1991 GMC K1500 - Page 8 - Answered Questions & Fixed issues

Looks like a bad MAP sensor to me.

the alternator will not die in one day unless there is a direct short causing diode or coil winding failure which would give signs of smell, melted wires. Disconnect battery and give full charge. what year is this? while vehicle is running you should be able to briefly disconnect positive battery post connection and vehicle will still run if alternator is good. For a new battery to die in one day, one of two things i think has happened. Either the batt is faulty from supplier,( not likely but i have seen it ) or there is a direct draw or grounding taking place whether its direct in the starter selonoid or a direct draw through accessories. Are you sure all switches are off ? Push switches (on interior lights) nothing like dome lights,delayed lights are staying on! Does vehicle start hard like it almost needs a jump. If it has to be (and it takes time). to find out what is drawing the power ( i am old school) disconnect positive power source on batt. 2) disconnect ignition power source on starter. 3) connect pos batt wire to starter, 4) touch positive cable to positive batt post and look for spark or contact. if this reacts then selonoid or starter motor is shorted drawing the current. Or if you have volt meter and know how to use it, this is good to. If checks good then hook ignition connection back on starter.(disconnect pos terminal on batt prior to re-connect) I think the battery is having the life sucked out of it by a short in the system ( A DRAW ) this could be a quick find or fix or this could take days to track down. alot of variables here to try to explain. but i would seek into the starter first as usually this drains the battery quickly .

Bad connection at battery or block ground.

Hi, the front axle has a sensor, that tells you with a light, that you are in 4wd. If the front axle actuator does not engage the axle, the light will not come on.The actuator is most likely at fault. If you remove the actuator, and press the button inside in, you may be able to engage the axle manually, and with the key on, see the light. I would consider checking to see if there is power, and ground ,key on, at the actuator. If there is, than you have an actuator, or internal axle issue. Good luck... Coop

Your problem, as to my knowledge, seems to be more of a ground issue, or power supply issue. Check the grounds throughout your vehicle, including the ground for the fuel pump.

Hi, you may have a torn fuel pressure regulator diaphram. The diaphram is behind a square cover on the side of the throttle body, that is held in by 4 screws. Take the diaphram out and check it for tears. If no tears, put it back the way you took it out and check your injectors. Can you see them squirting as you pull the throttle? Is the squirt the same for both? Is it a regular pattern or distorted? If you see issues there, you can take them out and try to clean them. If that doesn't work, replace an injector that has a poor or irregular flow pattern. Please let me know if you have any questions, and thanks for using FixYa.

P0420....Catalyst System Efficiency Below Threshold (Bank 1),i would be inclined to check the O2 sensors ,the two wires the same colour which is normally white should read 12v across them ,with connector off then these two wires should measure a resistance ,the other check requires a scope to read them but it should show 5 volts over a time scale on the scope with time scale decreasing with higher RPM ,but as this vehicle is 13 yrs old then i would be inclined to suspect the cat as breaking down inside and depending on mileage due for renewal as they dont last forever ,small exhaust and if smells a bit off or stinking of rotten eggs then renew the cat and the sensors ,Cats are good for around 150,000 then after that they start to clog up and the porcelane base break up .

Not too good. The least expensive change you can make is the oil. Go to a Mr Lube and have them do a hot change and put an additive into it. The new oil will help the clutches to grab and the additiv e will free up the valve body to shift properly. If that doesn't work you either need to rebuild it or replace it with a used one. Sometimes you can get lucky and find factory GM rebuild at the wrecker that will give you years of good use. The key is fresh oil and change it after the first 20k, then it's probably good for 60 more.

It sounds like a wire has chaffed and is rubbing on the truck somewhere. Since Chevy's seldom have trouble with the heater wires doing this I would start with the 4WD wire harness. Check it carefully and tape up any bare or near bare spots you find. Hope this helps.

replace the starter. Being a manual transmission you should be able to pop the clutch to get it going till you replace the starter. If you don't know how to pop the clutch follow these steps. That way you can still drive the car. When need to.

1. Get inside the vehicle and depress the clutch to shift the car into "Neutral." Insert the key into the ignition and turn it to the "On" position. This is the place the key would be after a normal turn of the ignition switch for starting. Instead, with a clutch pop, the ignition will already need to be on so that when the engine is turned over, the key is in the On position.
   
2. 
   Move the car in position to be pushed from behind or sent down a slope for the starting procedure. Check to see that the brakes will work when pressed and how hard the steering wheel will need to be turned before the vehicle is started. Power steering and brakes will make both systems work poorly until the vehicle is started.
   
3. 3 Sitting inside the driver's seat with the clutch depressed, put the shifter into first gear. Keep your foot depressed onto the clutch and the brake pedal without depressing the brake pedal. Roll down the window and signal to your helper to push. As the car rolls, you will steer toward any slope that will assist the helper in getting the car down the street. Allow the momentum of the vehicle to increase to constant motion.
   
