Top 20 1986 Chevrolet G20 Questions & Answers

Here is everything from 1982 - 87. The wiring and wire colors are all the same to the same sensors or components. Have fun! https://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80386616

There is usually only one battery in front of the driver ,under the hood in the engine compartment.

You have something draining power that should be switched off, or a short to ground in the wiring. If you disconnect the battery it will probably still be charged in the morning. Someone would need to pull fuses and disconnect components to find the power drain while watching the battery with a meter.

SOMETHING IS DRAINING IT OVERNIGHT, TRY DISCONNECTING 1 THING AT A TIME SUCH AS ALARM, CENTRAL LOCKING RADIO ETC.

The battery and or alternator maybe defective, even new parts can be defective, look into getting the alternator and battery checked, if they are good, than you have some other electrical problem, maybe parasitic draw.

Check battery terminals are shiny clean and tight . Have a load test done on the battery to check for dead cell.

If your planing to rebuild the carb take the number off the carb to the parts store and order the carb kit. It will come with the information you need.

Yes it can be adjusted. There should be 3 9/16 bolts holding it on that need to be loosened. You can get 2 of them from the front and the 3rd is on the back close to the exhaust manifold. My experience with GM 1/2 tons and cars tells me to use a prybar to make sure it is tight before you tighten the bolts back up. Hope this helps.

make sure of connection of fuel pump ,and check by ignition if it works or not.

I find this vacuum diagrams for 1986 Chevrolet Truck G30 1 ton Van 5.7L 4BL 8cyl (click over pic for zoom)...



Fig. 136: 1986 5.7L engine-Federal with automatic transmission (G10, 20 and 30 models)



Fig. 137: 1986 5.0L and 5.7L engines-California with automatic transmission (G10, 20 and 30 models)



Fig. 138: 1986 5.7L engine-Federal with manual transmission (G30 heavy duty models)



Fig. 139: 1986 5.7L engine-Federal with automatic transmission (G30 heavy duty models)



Fig. 140: 1986 5.7L engine-California with manual transmission (G30 heavy duty models)



Fig. 141: 1986 5.7L engine-California with automatic transmission G30 (heavy duty models)


Hope this helps; keep us updated.

poor mpg will be your find about 10 to 12 if a 8.50 ring gear is in the rear axle

This can actually be a complex problem due to the amount of things that can cause it. The vehicle is cranking but not starting. You first have to verify that you have fuel and spark. You also have a hei ignition system so you will want to make sure the wires are connected to the distributor. Mainly the rear two if one is not making contact you wont start.

If you haven't already to verify its not a fuel issue pour a small amount into the intake. If it starts you narrowed the problems down. It also has a crank sensor and a knock sensor. If the crank sensor or knock sensor is bad the vehicle will not start. Also check your fuses you may have inadvertantly blown the ignition or ecm/pcm fuses. 86 was a strange year for gm products. Some of their vehicles actually had 2 fuses for the ecm and if either were blown the vehicle wouldn't start.

Its hard to tell if you are saying it just wont start up or if the vehicle is not spinning at all. Hopefully this helps you narrow down the problem.

have the battery tested, you may have a weak cell.

If you are lucky a dealer may be able to get them, but all the years i have been doing this i have never found any. for 20 years now i have been bending my own brake lines. good luck with the dealer,

please help me out by leaving feedback. i hope my information will help.

rebuild carb yourself, unless housing is cracked. look online for rebuild kit. They usually come with instructions. If not, just take good notes while taking it apart so you get it back together right. Did they say what was wrong with it? What were symptoms?

give it a sharp tap with a hammer,poss rust has bonded the two bits together.

18436572 to the left of the square plug on the cap is # 1 plug ( where the power plug and distributor plugs are ) then clockwise from that is 8436572 assuming you have the 5.0 or the 5.7 engine the rotor has to point at the driver side front plug on engine thats number 1 with the engine at top dead center plug out engine on compression stroke timing mark on tdc or 0 degrees

Is it a single click? If it is, check your battery cables and be sure they are clean and secure. A loose connection can cause this problem.

the fusible link comes off the starter,it is connected to the large post on the solenoid,on the starter along with the positive batter cable,if it is burned into,it will pull apart like taffy.

check ecu computer