1993 chevy pickup hard starting and tach oscilates 200 rpm up and down
Just did a tune up, plugs wires cap and rotor. but it starts hard and when i do get going down the road at a steady speed rpm oscilates up and down 200 rpm but you dont feel the engine speed up or slow down. truck has 260,000 miles on it no major work done to engine.
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Re: 1993 chevy pickup hard starting and tach oscilates...
Sounds more likley you have an air leak this will cause bad starting as it is sucking air in instead of fuel when its cold and wnen it warms up idling will be eratic and misfire check all hoses gaskets relating to the inlet manifold or if its done that kind of mileage crankcase pressure could be the problem but i suspect an air leak yates210456
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wonder if its your neutral/safety switch ? just a thought, thinking outloud, automatic trans ? what about the (TV) cable, throttle valve cable, they need adjustment, controlsline pressure, its similiar to a vacuum modulator , maybe thats it, the modulator or its vacuum to it ! check all vacuum lines from intake manifold. hope this helps !
Had an 84 silverado 305 that did the same thing. Try giving it a full tune up. Plugs, wires... Mine turned out to be fouled plugs. I didn't find that out till after i tore it down & put a timing set in it. Wasn't getting good enough spark.
its possible it needs tune up but also check the timing. alot of chevy's spit and pop and when you shut them off and go to start later they wont, this is when the timing cam gear goes bad and out of time. turn crank to top dead center (TDC) on timing mark on front of engine cover or tab first, then remove dist cap and notice where the supply point of the rotor is facing. is it pointing to the # cylinder (very front of motor on the driver side)? Or is it aiming to the plug wire location on the dist cap that goes to the # 1 spark plug. ( the front plug on the driver side of motor )? If neither of these are in line then timing is out of wak. If it's all good then check plugs for old worn or burnt electrodes then check rotor with multi testor for current travel, then check cap for electrode failure and then check plug wires for current loss and burn. then perform a compression check on motor. (dry & wet)
5 years ago for cap & rotor???? It sounds like it's in dire need of a complete tune up - plugs. wires, cap, rotor, all fluids & filters ESPECIALLY fuel filter. I'd start there and run a good fuel system cleaner through it. Do your tune ups more frequently like every 30K - not wait 5 years!
You have a bad cam sesnor in the distributor- for certain. Rich Porter on ebay has the best reman for $200. Guaranteed fix. 99 was famous for this, runs cold for 15 mintues then acts up and quits, tach usually jumps around too.
Remove the Distributor cap and watch the rotor as you crank the engine. If the motor is turning over and the rotor is not moving then you have a broken Timing belt. If this is the case the Belt broken while the engine was running. I can tell you from experience, I owned one of these and mine did the same thing, Every valve in the head is bent. The good news it is not hard to replace on your own and it can be done without removing the engine. The bad news you have to remove your head and have it serviced by a shop.
The distributor will have white deposits on each metal tap inside cap and the rotor will be worn down. Take a look under the cap try not to disconnect the spark plug wires just unhook the cap and turn it so you can look inside. That's the easy thing to do. If the cap has the deposits you need a knew cap and rotor I would get knew wires and check your spark plugs as well.
It's not too hard. It's mounted under the distributor cap, in the distributor, you'll need to remove the rotor and turn the distributor shaft enough to get room to get it out of the housing. I would do a tune up at that time too, cap, rotor, wires and plugs.
There may be no injector pulse if the computor does not see a RPM signal. There will be no spark if the ignition module does not see a dist pulse from the dist pickup.......a RPM signal. Because you do not have both ......I would suggest to check/change the dist pick up. Follow the wires from the ignition module inside the dist to the pickup which is also inside the dist. If it is just a bad dist pickup....keep all your old parts as good spares. Also...is the dist turning? to provide a RPM signal? You will have to remove the dist to change the pick-up.....mark your timing locations......"rotor position" and "dist body location"before removal. A quick test before installing the "repaired dist" .....plug it in the the truck wiring and turn on the key....DO NOT CRANK THE ENGINE OR YOU WILL LOSE YOUR DIST ROTOR CORRECT POSITION......as you spin the dist by hand .....the injectors should spray.