2000 express hard to start cold

[zbird75]

2000 Chevy
express 4.3L

Every morning the only way I am able to get the van started is either with short bursts on the starter(takes about 10-15 times), or if I open the air box and spray some starting fluid, then It will run and die again but after that it usally will start and stay running. When I first get it to start and stay running, I have to let it idle for 3-5 minutes, if I try to rev the engine during this time it will just stall. outside temp around 20 degrees, problem was not as bad when warmer.

Fuel pressure, key on engine off 60 psi
running 55 psi
the pressure will hold over night at 60
I am getting good spark
NO CODES
I have a scanner and did notice that the coolent temp reads 170 degrees even when engine is cold?
I have replaced the coolent temp sensor, checked wiring to computer, seems fine, still reads 170 degrees, won't go lower but will rise as the engine warms up?
I am not sure what controls the injectors pulse width?
I think the injector need to spray more fuel on cold start up?

I have had problems in the past with vacuum leaks, the entire van sounds like a big vacuum leak but I can not find any anywhere and have been told that the engine sounds normal.

Was thinking that the ECM might be bad but before i try that looking for some other feedback, or ideas.

Thanks in advance.
Z

[MT-2500]

Originally Posted by zbird75

2000 Chevy
express 4.3L

Every morning the only way I am able to get the van started is either with short bursts on the starter(takes about 10-15 times), or if I open the air box and spray some starting fluid, then It will run and die again but after that it usally will start and stay running. When I first get it to start and stay running, I have to let it idle for 3-5 minutes, if I try to rev the engine during this time it will just stall. outside temp around 20 degrees, problem was not as bad when warmer.

Fuel pressure, key on engine off 60 psi
running 55 psi
the pressure will hold over night at 60
I am getting good spark
NO CODES
I have a scanner and did notice that the coolent temp reads 170 degrees even when engine is cold?
I have replaced the coolent temp sensor, checked wiring to computer, seems fine, still reads 170 degrees, won't go lower but will rise as the engine warms up?
I am not sure what controls the injectors pulse width?
I think the injector need to spray more fuel on cold start up?

I have had problems in the past with vacuum leaks, the entire van sounds like a big vacuum leak but I can not find any anywhere and have been told that the engine sounds normal.

Was thinking that the ECM might be bad but before i try that looking for some other feedback, or ideas.

Thanks in advance.
Z

How many miles on ut and when ws the last good AC delco tune up?

Fuel pressure is not good.

You need 65 lbs of fuel pressure engine cranking for a good cold start.

Which tempt sensor reading is bad?
Engine to pcm or air intake senbsor reading?

Both need to be reading right for a good cold start or hot start.
Are you sure you replaced the right tempt sensor.
Where was the one at you replaced?

You also need to find where the vacuum leak is.
Hook up a vacuum gauge and give us the vacuum readings at idle and at 2K RPM.

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.

[zbird75]

2000 Chevy express hard to start cold

The last time I had a good tune up (plugs, wires, cap rotor, and throttle body clean) about a year ago.
The van has 80K miles and I did the tune up at 60k

The fuel pressure is 60 Key on engine off
55 PSI when running, driving
If I snap the thriottle the fuel gauge will spike up to 62, then drop back to 55PSI
If I pinch off return line I am getting 70-72 PSI, KOEO, did not try starting not sure if should.
I left the gauge on for 3 days and came back and pressure was down to 25PSI If I let it sit over night the pressure holds
(also noticed that the fuel level gauge needle has started to vibrate when running)

I replaced the coolent temp sensor at the thermostat housing, its a two wire conector, sits in the upper intake manifold coolent passage.
The air intake sensor is in the air cleaner hose and that is reading pretty much the outside temp.

(No matter what temp outside my scanner is reading engine is 170 Degrees but will rise to 210 when warmed up)(the vans temp gauge reads cold, or under 100 degrees)

I have not been able to located a vacuum gauge yet, the holiday has set me back a bit. I am 99% sure that I have fixed all vacuum leaks, I was getting lean codes a few months ago, couldn't pass emissions, fixed a couple of old hoses and have not gotten codes back and was able to pass the test.

From the last post it sounds like the fuel pump is just not suppling enough pressure, The fuel pressure regulator I think should hold pressure for several days?
I have replaced the fuel pump in 2004 but when that happened I was getting an obviously low pressure reading.

[MT-2500]

Yes fuel pressure is low.
Run it down the road and get it warmed up good and watch pressure on the road.
Also engine tempt to VCM/PCM needs fixed.
And check them vacumn leaks.
If you have to replace fuel pump only replace with the oem type Delphi pump.

[MT-2500]

Also check ground and 12 volt power on fuel pump fuel and wiring plug in connector on transmission cross member.
Lot of problems with the connector plug in.
Let us know how it goes.

[zbird75]

When driving the van fuel pressure is constant at 55-60 PSI, the van runs good, excels good. Just can't get it to start in the morning when it's cold.

I decided to just drop the tank and test. I have 11.97 volts at pump, and a good ground. If I hook up my gauge directly to the pump, I am getting about 80 PSI, once the gauge rises this high, I turn off the power.

I did notice that if I remove the return line and run the pump that I am getting alot of fuel returning to the tank. I don't have an attachment to check fuel pressure returning to the tank but it's got to be aleast 40 PSI, I would think.

