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'99 runs like it's in molasses when full throttle

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  #11  
Old 06-18-2010, 08:12 PM
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Originally Posted by Nvidia78
Have you checked the tranny fluid level? does it smell, look burnt?
The level is fine. Didn't smell it though. I'll check more tomorrow and let you all know.
 
  #12  
Old 06-18-2010, 08:55 PM
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Nivida is correct also drive it down the road and look at your RPM gauge It basically should not go over 2000 RPM at a normal accell
 
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Old 06-19-2010, 02:02 PM
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Okay, I've done some testing and this is what I have found.

I took a ride down to the parts store and almost right away as I pulled out of my driveway, it was sounding like it was going to stall on me. Usually when that happens, I just let off on the gas a bit and it recovers. I was driving down the road and mashed the peddle down. It downshifted and I watched the rpm's and speed very slowly increase...but not by much. I did this for about 10-15 seconds and basically gained about 5mph or less. Driving back I did the same thing but when the truck was in 2nd gear. It downshifted and the rpm's and speed increased faster. The rpm's went all the way to 5k before it shifted hard.

I bought a fuel filter and a fuel pressure gauge. I tested the pressure before I did anything. It was 53 psi before I started it up. It slowly dropped down to 52psi. I then started the truck up and it stayed at 54psi. I revved it up and it was still at 54psi. I let it idle for a few minutes and it stayed consistent. I couldn't test it while driving as I don't understand HOW I can do this. The hose is only like 18" long. I would have to have the hood open and someone sitting in the engine compartment to see it.

I tried to replace the fuel filter, but the 16mm nut was basically round. It looks like it was really just corroded badly. I started to break out the vise grips, but had second thoughts because if it IS that corroded, I don't want it breaking on me and I'll be screwed. I'll have to take it to a shop I think to get it replaced if I need to.

After all that, anyone have any more thoughts or an idea as to what the actual issue could be?
 
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Old 06-19-2010, 09:49 PM
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ok now by the sound of that it is not the tranny.... fuel pressure is a bit on the low side, key on engine off should be around 60 psi, seems like your pump may be a lil on the weak side, how long did it take for it to bleed down to 52 psi?
 
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Old 06-19-2010, 09:52 PM
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Originally Posted by Nvidia78
ok now by the sound of that it is not the tranny.... fuel pressure is a bit on the low side, key on engine off should be around 60 psi, seems like your pump may be a lil on the weak side, how long did it take for it to bleed down to 52 psi?
I didn't exactly time it, but it was probably under a minute. I waited another minute or two and that's where it stayed steady at. So, could this be a fuel pump issue? Or maybe a fuel filter slightly clogged issue? Or could it still be a blocked exhaust?
 
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Old 06-19-2010, 10:00 PM
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Well to rule out the exhaust i would take it apart at the manifold on the flange. Take and tie the pipe up with a piece of bailing wire, take it out for a spin and see. You don't happen to have a California model with a pre cat before the actual cat do you? California models have 2 cats. If it does not run any better I would say have the fuel filter replaced and retest for fuel pressure. wait at least 15 min for fuel pressure test and see what it drops to.
 

Last edited by Nvidia78; 06-19-2010 at 10:04 PM.
  #17  
Old 06-20-2010, 10:15 AM
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No, it's not a California model. It will be a couple weeks before I can do anymore testing. I'm starting a job tomorrow and the next few weekends are going to be busy. Ug...this sucks.
 
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Old 06-21-2010, 09:22 PM
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Originally Posted by Nvidia78
Well to rule out the exhaust i would take it apart at the manifold on the flange. Take and tie the pipe up with a piece of bailing wire, take it out for a spin and see. You don't happen to have a California model with a pre cat before the actual cat do you? California models have 2 cats. If it does not run any better I would say have the fuel filter replaced and retest for fuel pressure. wait at least 15 min for fuel pressure test and see what it drops to.

Same thing I said
 
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Old 06-22-2010, 08:59 AM
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I have the same problem too! So I am curious what you find. I noticed that when I start it up after it has set for a few hours it does this. So what I do is when I start it up, pump the gas and rev the motor a little and it seems fine.
 
  #20  
Old 06-25-2010, 11:07 PM
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I have the same issue as well. When i tested the fuel pressure last weekend i had 60 psi with pump running but it immediately fell to like 52,53 psi once it stopped making noise. With engine running it was like 58 59 psi. Im going to test again tomorrow morning since i really dont remember, and due a vaccum test on it. Im leaning to the possibility of it being the fuel pressure regulator. The issue is most noticible on a large hill, it will do exactly what yours did, rpms will hit redline almost but your not going anywhere or on heavy accel. Replacing my fuel filter tomorrow as well though doubt it will work. I am having one trouble code that shouldnt be related, P0410, I had that for a while but im not worried about that one, living in SD we dont have emissions test.
 


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