slowly starts dropping to 44 psi. It stays there.
Is that enough PSI?

Technically, not on the original "spider" poppet injectors. I haven't looked in a long time, but IIRC spec was like 58 psi. Although both my old 4.3 and my 5.7 have always started just fine with 55 psi. I installed the updated MPFI on the 5.7 because I had a dead injector when I bought it. The MPFI can work with lower pressure.

The pressure drop is a concern too. You either have an issue with the FPR and or an injector that's leaking fuel. When that happens the fuel floods the engine and can cause issues with crank-no-fire. How long does it take to go from 55 to 44?

I've never tried this, but I've read once a guy opened the throttle body and primed the pump and saw with a flashlight a huge squirt of fuel getting dumped inside the intake! Massive flooded condition in that case.