99 Tahoe 5.7 only runs with ether shot

[trox]

Bought this truck from a friend that was told it needed head gaskets. 160k on the odometer. Battery was very dead as the truck sat for over a year after it quit so I dragged it home. Mech said the compression on the back 2 cylinders on both sides were 70 psi and quoted him $1500 to fix. I started to flush the water system to try the expensive blue wonder stuff for head gasket leak repair. It worked in my old Ford Escort so I thought it was worth a shot here. The engine wouldn't fire and I wanted to flush the system as good as possible so while cranking I gave it a shot of ether and found it would run as long as I kept shooting it. I was curious what the plugs looked like since it sounded like it was firing on all 8 when it was running. While the plugs were out I checked compression and found them all to be at least 195 to 205 psi. Does good compression mean I have good head gaskets? I put new plugs in and it sounds good as long as I shoot in some fuel, I'm using gas now instead of ether. Now I'm focusing on getting fuel all the way to the cylinders. I can hear the pump run for 2-3 seconds when I turn the key on. I haven't worked on a newer Chevy since I rebuilt the motor in my 69 Vette. And that ain't nothin like this motor. I'm waiting on manual from Ebay to see where and how to check fuel pressure. Was told he had the fuel pump replaced some time ago at a cost of nearly $700. Don't know what brand was used though and from what I've read, it matters. Sorry for the lengthy thread but I got this thing for $1500 and it's loaded. Be cool if it's not too expensive to fix. Could the security system prevent fuel flow? It's an aftermarket install from Clifford. The Security light comes on when the turning the key to the start position then goes out and stays out. Fuses to the computer look good.

[j cAT]

this could be the fuel pump.if you hear the pump running the pressure check at the passenger side fuel rail should be 53-62psi...with key on engine off..with the pump stoping it should hold pressure..if it drops fast you need to replace ..replace the fuel filter and the fuel pump relay also.make sure the fuel tank ground and the fuel pump connectors are good.when replacing the pump make sure the pick up tube is good if not replace.. must fit tight, if it sucks air it will fail/ruin pump..

never operate vehicle with less than 1/4 tank..

[MT-2500]

If it starts on starter fluid or gas in intake it has a fuel delivery problem.

Confirm good fuel pressure.

You should see 65 lbs key on engine prime up and 65 cold cranking.

Also make sure gas in tank and gas is good.

Add some fresh fuel.

I would hold on the head gasket stuff and check it out first.
Good compression is a plus but does not rule out bad head gaskets.
Any coolant in oil.
Get it running good and see if it heats up any or builds pressure in rad or leaks coolant in oil or out tail pipe.
They make a block/head gasket tester that will show up bad head gasket leaking exhaust in coolant.
But keep in mind head gaskets can lkeak 2-3 ways.
Get that fuel pressure up and engine running and post back how it goes.

That engine has more intake leakage than head gasket problems.
Look for coolant leaks at back and under side and on top and front of intake and or leaking oil pan.

.

[j cAT]

The Security light comes on when the turning the key to the start position then goes out and stays out. .[/quote]

if the engine will start then die quickly this can be the security system. if the light goes out this is normal..

[trox]

Thanks for getting back to me. The oil is good. The last owner said this all started with the temp gage climbing on the way to work, turned around and went home to add 1.5gals of water. Drove to work for a couple weeks then it died. Any heads up on the fuel pressure check? Can I get a gage from O'reily's? Any other special tools? Where will I tap into the system? Will a code tester tell me anything?

[MT-2500]

Most parts places loan or sell or rent fuel pressure testers.

The gauge will hook into the scrader valve on fuel in rail.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
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.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding 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 in system.
Post back fuel pressure readings.

[MT-2500]

Code readed will show OBD11 codes.

[trox]

Thanks a ton guys. I will post my results.

[trox]

Update: I got a gauge kit from Autozone. Tapped into the line going into the fuel filter. Turned the key on and off a couple times to get air the air out and got about 45 psi at the most. Same with cranking. The pressure rises a little when I turn the key off. Still not much more than 45 psi. From that I recon the pump is toast. It is a replacement from a couple years ago from what I was told. I still don't have my book yet. Any tips or tricks on removing the tank? I see two straps, can I let them loose and support it to get to the top of the tank?

[j cAT]

Originally Posted by trox

Update: I got a gauge kit from Autozone. Tapped into the line going into the fuel filter. Turned the key on and off a couple times to get air the air out and got about 45 psi at the most. Same with cranking. The pressure rises a little when I turn the key off. Still not much more than 45 psi. From that I recon the pump is toast. It is a replacement from a couple years ago from what I was told. I still don't have my book yet. Any tips or tricks on removing the tank? I see two straps, can I let them loose and support it to get to the top of the tank?

remove as much fuel as you can then drop tank...be sure to dissconnect the fuel lines/fuel fillerhose/ground straps..and other electricals...

the fuel tank straps check for rust damage..

when installing the delphi fuel pump make sure the pickup hose is secure...if this is loose if will suck air and damage new pump...when you get it all together check pressure ..make sure its correct ..replace fuel relay and filter as well...

[trox]

Soooo... I'm dropping the tank a little at a time and see the hoses and electrical connect on top (2 electrical connects) I disconnect the elec connectors and need a hose coupling tool for the 2 hoses. The small middle tube is empty on the tank pickup side. I can't remove the small vent hose at the front top of the tank. It has a special coupling but not like the big hoses. There's a white piece that looks like you should be able to squeeze and should come off but it's not budging, any ideas there? Other than that, it's ready to come down. Will pick up fuel coupling tool tonight and try again tomorrow.

[MT-2500]

You should not need a special tool.
The small line you squeeze the outer lips on ring and twist and pull easy.
The other two you squeeze the white plastic taps and twist and pull easy.

[roadrunner2]

Make certain you have disconnected the NEG battery cable before working with the fuel tank electrical connections.

[trox]

Got the pump changed out and it started right up. Pressure is 63 with key on engine off. 56 with engine running. I hope that's good. Wait a minute though. Still have a head issue. Water in the oil. Drained the oil and drained the water several times and put the blue expensive stuff in to hopefully fix my problem. Ran for the 50 minutes the bottle called for. After about 5 minutes the water stopped coming from the tail pipe and the oil on the dip stick was looking OK. Gonna drain and refill my oil tomorrow. Let you know for sure if the blue stuff did the trick.

[roadrunner2]

Originally Posted by trox

Got the pump changed out and it started right up. Pressure is 63 with key on engine off. 56 with engine running. I hope that's good. Wait a minute though. Still have a head issue. Water in the oil. Drained the oil and drained the water several times and put the blue expensive stuff in to hopefully fix my problem. Ran for the 50 minutes the bottle called for. After about 5 minutes the water stopped coming from the tail pipe and the oil on the dip stick was looking OK. Gonna drain and refill my oil tomorrow. Let you know for sure if the blue stuff did the trick.

Keep in mind that water coming from the tailpipe is likely just normal condensation emptying out as the exhaust warms up.