1999 Chevrolet Silverado, WONT START

[rhandwor]

If you have the k-d disconnect tool I would remove the 4 short lines that attach to the fuel tank and fuel rail. Only try one at a time so they don't get mixed up and do the supply first. I would suspect if one suffered from internal collapse it would be the metallic cloth covered one the inlet as you pinched off the return. You could also blow through it with an air hose.They are short enough that you should be able to see through it. I have had brake hoses collapse internally and you couldn't bleed them.
I would suspect your gage is reading slightly high 5 or 10lbs. I would check to see if you can blow through the fuel filter. I would also check the directional arrow to be sure it isn't installed backwards. I would do this first.
You are learning alot so it isn't a loss by any means. You could pinch off the return line by the tank and retest. If this works try the origional regulator and by an adjustment tool and try to adjust. Mine uses a T-10 tamper proof torx.

[MT-2500]

Originally Posted by rmweber

All,

I worked on the truck some more today,

1.) I took the bed off the truck to get at the pump. I put a T on the send line and put the guage on it and clamped the exit side. It measured 90psi.

I am not sure if this is a valid test though, since one side was clamped. I was not able to put it in line due to the fact that I could not adapt to the line. I tried to put it inline in place of the filter, but also could not adapt to the guage there.

Is it valid to test the way i did?

If it is, then that would suggest there is something wrong in the line somewhere..... I inspected the line, and it is well protected, very unlikely a stone would have hit it. I did not see anything obvious.

I did purchase a new pump, but I do not want to put it in if the one I have is not bad. It was EXPENSIVE.

ANY IDEAS?

Oh by the way, the dealer said that it should run on 55psi, and that that issue with the injectors not firing was related to another engine and does not apply to mine. However, the manual still says it should be 65.

I also attempted to reset the security system per the dealer by turning the key on but not starting the engine for 15 min, then off then on for 15 min, then off then on for 15 min.

No dice.

2.) I also tried to just put the guage inline right at the pump. I took a short hose from the send line, through the T and then right back into the pump return. That did not seem to work very well, it only measured about 10psi.

HELP! Now I have my cap and bed taking up another whole parking space! AHHHHHRGGHHHH....

One more time.
I assume you can still start and run it.
Here is the proper procedure for checking the fuel pump and pressure.
Make sure your gauge is correct and acurate. 2-3 lbs off will mess up testing.
Proper testing is the only way you are going to know what is bad on it.
Good Luck
MT

Hard to start cold.
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.

[rmweber]

Originally Posted by MT-2500

One more time.
I assume you can still start and run it.
Here is the proper procedure for checking the fuel pump and pressure.
Make sure your gauge is correct and acurate. 2-3 lbs off will mess up testing.
Proper testing is the only way you are going to know what is bad on it.
Good Luck
MT

Hard to start cold.
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.

Can you tell me did I perform the test at the pump correctly? I took a piece of hose from the send port on the pump to a T and then the other side of the T to a piece of hose that was clamped off. The top of the T went to the guage. It read 90psi. Is that a valid test or does the guage have to be inline?

It seems if it read 90psi the pump is good and it would point to a bad fuel line somewhere.....

[MT-2500]

Originally Posted by rmweber

Can you tell me did I perform the test at the pump correctly? I took a piece of hose from the send port on the pump to a T and then the other side of the T to a piece of hose that was clamped off. The top of the T went to the guage. It read 90psi. Is that a valid test or does the guage have to be inline?

It seems if it read 90psi the pump is good and it would point to a bad fuel line somewhere.....

Kinda of a round about way but a good test on full pressure.
But was the fuel pump hot after running on road or just a cold One shot test?
But you also need to go threw the other test I posted.
Fuel pumps can fail cold or hot or just get weak after running.
Or can be losing pressure at fuel regulater or injector body.
You need to threw the complete test to find out if pump or other stuff is the problem.
Good Luck

[rmweber]

Originally Posted by MT-2500

Kinda of a round about way but a good test on full pressure.
But was the fuel pump hot after running on road or just a cold One shot test?
But you also need to go threw the other test I posted.
Fuel pumps can fail cold or hot or just get weak after running.
Or can be losing pressure at fuel regulater or injector body.
You need to threw the complete test to find out if pump or other stuff is the problem.
Good Luck

No, the pump was not hot. The truck will not run. It has been broken down for several weeks in a parking lot.
I tested the pressure by turning the key on and watching the guage.
What other test did you mention? I tested at the manifold, 55psi. I tested with the return clamped, 55psi. I tested while cranking, 55psi. I tested at the pump, 90psi. I am attempting to test inline in place of the fuel filter.

I replaced the regulator and the filter.

Thanks again.

[rmweber]

All,

Ok I give up. I am going to have it towed to the dealer.

