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NCOR
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Discussion Starter · #1 ·
When I start my truck it starts right up no problem, idles right where its supposed to be and sounds fine. When I shift into drive and actually give it gas, sending my rpms up to anywhere from 1.5k to 3k, my truck sounds like I dont have flows (which i do) and is really sluggish, it is much worse with the ac on. Once the temp goes up the truck runs just fine, no issues. That usually takes 3-5 minutes of city driving. I was thinking it was a tranny issue with cold fluid and the torque converter not working right. It does not throw the SES light on.

It used to work just fine all the time, even at startup, so I know this isn't normal.
 

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Doesn't really sound like a tranny problem to me, but... kinda hard to troubleshoot...

When you say rpms go anywhere from 1.5k to 3k, does the truck move accordingly?
 

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NCOR
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Discussion Starter · #3 ·
I know what you mean, but its just strange. Yes the truck moves accordingly to the rpm's, but the motor will not rev as quickly as it does warm (by alot). Either way it seems to come and go, so until something breaks Ill just have to deal.
 

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does it seem like the engine is kinda hard to get those rpms up at time and that you have to give it more gas to get it going? Kinda like a slow hesitation
 

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NCOR
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Discussion Starter · #6 ·
Thats what Im talking about Smith, a hesitation by the RPM's while under load, cold. A fan clutch could be at fault here? I can't remeber he exact way to test the fan clutch, turn the motor off and if the fan stops at the same time its still good. Is that right?
 

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bggrnchvy said:
Thats what Im talking about Smith, a hesitation by the RPM's while under load, cold. A fan clutch could be at fault here? I can't remeber he exact way to test the fan clutch, turn the motor off and if the fan stops at the same time its still good. Is that right?
My truck and many others do the same. The rumor i have heard on it is that its a fuel pressure issue. Ive heard many people claim that cranking up the fuel pressure closer to 13 psi will cure this because many trucks range from 11-13 and 11 is too lean while close to 13 is just right. there is a few how to's on how to do this but i dont know of any and havnet tried myself.
 

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NCOR
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Discussion Starter · #8 ·
Ok, any ideas where to get that information? We are both talking about Vortec motors right?
 

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bggrnchvy said:
Ok, any ideas where to get that information? We are both talking about Vortec motors right?
Can't be, Vortec motors run at about 60psi fuel pressure, TBI's run at 11-13 psi.

I don't see how fuel pressure could have anything to do with it because the condition goes away once the motor warms up.
 

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NCOR
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Discussion Starter · #10 ·
Thats what I thought, Vortecs run at 55-60 psi for feul because of 8 injectors vs. TBI's 2. So its not a fuel problem, thats a good sign. Maybe a bad fan clutch...is my procedure I stated above right to test the fan clutch? If it is I will go check soon and be able to tell one way or the other.
 

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bggrnchvy said:
Thats what I thought, Vortecs run at 55-60 psi for feul because of 8 injectors vs. TBI's 2. So its not a fuel problem, thats a good sign. Maybe a bad fan clutch...is my procedure I stated above right to test the fan clutch? If it is I will go check soon and be able to tell one way or the other.
Well i didnt realize you have a vortec :crazy: . Tbi motors do have this prob though. I think but not sure but probably the reason that once warmed up in a tib that it goes away is because its hot and better burn off of the fuel its getting. Now relating the 2 probs together when did you last change your fuel filter
 

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NCOR
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Discussion Starter · #12 ·
A week ago, its been happening since before I did it.
 

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NCOR
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Discussion Starter · #13 ·
Could it be my fuel pump going out? How can I test my pressure? I know there is a port on the fuel rail somewhere and what tool do I need(specifically)?

P.S. Vortecs where standard on '96-early '98 trucks and SUV's.
 

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yeah, you need a fuel pressure tester :D It goes on the valve on the fuel rail i think.

The fan should stop spinning when the engine shuts off, and yet not be so tight that you can't move it with your hand when the engine is off.
 

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NCOR
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Discussion Starter · #15 ·
Your kidding, a fuel pressure tester, really. I would never have guessed. Any idea how much these cost and how easy it is to use it on a Vortec 350?
 

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NCOR
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Discussion Starter · #16 ·
Well I checked my fan clutch and that thing is outta here! I stopped the motor while staring right at(ahhh...remote start) and the motor quits and the fan just turns and turns and turns until air resitance kills it. I assume replacing it is simple removing the fan shroud and unbolting it from the motor and puting the new clutch on the old fan, and then the reverse. Sound about right? Any brand of fan clutch I should get that will last longer than other? Oh and will this hurt my truck if I don't fix it for a week and half(soonest I can be home)?
 

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Well, there isn't really anything else to call it. Its just a tube with a valve on one end and a guage on the other. Never bought one so I can't tell you how much, but I wouldn't be surprised if an auto parts store rented them out. Should be very easy to use, pretty much just plug it into the port AFAIK.

Yeah sounds like your fan clutch is worn out. Replace it fairly soon and watch your temp guage until then. If you do any stop/go and city driving that is when it is likely to overheat since the fan won't be doing anything, should be fine on the freeway though.
 

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NCOR
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Discussion Starter · #18 ·
Alright, thats kinda what I thought. The only driving I will be doing is a 2 hr trip to and from SLO and a 3 hr trip home, both at speeds in excess of 60 mph, so I should be fine. This would also be why my truck gets a little hotter than normal. I thought I was just seing things.
 

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NCOR
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Discussion Starter · #19 ·
Well I went and got a new fan clutch at Autozone in anticiaption of going home in 2 weeks to my tools to replace it. Unfortunatly I couln't resist. The end result, new fan clutch installed with two cresent wrenches in a college parking lot. My fingers hurt and whoever thought a single bolt would be a good idea is a jackass! The old design of 4 would be so much easier to work on.
 
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