1998 Chevy Silverado problem, please help

[ZL50068]

Hey guys, I got a 98 silverado with 230,000 miles. It has a new(rebuilt) motor as of 1200 miles ago. My problem is that sometimes it coughs and sputters under acceleration. Sometimes is idles rough and I cant really stomp on it or it just kinda sits there and sputters, gotta ease into the gas. Its the worst when the motor is warm and I shut it off and a couple minutes later start it up and go, I gotta hold the gas at about 1/4 throttle, anything more than that it coughs and sputters like it aint getting fuel, then about 1/2 mile later it clears up but it still aint quite right. Fuel pump or injector issue? any ideas? thanks....

 

[Ollie]

Fuel filter??
Check the fuel pressure.

If it was an injector it would be rough pretty much thru the whole power bank. They usually don't work at one RPM and fail at another, If they are bad, they are bad through out the RPM range and actually get worse with higher RPMs.

 

[hilinerider]

got one with 212,000
fuel filter

run a couple cans of sea foam thru it evry couple months, really helps

 

[6Mile]

Are you running a washable air filter (K&N, etc.)? If so I would bet money that the MAF is bad. The oil that is used on these type of filters gets on the sensors and muckes them up.

 

[ptofnortn]

If its not the fuel filter it sounds like a bad fuel pressure regulator.

 

[Gainster]

^^^ I have seen what all 3 of these guys have said as a possible cause, Do you have a check engine light on? If so get it scanned & let me know what code you have.

On a side note I had a Duramax in 2 weeks ago with a very simular problem, It was nothing more than a rodent nest in the airbox, Cleaned it out & has ran great since.

 

[ZL50068]

No check engine light on, but I do have a K&N air filter on, I will start with a fuel filter and go from there..

 

[Gainster]

No check engine light on, but I do have a K&N air filter on, I will start with a fuel filter and go from there..

Ok good start, I tell all my customers to change the fuel filter on the classic trucks every year. Once you buy a fuel pump module you will know why & I believe a restricted fuel filter could be part of the cause of seeing so many pumps burned up, Along with people always running below 1/2 tank of gas.... The gas sloshing around in the tank keep the pump cool.

Next buy a spray can of Mass Airflow spray cleaner, Some say they cant be cleaned but we have cleaned many with great results. Be careful of the thin metal lines in a sensor but spray clean it real well. K&N says oil cant get on the MAF sensor but BS we have seen it too many times. All it takes is a mist of oil to screw up the readings of the MAF.

Good luck

 

[Snowizard]

Since the engine has been apart recently, could there be a wierd vacuum leak somewhere?
$0.02

 

[Gainster]

Since the engine has been apart recently, could there be a wierd vacuum leak somewhere?
$0.02

? Intake gaskets, Not like we've never seen that before

 

[6Mile]

No check engine light on, but I do have a K&N air filter on, I will start with a fuel filter and go from there..

Ding, ding, ding. We have winner. Try the MAF cleaner spray first as it is the lease expensive, and go a head and replace the fuel filter. The MAF will not always trip the CEL until the readings are really out of whack.

If cleaning the MAF does not work then replace it. Napa sells re-manufactured units that are about 150.00

Then Ditch the K&N and go back to stock paper filters. All the marginal savings in fuel you may have realized since the K&N was installed as of now have been erased with the cost of the replacement MAF.

 

[winter brew]

my first thought was intake manifold leak....spray some ether.

 

[Pit Crew]

350 vortec?



i've had a couple and the cap and rotor corrode out often

 

[Gainster]

350 vortec?



i've had a couple and the cap and rotor corrode out often

True, GM has a TSB about cleaning the vent hole in the distributor housing to prevent that very issue.