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93 3500 454 sputter and die question

teambldr

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teambldr Enthusiast

teambldr

Posted
Posted

Hi,

 

Yesterday I had a situation happen that has baffled me in general. I went to the store, the truck started fine, drove fine there, restarted fine there and then on the way back it acted like it was out of gas for a moment then performance returned. I got another block down and it died. I tried to restart it and it fired but would not stay running. It only fired 2 times out of 30 to 40 attempts.

 

Then today, after it sitting all night, I went out and started it right up. It ran fine for quite awhile and was pretty well stable after it was warm.

 

Then, I went to drive somewhere tonight and it died again 4 times in 5 blocks. I was able to restart it though each time with 4 to 5 presses of the gas pedal and then turning the key.

 

After checking out most of the obvious stuff this is my plan of attack: (please feel free to add anything that you think I should look at or replace as well)

 

Clean the injectors

Add fuel stablizer to the tank

Change the fuel filter

Replace the rotor and cap

Replace the PCV valve

 

Anything else I should check?

 

Any help would be appreciated.

 

Thanks

teambldr Enthusiast

teambldr

Posted
  • Author
Posted
Anything else I should check?

 

Fuel pressure. Sounds like it might be a pump on its way out.

 

 

 

 

 

Thanks. I will check that out as well.

 

I was leaning towards fuel system things from the getgo although I did not want to rule out electronics as well.

 

Is there a filter inside the tank as well as the external one? If so, should I replace that as well?

 

 

 

Thanks!

Butch 02 Denali Enthusiast

Butch 02 Denali

Posted
Posted
Anything else I should check?

 

Fuel pressure. Sounds like it might be a pump on its way out.

 

 

 

 

 

Thanks. I will check that out as well.

 

I was leaning towards fuel system things from the getgo although I did not want to rule out electronics as well.

 

Is there a filter inside the tank as well as the external one? If so, should I replace that as well?

 

 

 

Thanks!

 

 

 

 

 

There should be a fine metalmesh "sock" on the fuel pump intake in the tank. definatly replace that if you have to do the pump.

teambldr Enthusiast

teambldr

Posted
  • Author
Posted
Anything else I should check?

 

Fuel pressure. Sounds like it might be a pump on its way out.

 

 

 

 

 

Thanks. I will check that out as well.

 

I was leaning towards fuel system things from the getgo although I did not want to rule out electronics as well.

 

Is there a filter inside the tank as well as the external one? If so, should I replace that as well?

 

 

 

Thanks!

 

 

 

 

 

There should be a fine metalmesh "sock" on the fuel pump intake in the tank. definatly replace that if you have to do the pump.

 

 

 

 

 

After talking with a few others I have come up with a couple other things that could do this as well.

 

1. The Fuel Regulator

 

2. The ECM

 

In laymans terms (since I am a layman :rant: ) the process as I understand it is as follows:

 

The fuel pump pumps the fuel through the fuel filter and up to the fuel regulator. The regulator then passes the fuel to the injectors that are controlled by the throttle position sensor and the ECM (controlling fuel/air mixture).

 

The fuel pump is a heavy duty one on my truck and since the problem is intermittant, is less likely to be the culprit unless of course the pump is clogging and unclogging, but that would have been seen in performance most likely prior to to dying engine issue.

 

The fuel filter is a light switch issue. Either it is good or bad. Since it is chicken soup it is a no brainer to just replace it either way. But, the way that the issue presents itself with the intermittant dying chances are very good that the fuel filter is not the issue.

 

The fuel regulator is a very likely candidate based upon its function and the way that the issue comes up.

 

The injectors seem to be flowing fine with my observations. No difference in flow side to side and the clicking rises and falls with the increase in RPM.

 

This leaves the ECM as the final piece in the puzzle. This is something that I cannot find a lot of information on online or in the manuals. All I have been able to asociate with it is the air/fuel mixture control. If it has the ability to cut out fuel supply on an intermittant basis is not something that I have been able to establish.

 

Any input on the ECM and the other information I have found?

 

Any help would be appreciated.