I put my guage on a friends 04 tahoe and it read 55psi with the key on, and then about 40 psi while running.

Since his truck runs fine, I think my 55psi is fine.

I think I have wasted a bunch of time chasing down a fuel problem when it seems now like it might be a sensor or computer issue.

Thanks for all the help. I will post back the results.

[rhandwor]

Stop and think you said the truck ran when you sprayed starting fluid in it.
This means you have spark.
You said it tried to start when cranking this means you are getting power to the injectors.
You said you had 55psi at the fuel rail with the return pinched off.
You said you had 90psi at the pump with the return pinched off.
If you said 60psi water at the kitchen sink and 20psi in the bathroom your wife would say you had a problem. The engine is telling you that it has a problem.
Fram had a recall on filters for your truck. I asked you to check for proper flow direction fram stamps an out on the side with the flange. This is the engine side. I also asked you to blow through it if it has a problem you can't do this. I also told you how to check inlet hoses to the rail.
At least pinch off the return at the tank and retest. If you get 90psi unpinch to you get 65 and try to start.
If you go to the dealer you will pay triple what you paid for the pump a new filter and new hoses.
Also your gage is way out of calibration if it was just purchased new ask for a new gage. It took you 4 days to pinch off a hose but you got the bed off in a day so you must have mechanical ability. Just use your head and think what you are doing. The big thing is to have confidence you can do it which if you quit you will never get.

[rmweber]

Originally Posted by rhandwor

Stop and think you said the truck ran when you sprayed starting fluid in it.
This means you have spark.
You said it tried to start when cranking this means you are getting power to the injectors.
You said you had 55psi at the fuel rail with the return pinched off.
You said you had 90psi at the pump with the return pinched off.
If you said 60psi water at the kitchen sink and 20psi in the bathroom your wife would say you had a problem. The engine is telling you that it has a problem.
Fram had a recall on filters for your truck. I asked you to check for proper flow direction fram stamps an out on the side with the flange. This is the engine side. I also asked you to blow through it if it has a problem you can't do this. I also told you how to check inlet hoses to the rail.
At least pinch off the return at the tank and retest. If you get 90psi unpinch to you get 65 and try to start.
If you go to the dealer you will pay triple what you paid for the pump a new filter and new hoses.
Also your gage is way out of calibration if it was just purchased new ask for a new gage. It took you 4 days to pinch off a hose but you got the bed off in a day so you must have mechanical ability. Just use your head and think what you are doing. The big thing is to have confidence you can do it which if you quit you will never get.

1.) I checked the filter and the out is indeed toward the engine.

2.) I will blow through it, even though it is brand new and passing fuel and there is plenty of pressure at the rail, which is the same as another vehicle that runs fine.

3.) Why do you think the guage is out of calibration?

4.) The 90psi from the pump was to a dead head right at the pump. It did not go all the way to the engine, it was not an inline test. I have not been able to find fittings and hoses to adapt to the ones on the truck to allow an inline test. I could try to pinch the return at the pump, but I already did that right at the engine, and the pressure did not increase. So why would it help to do the same test again by pinching off at the pump this time?

This would all be much easier if the truck was at my residence which it is not. It is not in a well lit shop with all my tools. Blah Blah Blah.

I may give it another day or two of testing. I dont think I have a fuel supply problem though.

The shop manual says to:

1.) Check the Fuel injector coils

2.) Spark plugs

3.) EGR valve

4.) Ignition control circuit

5.) Restricted exhaust

6.) Throttle postion sensor

FYI

Thanks!

[MT-2500]

Originally Posted by rmweber

All,

Ok I give up. I am going to have it towed to the dealer.

I put my guage on a friends 04 tahoe and it read 55psi with the key on, and then about 40 psi while running.

Since his truck runs fine, I think my 55psi is fine.

I think I have wasted a bunch of time chasing down a fuel problem when it seems now like it might be a sensor or computer issue.

Thanks for all the help. I will post back the results.

You are welcome.
You have not wasted your time.
You gave it your best shot and done what you could.
From what you told us you have a fuel problem.
Your friends Tahoe may be a different set up on fuel pressure.
You have to have the 65 lbs lbs of pressure at injectors for your truck to start cold.

Good luck and
Let us know how it goes.

[MT-2500]

Originally Posted by rmweber

No, the pump was not hot. The truck will not run. It has been broken down for several weeks in a parking lot.
I tested the pressure by turning the key on and watching the guage.
What other test did you mention? I tested at the manifold, 55psi. I tested with the return clamped, 55psi. I tested while cranking, 55psi. I tested at the pump, 90psi. I am attempting to test inline in place of the fuel filter.

I replaced the regulator and the filter.

Thanks again.

