89 GMC Sierra, was runnig good and next morning wouldn't start without flooring gas pedal, big black smoke coming from exhaust, we have changed the module, the coil, cap & rotor & wires, spark plugs are new, new gas pump and filter and relay, as well as a new map sensor and idle air control valve as well as pcv valve now truck won't start at all. Can you help us?? Please and thank you.

Maybe to much fuel. Does your coolant gauge work or register? Could be the ECT sensor. Could be fouled plugs also. Do you have smoke coming out the back? is it black smoke?

The first things I would try would be pulling the vacuum hose off of the fuel pressure regulator and look for presence of fuel,if there is fuel the regulator has failed.Next would be to clean the mass air flow sensor.Also a good tune-up would help fuel mileage as well.

When your replaced the pump did you replace the fuel filter? You may have a fuel pump relay causing you some grief. I believe it is located in the engine compartment in the fuse center on the left inner fender. Check the relay and any related fuses. Check the electrical connection at the pump. They had problems with some of them and they would get kind of hot and distort and corrode. They have new updated ones that can be easily installed.

I am having the same problem. I would really appreciate it if you have found a solution to this problem to em me. I have checked the fuel pressure, map sensor, TPS sensor and even tried a new ECM. None of them was the problem. Every once and a while I will get it to start and then after about a minute the idle will speed up and I can tell that it is getting too much gas. Then the times that it won't start I try holding down the gas so that it shuts off the fuel supply and once it begins to fire the injectors begin to just dump way to much gas into the throttle body. Let me know if you have found a solution. It info would be very much appreciated. [email protected]

first ,l want to know whether is caburettor type or injection,if carb check your carb float, injection you should get a car scanner read for fault code maybe air mass sensor, coolant temperature sensor or 02 sensor

If you have excessive white smoke coming from the vehicles exhaust, it sounds like your headgasket is failing. Especially having a rough idle too. Check your coolant level, does your exhaust smoke smell sweet, like Antifreeze? If so, the gasket has blown. Hope this helps...

If it is an automatic,it sounds as though the trans is shot. Will have to come out and be broken down, to find the issues

This is what i would try (cheapest first) redexe/wyyns
injector cleaner,double dose,then i have put 1gal gas in 10gal diesel to increase burn temp (you may encounter a hot start problem temporarilly)then if still smoking, get a compresion check on the engine(this will tell you volumes)
by the way the NATO tanks put in 1/3 gas in diesel to stop it freezing in arctic conditions.any more than 1/3 can result in problems.

turn the key to the on position and press the gas pedal to the floor 6 times in rapid succession. than start the trurck without turning the key off

Sounds like you need a coolant temp sensor. You want the one that reads the computer, not the gauge. This is a common problem on these trucks.