20 Most Recent 1985 GMC C1500 Questions & Answers

electrical fault have you check main engine fuse. may have a faulty earth and sorted out the ignition.

1985 GMC C1500 | Answered on Sep 25, 2013

Try the rear main seal

1985 GMC C1500 | Answered on Sep 24, 2013

Start by checking the clutch master cylinder and if that's fine you might have a clog hose

1985 GMC C1500 | Answered on Jan 06, 2013

Is your misfiring condition on a specific cylinder or just random or multiple misfire.

Symptoms may include:
  • the engine may be harder to start
  • the engine may stumble / stumble, and/or hesitate
  • other symptoms may also be present

A misfinring condition may mean that one or more of the following has happened:
  • Faulty spark plugs or wires
  • Faulty coil (pack)
  • Faulty oxygen sensor(s)
  • Faulty fuel injector(s)
  • Burned exhaust valve
  • Faulty catalytic converter(s)
  • Stuck/blocked EGR valve / passages
  • Faulty camshaft position sensor
  • Defective computer

About possible solutions, if there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day

1985 GMC C1500 | Answered on Feb 15, 2012

High HC counts are due to a rich mixture, too much fuel. How does the truck run normally? To adjust the fuel mixture at the carburetor, make sure the truck is at operating temperature. Turn the idle mixture screw clockwise until the engine starts to lag then turn the screw back just until it runs smooth. Also make sure you have fresh oil as this could cause high HC's as well since fuel gets into the oil and make sure your PCV valve is operating correctly. If you can't get it adjusted correctly, you may have to pay a shop to hook it up to the emissions machine to get the mixture correct, unfortunately.
Hope this helps. Good luck!

1985 GMC C1500 | Answered on Apr 09, 2011

Engine code W : 0.035"
Engine code Z : 0.045"

1985 GMC C1500 | Answered on Nov 22, 2010

yes check your grounds and fuses

1985 GMC C1500 | Answered on Apr 16, 2010

there is a dip stick handle on the pass side of the truck far back towards the fire wall thats the one u use not the one on the block

1985 GMC C1500 | Answered on Apr 11, 2010

Your carb needs rebuilt, the float is to high or just really crapped up inside. You are dumping fuel in. Lee

1985 GMC C1500 | Answered on Feb 20, 2010

Play in the steering is most often your tie rods/ tie rod ends... Have these checked first.. Then go onto your pitman and idler arms...They can also cause play in steering...

1985 GMC C1500 | Answered on Jan 25, 2010

sounds like u need a tune up....if a starter turns it,s not bad

1985 GMC C1500 | Answered on Nov 29, 2009

Good day
What size Eng? Gas or Diesel? Please let me know then I can help you.


1985 GMC C1500 | Answered on Sep 15, 2008

Might be caused by tranny filter being dirty

GMC C1500 Cars &... | Answered on Feb 03, 2019

it's the connector tape on main harness it could be Inside isolator

GMC C1500 Cars &... | Answered on Oct 23, 2018

Hi, P0122 code i think reads as "low input" on the fault text, if thats so, the fault is most likely with the wiring to/from the tps, low input codes would usually relate to a short on the wiring so check for any chaffing or corrosion on wires and multiplug connectors, ideally you need to check voltages at the tps connector.

GMC C1500 Cars &... | Answered on Dec 31, 2017

Have you tried replacing the fuel pressure regulator in your EFI (carburator) Sorenson sells a kit that has all the gaskets, screens and regulator for around $30.

GMC C1500 Cars &... | Answered on Sep 29, 2017

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