98 Silverado Won't Start

Dylansdad · December 19, 2008

After sitting all week, the truck will not start. It has the 5.7, and will crank all day, but not start. I checked for fire with the old screwdriver in the plug wire end and it appears to be firing fine, but doesn't start. I can hear the infamous whine from the fuel pump when I turn the key on and I can smell gas after cranking it over for a short while, but nothing else is happening.......and yes it has 3/4 tank of gas.

Help?

Zembonez · December 20, 2008

After sitting all week, the truck will not start. It has the 5.7, and will crank all day, but not start. I checked for fire with the old screwdriver in the plug wire end and it appears to be firing fine, but doesn't start. I can hear the infamous whine from the fuel pump when I turn the key on and I can smell gas after cranking it over for a short while, but nothing else is happening.......and yes it has 3/4 tank of gas.

Help?

No help here Rick but I'll give you a free bump back up top. Maybe somebody can chime in.

green 788 · December 20, 2008

If it's been dumping gas into the intake while you've been cranking the engine, you may have a lot of fuel in your crankcase oil now. Just something to consider for after you get the truck running... an oil change would be in order. You'll smell the gas on the dipstick, and the oil will be very thin...

But on to the problem...

Here's what I have done in the past. (I'm not telling you to do this, just telling you what I have done)... ;)

Shoot a little bit (3 second burst) of starting fluid (ether) onto the air filter, and see if the engine wants to start and run for a second or so.

If it does, then suspect a fuel problem, such as a clogged fuel filter or a bad fuel pressure regulator (not letting the pressure go up high enough to open the injectors).

If the truck makes no attempt to start and run on the ether... then there's probably an ignition timing issue (since you've already verified fire on the plug wires).

A crankshaft position sensor can be the problem if it's electrical. Many engines go into "limp mode" when the CPS (crankshaft position sensor) fails, and the computer will just use the last good data it got from the CPS to keep the engine firing. But once you shut it down, it will not re-start because the computer doesn't know where the crank is, and it won't know when to shoot the fuel and when to make the spark. This is called "duh" mode. (Just kidding).

Since your truck was presumably running fine before parking it, I'd suspect this second scenario. Hopefully it won't be a computer failure, but that would be a possibility (not as likely, though, as a CPS failure though, I wouldn't think).

If you can get a diagnostic box to the truck, you should be able to read the fault code pointing to the problem.

Good luck. Let us know what you find.

Dan

pennzoil29 · December 23, 2008

If it's been dumping gas into the intake while you've been cranking the engine, you may have a lot of fuel in your crankcase oil now. Just something to consider for after you get the truck running... an oil change would be in order. You'll smell the gas on the dipstick, and the oil will be very thin...

But on to the problem...

Here's what I have done in the past. (I'm not telling you to do this, just telling you what I have done)... ;)

Shoot a little bit (3 second burst) of starting fluid (ether) onto the air filter, and see if the engine wants to start and run for a second or so.

If it does, then suspect a fuel problem, such as a clogged fuel filter or a bad fuel pressure regulator (not letting the pressure go up high enough to open the injectors).

If the truck makes no attempt to start and run on the ether... then there's probably an ignition timing issue (since you've already verified fire on the plug wires).

A crankshaft position sensor can be the problem if it's electrical. Many engines go into "limp mode" when the CPS (crankshaft position sensor) fails, and the computer will just use the last good data it got from the CPS to keep the engine firing. But once you shut it down, it will not re-start because the computer doesn't know where the crank is, and it won't know when to shoot the fuel and when to make the spark. This is called "duh" mode. (Just kidding).

Since your truck was presumably running fine before parking it, I'd suspect this second scenario. Hopefully it won't be a computer failure, but that would be a possibility (not as likely, though, as a CPS failure though, I wouldn't think).

If you can get a diagnostic box to the truck, you should be able to read the fault code pointing to the problem.

Good luck. Let us know what you find.

Dan

May also be the camshaft positioning sensor located under the dist. cap. My truck wouldn't start when it went bad.

Dylansdad · December 23, 2008

Ok now what....I scoured the internet and got many useful hints on some things to check on why this thing will not start, I had already done the obvious such as checking fuses, etc.

1) Fuel pressure, 2) fuel pressure regulator, 3) crank sensor 4) cam sensor, 5) ICM

these are just for starters....but I get home from work and go out to see if the security light may be blinking when I turn the switch on....I turn on the switch, all the standard buzzers go on, the fuel pump hums and cuts off, all is silent.....the security is not on....and then I hit the switch and VROOM this truck fires right up.....running just as fine as it did when I parked it a week ago...I go in the house and leave it running to warm up....it was 20 degrees....come out a while later, it is purring like a kitten....I get in it and drive around for 30-45 minutes, soft, hard whatever I do it never misses a beat...I go home and park it again, cut it off and fire it right back up.......all is good with the world again......only thing is I am afraid to take it anywhere that I have to cut it off as I don't know if it will start or do what it did this past weekend, it is not fun to work on it away from home in a parking lot somewhere, but in light of it running again, where do I go from here....I can not go forever with only driving it when I am not going to cut if off when I get back home....any thoughts or ideas of what to check or do now would be greatly appreciated !!