Top 20 1991 GMC Sierra - Page 2 Questions & Answers

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Now check if the vacuum operated doors work when you command various vents. There should be a vacuum line from the intake manifold that goes through the firewall and into a pod-like device on the back of the controls. From there vacuum lines run to the various doors. See if you still have a vacuum signal from any of them.

dave ,do you have it wired backwards? or there isn't enough pressure on it to activate . check that linkage is adjusted correctly

Pressure regulator or fuel injector lines leaking. The check engine light is on?

If that's all you have to offer then I would say your map sensor is bad...

run fault codes and check for MAP/MAF/VAF sensors and the HO2S sensor operation

When was the last time you change your fuel pump ? most of the time people over look the fuel pump and just change the filter.

Changing parts is not a solution or fix Testing a vehicle to find a problem is Once a problem is found, then the solution is usually there in front of you It starts Is the fuel pressure correct? Feathering the gas,that would pertain to the TPS Sensor Was that tested? MAP-no control over that,do you have vacuum leaks & were any of the maps tested & correct for your elevation or vehicle specs Spark Plugs Good Rotor & Cap Clean Vacuum Leaks? Got an IAC Valve at base of throttle body to clean or replace?

Have you plugged in a new map sensor and this happens, or just the original one? Could just be a bad sensor. Also you could have broken /exposed wires that are shorting out.

Remove spark plug cylinder #1 place cylinder end of compression time. Crankshaft pulley timing mark at 0 degree remove distributor cap then find on the cap where is the number 1 cylinder while placing distributor in place place rotor to face cylinder 1 wire replace cap and wires start engine and move dist. to the best rpm then with timing light adjust timing hope it help

try this, disconnect map sensor while running. if it runs a lot worse or rough. map is ok. but if it does not make a difference the way the engine runs it is bad. if disconnected the engine may shut off. this tells you the sensor is doing its job. yes they can go bad!

you said everything is changed out ( i assume this includes the computer or at least the hypertech chip upgrade ) if a chip upgrade was done you will find that one of the pins has been bent over and is not making connection, repair this chip, then try again .

The pump should turn on for 2 seconds with the key in on position. Then the computer will turn the pump off, and won't turn it back on until the engine is cranking. The 2 second period is to put pressure in the line and the fuel rail. It should hold pressure for about 15 or 20 minutes that way, before slowly bleeding off. It sounds like yours is working right.

Check fuel pressure

remove the drive shaft . drill a small hole in the seal face and insert a self tapper screw in it . Use something like a slide hammer or a lever and pull the seal out . insert the new seal and tap into place hitting on the outer edge only. A piece of pipe the is the same diameter as the outer edge of the seal is good. there may be some fluid loss so be prepared to catch it so that you know how much to put back in.

Only if you have a clutch assembly that is exposed. Chances are, no.

it might be you ignition coil that needs replaced

DL the opertators guide.its free for allcars.google it. " 2002 GMC Sierra 1500 operators guide"that trick works for all cars made,no need to guess.if your is lost. RTM

Ignition 'Spark' present ?? If you need further help, reach me via phone at https://www.6ya.com/expert/ralph_2f0886b7d6af32ce

If you can hear the starter then the solenoid is working as it has to work for the starter to make a noise.