2000 s10 blazer 4.3 starting problems

[NHRA]

ok just got this blazer 4.3 motor, starts sometimes and other times just cranks over
dont have a scanner to see the codes if any, but has new fuel pump
ran fuel presure test has 61 lbs with the key on and does not leak down
at all.
when i get the truck running it has 52 lbs running and idle it up goes to 58 lbs
is this close to what it needs?
also when its running has bad bog when you give it some gas and will only get up to around 45 mph driving.
could this be a bad control module? or possiable maf sensor?
thanks guys<<<<<<<<

[NHRA]

do these post have to be approved before they show up?
this post dont show when i hit new post..........thanks

[MT-2500]

Originally Posted by NHRA

do these post have to be approved before they show up?
this post dont show when i hit new post..........thanks

No.
When you make a new post/New thread it goes into the forum you posted in.

Go to that forum and you can read your post.
If any one answers it you will recieve a E mail thah someone has answered.
As you should get a e mail from this.

Your hard to start may be low fuel pressure.
For a cold start you need 65 lbs of fuel pressure engine cranking to squirt injectors.

Just a New fuel pump does not mean or always give you good fuel pressure.

Was the new pump a junk after market pump or a good AC/Delphi pump.
Airtex and other aftermarket pumps have a very high fail rate.

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.


Run a full fuel pressure test as outlined below.

[NHRA]

Originally Posted by MT-2500

No.
When you make a new post/New thread it goes into the forum you posted in.

Go to that forum and you can read your post.
If any one answers it you will recieve a E mail thah someone has answered.
As you should get a e mail from this.

Your hard to start may be low fuel pressure.
For a cold start you need 65 lbs of fuel pressure engine cranking to squirt injectors.

Just a New fuel pump does not mean or always give you good fuel pressure.

Was the new pump a junk after market pump or a good AC/Delphi pump.
Airtex and other aftermarket pumps have a very high fail rate.

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.


Run a full fuel pressure test as outlined below.

ok another question....lol
is there any code readers out there that will read fuel presure?

[MT-2500]

Originally Posted by NHRA

ok another question....lol
is there any code readers out there that will read fuel presure?

No.
Outside of a few systems that Have a fuel pressure sensor on fuel rail that will set a code for low fuel pressure.
And a few codes can be caused by low fuel pressure.
But you will need.
A good actuate fuel pressure gage is needed for checking and reading fuel pressure.

[NHRA]

ok what i have is a fuel pressure gauge that only has a 2- 3 foot hose
no chance of seeing that while i drive............ok does the fuel pressure Reg.
show on the gauge as far as it being bad? and not the fuel pump
in other words if the fuel pump is putting out 70 psi would the Reg.
be bad and should read more if it was replaced?
i thought seens it doesnt bleed down the reg was good? am i wrong on that.......
again thanks and sorry for some many questions
im old school and i can work on non-computer cars but this on has got me.............cheers

[MT-2500]

Originally Posted by NHRA

ok what i have is a fuel pressure gauge that only has a 2- 3 foot hose
no chance of seeing that while i drive............ok does the fuel pressure Reg.
show on the gauge as far as it being bad? and not the fuel pump
in other words if the fuel pump is putting out 70 psi would the Reg.
be bad and should read more if it was replaced?
i thought seens it doesnt bleed down the reg was good? am i wrong on that.......
again thanks and sorry for some many questions
im old school and i can work on non-computer cars but this on has got me.............cheers

A gauge does not say if regulator is bad.
A gauge only reads the pressure where it is tapped in.

The pump on yours should have 95-105 lbs direct fuel pressure.

The pump has to put out more pressure and fuel volumn than the regulated pressure for the regulator to hold it at the correect pressure.

Test pump for good volumn and pressure then test the regulated pressure.

You need to get a hose extension so you can check and watch the pressure onthe road and let it run for a 1/2 hr or more to make sure pump is not losing pressure afte it gets hot.

Post back your pressure readings as outlined.

[NHRA]

Originally Posted by MT-2500

A gauge does not say if regulator is bad.
A gauge only reads the pressure where it is tapped in.

The pump on yours should have 95-105 lbs direct fuel pressure.

The pump has to put out more pressure and fuel volumn than the regulated pressure for the regulator to hold it at the correect pressure.

Test pump for good volumn and pressure then test the regulated pressure.

You need to get a hose extension so you can check and watch the pressure onthe road and let it run for a 1/2 hr or more to make sure pump is not losing pressure afte it gets hot.

Post back your pressure readings as outlined.

yeah i'll have to buy longer hose for the gauge .
had a freind of mine that owns a mech. shop tell me he would bet i have
a plugged up Cat. converted my next question would be can i take the Cat. converter
out and not use one?
would the O2 sensor still work ok?
thanks ..cheers

[MT-2500]

Originally Posted by NHRA

yeah i'll have to buy longer hose for the gauge .
had a freind of mine that owns a mech. shop tell me he would bet i have
a plugged up Cat. converted my next question would be can i take the Cat. converter
out and not use one?
would the O2 sensor still work ok?
thanks ..cheers

If operated on a federal funded higtway.
Removing cats is a illegal operation.
Ever hear the saying?
Trip Up The River?
A person can even get a year or two jail bird time and big fine in the rear like up to 10-20 grand.
But.
Yes 02 sensors will still work if working before but removing cat will create other problems.
Engine will not run as good with cat removed verses a good cat onthe exhaust system..