Is this normal? Should a simular amount of fuel be pumped to the engine and then return to the tank?
The fuel pressure regulator is under the upper intake manifold and really don't want to remove it, if this is normal.


I still have no idea about how to check either VCM/PCM, I am trying to locate known good parts, replace and see if readings are better. The parts are $$$ with a no return policy.

[danielsatur]

Symptoms of a hard cold start is a bad or dirty MAF/IACT sensors. ''No codes / Tbl cold start''
The PCV emissions will contaminate these sensors.

[MT-2500]

Originally Posted by zbird75

When driving the van fuel pressure is constant at 55-60 PSI, the van runs good, excels good. Just can't get it to start in the morning when it's cold.

I decided to just drop the tank and test. I have 11.97 volts at pump, and a good ground. If I hook up my gauge directly to the pump, I am getting about 80 PSI, once the gauge rises this high, I turn off the power.

I did notice that if I remove the return line and run the pump that I am getting alot of fuel returning to the tank. I don't have an attachment to check fuel pressure returning to the tank but it's got to be aleast 40 PSI, I would think.

Is this normal? Should a simular amount of fuel be pumped to the engine and then return to the tank?
The fuel pressure regulator is under the upper intake manifold and really don't want to remove it, if this is normal.


I still have no idea about how to check either VCM/PCM, I am trying to locate known good parts, replace and see if readings are better. The parts are $$$ with a no return policy.

Do not worry about return line pressure.

Cold cranking is the pressure you need to be up to par.

Check cold start engine cranking pressure.
You need 65 lbs on a cold start for the injector to squirt fuel.
Even a few lbs or 2-3 lbs can cause a hard cold start.

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.

[danielsatur]

The ECU/PCU needs the right data from a MAF/ IACT sensors, it can give a longer fuel pulse, like a choking (Rich) effect for cold start!

[hellah fresh]

HEYY!!!! This is the exact same problem i have having. Didn't mean to jack the thread but yes when its cold it will start... but once warm its hard to start.

[zbird75]

O.K. here is an update

After researching the Engine coolent temp sensor specs are a 5 volt ref. signal from the ecu.
I had 2.9 volts coming directly off the pin 23(yellow wire) to the sensor. No shorts, or opens.
I replaced the ecu,
Now I have my 5 volt ref. signal and the the sensor is reading the correct outside temp, (on the scan tool)
I bought the ecu from Lee auto part, I also had sent it out to have it flashed for the vehicles vin and service number.

NOW the security light is flashing and the car will not crank and has no fuel pressure.

Is there something I am not doing?
I can not find any procedure such as leaving the ignition key on for a certain amount of time, or something?

Lee auto has told me that by having it programmed to the vin, it should have taken care of this problem and will not replace it.

Any information on what to test, or check would be very helpfull.
Thanks

[MT-2500]

Originally Posted by zbird75

O.K. here is an update

After researching the Engine coolent temp sensor specs are a 5 volt ref. signal from the ecu.
I had 2.9 volts coming directly off the pin 23(yellow wire) to the sensor. No shorts, or opens.
I replaced the ecu,
Now I have my 5 volt ref. signal and the the sensor is reading the correct outside temp, (on the scan tool)
I bought the ecu from Lee auto part, I also had sent it out to have it flashed for the vehicles vin and service number.

NOW the security light is flashing and the car will not crank and has no fuel pressure.

Is there something I am not doing?
I can not find any procedure such as leaving the ignition key on for a certain amount of time, or something?

Lee auto has told me that by having it programmed to the vin, it should have taken care of this problem and will not replace it.

Any information on what to test, or check would be very helpfull.
Thanks

Make sure battery is up good.

Go for a relearn on it.

Turn key on for 10 minutes and watch security light.
Should go off after 10 minutes.

Then key off and on for another 10 minutes until light goes out.

Then key of and on one more time for 10 minutes until light goes out.
Then key off and then it should start if relearn took good.
If not post back and tell us what the security light is doing after relearn
Like key on light on and the off or is light still flashing.

Also you may need to have a battery charger on it to keep battery up from30 minutes key on.
Good Luck
Let us know how it goes.

[zbird75]

Sorry about the delay,
So I figureed it out. After putting in the new ECM, the security light was on. Leaving the ignition key on in the run postion for 10 min, in 3 cycles, turned off the security light. Must have battery charger on for it to work properly.

After vehicle still would not start, So I was able to find a guy with a tech 2 scan tool, to come by and check. He found that because I put in a new ECM, that the ignition switch was not reading properly and was not allowing the vehicle to start.

To make a very long story short, I replaced the ignition switch and the van is now running great. Thank to everyone whoi helped.

Z

[MT-2500]

Originally Posted by zbird75

Sorry about the delay,
So I figureed it out. After putting in the new ECM, the security light was on. Leaving the ignition key on in the run postion for 10 min, in 3 cycles, turned off the security light. Must have battery charger on for it to work properly.

After vehicle still would not start, So I was able to find a guy with a tech 2 scan tool, to come by and check. He found that because I put in a new ECM, that the ignition switch was not reading properly and was not allowing the vehicle to start.

To make a very long story short, I replaced the ignition switch and the van is now running great. Thank to everyone whoi helped.

Z

Late /delay is better than never.
A lot of posters never post back how it went.
Thanks for posting back the fix and how it went.