 

Thanks

 

Updated Information:

 

Replaced the fuel regulator, cleaned the injectors, added fuel cleaner and octane boost to the tank, replaced the fuel filter, checked the fuel pump fuse and relay *fuse good and relay clicking when activated, and a couple other checks.

 

Only 3 things left that can shut down fuel flow:

1. Fuel Pump

2. Throttle Position Sensor

3. ECM

 

Going to replace the TPS and do a fuel pressure test tomorrow. If there is good fuel pressure then it has to be the ECM. :devil:

 

Note: One time when it shut down I was watching the injectors, the truck was on a smooth idle and purring. Then, in an instant, the fuel stopped. Nothing was touched, it just stopped.

teambldr Enthusiast

teambldr

Posted
  • Author
Posted
Anything else I should check?

 

Fuel pressure. Sounds like it might be a pump on its way out.

 

 

 

 

 

Thanks. I will check that out as well.

 

I was leaning towards fuel system things from the getgo although I did not want to rule out electronics as well.

 

Is there a filter inside the tank as well as the external one? If so, should I replace that as well?

 

 

 

Thanks!

 

 

 

 

 

There should be a fine metalmesh "sock" on the fuel pump intake in the tank. definatly replace that if you have to do the pump.

 

 

 

 

 

After talking with a few others I have come up with a couple other things that could do this as well.

 

1. The Fuel Regulator

 

2. The ECM

 

In laymans terms (since I am a layman :seeya: ) the process as I understand it is as follows:

 

The fuel pump pumps the fuel through the fuel filter and up to the fuel regulator. The regulator then passes the fuel to the injectors that are controlled by the throttle position sensor and the ECM (controlling fuel/air mixture).

 

The fuel pump is a heavy duty one on my truck and since the problem is intermittant, is less likely to be the culprit unless of course the pump is clogging and unclogging, but that would have been seen in performance most likely prior to to dying engine issue.

 

The fuel filter is a light switch issue. Either it is good or bad. Since it is chicken soup it is a no brainer to just replace it either way. But, the way that the issue presents itself with the intermittant dying chances are very good that the fuel filter is not the issue.

 

The fuel regulator is a very likely candidate based upon its function and the way that the issue comes up.

 

The injectors seem to be flowing fine with my observations. No difference in flow side to side and the clicking rises and falls with the increase in RPM.

 

This leaves the ECM as the final piece in the puzzle. This is something that I cannot find a lot of information on online or in the manuals. All I have been able to asociate with it is the air/fuel mixture control. If it has the ability to cut out fuel supply on an intermittant basis is not something that I have been able to establish.

 

Any input on the ECM and the other information I have found?

 

Any help would be appreciated.

 

Thanks

 

Updated Information:

 

Replaced the fuel regulator, cleaned the injectors, added fuel cleaner and octane boost to the tank, replaced the fuel filter, checked the fuel pump fuse and relay *fuse good and relay clicking when activated, and a couple other checks.

 

Only 3 things left that can shut down fuel flow:

1. Fuel Pump

2. Throttle Position Sensor

3. ECM

 

Going to replace the TPS and do a fuel pressure test tomorrow. If there is good fuel pressure then it has to be the ECM. :banghead:

 

Note: One time when it shut down I was watching the injectors, the truck was on a smooth idle and purring. Then, in an instant, the fuel stopped. Nothing was touched, it just stopped.

 

 

 

 

 

Update on the situation:

 

Replaced the fuel pump and screen, replaced the fuel pump relay and the computer (ECM). The problem has not corrected. Fuel is not flowing unless I get it running and keep the RPMs up around 1200. As soon as I let it drop below that it died and did not refire at all after.

 

When I did the computer control I put my chip back in it. Can the chip cause the issue? I don't know. Now I am going to see if I can find a series one code reader to get more info (if possible).

 

This is a real bummer.

