Need more help.

Well i replaced my fuel pump last week thinking that would help my problem with my truck. With the fuel pressure messing up ect.

I have not been able to test the fuel preesure yet.

But now my truck is starting to hesitate every so often when i take of, driving down the road or even sitting at ideal. It does not always do it just every so often. It was doing it before the fuel pump swap also.

Also when i changed my fuel pump i saw a 12"x12" or so black box on the passanger side of the fuel tank with one of the fuel lines running to it and was wondering what it is?
Thanks guys

Plug's, plug wires and associated connections are a good start. Also, if you have access to a tech 2, run an injector test.

Not totally up to speed on the truck stuff, but these are some common places ive had issue in other vehicles.

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Originally Posted by CooperS7777

Plug's, plug wires and associated connections are a good start. Also, if you have access to a tech 2, run an injector test.

Not totally up to speed on the truck stuff, but these are some common places ive had issue in other vehicles.

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Check your battery connection as well. My truck was hesitant at idle and it drove me crazy i couldnt figure it out, and then i seen that my positive cable was loose....

also might wanna clean youre maf and throttle body, if ya hadnt yet...

EVAP canister is the black box.

Okay guys i have cleaned the maf and throttle body and checked my plug wires and i had just replaced my plugs in june. All my wires are factory except the two by my headers on the driver side. When i am sitting at idel it does not do it to bad but if i but it in gear and just sit there it will start the stumble/ hesitate. But not all the time just does it 1 to 4 or so times and then quites for awhile. I found it does it mainly when the truck gets hot and not so much in the morning drive to work. Does anyone have a idea where to look next? Thanks guys

You need to actually take out the plugs and inspect the porcelain for cracks. Look close. If thats not it, you need to get it scanned.