99 Chevy Express van (350) Stuttering problem HELP!

[hybridb18]

This is my moms van, it's got a horrible stutter at low rpms. It will rev just fine at half throttle. But the instant that you floor the gas, from a stop/slight roll/while the van is parked/in reverse it stutters severely. Im borderline scared to pull out in front of traffic, fear of getting hit.
I just this weekend replaced the spark plugs gapped at .060",replaced the plug wires, distributer cap, rotor, and fuel filter. I also pulled out the MAF and cleaned it(wasnt really dirty). Air filter is a little dirty, but i doubt its the problem.
We have tried all different brands of gas (shell, thortons, sunoco, speedway, ect). The van only has 68K on it, and we have owned it since it was new. Have all the service records ect.... This stutter issue has been getting worse over the last 6 months or so.

Im out of ideas here, im thinking maybe its the fuel pump. I need to get a fuel pressure gauge to check the pressure. But other than that, im lost. No check engine light either.....'

Any Ideas???

[WhiteT]

Vortec 350? If I recall, the "spider" looking fuel injectors get clogged easy. I went through that in a 96 truck I used to have. I would check to see if it has any codes.

[69camaro5speed]

Check distributor gear for wear happens all the time.They wear out all the time

[WhiteT]

Originally Posted by 69camaro5speed

Check distributor gear for wear happens all the time.They wear out all the time

I think if that's the case, doesn't it show a code for a bad cam sensor signal? Think I went through that too on that truck. It had about 190k when I sold it, had 20k when I bought it. Then you need a snap-on scanner to set the dist from what I remember

[hybridb18]

its the vortec 350. Its not throwing any codes. A worn out gear would make sense, never know that could happen

[WhiteT]

Did you have codes checked? Or are you just going by the fact the ces light isn't on?

[hybridb18]

the light is not on, so no reason to check

[WhiteT]

wrong. Actually the computer will store codes. It probably has a misfire or similar code. May point you in the right direction.

[hybridb18]

ill check on that gear tomorrow. Makes perfect sense.... If it has codes but no CEL do I need to have them cleared?

[69camaro5speed]

Originally Posted by WhiteT

I think if that's the case, doesn't it show a code for a bad cam sensor signal? Think I went through that too on that truck. It had about 190k when I sold it, had 20k when I bought it. Then you need a snap-on scanner to set the dist from what I remember

If the signal gets that bad (it might not for sure) but it will quit running because the distributor Isn't turning.Just a idea to look at and yes needs sinked in once its out then back in so dont work on it where you cant get it back in and going

[Kisor]

Fuel pressure or a bad/weak coil could cause these conditions.. those engines run 60+psi fuel pressure so make sure its at least that much.

[Grand National Propain]

Originally Posted by Kisor

Fuel pressure or a bad/weak coil could cause these conditions.. those engines run 60+psi fuel pressure so make sure its at least that much.

X2 the vortec truck motors are pretty sensitive to low fuel pressure. If it's more than 3-4 psi below spec, it'll run horribly. Put a fuel pressure gauge on it and see what it drops to when the spuddering starts.

90% of the time when people bring this complaint to me, it turns out to be the fuel pump.

[Grand National Propain]

And there won't be any codes if its the fuel pump. For some reason they never set codes for running lean or missfiring until it's REALLY bad.

[bestracing]

Originally Posted by Grand National Propain

And there won't be any codes if its the fuel pump. For some reason they never set codes for running lean or missfiring until it's REALLY bad.

+1, Ain't that the truth!!

The external HEI coil can have the insulation go bad. You can check this by going somewhere where it is dark and open the hood and watch the arear around the coil. If the insulation is weak you will see a corona around the metal band tha goes around the coil. Kind of looks like flames. Had this happen to an 86 S-10 truck. Just replace it with a stock coil if it is bad. The CEO of MSD told me you couldn't get a better coil (higher energy) than GM's OEM coil.

[Speed Kills]

Originally Posted by Grand National Propain

90% of the time when people bring this complaint to me, it turns out to be the fuel pump.

I'm going to go with this.

The fuel system will have a service port on it somewhere by the intake. Go rent the guage kit and check the FP.

[69camaro5speed]

so is it fixed?

[hybridb18]

well, i have changed out the plugs, plug wires, distributer cap, rotor and fuel filter. I even pulled out the distributer to check out the gear. The gear looked brand new, wasnt knife edged or anything. The problem still exists. I need to get ahold of a fuel pressure tester still, but im slacking on that.

[69camaro5speed]

yeah hope thats it,the spider in the intakes some times leak also

[Kisor]

Go buy a coil and throw on there... I'm going 95% on that is your problem....