4. 4 Release the clutch quickly and be prepared to throttle the gas pedal as the engine is turned over by the motion of the vehicle. When in gear, the engine will be forced to crank and the ignition will send a spark for a start. The quicker the vehicle is going before the clutch is released will determine how many times the engine will turn over. More cranks equal more opportunities to ignite the gas and air for combustion and the engine to start without a battery or starter
   

Transmission fluid is likely too low, when the drive shaft was removed to replace the u joint, trans fluid needs to be topped off. Also, you may want to replace the vacuum module or at least check the vacuum connection. if none of these procedures work, the the trans had another issue not related to the drive-shaft.

There is more than just ignition that could be the issue, including fuel injectors and EGR. Try this link to see if you get more ideas:

http://www.engine-light-help.com/P0300-check-engine-light.html

Interference may be caused by non - resistor spark plugs. If you don't want to change your plugs for resistor plugs, you may be able to get an inline resistor for the antennae from your local electronics supply store, like radio shack. Failing that, you can buy a cb antennae with a built in resistor coil that will also do the job. If you buy the new antennae, go to a cb shop to have your antennae tuned to your cb - it will increase your range and clean up your sound too.
Hope this helps, and please rate my solution!!

Check your fuses. Fuse is usually located inside the cab

5.0L and 5.7L Engines To Remove:

1. Remove the crankshaft balancer.
2. Drain the cooling system.
3. Remove the water pump.
4. Drain the engine oil.
5. Remove all engine oil pan fasteners except two nuts at rear of engine.
6. Separate the engine oil pan from the front cover.
7. Disconnect the crankshaft position (CKP) sensor wire.
   
   
8. Remove engine front cover.
   
   
9. Pry the oil seal from the front cover.
10. Inspect the front cover seal area and crankshaft balancer seal area for damage.
    
    
11. Rotate the crankshaft until the timing marks on the crankshaft and the camshaft sprockets are aligned.
12. Remove the crankshaft position sensor reluctor ring.
    
    NOTE: Free play on the slack side of the camshaft timing chain must measure less than 0.43 inch (11Mm) or timing chain and sprockets must be replaced.
    
13. Remove the camshaft sprocket bolts.
14. Remove the camshaft sprocket.
15. Remove the camshaft timing chain. NOTE: Do not turn the crankshaft assembly after the timing chain has been removed in order to prevent damage to the piston assemblies or the valves.
    
    
    
16. Remove the crankshaft sprocket using J 5825-A.
17. Remove the crankshaft balancer woodruff keys (if required).

To Install:

1. Install the crankshaft balancer woodruff keys into the crankshaft.
2. Align the crankshaft sprocket keyway with the crankshaft balancer woodruff key. WARNING
   Wear eye protection when installing crankshaft sprocket.
   
   
   
3. Use J 5590 to install crankshaft sprocket.
4. Install the camshaft sprocket and camshaft timing chain.
   
   
5. Ensure that the crankshaft sprocket alignment mark is in the 12 o'clock position and the camshaft sprocket alignment mark is at the 6 o'clock position.
6. Install the camshaft sprocket bolts and tighten the camshaft sprocket bolts;
   • Torque to: 18 ft. lbs. (25 Nm)
7. Install the crankshaft position sensor reluctor ring until completely seated against crankshaft sprocket. NOTE: The composite type engine front cover and seal must not be reused. Always install a new engine cover with a new seal.
   
8. Install new engine front cover and bolts.
   • Torque bolts to: 106 in. lbs. (12 Nm)
9. Clean sealer from corners of oil pan gasket where it meets the engine front cover.
   
   
10. Apply a 0.196 in (5 mm) bead of adhesive, GM P/N 12346141 or equivalent, 1.0 in (25 mm) long to the engine front cover to engine block junction.
11. Install oil pan bolts.
    • Torque bolts to: 106 in. lbs. (12 Nm)
12. Tighten oil pan nuts.
    • Torque bolts to: 18 ft. lbs. (25 Nm)
13. Connect the crankshaft position sensor wire.
14. Install the water pump.
15. Install the crankshaft balancer.
16. Fill the engine to the proper level with oil.
17. Fill the engine to the proper level with coolant.
18. Test drive the vehicle to confirm the repairs.

adjust the stricker bolt on door pillar . on door grap side of door move up - down to see if has play in door after replaced door pins -bushings

Same issue and it is a pain in the *** to spend ten minutes trying to shift to 4wd and get it to go in or out. Did replace the actuator on the differential and it still does not work correctly.

What year is it? Ignition module?

if it was me i would stop by my local library and see if i could get my hands on a Haynes auto repair manual for my truck or stop by your local GM dealership in the parts department and see if they can help you wish you the best of luck Michigan Man.

YES! Stop spending the money on this! Get the ECM interrogated.

You have 2 sensors....1 in front of the catalytic converter and one after it.