joshm

I have a 1997 k1500 350 that just this afternoon decided it would not start. Ran fine all day yesterday but this afternoon would buck and stumble while attempting to start. I had this problem last year and the culprit was a cracked distributor cap. So my first course of action was to replace both the distributor cap and rotor. Still stumbled and bucked while attempting to start. Next, I checked all the fuses in both engine and passenger compartments all of which are fine. I then checked spark with an old plug and it produced a nice strong blue spark. After a new set of plugs I noticed there were two on the drivers side that were fouled pretty badly with somewhat grainy deposits on the ends. Tried starting again and the vehicle still stumbled but did not buck much at all (seems like a slight improvement). Consulted a local auto shop, where they loaned me a fuel pressure testing guage. I was told a reading of anything below 60psi and the vehicle will not start, anything above would be sufficient. Upon testing pressure yeileded consistant 62-63 psi readings. I then bled off a quart mason jar of gas for inspection, I noticed some sediment in the bottom and a bit of water along with amber colored fuel. My next step was to bleed around 1 gallon of gas from the tank hoping if there were sediment or water it would be removed. After doing so I replaced the fuel filter, bled another 2 quarts through the valve on the fuel line before the intake and checked the third quart for sediment and water. The gas came out clean and water free. Again I tried starting the vehicle only to find my efforts were still in vein, the vehicle still stumbles while trying to start. Any suggestions are greatly appreciated.

golfer

Curious... is this only happening at cold start ??
Once it's finally started does it run better after awhile ??
When you say it's stumbling do you feel that's because of too rich or too lean condition ??
Are there any problem codes ??

There may be problems with the IAC , MAS , cam sensor or crank sensor circuits , vacuum leak.

joshm

This just happened yesterday for the first time in about a year (last time was cracked distributor cap), it wont run at all. Engine stumbles periodically while turning over as if it has fired on at least one cylinder, but refuses to start.

lost_in_alabama

My thought is that the timing chain jumped. How many miles on the engine? If it will start if you retard the ignition timing, then that might be it.

joshm

350 has 93k and some change on it, not sure if I would want to mess with timing being that its mostly computer controlled through the distributor. Towed it to a local shop yesterday after running out of ideas aside from: 1. A sensor of some sort. 2. ECM issue. Since I dont have diagnostic computers going any further in depth seemed a bit too risky. Later in the day I recieved a call shortly after, wondering if I had toyed with the distributor at all. The mechanic said it was sounding like a timing issue. I rattled off the list of everything I checked and replaced. Hopefully I'll hear back today that its fixed. I'll let everyone know what they find out. Thanks for the suggestions

SRoth

I went to start my truck today and from what you have described above, my truck is having the EXACT same problem. Please post the results from the mechanic as soon as possible. thanks

bk94si

When did you last put gas in it? Maybe you got some contaminated gas.

joshm

Well the shop finally got it running, turns out the brand new distributor cap was defective. The #3 cylinder trace inside the cap shorted directly to the pin for the coil, number 3 had all kinds of spark while the rest of the cylinders barely had any. The mechanics also mentioned that the fuel pump relay had intermittent failure while they were working on it. the final problem was that supposedly some of the lifetime warranty wires I had put in a few years ago had also died, so I'm off to Napa today to get reimbursement for wires cap and attempt to argue over some of the labor charges. They also mentioned that the screw holes for the distributor cap in the distributor were broken (which I dont recall when I replaced the cap last time). I'm not quite sure how thrilled I am about this new problem, I guess it will depend on whether or not the distributor base can be repaired or replaced without too much hastle. Also mentioned that the ignition will need replacing. I had figured it would since the key has not turned into the acc position for several months. It's becoming progressively harder to get the key to turn at all from the off position. All and all I was only billed for 3 hours of labor even though it was at the shop for 2 days. Thanks for the help, hope this can be of use in the future.

golfer

Glad you got to the bottom of the problem.
Dosen't that just tick you off when the " NEW " parts are junk then really gets you chasing around.

opie4487

AWESOME...
I found that useing AC DELCO parts is best!!....Every time I've tried other brand plug wires/distributor/Ect...I found that they Arced terrible