99 monte carlo surges

[chevy66thunder]

I have a 99 monte LS with a 3.1 Liter, with the cruise on or off or running throttle with foot, if the car needs to increase in speed a little the car surges enough to see it on the tach. I've changed fuel filter, plugs, plug wires,map sensor, throttle position senor and the fuel pressure is at 36lbs and it still does it. any other ideas please, thanks

[corning_d3]

Your fuel pressure is really low. It should run 41-47psi with the key on, engine off.

[richtazz]

pull the vacuum line off the FPR and see if the fuel pressure jumps back up to the 41-47psi level, as a drop of 4-psi or so (engine running, vacuum applied) is not out of range. If this issue happens after the TCC locks the torque converter (45mph or higher), a surge in RPM is normal as the TCC unlocks, and the RPM should increase.

[chevy66thunder]

here's a little more info, i double checked the fuel pressure and it is running 43-44 lbs, (key on , engine off), with engine running it is 36lbs and if I hit the throttle it jumps up to around 45-47, any other info would be appreciated.

[gw84]

Originally Posted by chevy66thunder

here's a little more info, i double checked the fuel pressure and it is running 43-44 lbs, (key on , engine off), with engine running it is 36lbs and if I hit the throttle it jumps up to around 45-47, any other info would be appreciated.

Is it just me or is this mainly happening on '99 GM vehicles? My '99 Lumina LTZ has a similar problem. Does yours do it after driving for an hour or so? Mine's only done it about 3 times in 3 months and only while driving on the highway for over an hour. I haven't done any of the basic stuff yet (fuel filter, plugs, wires, etc) because it hasn't seemed to help anyone who has the problem. I'd like to wait to find something that works for someone else and try that. Might we be looking at injector problems here???? I just wanna SCREAM!!!!!!! OK I'm good

[corning_d3]

My '96 Monte used to do it when it was warmed up, now it's doing it all the time under light acceleration..

EDIT: I drove a '99 buick with the 3100 today, and it did the same thing...

[richtazz]

It sounds like you may have a vacuum leak at the intake manifold, causing incorrect vacuum at the FPR. Try unhooking the vacuum hose at the FPR with the car running, and see if the fuel pressure jumps back up to the 43-47 range. If so, check for vacuum leaks in and around the intake. The 96-up 3100's are famous for intake gasket issues, which can also cause coolant to get in the oil. When this happens, it can wash the crank bearings and cam lobes of oil and toast the engine. Check the oil for murkiness/cloudiness and check to see if you're losing coolant.

[gw84]

I got a decent suggestion in another thread. They suggested disconnecting the MAF sensor (if problem persists, that's not it). Any thoughts???

[bobbybizzle]

Originally Posted by corning_d3

My '96 Monte used to do it when it was warmed up, now it's doing it all the time under light acceleration..

EDIT: I drove a '99 buick with the 3100 today, and it did the same thing...

I have the exact same problem with my 98 monte carlo. Did you ever figure out what was wrong?

[maxwedge]

4 year old thread here, if no reply start a new thread.