GM Repair Problems? Ask GM Repair Expert Now.
Hi there, I am Cam. Can i get your first name pleasE?wIth your truck, do you get any codes set with it? P0191?
I had a medical emergency at that time, and for some reason no ones decided to help you out, and for that I am sorry. I and none of my co experts are office people, we work in the shop and I can only assume that if no one else helped you, that they did not know how to help you. I am online now, and would like a great deal to help you solve your issue.
The one thing I thought I did ask was if you removed the Fuel pressure regulator #1 and checked it for metallic or other debris. Did you do that? If not, can you?
OK, your last question is not coming up, what was your cranking PSI? I recall we tested some return fuel rate, and that you replaced the valve on the front of the drivers side fuel rail. "Had we looked at the fuel pump itself?
Upload it to dropbox then send me the link.
Or put it on Youtube and same, send the link,
I will keep an eye out .
I am not sure what to suggest. Can you cut down the size?
The system is not designed to hold pressure. It is designed to build the pressure during cranking. You know as well as any that it should build it inside of a second or so. You mentioned its not building high enough so we have to deal with a pump issue. You replaced both regulators so all that is left now is a faulty injection pump.
It would not be a pressure sensor. Your desired fuel pressure will always be higher, even with the engine off, but that is not a problem. If we cannot get enough cranking pressure then we need to look at your injection pump as a possible issue.
Here is a document I would like you to follow through.
No, you need a pressure vacuum gauge. The port top and Center by the thermostat housing is where you attach it. But you can use a generic gauge and detach the hose into the back of the port.
Crank it with the key normally as if you are trying to start it.
2 ml at 1800 is perfect. Everything is pointing to a bad high pressure pump.
Yes it's all about verifying that commanded and actual throughout the range all are within 100 psi of each other.
Ok, it looks like at the higher rpm it does not match and that means the regulator 1 is bad on the pump. Now the fact you changed it means the pump is bad and unable to meet the high pressure needs.
Ok. Replace #1 and evaluate the issue. If it remains the. We move to the pump.
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What was the substance on the unit?
Some of the issue might be the software in the scanner. Either way it's almost midnight and I get up at 6. I will log back on then.
That looks like rust!, Did you find that anywhere else in the system?
OK, as long as your sure. If there is more debris or contamination in there, it would take out the whole system again. For now, lets change FPR #1 on the pump and see what that does for the pressure inconsistencies.
I will get what I have to you when I get to work in
Ok, sorry I was driving to work. You have tested the regulator #2. IF you go back to the document, you will see that it explains when each is operational. #2 controls the pressure up to 1700 RPM. While I could not see the RPM on your scanner, I can assume based on your testing of the return rate that #2 is operating and when you compared actual to desired pressure, they matched at lower RPM and pressure. This all leads me to the conclusion that your regulator #1 is at fault.
Understood Tye, we need to replace that regulator #1 as the diagnosis we have completed thus far points directly to that.
OK, sounds like a plan. Thanks for working with me. Cam certain with your determination we can get to the bottom of this.
3ml each for 15 seconds cranking or idling.
Absolutely. How many injectors have 10ml?
these injectors use a bit of fuel to open the main injector, hence the allowable 3ml in 15 seconds. More than this is basically a fuel leak but its being returned to the tank.
That shows me you have 5 that need to be replaced. This is a problem. You replaced them a year back, so that means that either they are bad out of the box or there is something that took them out, be it from the fuel system failure or from contaminated fuel.
No, that is not controlled by the computer. That is a physical aspect of the injector. Returning too much is purely a mechanical issue in the injector. All the computer does is open the small solenoid that allows that fuel to be used to open or fire the main injection.
This leads me back to the why. Here is my new suggestion. With the junk you showed me in the fuel rail and on the sensor, and with your hard start issue, fuel pressure irregularities and now return rates, well let me say, if you were to have this in the dealer, I would be suggesting the replacement of the whole system and cleaning out the tank. The issue will be getting out the contaminants in the system. Its bad enough that GM just replaces it all to be sure they get it all.
Either from contaminated fuel or fuel system component failure.