My '97 2500 (5.9L Gas) won't start. It has a had a problem for a a few months now where if I don't use it for a few days it is very hard to start, but if I do get it running and then remember to start it and run it everyday, it seems to be fine. What happens after it sits for a few days is it will crank forever and if I hold the throttle at WOT, then it might catch and if it does, it runs really bad for a short bit and then finally "catches" and then runs and starts fine the rest of the day.

Now, however, it won't start at all and when it tries to catch it backfires up through the throttle body. You can see some white smoke too and it makes a loud noise like it's gonna throw a rod or something and then it dies. I have tried some starter fluid to see if it is a fuel delivery problem and it doesn't help. You can also smell gas after a while like it's getting flooded, so it seems to be getting fuel.

I have replaced the coil and bought a distributor cap and rotor. Haven't replaced these yet, as the distributor seems pretty buried and looks like a real pain to get to in order to do the cap and rotor. Does replacing the cap and rotor seem like the next step in the right direction in troubleshooting the issue, though?

 

If the cap and rotor have been on there for a long time, it couldn't hurt.

How is your fuel pressure? That could lead to long cranking and no start. Not necessarily the backfire, though.

 

Yes indeed, cap and rotor seem like likely culprits. And it's the time of year for it, too, when low overnight temps cause condensation inside cracked distributor caps, which causes arcing, which causes carbon tracking, which causes adjacent terminal firing, which causes backfiring and smoke in the intake manifold, and can cause a really loud noise when a spark plug fires really, really early in the compression stroke and stops the engine dead in its tracks.

And, apparently, it causes run-on sentences, too.

 

Thanks. I'll try the cap and rotor and report back if it fixed it.

The distributor looks hard to get too. I hope it isn't as hard to do as it looks.

 

Inb this case, looks are NOT deceiving! Sorry.

 

You will be working blind is the best way to describe it.

 

It's hard to get to. I use a Tire Step to get myself up in there, other guys lay a piece of plywood over the radiator shroud and atop the fenders to get a platform to lie on. It helps to have a fair sized inspection mirror, too. And lots of patience.

Those fasteners like to break, so apply plenty of penetrating oil in advance of the job, and give 'em a good whack with a hammer (through a steel rod, of course) to bust up the corrosion before you start.

 

Replaced the cap and rotor. It was a real pain. Thanks for all the advice. The old cap had some nice corrosion on the inside contacts, so it needed to be done.

The truck starts now, but runs rough and stalls if I take my foot off the gas. Wonder if I got a vacuum leak or a misfire on a cylinder?

 

Didja reset the PCM as part of the job? If not, give that a try. Just disconnect the negative terminal and let it sit for ten minutes or so, then hook it back up and give it a go. You might double check the plug wires for correct connections and routing while you wait. I like to follow that with a warm-up, then find a spot where I can cruise at 40MPH for a mile or so to allow the PCM an opportunity to recalibrate the IAC.

 

Found out what the cause of the hard starting and no idle was. A small vacuum hose on the front of the throttle body was cracked and falling apart (one side of it was plugged into the throttle body, the other to a black plastic vacuum line. The cracked rubber piece was probably not more than 1-2 inches long). I noticed someone had "Jerry rigged" it before using some gasket sealant, but obviously that was a temporary fix.

It starts up great now and will idle, but it runs a little rough, like a cylinder is not firing. So I checked the new distributor cap and found #7 wire was not plugged in. I thought to myself, "That's gotta be it", and found the hanging wire and plugged it in the cap.

No dice. Ran the exactly the same. I checked the other wires (by feel, of course, since it is ridiculously hidden back there) and they all seem to be plugged in.

When it runs rough it also makes a small knocking noise. It never did this prior to my replacing the parts I just did. It did backfire bad a few times while diagnosing the problem, so I hope it didn't damage anything.

Do you think I may have got one of the plug wires on the distributor crossed or in the wrong order? I am thinking maybe I need to replace the wires and plugs next.