If the pump is putting out 90 lbs of pressure and you only have 55 at injector rail/test port.
It is losing 35 lbs of pressure some place.
Is it holding a steady 55 at test port.
If so it is bypassing the fuel pressure regulator.
90 lbs at pump and with return line pinched off you should have 90 lbs at fuel rail test port.
If not that is your problem.
55 lbs of pressure will not start it.
A good pressure regulator will hold the pressure back at 65 lbs.

Do a retest and make sure you have the return line pinched off or blocked off.
Post back the pressure with return line pinched off or blocked off.
Then if fuel pressure does not come up retest the fuel pump direct pressure.
It may not be putting out full pressure all of the time.

[rhandwor]

You didn't say if you had a fram filter. Blue bowtie posted a recall for this type of filter. It apparently isn't machined correctly at the thread area and leaks this could be your problem. Wrap the filter with a dry towel if it is wet from gas this is your problem.
If the pump put out 90psi at the fuel tank it should have had within 1psi of this or at least 89psi at the fuel rail. Pressure doesn't drop that fast as no metal is bent it has to be (the filter)( a hose coming apart inside )( dirt in the fuel rail.)This assumes both tests were done correctly. (In fact basic electrical courses teach this as an example.)
Pressure is like electricity if you have 12volt at the battery you should have 12volt at the starter. If you only have 8volt the starter doesn't work correctly.
When you started with starting fluid you ruled out almost all of the manuals checks. Also when it tried to start it shows power to the injectors. Apparently the low fuel pressure causes a lean fuel mixture and you don't fire. Like the old choke that added extra fuel to start. This is why you need extra fuel pressure to start.This is why at idle the pressure drops and goes up when the engine is loaded. Vacuum is high at idle and drops as the engine speed picks up.

[rmweber]

Ok,

I will retest with return blocked. I think I can block it back at the pump, or right at the fuel rail, however, I think that I previously tried to get that connection off and I could not, I think I may need a special tool for that.

The thing is that I am not seeing any fuel leaks around the filter or anywhere along the lines. There is one place up front where they bend to go up to the engine. They turn into rubber or something flexible for about 6 inches there and those connections are corroded on the outside. No suprise there.

How about this. What if I buy a 12 or 15 foot section of rubber hose and run it all the way from the pump, outside the truck to the fuel rail? That would test the whole line right? Maybe a long way around but at this point I have no idea where a possible blockage might be.

I do not have a fram filter I dont think, but I cannot really recall what brand it was. It was not in an orange FRAM box though...

More later, If it stops raining I will try to do more tests tonight.

Once again though, do you know if it is valid to test pump pressure to a dead head or do I have to be inline??????

Thx

[MT-2500]

Originally Posted by rmweber

Ok,

I will retest with return blocked. I think I can block it back at the pump, or right at the fuel rail, however, I think that I previously tried to get that connection off and I could not, I think I may need a special tool for that.

The thing is that I am not seeing any fuel leaks around the filter or anywhere along the lines. There is one place up front where they bend to go up to the engine. They turn into rubber or something flexible for about 6 inches there and those connections are corroded on the outside. No suprise there.

How about this. What if I buy a 12 or 15 foot section of rubber hose and run it all the way from the pump, outside the truck to the fuel rail? That would test the whole line right? Maybe a long way around but at this point I have no idea where a possible blockage might be.

I do not have a fram filter I dont think, but I cannot really recall what brand it was. It was not in an orange FRAM box though...

More later, If it stops raining I will try to do more tests tonight.

Once again though, do you know if it is valid to test pump pressure to a dead head or do I have to be inline??????

Thx

The best place to pinch the return line is at the engine and frame where the rubber part is.
Pinch it off and give us a reading on fuel pressure.

[rhandwor]

If you had 90psi at the pump discharge tube at top fitting coming out of the tank you should have had at least 89psi at the fuel rail test. If you use gas hose designed for this pressure it would be a valid test. If you disconnect the metal clad line and hook up your gage at this point it would be much cheaper.
I found a filter with a quick disconnect and you could disconnect the bottom rubber hose and use a piece of 5/16 fuel hose pushed on and clamped with a bolt in the end also clamped to the rail. Try to control costs and complete the test.
If I didn't think you had 90psi I would have told you to install a new pump which you purchased.

[GMMerlin]

Alright guys we are getting WAY off base on this one.
First off look at this.
Turn ON the ignition leaving the engine OFF, the fuel pressure should be 415-455 kPa (60-66 psi) when the pump is running
If you do not have this pressure, the engine WILL NOT start. The reason is this engine has a poppet type injection system and if the pressure is not within specs, the ball will not be forced off the seat and fuel will not enter the engine.

The test you are performing by dead heading the pump is NOT A VALID TEST!
If the poppets are stuck closed, fuel will not enter the engine no matter what fuel pressure you have.
There is a procedure to unstuck the poppets available at your GM dealer..have your dealer reference TSB 00-06-04-003B