1997 K1500 Intermittent Running

[AnchorJoe]

I have a 1997 K1500, 4WD P/U, that for some reason this morning decided to stop running. I attempted to restart the engine several times with no success. I turned the after market radio off so I could listen to what it was doing during the starting process. Once I did this, the engine started and I proceeded to work in which I was about 1mi away from when this happened. While I was driving the truck, it seemed a little different to drive (i.e. steering didn't seem normal, engine seemed to be running a little rough). As I pulled into the parking lot at my work it was still running, but as I swung the truck around to pull into my parking space it stalled again forcing me to coast into the parking stall. I attempted to start the truck again and it would start. I left it sitting for about 30min and came out to try it again, in which it fired right up as nothing was wrong.

I am suspecting the fuel pump (ugh, I think it is in the tank and the tank is 3/4 full) since I am working a similar issue on my sisters 97 Blazer in which it is the pump. However; in talking to a few of my co-workers, it was mentioned that it might be the alternator. I am hoping that someone in cyberworld will have some expertise on this fault that can help me out. Also, when I did go back out and try to start it, I could hear the fuel pump running. Can these things go intermittent?? Help...

[Pamsdad]

My guess wouldn't be the alternator. Hook up a VAT and check it. Eliminate the possibility of a bad alternator.

Fuel pumps are all too common on GM's. You will need to hook up a fuel pressure tester to determine if your pump is working intermittently or not. When is the last time you changed the filter?

Gauge don't lie...

[AnchorJoe]

Well, I got the truck into my garage and start checking things, and before I could verify the alternator was working it stopped running. I did pull the filter, in which I have never changed in 90K miles (I know bad owner, I just can't fix what ain't broke) and the filter was plugged about 80-90%. Ran to the locate parts store and picked up a new Fram filter and put it on. Attempted to start the truck and it started and ran for about 2-5min and died and I haven't been able to get it going since.

In reviewing the Haynes book on the truck, I am suspecting one of two parts (Regulator or pump). I am going to take a stab and pull the regulator and replace and/or clean it and try it again. I am leaning this way since I can occasionally hear the pump turning on and running. Am I way off here???

Thanks for the helpful information... though..

[Silverado Brethern]

an easy way to know if the alternator was bad would be if your battery light is on, if its not its not the alternator cuz when the alternator dies the truck will run off of the battery until it goes dead..been there done that. i had this problem with my 97 and i had to replace all the plugs and wires...mudhole related im assuming however. but GM is known for having a fickle fuel delivery system, im assuming you mean fuel filter when you say you replaced the filter, if not do so. if that doesnt solve the problem then i would say there is i very strong probabilty that it is the fuel pump. not a desireable thing to replace but if its not that then you are back at guessing game.

[Pamsdad]

Joe

Changing fuel filters is maintenance. Not 'Fixing what ain't broke'.

If you hear the pump cutting in & out, chances are it's not the regulator. It's either a bad pump or bad connection.

[AnchorJoe]

I guess using the analogy "Fixing what ain't broke" was bad. In researching maintenance on this engine/truck, I was informed by a GM rep that nothing needed to be done to the truck till 100K. Which I must admit is against everything I know mechanically with regards to maintenance.

I am now to the point of acquiring another gas can to get more of the fuel out of the tank before I drop it for the pump. Can anyone tell me how to know for sure the pressure regulator is bad. If I pull it out, is there a way to tell it is bad?? I am really new to fuel injection, so I want to make sure I am doing the due dilagence here.

Thanks...

[Jeremy-WI]

Check battery connections and the ground wire that hooks up on the thermostat housing. The easiest way to get the pump out is to remove the bed from the truck and move it back a foot or two. I think there are 8 bolts holding the bed down, you have to remove a couple bolts holding the tank filler neck, a ground strap, and unhook the taillight harness connector.

You should really do a fuel pressure test, key on engine off, pressure should be 60-66 psi and hold steady when the pump quits

[AnchorJoe]

Jeremy,

Thanks for the helpful pump replacement shortcuts. I think that will make pump replacement alot easier than dropping the tank. I have now pulled the fuel pressure regulator to inspect it and it appears to be clean. I can also blow air through the center hole and feel it coming out the outer openings. I guess my next stop is the pump. I will let you all know updates as I get there. Thanks...

[Jeremy-WI]

Did any area near the fuel regulator look wet? There shouldn't be any sign of fuel in the upper intake area

[AnchorJoe]

Nope, not at all. There was fuel on the inside area where the regulator plugs in, but nothing on the intake area where the injector lines plug into. Also, the screen on the regulator appeared to be fairly clean. Should I assume it is good??

[Jeremy-WI]

It may be good if it isn't weak and sending too much fuel back through the return line, but its usually a good sign when the upper intake is dry

[AnchorJoe]

I believe I have found the problem. I pulled the bed off this morning to pull the fuel pump thinking that it was bad. Upon pulling the pump out of the tank, I looked at the wiring to find the positive terminal to the Pump a little melted and charred black. I also found the wire at the connection to be melted. So, now I need to locate a new wire harness for the pump/sending unit assembly. I checked with the local dealership and "ouch" those are expensive. I have to get the whole sending unit/pump assembly with all the metal hardware it through them it will run around $350-600 depending on what unit I have to get, yeah don't see that happening. I will check salvage yards for now and see if I can locate a new harness and go from there.

I appreciate everyones assistance on this...