Vortec 350 shutting down around 4,000 RPM's????

Beyer · Oct 26, 2009

OK, got everything running again and now I am having an intermittent problem with the motor (when under a load) will lose power, almost like it is shutting down. I think it is happening at about 4,000 RPM's. Normally I can rev to about 5,500 RPM's. At an idle, it will go to 5,500 RPM's no problem. I replaced the fuel filter, cleaned the air filter, cleaned the mass air flow sensor, and am getting ready to change the fuel pump (E8248). I do not think it is the fuel pump since it has 55 psi at start-up and goes to about 60 psi when I rev the engine (in park, not under a load). Someone else mentioned a collapsed fuel line. I am running the 3/8" fuel injection hose with the lining inside of it. This is a little more complicated to check because I have to pull the seats, to pull the tranny cover, to get to where the fuel lines attach to the hard lines coming from the motor. :

Also, I run a check engine light and it is not throwing any codes, so I think my O2 sensors are good.

Anyone have any other ideas. Does a damaged fuel line seem like it could cause this? Could it electrical (please say no

uke

?

YOUNG · Oct 26, 2009

Fuel pressure at wot in park doesn't mean much. Check the fuel pressure UNDER A LOAD AT WOT.

benfowler87 · Oct 26, 2009

Had this happen to one at the dealership. It's going into reduced power mode if it's the same type problem. A ground wire wasn't properly grounded on the one I saw.

Beyer · Oct 27, 2009

benfowler87 said:
Had this happen to one at the dealership. It's going into reduced power mode if it's the same type problem. A ground wire wasn't properly grounded on the one I saw.

A ground wire to the pump? Engine harness?

Beyer · Oct 27, 2009

YOUNG said:
Fuel pressure at wot in park doesn't mean much. Check the fuel pressure UNDER A LOAD AT WOT.

I will try to do that after my new pump gets here.

CHASMAN9 · Oct 27, 2009

Stupid question or suggestion. Have you disconnested the power to the computer for 10 minutes and let the computer reset? I had an old Z-71 that used to have a similar problem and did this and seemed to work. Just a suggestion. :dunno:

Beyer · Oct 27, 2009

CHASMAN9 said:
Stupid question or suggestion. Have you disconnested the power to the computer for 10 minutes and let the computer reset? I had an old Z-71 that used to have a similar problem and did this and seemed to work. Just a suggestion.

I have done this in the past to help with clearing the check engine light codes, but have not tried it this time. My new pump will not be here until today or tomorrow. I will unplug it and try that as well.

Thanks.

CHASMAN9 · Oct 27, 2009

Beyer said:
I have done this in the past to help with clearing the check engine light codes, but have not tried it this time. My new pump will not be here until today or tomorrow. I will unplug it and try that as well.

Thanks.

Hope it helps, if not, check your muffler bearing. It might be loose... laughing1

pillsbury · Nov 1, 2009

Where did you buy this motor from and who built it for you. good luck on the fix. sorry to see u r having issues.

benfowler87 · Nov 1, 2009

Beyer said:
A ground wire to the pump? Engine harness?

A body ground on the engine harness.

Beyer · Nov 2, 2009

benfowler87 said:
A body ground on the engine harness.

It did seem a little inadequate, so I grounded it straight to the battery (battery grounded to chassis). I am running again this weekend. I hope to see if it is better than. I also replaced the fuel pump, fuel lines, reset the computer, and rebled the air out of the fuel line.

blacksheep10 · Nov 2, 2009

Beyer said:
It did seem a little inadequate, so I grounded it straight to the battery (battery grounded to chassis). I am running again this weekend. I hope to see if it is better than. I also replaced the fuel pump, fuel lines, reset the computer, and rebled the air out of the fuel line.

ready to change your user title under your pic?