97 tahoe will turn over but wont start

[DaltonZ]

Can anybody help? i have a 97 tahoe that wont start. Cut off while driving and hasnt restarted since. Have checked for spark, fuel, and air. Cant figure out the problem. Has anyone else had the same problem or know what it is?

[maxwedge]

Originally Posted by DaltonZ

Can anybody help? i have a 97 tahoe that wont start. Cut off while driving and hasnt restarted since. Have checked for spark, fuel, and air. Cant figure out the problem. Has anyone else had the same problem or know what it is?

Welcome to AF. Do you have 60 psi fuel pressure, will it start with carb cleaner sprayed into the intake, I assume you have spark at the plugs? You say you have checked these things but how, no clear indication of where you are with this.

[primal1]

Originally Posted by DaltonZ

Can anybody help? i have a 97 tahoe that wont start. Cut off while driving and hasnt restarted since. Have checked for spark, fuel, and air. Cant figure out the problem. Has anyone else had the same problem or know what it is?

i believe there is a tsb that says a build up of corrosion between the 2 battery cables that side mount to your battery causes this. give that a whirl, it could also be your anti theft.

[mrgoodwrench69]

I had the same problem, the fuel pump was bad. The tech told me it was only putting out about 40 psi, and it should have been 65psi. The pump sounded fine to me, so I thought it must have been something else. My 97 is in the shop as I write this getting another fuel pump, this one is free under lifetime warranty. Hope this helps.

[glenncof]

My 1997 fuel pump went out at about 125K. Died right on the highway.

There is a relay under the hood. I read there is a relay bypass connection to test the pump but I couldn't find it. The relay should feed 12V right when turning the ignition on but shuts off in a few seconds if engine doesn't start.

You could listen for the whiny pump. I would have someone else turn key because it won't be on long.

There is also a fitting for pressure check with a plastic cap above the intake manifold. I found no/little residual pressure when pressing the ceter of what looks like a tire valve.

Also, I had dealer replace it at $1000. Replacement pump failed within three months. They claimed filter was bad, melted connector. I read about connector problems with OEM pump, I mentioned this to them the first time but I'm dumb consumer.

There is also a way to replace the motor and not the full pump assemble, so I have read. Save lots of money.

[MT-2500]

Originally Posted by DaltonZ

Can anybody help? i have a 97 tahoe that wont start. Cut off while driving and hasnt restarted since. Have checked for spark, fuel, and air. Cant figure out the problem. Has anyone else had the same problem or know what it is?

Welcome to AF on your first post.
Guide lines on fuel pressure check are.
Give us your pressure readings.
MT

Hard to start .
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

[DaltonZ]

Thanks for the welcomes. I did get it started when i sprayed starter fluid into the throttle body, i just found out that i dont have 60 psi but only 20 psi. i checked the fuel pressure on the rail with a guage. i checked the spark with a screwdriver and watched the spark arc to my exhaust manifold. I assumed it was the fuel pump but wasnt sure. I work on deisels not to keen on the gas side of the house. My coworkers said that it probably wasnt the fuel pump cause it is priming but now i am sure it is. I still am going to check the pulse modulation to make sure my injectors are getting a signal to fire. Are there any other tests that i should do?

[MT-2500]

Originally Posted by DaltonZ

Thanks for the welcomes. I did get it started when i sprayed starter fluid into the throttle body, i just found out that i dont have 60 psi but only 20 psi. i checked the fuel pressure on the rail with a guage. i checked the spark with a screwdriver and watched the spark arc to my exhaust manifold. I assumed it was the fuel pump but wasnt sure. I work on deisels not to keen on the gas side of the house. My coworkers said that it probably wasnt the fuel pump cause it is priming but now i am sure it is. I still am going to check the pulse modulation to make sure my injectors are getting a signal to fire. Are there any other tests that i should do?

Yes sir find out why you do not have 65 lbs of fuel pressure.
You can not leave home without it.
Did you go threw the fuel pressure test as outlined.?
MT

[glenncof]

20 psi means pump must be running but this has got to be fixed if correct.

Two things to check; fuel regulator on the manifold and fuel filter on driver side frame rail. Some people claim clogged filters but I never have had to my knowledge.

[DaltonZ]

yes sir i did. i followed them to the t.

[mrgoodwrench69]

Originally Posted by glenncof

20 psi means pump must be running but this has got to be fixed if correct.

Two things to check; fuel regulator on the manifold and fuel filter on driver side frame rail. Some people claim clogged filters but I never have had to my knowledge.

There is a schrader valve on the fuel line located before the regulator. The tech tested at this valve and it showed only about 40 psi. Any how, I now have a new fuel pump, which came as a complete assembly. For about the last year, it would take about 3 to 5 seconds for my 97 to fire, now it fires just about instantly. This also could be a sign of a pump going bad. The tech also said that running a low fuel tank could also contribute to a pump failure due to overheating, the higher the level in the tank, better cooling. Good luck!

[Blue Bowtie]

That's not entirely true on later designs The fuel pump is housed in a removeable well in the tank. The fuel return line empties into this well to keep the fuel pump constantly immersed in fuel, and keeps the fuel moving so that the pump heat can dissipate.



Another thing to check is the voltage at the pump. Even a new pump won't make adequate pressure if the voltage at the pump terminals is low. Either way, you definitely need at a minimum 61 PSIG to operate the injector poppets.

You can test pressure at the Schrader valve at the fuel line to the CFI unit:



You won't have to remove the upper plenum as shown in the photo. I did that to adjust the pressure regulator (which is why I have a vacuum pump on the regulator).

[DaltonZ]

how do the fittings on the pump come off??? have tried some tools from advance but nothing has worked for me.

[MT-2500]

Originally Posted by DaltonZ

how do the fittings on the pump come off??? have tried some tools from advance but nothing has worked for me.

They are usually squeeze lock type fittings.
Look at them real close.
Most do not require tools just squeeze in right place.
The middle one usually is a side squeeze.
Other two squeeze the white clip on ends.

MT

[DaltonZ]

i tried to squeeze them but it didt work. i dont have a middle line just the two outer lines. isnt the middle one just a vent?