# 98 Vortec 350 NO POWER



## jb1390 (Sep 23, 2008)

Hello all, I have a 1998 chevy 2500 8 lug. Seems to have no power at all, especially on hills. Runs ok flat. If you mash the pedal down it goes better, at higher rpms as expected. I tow with it-with 4000 pounds behind it, on some back roads in Connecticut, it couldn't hold 2nd gear! I think with the power ithas now, I would have to do some of my driveways in 4Low to even get up them. Last year I don't remember having this problem at all. Here is stuff I have replaced

Plugs, wires, cap, rotor
Fuel filter
New injection system
cleaned MAF sensor
New Map sensor
Compression is good the whole way around

I did a fuel pressure check a few months ago, and it seemed to read fine (60 psi). The truck seems to have less power now than it did then, and the fuel pump is making more noise, and fluctuating in noise. Also have a little bit of a rough idle. Truck starts right up, even when it has sat for a few days. Do fuel pumps go bad slowly-causing a lack of power and it will eventually die? I am nervous to just toss one in for the heck of it, cuz they are upwards of $300. 

Any ideas are welcome-I'd love to be able to beat my mom's minivan in a drag race sometime soon - yes it is that bad.


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## 2COR517 (Oct 23, 2008)

What brand are your plugs, and what is the gap? Try cleaning the TB and running SeaFoam through the intake.

http://www.plowsite.com/showthread.php?t=82292&highlight=induction+cleanup


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## jb1390 (Sep 23, 2008)

Plugs are correctly gapped ac delcos (I think .060") Did the seafoam thing, and I cleaned out the intake when I was in there doing the injectors.


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## jb1390 (Sep 23, 2008)

One other symptom i can think of that has gotten worse recently-
I hold the accelerator pedal steady climbing a hill-the truck will pull, maybe it loses speed some, but then all of a sudden with no change to the pedal, it will have significantly more power for 5-10 seconds, then go back to being slow.


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## 2COR517 (Oct 23, 2008)

Tighten your gaps down to .040". Made a tremendous difference for me.


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## jb1390 (Sep 23, 2008)

I'll try the gaps and see if it helps-any chance the fuel pump is weak when warm or something? It (the pump) has been sounding differently lately, but is 300 for a new one so if it's a gamble I'd like to at least hear of someone that has had one act similarly.


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## 70monte (Feb 5, 2008)

check your coil. I've had a lot of problems with my coil body arcing to the square metal piece that surrounds the coil body. Look for white burn marks on the coil body. My 98 K1500 with the 5.7L shows the same kind of symptoms when my coil starts arcing. I don't know why mine does this but I've probably had around five sets of ignition components in this truck since new. This all started after my first intake manifold gasket replacement by the dealer at around 25,000 miles and I've been fighting it ever since.

Wayne


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## 2COR517 (Oct 23, 2008)

JB - get yourself a fuel pressure gauge. About $40 at AutoZone. Get one with a long enough hose so you can drive down the road with it connected.

Wayne - do you have your gaps down to .040"? The big gaps put a much greater load on the ignition components.


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## 70monte (Feb 5, 2008)

No, I don't have my gaps down to .40 They are still at the factory .60 I'll try the lower gap and see what happens. Thanks.

Wayne


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## jb1390 (Sep 23, 2008)

I have a friend that has a fuel pressure gage-I am heading to his house with a trailer on Saturday morning to see how it does. I will post back after that is done.


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## brad96z28 (Aug 21, 2005)

Make sure to ck fuel VOLUME its equally as important as pressure. U can have plenty of pressure and little volume.It often goes unchecked and unmentioned for some reason.


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## 2COR517 (Oct 23, 2008)

brad96z28;816634 said:


> Make sure to ck fuel VOLUME its equally as important as pressure. U can have plenty of pressure and little volume.It often goes unchecked and unmentioned for some reason.


What's the procedure?


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## brad96z28 (Aug 21, 2005)

Open the valve on ur fp gauge while engine running Insert hose into clear container Should have a few ounces in about 5 to 10 sec. Should have good steady flow.

I would also be looking into a possible restricted cat converter. I doubt ur gona have a back pressure gauge .So u could also try a test drive with the exhaust disconnected before the cat just to see if it helps.


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## augerandblade (Jan 17, 2009)

Check for plugged exhaust. Catalytic converter may be plugged


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## T-Trim (Nov 8, 2005)

augerandblade;816747 said:


> Check for plugged exhaust. Catalytic converter may be plugged


I agree. What goes in must come out.


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## 2COR517 (Oct 23, 2008)

brad96z28;816742 said:


> Open the valve on ur fp gauge while engine running Insert hose into clear container Should have a few ounces in about 5 to 10 sec. Should have good steady flow.


Good tip, thanks.


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## jb1390 (Sep 23, 2008)

*I think it is the cats*

Fuel pressure is fine. TPS and other sensors are fine on the computer (but maybe we didn't look close enough at the MAP, and here is why)
I just did a vacuum test while driving. I had done one before at idle, and revved it up to 2500 rpm-all showed fine. That is how I thought you tested cats. I thought to test it today while driving, so I set up my gauge so I could see it. I put it in gear-vacuum went from 20 down to 15. I then pulled out onto the road, gave it 15-20 percent throttle-and the vacuum went completely to ZERO!!!
So the cats are coming out. I will post later on whether this definitively solves it. Thanks for your help.


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