runs bad when wet

[trans_am_87]

I got a 95 blazer that runs what seams to be lean when wet. I replaced the plugs wires and cap. but that wasn't the problem. the odd part is when it acts up and you push the gas to the floor it kicks in for as long as you hold it to the floor. and the truck runs fine on clear days.

[82Stang]

Originally Posted by trans_am_87

I got a 95 blazer that runs what seams to be lean when wet. I replaced the plugs wires and cap. but that wasn't the problem. the odd part is when it acts up and you push the gas to the floor it kicks in for as long as you hold it to the floor. and the truck runs fine on clear days.

Did you change the rotor too?
I've seen where the dist components get moisture and have the same problems. Or maybe the pickup/module under the dist cap could be causing some of this.

If it is running lean then there's a good chance an O2 sensor is bad.

[trans_am_87]

I changed the rotor. and I got the O2 sensor unpluged

[Spectria, L1 MT]

What do you mean "I got the O2 sensor unplugged"?

Do you mean you disconnected it, or you took it out and "cleaned" it somehow.

There is no good way to clean a fouled O2 sensor, get a new one if it got plugged up.
BEFORE you put in the new one, find out what plugged up the first one, 'cause it will happen again.

What do you mean "seams to be lean when wet"?

Do you mean it seemed to misfire like fuel starvation, or misfire like ignition misfire? You changed the obvious ignition parts with no improvement, so it must be fuel related. The wet condition is the unknown...

If you push your foot to the floor, the trans kicks down and most misfires will improve at higher RPMs with less load. The TPS also indicates WOT and takes the system out of closed loop temporarily (defeats the O2 sensor input) and runs in a preprogrammed mode.

The Pick-up coil may be intermittant, but it wouldn't cause a lack of power, it is either on or off. If it is off your engine does not run, if it is on it runs. It would be like turning the key on and off as you drive, rather than a lack of power.

None of these things explains the wet or damp conditions that seam to cause your lack of power.

Check the trouble codes and repost with that info.

[trans_am_87]

the only code I get is for my O2 sensor so i disconected the wire to it. and it runs the same way. and it dosn't matter the RPM I drove in 1st gear and it would not go till I stepped on it

[82Stang]

Originally Posted by trans_am_87

the only code I get is for my O2 sensor so i disconected the wire to it. and it runs the same way. and it dosn't matter the RPM I drove in 1st gear and it would not go till I stepped on it

If you got a code for the O2 sensor then you have to start there. Unplugging it I don't think will verify it's not that.

[trans_am_87]

I replaced th O2 sensor this last weekend. now I seem to have a different problem. the truck won't rev out it cuts out at 1/4 throttle.My engine light is now out. I got no codes when I scaned it.

[82Stang]

Originally Posted by trans_am_87

I replaced th O2 sensor this last weekend. now I seem to have a different problem. the truck won't rev out it cuts out at 1/4 throttle.My engine light is now out. I got no codes when I scaned it.

I'd guess maybe the coil is cutting out. It will cut out under load and higher rpm's rather than low rpms and no load. Hope this helps.

[wafrederick]

The vortec 350s and 4.3s are known for eating coils.Inside the distribitor is the cam sensor and the pick up for the injectors only.It has the early Vortec distribitor you have to set with a scan tool instead of using a timing light.

[trans_am_87]

I got the coil checked. it was alright.
I think it is a fuel issue. it is starving itself

[trans_am_87]

I replaced the fuel pump. now it is working fine. I think I had 2 problems

[trans_am_87]

OK. I am getting annoyed. the truck worked good for 3 days. now it won't rev out again. I am getting 56 psi. fuel pressure. and it will rev out as long as there is no load on it. but when driving down the road and you kick it down a gear. it trys to go but won't.

[Gabe25]

Originally Posted by trans_am_87

I replaced the fuel pump. now it is working fine. I think I had 2 problems

OK, when you changed the fuel pump. What was your pressure reading. You need at lease 60 psi. Did you change your fuel filter? If your fuel filter is restricted. It would cause the trouble that you are having. Try changing the fuel filter and recheck your presssure. Let us know what you find.

[trans_am_87]

I changed the filter when I changed the pump. that is the pressure I get

[old_master]

Check fuel pressure and leakdown. Key on, engine off, pump running: Must be 60psi to 66psi. Must remain above 55psi for 3 to 5 minutes after the pump shuts off. Post your results.