C/K Man Enthusiast

C/K Man

Posted
Posted

The ECM gets an RPM signal from the ignition module and the pickup coil (not the ignition coil) in the distributor. If the ECM does not get the signal, it won't allow the injectors to pulse. I have seen the module go out in TBI G.M. trucks, and when it does, you will not see any fuel coming out of the injectors. Also, did you make sure that the fuel pump electrical connector was in good shape?

teambldr Enthusiast

teambldr

Posted
  • Author
Posted
The ECM gets an RPM signal from the ignition module and the pickup coil (not the ignition coil) in the distributor.  If the ECM does not get the signal, it won't allow the injectors to pulse.  I have seen the module go out in TBI G.M. trucks, and when it does, you will not see any fuel coming out of the injectors.  Also, did you make sure that the fuel pump electrical connector was in good shape?

 

 

 

 

HI and thanks for the input.

 

I have not checked the ignition module or pickup coil as of yet.

 

Yesterday we were able to get it running again and all seemed to be ok as I ran it for a few miles, filled the tank up and ran it a few more with no hiccups. Let it sit overnight then went to use it this morning (cold and raining). It started and within about 20 seconds died. Tried a few times to get it started after then shot a little carb cleaner in the throttle body and it fired up again. Let it idle for about 4 minutes then went off to take the kids to school. Got about 3 blocks and it died again not to restart after.

 

Here is an update on observations from yesterday:

Turn the ignition to the on position and the relay clicks, the pump whirs and the regulator makes a noise as well. We were able to isolate the wire in the harness next to the firewall behind the motor that when 12 volts are touched (a sec) to it that it activates all the fuel system (minus the injectors). The fuel pump is turning on and has good pressure at the TBI all the time.

 

The best way to explain what it is doing is that the truck is telling the system not to let the fuel injectors open or not telling them to open time to time.

 

The ECM (not the chip) was replaced

The fuel pump replaced

The fuel filter replaced

The regulator replaced

The fuel pump relay replaced

The PCV was replaced

The cap and rotor were replaced

The tank got 104 and injector cleaner added

Cleaned the injectors

Checked the FP fuse (under hood)

Checked all wires near ECM, under hood and to fuel pump

Checked for codes, none coming up

Bled the fuel system at the TBI after replacing fuel filter and pump

 

I will check out the ignition module and pickup coil as you suggest.

 

Any other suggestions would be great.

 

Thanks again

teambldr Enthusiast

teambldr

Posted
  • Author
Posted

Update:

 

Got the truck running long enough to drive it to the shop. One block away from the shop, in a driving, cold rain storm, it chose to die again. :fume:

 

I walked to the shop and the guy that normally helped me was not in and was not going to be in that day. So I calmly asked the the shop to order the Ignition Module for me and that I would put it in where it was sitting (since it was going to be an hour for a tow truck).

 

They ordered it and I put it in right there in the street. When I went to start it the batteries were dead. So I walked back and got someone to come give me a jump.

 

One touch and "Vroom". Idle was smooth, no loping, no cutouts.

 

Obviously I am cautiously optimistic that this was the magic part due to it being the only part replaced and its actions upon starting as well as for the rest of the day.

 

Observations: The ignition module that I took out had a small amount of "white" stuff just like you would find on a battery terminal within the two screw holes that mount it down to the distributor. On the metal plate under it and on the mounting surface on the distributor side, there was no lubrication present as is required to assist in reducing heat buildup within the module.

 

Future plans: What I did last night was to order a cable that adapts an OBDI to a laptop for 65.00 from http://www.wotelectronics.com/index.html and software from http://www.ttspowersystems.com/ that will allow me to be able to read the codes, toubleshoot and even see results of additions or changes that I may do to the motor and transmission. The software is 95.00. This is much better pricing than Autozone for their reader and gives tons more data. Autozones was about 300.00 plus.

 

I am also going to re4place the spark plug wires as I saw a little bit of that same white buildup inside there along with replacing the plugs themselves.

 

I am going to watch the truck for a few days before planning any distance travel but based upon it being one part that was done and the truck recovering as soon as it was replaced, I feel pretty good that this was the magic part to fix it.

 

Thank you all for your assistance as well. Your ideas helped a lot.

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