My friend owns a 1997 S10 4x4 with the 4.3L Vortec Engine in it with approximate 118,000 miles on it.

During acceleration, vehicle is running extremely rough or not accelerating at all. Speeds at this point will barely reach above 40mph. This is after approximately 1.5 miles of driving time, so barely enough time to warm up.

However, the vehicle runs smoothly in idle.

Fuel filter has been changed, MAP sensor has been changed and the fuel pump is only 18 months old.

They are kind of trying to troubleshoot it. Bad gas has been mentioned, but I'd like an opinion here also since most of you seem to know what you are talking about.

Thanks in advance

Rose

Is the Check Engine light on?

No, there are no Malfunction Lights on at all, which is why I'm guessing they are wanting to look at bad gas....

However, this has been a steadily worsening problem for this truck...so I'm thinking bad gas is not the issue....though i could be wrong.

have you done a fuel pressure check ?

have you double-checked your plugs, plug wire connections, and firing order?





My friend owns a 1997 S10 4x4 with the 4.3L Vortec Engine in it with approximate 118,000 miles on it.

During acceleration, vehicle is running extremely rough or not accelerating at all. Speeds at this point will barely reach above 40mph. This is after approximately 1.5 miles of driving time, so barely enough time to warm up.

However, the vehicle runs smoothly in idle.

Fuel filter has been changed, MAP sensor has been changed and the fuel pump is only 18 months old.

They are kind of trying to troubleshoot it. Bad gas has been mentioned, but I'd like an opinion here also since most of you seem to know what you are talking about.

Thanks in advance

Rose

Here's where you check the fuel pressure on your '97. A fuel pressure test kit is available at most chain type auto parts stores.

http://i131.photobucket.com/albums/p288/Clunk_/Image026.jpg

Fuel pressure is not monitored by OBDII, so that is a possibility. Secondary ignition is not directly monitored by the OBDII system either. This includes the distributor cap, rotor, spark plug wires, spark plugs and the ignition coil. The distributor cap is a very common problem, especially in high humidity, (rain etc). The SES (Service Engine Soon) light may or may not come on during the missfire. A P0300 series DTC (Diagnostic Trouble Code) may be set, but not always. Hope this helps.

Thanks!!

You guys have been great and I know this has been a help to him!!

:)