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truck stutters and wants to stall????

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hey. i have an 2002 sierra 2500 hd with a 6.0. it ran fine yesterday. i parked it last night and went to start it this morning. it started but the rpms dropped to about 200 and it stuttered but didn't stall. i revved it and same thing....it would go up and then drop to about 200ish and then go back up to steady idle...around 600 rpm. i'm thinking its the fuel pump because the truck just broke 100k miles? any ideas before i pull the fuel pump? is there a way to test the pump? thanks!!

ps...95 sierra with 5.7 won't start at all. i know it is getting fuel and air and i pulled a plug and cranked it with the plug next to the header and saw that it is getting some spark. the cylinders are supposed to have 150 psi and i just did a compression test which showed that i have about 145 so it has plenty of compression...i'm thinking it may be a weak spark but it has bosch platinum plugs and i just tried putting a brand new coil in...also has a brand new cap and rotor. the truck ran fine when i pulled it in the garage and an hour later wouldnt start...the cap, rotor, plugs, and wires are fine as far as i know? sorry for the loooong post but i'm out of trucks now haha

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on your 6.0 before you pull the pump check the filter easy to do

also on your 6.0 take it in the shop hook up to the computer can tell you if any banks are lean/rich and how everything is going

also sound like a plug could have gone bad when was last time you changed them?

i would recommend plugs/air filter/ tranny oil change/ and a new fuel pump

only $ 100 bill to do it all

when you worked on your older truck you didn't change the timing at all?

i would recommend borrowing a spark tester that way you know you have spark and the right amount

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hey. i have an 2002 sierra 2500 hd with a 6.0. it ran fine yesterday. i parked it last night and went to start it this morning. it started but the rpms dropped to about 200 and it stuttered but didn't stall. i revved it and same thing....it would go up and then drop to about 200ish and then go back up to steady idle...around 600 rpm. i'm thinking its the fuel pump because the truck just broke 100k miles? any ideas before i pull the fuel pump? is there a way to test the pump? thanks!!

Start by doing a fuel pressure test at the engine compartment schraeder valve.

ps...95 sierra with 5.7 won't start at all. i know it is getting fuel and air and i pulled a plug and cranked it with the plug next to the header and saw that it is getting some spark. the cylinders are supposed to have 150 psi and i just did a compression test which showed that i have about 145 so it has plenty of compression...i'm thinking it may be a weak spark but it has bosch platinum plugs and i just tried putting a brand new coil in...also has a brand new cap and rotor. the truck ran fine when i pulled it in the garage and an hour later wouldnt start...the cap, rotor, plugs, and wires are fine as far as i know? sorry for the loooong post but i'm out of trucks now haha

Sure you got the wires back on the right leads on the cap?

I've seen it done MANY MANY times, even by experienced techs.

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first one sounds like my 01 5.3 chevy. started doing that until i got 3 blocks away from my house, then the fuel pump took a S. you might want to change the filter first and see if thats the culprit. then like chicken hauler said do a fuel pressure test. we borrowed a fuel pressure gauge that hooked into a fitting on the fuel rail. When it showed zero psi we went the next day and bought a new one. pretty easy to put in with a cherry picker. just unbolt the bed and lift, then move it back about a foot . . now you have a open area to easily replace it.

hope this helps.

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Oh, almost forgot-before you install a new pump, check to see what voltage is at the connection-low or no voltage means the issue is electrical and not the pump.

If you do install a new pump, be sure to change the filter-dirty filters that are plugged raise hell on fuel pumps (work twice as hard to overcome the restriction).

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thanks everyone for all the input :worthy:

heinracing, the 6.0 has a CAI with a clean filter, the tranny oil was changed about 600-800 miles ago, and the plugs might have gone 15k miles?? plugs should last alot longer than that right? and as far as the old truck goes, i dont think i messed with the timing?? i think its all electronic advance unless there is still a way to mess with it?

chickenhauler, i double and triple checked all the plug wires and they are all connected correctly. i will definitely do a fuel pressure test asap. probably tomorrow if i can get my hands on a gauge to do it. also, what connection were you referring to? on the pump?

250Rnut, i like the idea about the cherry picker although i don't have access to one...i am definitely going to go the route of sliding the bed back rather than dropping the tank though!

again thank you to every1 who responded!!!! oh and I'm not sure if any1 asked but the fuel filter was replaced about 3k miles ago as well... 👍

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Yes, the connector at the pump where the wiring plugs into the pump. Should have at least 12.5 volts there.

While you're at it, check the voltage at the battery-you can have enough juice to spin the motor, but not enough for the computer to function.

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Yes, the connector at the pump where the wiring plugs into the pump. Should have at least 12.5 volts there.

While you're at it, check the voltage at the battery-you can have enough juice to spin the motor, but not enough for the computer to function.

thanks!!!

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the ignition module is what was causin the problems in the 95 so that was a fairly cheap fix...the 02 is running perfect again 👍:worthy::busted: go figure....never did anything but its running flawlessly so i figure ill mess with it when it messes with me lol. thanks again guys

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A GM truck with a 100K needs a fuel pump. If not now, very soon, but I would just guess now. Its a good idea to keep a good filter in it, but rarely does a filter fix it.

Have it pressure checked and scanned to check fuel trims. This will give you some indication if the pump is weak. Once my trucks hit 90-95K they automatically get a pump as a preventive measure. I would rather do it on my schedule rather than having problems out of town in 100+ degree heat.👍

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We did the old knocking on the tank, and that got another 10K miles out of my brothers truck since he couldnt afford the parts

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We did the old knocking on the tank, and that got another 10K miles out of my brothers truck since he couldnt afford the parts

Yeah that can work... for a while 👍 . I just couldn't take knowing something is wrong .

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