Question about 1994 Chevrolet S-10

1 Answer

Rpm bounces from 1500 to 500 and back again

Replaced: fuel pump (2/05) and filter (2/09), PCV valve (2/09), EGR valve (2/09); fuel pump output is up to spec, there aren't any codes to read and I don't know what to do next. Please advise I'm at my wits end.


Posted by on

  • 1 more comment 
  • whooui Feb 27, 2009

    carhob, no it doesn't just do it at idle but the PU is subject to stalling at idle then unless I drop it into netural and rev the motor. During it's unnoticable when excelerating but at cruising I can feel the variations. It was recommended to check for holes or cracks between the air cleaner and the throttle body but the mechanic says I don't have any sensors in between that would registar or cause a false reading. The mechanic also checked/tested the idle control sensor and it well within specs.

  • carhob May 11, 2010

    could be fuel pressure reg.,faultyor dirty injectors,if you didnt do this yet ,iwould have inj. syst.cleaned by your mec.

  • carhob May 11, 2010

    does it do it only at idle


1 Answer

  • Level 1:

    An expert who has achieved level 1.

    Problem Solver:

    An expert who has answered 5 questions.

  • Contributor
  • 4 Answers

I have the same problem with my 94 s10 4.3 cpi.... I have been told after replacing fuel filter; 3 sensors; cap, rotor, plugs & wires; spider injection assembly; and a coil (and i could have even left something out the list is so long), that it is probably the 02 sensor by the cat converter. If not that then my injectors are already bad...oh yeah plus I cleaned the EGR valve. Does this only happen to you after you vehicle warms up? cuz thats when it goes crazy for me.

Posted on Oct 03, 2010

1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

1993 3.4l camaro Idles fine when first started. After a few seconds it idles rough and rpm drops. No power when driving. RPM will not go above 3000 even if floored when driving.

there are a few reasons to ur problems 1st check and or replace fuel filter -check and or service egr valve -carbon usually builds up in and around valve causing rough idle -no power and can cause non start problem ---also air filter - fuel pump-bad gas -timing skip-pcv valve-catalytic converter clogging these are some of the problems usually one of the first 2 is the problem good luck

Jun 21, 2011 | Chevrolet Camaro Cars & Trucks

1 Answer

1995 old acheiva hard to stay running when first starting after it warnup it ok

Sounds like no gas is getting to the carb. Or it can be a fuel issue. Bad fuel pump or clogged filter can be the reason, it can be solved by replacing the fuel filter and fuel pump fuse..
Failing EGR or PCV valve. Changing the PCV valve; this can affect starting, especially in cold weather and will allow you to start the car, but then it will die. EGR is similar, but affects more than just starting. The PCV tends to be ok after warm-up.
Everything on a car works together: Simple oil change or air filter change, or fuel filter change make a car start better.
Also there could always be a malfunctioning sensor, you can test this with the help of a mechanic or buy buying an OBDII code-checker at a store.

Let us know if you need further clarification else please accept the solution.
Thanks for contacting

Mar 21, 2010 | Oldsmobile Achieva Cars & Trucks

1 Answer

Runs but dont want to idle smooth tech 4 motor sometimes it smooths out then rough again thanks

1 Inspect M.A.P. Sensor Faulty M.A.P. Sensor. 2 Inspect EGR Valve Improperly Functioning or Faulty EGR Valve. 3 Inspect Fuel Injector Dirty or Worn Fuel Injectors. 4 Inspect Idle Air Control Valve Damaged, Loose, or Faulty Idle Air Control Valve. 5 Inspect Idle Speed Actuator Damaged, Loose, or Faulty Idle Speed Actuator. 6 Inspect Throttle Position Sensor Faulty or Incorrectly Connected Throttle Position Sensor. 7 Inspect Fuel Filter Clogged or Dirty Fuel Filter. 8 Inspect PCV Valve Plugged or Damaged PCV Valve. 9 Inspect Carburetor Worn, Faulty or Damaged Carburetor. 10 Inspect Valve Burned, Worn, or Sticking Exhaust Valves. 12 Inspect TimingSet Slipped TimingChain or Worn TimingGear(s). 13 Inspect Fuel Pump Faulty Fuel Pump. 14 Inspect Camshaft Camshaft Lobes Worn. 16 Inspect Point Set Burned, Worn or Incorrectly Set Ignition Points.

Jul 01, 2009 | 1988 Chevrolet S-10

1 Answer

'94 s10 4.3L Vin (W) RPM bounces from 500 to 1500 and back again. replaced: fuel pump (2/05) and filter (2/09), PCV valve (2/09), EGR valve (2/09); fuel pump output is up to spec, each time I did...


It sounds like the (TPS) is bad on it it will cause this problem but it should show a trouble code . The (TPS) is on the throttle body this is what it sounds like to me.

Feb 26, 2009 | 1994 Chevrolet S-10

1 Answer

4.3L V6 Vin W. RPM bounces from 500 up to 1500 and back again

look for a vacuum leak or rather listen for one

Feb 26, 2009 | 1994 Chevrolet S-10

Not finding what you are looking for?
1994 Chevrolet S-10 Logo

205 people viewed this question

Ask a Question

Usually answered in minutes!

Top Chevrolet Experts


Level 3 Expert

71338 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22059 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

7018 Answers

Are you a Chevrolet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides