9 replies to this topic

[Private_Ops]

Bought a new to me 98 2dr Jimmy a couple weeks ago. 112k miles.

So far its in good shape but it's got some issues.

I've done a tune up (Cap, rotors, wires, plugs). (It was doing as described before the tune up)


Occasionally it will idle rough as well as start missing on take off. (Can be sitting a stop sign, go to take off and it just falls on its face, missing and such, give it a little more throttle and it takes off.

It'll also start rough, turn the key, it will act like its gonna die then fire on a cylinder, then another, then another, untill it finally idles up and settles down normally.


Aside from this, it runs fine otherwise, plenty of power, doesn't appear to be eating coolant.


My only guess is the spider injector, how can I check this? Also, the SES light isn't on so I presume no codes.

Edited by Private_Ops, 29 February 2012 - 12:24 AM.

[RareBreedZ]

check the fuel pump ground and pressure first.

what brand of parts did you use for the tune up?

[Private_Ops]

check the fuel pump ground and pressure first.

what brand of parts did you use for the tune up?

AC delco plugs, everthing else was Autozone stuff.

Not sure how to check pressure (nor do I have anything to do that, my step dad might), and where is the pump ground at?

[RareBreedZ]

check the fuel pump ground and pressure first.

what brand of parts did you use for the tune up?

AC delco plugs, everthing else was Autozone stuff.

Not sure how to check pressure (nor do I have anything to do that, my step dad might), and where is the pump ground at?

FP ground is at the rear driver side. I would suggest getting an delo rotor and kap, that should solve it.

[Private_Ops]

check the fuel pump ground and pressure first.

what brand of parts did you use for the tune up?

AC delco plugs, everthing else was Autozone stuff.

Not sure how to check pressure (nor do I have anything to do that, my step dad might), and where is the pump ground at?

FP ground is at the rear driver side. I would suggest getting an delo rotor and kap, that should solve it.

I'll check and clean the ground, not sure replacing the cap and rotor will fix it, it's the same stuff on the Blazer and it's been fine.

[Cody_Becker]

Is the check engine light on? If so whats the codes? Is is flashing? (If yes, then its most likely plugs/wires) I know you replaced the wires and plugs but have you double checked to make sure they are installed correctly? How many miles is on the vehicle? Maybe you should get a fuel test ran to make sure your filter isn't clogged?

[Private_Ops]

Is the check engine light on? If so whats the codes? Is is flashing? (If yes, then its most likely plugs/wires) I know you replaced the wires and plugs but have you double checked to make sure they are installed correctly? How many miles is on the vehicle? Maybe you should get a fuel test ran to make sure your filter isn't clogged?

No light, so I presume no codes.

Most of your question is answered in my OP.

[Cody_Becker]

Run a fuel pressure test should sit between 55-60. If I remember correctly. Also check your spark. Make sure it is consistent, and make sure you don't have a crack on your ignition coil.

[Bobbing]

Fuel pressure should be between 60-66psi and not bleed off. If pressure bleeds off fast, its more than likely a bad FPR.
You may have a bad injector(s) (sticky or leaky)
If that all checks out, do a compression test next. May have a weak cylinder or two.

[Truk]

1st thing, I would change the fuel filter first no matter what, it's probably original and due even if it's not the problem. My father in laws Blazer would sputter and nearly die when you gave it gas, and it was a clogged filter.

2nd thing, it is possible the fuel pump has the right pressure at idle, but does not flow enough to supply the engine when you give it gas. Check the sticky for how to test this.

If it was the spider you would probably smell gas.

Edited by Truk, 29 February 2012 - 06:47 PM.