1998 Chevy Silverado Z71 intermittently won't start?

Question

truck runs fine for weeks, then just all of a sudden, usually in the morning will not start. then later in the day truck will start. sounds like it may have been flooded with fuel. any ideas of what the problem is and how to fix it, is appreciated.

Answer 1

Just guessing, but sensors such as TPS, air temp, engine temp, oxygen sensor, crankshaft position, manifold absolute pressure could be possible faults.

Although you mention too much fuel, it would be helpful to check the fuel pressure during a no-start conditon. Is the fuel pump failing?

If it was *my* truck, it would scrutinize the air temp sensor, tps and manifold abs pressure the most closely. Clean the engine and go over it thoroughly for chaffed wires. Dump out the check engine codes, then look up the problem in a table.

Best of luck to you. The Z71 is a lovely truck. :)

Answer 2

Have same 1998 Silverado with 5.7 engine, will not start when conditions are damp and humid. Nothing to do with sensors or fuel pumps but condensation on underside of distributor cap, have changed mine on three occasions and works for about a year. Short term remedy is to place an old style trouble lite over distributor and wait an hour, heat dispenses moisture and starts fine.

Answer 3

Since they've introduced ethanol to gas recently there have been a lot of fuel pumps replaced. The fuel pump may be going bad.
When it doesn't start...Open up the hood and press the fuel rail schrader valve in. It looks like the valve stem on your tires...But it's on the fuel rail your injectors are hooked up to. See if the fuel comes out under pressure with the key in the on position. If not it's an intermittent problem with your fuel pump, Or fuelpump relay. If it is getting fuel..Wait for fuel to dry some that sprayed out..then check for spark. If no spark you may have the Ignition control module going out.
It's what the coil packs for your spark plugs are bolted to. They tend to have intermittent problems when they go out too.

Answer 4

Could be a leaky injector. Possibly a security key getting ready to bite the dust. Maybe a bad fuel filter. Shoot a little starting fluid in it tomorrow morning. If it fires right up, then it's definitely a fuel related problem. If it doesn't fire up, then it's very possible that you have a troubled security key or problem with the ignition system. Good luck.

Answer 5

The answer referring to ethanol in the fuel is correct. He has a lot of good things to look at. One thing not mentioned is carbon build-up. It has become more common, even with fuel injected cars. The problem stems from such fine spray patterns in the injector itself. There is a new fuel, with lots of extra detergent to combat this (at the request of several of the big auto makers.) The problem is most likely to happen if you drive a lot of shorter distances, or in colder climates where you let it idle for long periods to warm up. A simple fix for this is to go to your local Chevrolet (or other GM dealer) and buy a jug of their fuel system cleaner. You just pour it in the tank. It is extremely powerful! It costs about $23.00. Driving on one tank of fuel with the cleaner should fix the problem if it's due to carbon build-up. It's simple, it's fast, and it's relatively cheap, and you likely could use it regardless. I sell a ton of this to retail customers and independent shops, and they love it!

Answer 6

Your main consideration for these trucks will be use. If you are planning on pulling trailers around a lot like I do, you are going to want the larger motor in the full size truck. If you are wanting fuel economy while being able to put something in the bed of the truck and haul around your buddies, the colorado would be better. Its really going to depend on what you want too. The four doors of the smaller truck are going to be a bigger entrance than the two main doors and the third small door for getting stuff into and out of those trucks. There is a substantial difference in the towing capacity.