97 305 vortec starting issues

[chuck60]

Hi

New to forum.
I have a 97 chev c/k. 305 vortec 5 spd manual with starting problem.
If I turn key to crank it will crank with normal starter sounds but not fire.
If I crank for less than 2 sec and release key it starts. Found this when
cycling fuel pump to build pressure. Has spark when cranking but not starting.
Runs great once started. Truck has 58k (low) miles, all orig.

[MT-2500]

Originally Posted by chuck60

Hi

New to forum.
I have a 97 chev c/k. 305 vortec 5 spd manual with starting problem.
If I turn key to crank it will crank with normal starter sounds but not fire.
If I crank for less than 2 sec and release key it starts. Found this when
cycling fuel pump to build pressure. Has spark when cranking but not starting.
Runs great once started. Truck has 58k (low) miles, all orig.

Check fuel pressure for up to specs.

[j cAT]

Originally Posted by chuck60

Hi

New to forum.
I have a 97 chev c/k. 305 vortec 5 spd manual with starting problem.
If I turn key to crank it will crank with normal starter sounds but not fire.
If I crank for less than 2 sec and release key it starts. Found this when
cycling fuel pump to build pressure. Has spark when cranking but not starting.
Runs great once started. Truck has 58k (low) miles, all orig.

what are you talking about with spark good then missing on starting , explain...?

since it runs good after it starts I would look at the fuel filter and the ECT along with the injectors working correctly when cold. this TBI ..?

[chuck60]

Hi
Had some time to look at it and ran fuel pressures.
Key on cycle pump 58psi. Cranking drops in 1 sec to about 40psi.
Running 58 to 59 psi. Punch it while running 67 to 69. Do not have gauge
setup to road test. Relay? Ignition switch? Fuel pump? 10.5 volts at bat
when cranking. Is there place to check volts at fuel pump without tapping?

[MT-2500]

Originally Posted by chuck60

Hi
Had some time to look at it and ran fuel pressures.
Key on cycle pump 58psi. Cranking drops in 1 sec to about 40psi.
Running 58 to 59 psi. Punch it while running 67 to 69. Do not have gauge
setup to road test. Relay? Ignition switch? Fuel pump? 10.5 volts at bat
when cranking. Is there place to check volts at fuel pump without tapping?

Your fuel pump is weak.!!!!!!!!!!!!!!

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 CSI fuel inj. should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
SFI is 4 lbs lower.
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.

[j cAT]

Originally Posted by chuck60

Hi
Had some time to look at it and ran fuel pressures.
Key on cycle pump 58psi. Cranking drops in 1 sec to about 40psi.
Running 58 to 59 psi. Punch it while running 67 to 69. Do not have gauge
setup to road test. Relay? Ignition switch? Fuel pump? 10.5 volts at bat
when cranking. Is there place to check volts at fuel pump without tapping?

with the ignition on engine off if the battery volts are 10.5 vdc then you had a dead battery cell. low volts to the pump will effect pressures.

[Schurkey]

Originally Posted by chuck60

10.5 volts at bat when cranking.

Originally Posted by j cAT

with the ignition on engine off if the battery volts are 10.5 vdc then you had a dead battery cell. low volts to the pump will effect pressures.

The way I read it, he has 10.5 volts WHILE CRANKING. That would be acceptable although a bit low at least for this time of year--it can't be THAT cold out.

Originally Posted by chuck60

Is there place to check volts at fuel pump without tapping?

No. Testing voltage will require you to create a test-point as close to the pump as possible. When I did this on my '88, I used a pair of four-pin Weatherpac connectors and pins, strung some wire between each of the four pins, and then unplugged the vehicle wire harness near the frame, installed my home-made jumper assembly, then punctured that for voltage access. Keeps corrosion out of the vehicle harness.

Be aware that at least for earlier vehicles, corroded connections INSIDE THE TANK were responsible for a fair amount of voltage drop, and it's impossible to test this without removing the pump/hanger assembly.

[chuck60]

It starts now. Lifted box and slid it back. Found leak in tank between hose and pipe
just above fuel pump. Plastic clamp. Fixed leak, stopped pressure from dropping
but still didn't have correct pressure. Replaced pump, problem fixed.

Thank you for all the help.
P.S. 10.5 volts was with starter cranking, after alot of start attempts.

[MT-2500]

Originally Posted by chuck60

It starts now. Lifted box and slid it back. Found leak in tank between hose and pipe
just above fuel pump. Plastic clamp. Fixed leak, stopped pressure from dropping
but still didn't have correct pressure. Replaced pump, problem fixed.

Thank you for all the help.
P.S. 10.5 volts was with starter cranking, after alot of start attempts.

Thanks
For posting back fix and how it went.