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1994 GMC Sonoma - Page 8 Questions & Answers
My truck is jerking and
this could be from a faulty fuel filter which is almost clogged, or possibly a fuel pump on its way out... timing could be off, or an electrical issue, such as a bad ground in the system.. have to scan it from autozone or advance maybe a code will come up...
Whrn i hit the breaks
Hi, the brake light circuit runs through the 4 way switch, and this switch can go bad, there was a recall on them at one point, try wiggling the 4 way switch, and see if this makes a difference. If you see it does, you should contact a dealer to see if it is subject to the recall. Good luck...Coop
I have a 1994 gmc
Try a local wrecking yard (now called a recycler) Will cost less than new. get one from a vehicle with lower miles if possible.
Code 72 antilock brake light on. engine does not
72 Transmission code - Vehicle Speed Sensor (VSS) signal loss (4L60-E)
This code is the result of a failed VSS module. This device is the principle speed rate indicator that relays information to the speedometer and other monitoring or corresponding devices, as well. It may need to be adjusted or replaced. Have this device inspected for faults, immediately.
Concerning your Anti-lock brake light:
This could be a totally unrelated issue concerning the state of the anti-lock braking assembly. I would suggest to have this area inspected for faults, as well. Most anti-locking mechanism are linked to the VSS to monitor speed when hard braking is administered. This information is used to calculate the rate of speed and the amount or resistance needed to stop the vehicle safely, without skidding.
Truck won't start but sounds like it wants to
1. Take the air cleaner off and spray starting fluid in the intake for about two seconds.
2. Attempt to start the vehicle. If it runs on the starting fluid, you have a gas problem, if it doesn't, its spark.
3. Once you have determined which it is, you can repost for more specific information.
4. If its a gas problem, make sure it has good gas (fuel gage may have quit). When you go on the key, you should be able to hear the whining of the fuel pump cycle on, then stop. Have a helper go on the key, while you listen for the whine of the pump underneath. You should be able to locate the fuel pump and hear it if it is working. If the fuel pump is working, try changing the fuel filter.
5. If you have a spark problem, a likely culprit is the distributer, and rotor. These are fairly easy to replace. Its time for new spark plugs, wires, distributer rotor and cap if this wasn't done recently.
Fuel pump not coming on
look for the fuel pump fuse and check it. If it is good , remove the fuse, turn on the ignition switch, take a voltmeter and ground the black lead to a good ground on the metal area surrounding it and take the red lead and check for voltage on either bare pin where the fuse was. One of them should read at least 12volts. If so, voltage will have to be checked at pump at the fuel tank.either no voltage at the pump due to loose connection at pump or, fuel pump is dead also could be a broken wire to the pump..hayne's manuals have a good outline for testing this procedure.
I have a 1994 GMC Sonoma 4.3L Votec we have
If the filter is not seated on the new fuel pump properly or has fallen off after installation it will ruin the pump immediately. I have seen many people do this. It is a very common problem when changing the fuel pump.
New fuel pump, but still
I would check to see if you are getting power to the fuel pump. You may have a blown fuse, or bad relay. Sometimes you can get a defective fuel pump.
Some times my truck wont start I think it may be
If you have the tools to check fuel pressure, this will be the best way to check for fuel pump operation.
You check for fuel pressure at a schrader valve on the fuel rail.
It could also be an goofy acting fuel presure regulator
94 gmc sanoma. heater dampers
From the feed line under the hood,have an
assistant(engine off) blow cigarette smoke into the line,you should be able to see exactly where the leak is.Often is is a hose,not the switch itself.
I have 4 cyln 5 speed gmc .truck just started
I hear you!
Bad input = Bad output
Start testing the computer inputs -
1) Air Charge Sensor (Resistance measurement - OHM meter needed)
2) Coolant Temp Sensor (Resistance measurement - OHM meter needed)
3) Crankshaft Sensor (Test procedures off the ignition amplifier)
4) Detonation Knock Sensor (This can cause your symptoms if there are any rattles in the motor or exhaust pipe - like a loose heat shield or bracket causing the rattle will be picked up by the knock sensor - which in turn retards the timing causing a stumble and hesitation)
5) MAP (Manifold Absolute Pressure) Sensor (make sure the plug contacts to it AND all of your other inputs are not corroded - also check the vacuum line going to the MAP and make sure there are no leaks, cracks....)
6) O2 Sensor (Would normally show up on computer as needing replacement - not always though )
7) Throttle Position Sensor (this is a variable resistor, which can and does get wear spots on it - sending incorrect voltages to computer causing your stated symptoms too. A good analog meter would be nice to test this. engine off, key on - You can tap into the voltage side and watch the needle carefully while slowly opening throttle to wide - and back to close. If the needle on the meter moves smoothly from one side to the other without and dips or jerking motions, then the TPS is fine - of course the voltages need to be within parameters)
You can find all of the testing procedures and vehicle specific data at alldatadiy.com
Good Luck.
Hi i have 94 sonoma 2 wh drive 4 cyln.just did
im a chevy guy but i also know a bit about gmc and the one thing i can tell you is that both have problems with the distributer having to much play in it to check it you just pull off the cap and leave the rotor on and see if you cna move the shaft to either side replace it if it has play also check to make sure you have the gap in the plugs set right if its a sencer problem your check engine light will come on.
Have a rough idle that
One way to try to decarbon is with air cleaner removed run the engine until hot rev up engine to about 2,000 rpm and pour some water ( a couple of quarts ) down into the throttle body pour as fast as you can without stalling the engine.This will create steam in the combustion chamber loosing up some of the carbon deposits .You may have to repeat more than once.. Then after drive on highway a little to help blow out...
How to disconnect fuel line from 1994 Sonoma GMC
hi ... Raise and support the truck ... just enough to reach the fuel and vent lines. Disconnect the fuel and vent lines using the needle-nose pliers ...there clamps might need screwdriver might wanna drain the tank , if been sitting for long time water and rust mess up your fuel pump,causeing the fuel filter fail. thanks
Where is the pcm located
The PCM for what ?
There are several PCM ( part controle modules) in any given vehicle... Most are integrated in the ECU .
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