Before you think about cat make sure that is the problem.
There is several test for bad cats.
Back pressure test.
Engine vacumn at idle verses vacume at 2K RPM.
And even the open up exhaust exhaust system just for a test not a perment fix.

I have never had a cat that would give/cause a no start.

[cj091184]

I have had a cat cause a no start problem, on 84 firebird, took it to the shop and had the exhaust welded back together left the shop driving, made it about a block and it craped out. would start but stalled after about 5-10 seconds, and then would not start unless you let it sit for like 1/2 an hour then it would start for 5-10 seconds and stall. I pushed it back to the shop and they drilled a hole in front of the cat and it ran just fine.

I have had the bad bog problem, "almost like your running out of gas?". I had an oldsmobile ciera 94' 2.2 that was running 12 psi, was hard to start and if you gave it to much pedal it would be all boggy, (THE ONLY WAY TO MAKE IT START WAS TO TURN THE KEY ON AND THEN OFF THEN ON THEN OFF, SEVERAL TIMES THEN START, YOU COULD THEN BABY IT UP TILL IT BOGGED, THEN LET OFF A LITTLE TO TRICK IT TO SHIFT TO THE NEXT GEAR THEN BABY IT TILL IT BOGGED ECT EACH TIME GAINING SPEED) its all engine rpm it should run and idle even with low pressure just wont go if you demand rpm "fuel pump replaced ran great" also all with a leaking head gasket not blown"

also even with a short hose on your gauge you can secure it under the hood and drive the truck "you wont get to monitor but you said it doesnt drop so after drive youll get a highest pressure reading"

if pressure is higher or lower than spec at any time you need a new pump.
autozone.com has free repair manuals with all specs

2000 S-10 GM service manual calls out for 60-66 PSI. Higer or lower will throw CEL.

double check your filter and make sure coils are good

also double check the fuel pressure behind the filter

[MT-2500]

Originally Posted by cj091184

I have had a cat cause a no start problem, on 84 firebird, took it to the shop and had the exhaust welded back together left the shop driving, made it about a block and it craped out. would start but stalled after about 5-10 seconds, and then would not start unless you let it sit for like 1/2 an hour then it would start for 5-10 seconds and stall. I pushed it back to the shop and they drilled a hole in front of the cat and it ran just fine.

I have had the bad bog problem, "almost like your running out of gas?". I had an oldsmobile ciera 94' 2.2 that was running 12 psi, was hard to start and if you gave it to much pedal it would be all boggy, (THE ONLY WAY TO MAKE IT START WAS TO TURN THE KEY ON AND THEN OFF THEN ON THEN OFF, SEVERAL TIMES THEN START, YOU COULD THEN BABY IT UP TILL IT BOGGED, THEN LET OFF A LITTLE TO TRICK IT TO SHIFT TO THE NEXT GEAR THEN BABY IT TILL IT BOGGED ECT EACH TIME GAINING SPEED) its all engine rpm it should run and idle even with low pressure just wont go if you demand rpm "fuel pump replaced ran great" also all with a leaking head gasket not blown"

also even with a short hose on your gauge you can secure it under the hood and drive the truck "you wont get to monitor but you said it doesnt drop so after drive youll get a highest pressure reading"

if pressure is higher or lower than spec at any time you need a new pump.
autozone.com has free repair manuals with all specs

2000 S-10 GM service manual calls out for 60-66 PSI. Higer or lower will throw CEL.

double check your filter and make sure coils are good

also double check the fuel pressure behind the filter

A no start is no start.

Start and stall is a start and stall.

The computer and or check engine light does not know what fuel pressure is and does not set a code or make the check engine light come on if fuel pressure is not up to specs.

But if fuel pressure is way off may set a running lean or running rich code.

To do a proper test on a fuel pump it you need a fuel pressure gage set up that will show pressure running on the road after engine and pump are hot and with engine under load.

[cj091184]

Originally Posted by MT-2500

A no start is no start.

Start and stall is a start and stall.

The computer and or check engine light does not know what fuel pressure is and does not set a code or make the check engine light come on if fuel pressure is not up to specs.

But if fuel pressure is way off may set a running lean or running rich code.

To do a proper test on a fuel pump it you need a fuel pressure gage set up that will show pressure running on the road after engine and pump are hot and with engine under load.

mt is right, sorry was tired last night,
cel wont throw just from fuel pressure and putting the gauge under the hood will NOT give you a highest pressure reading because if the pressure goes down that is what you will see.

though you did say you could get it running and pressure is in the 50's
should be 60-66 so I would say your out of spec, make sure filter is correct and installed proper, that lines are not clogged an then retest, if still in the 50's I would think your pump is weak.

[NHRA]

turned out to be the control module <<<<<<<<<<<<<<<<<< cheers

[MT-2500]

Originally Posted by NHRA

turned out to be the control module <<<<<<<<<<<<<<<<<< cheers

To help others on here tell us how you found bad the control module?
How about that fuel pressure?
Did you do anything on it?
If not you may still have problems.

[NHRA]

Originally Posted by MT-2500

To help others on here tell us how you found bad the control module?
How about that fuel pressure?
Did you do anything on it?
If not you may still have problems.

fuel presure is at 62 psi
installed new control module, cranks and runs like it should now.