2000 Sierra 1500 4.3 Died Today

g0speedracer · June 5, 2007

I have a 2000 Sierra 1500 4.3l with 110k which suddenly stalled on me today while driving. Since then it will not start. I have checked the fuel pressure and can see roughly 60psi when cranking the engine and it drops to about 54psi when I turn off the key. The fuel pump sounds like it is making noise when I turn the key.

I replaced the distributor cap and rotor and checked spark on one of the plugs. I did notice the old rotor had quite a bit of play in it which was still there when I put the new one on. Not sure if this is normal or not. I also checked all the fuses in the engine bay.

I have only had the truck for about a month and the gas gauge was not working properly when I bought it. This led me to think it could be the fuel pump but it looks to be producing the needed pressure. It looks like an OEM fuel filter and I have no idea the last time it was changed. At this point I am a bit lost on what to do next. I bought a FPR just in case but from the looks of it I may need to take off the intake manifold to get to it. Anyone have any ideas?

Drunken Sailor · June 5, 2007

There are only 3 things that can stop a vehicle from starting - loss of fuel, spark or compression. It sounds like you have fuel, so that's out. A plugged filter won't stop a vehicle from starting, it will only reduce volume, not pressure. You said you checked for spark; is there any? Check on at least 2 plugs. Lastly, check compression. Suddenly losing compression is highly unlikely unless your timing chain broke. Have somebody crank the engine and look in through the oil cap to see if the rockers are moving. If they aren't, the chain is broken.

g0speedracer · June 5, 2007

I only had time to check one plug for spark and it was there. The plug was somewhat dirty and smelled like fuel. I will check the rest of the plugs and the rockers tomorrow. Thank you.

MrTrot · June 5, 2007

I only had time to check one plug for spark and it was there. The plug was somewhat dirty and smelled like fuel. I will check the rest of the plugs and the rockers tomorrow. Thank you.

if you have compression, spark and fuel you should get fire... Even if somehow the timing jumped, you will get fire and resultant backfire or knock but if everything is basically there you will get something. Check for spark first, then fuel. If you have spark, you could inject a little fuel (teaspoon) in the cyclinder and crank to check for firing. Good luck.

g0speedracer · June 8, 2007

Ok, here is the update.

I took each plug out and tested for spark. They were all a bit wet with fuel so I dried them off and gave the engine a couple cranks to clear the cylinders. I put all the plugs back in and suprisingly it started back up.

I drove it home and decided to replace the fuel pump anyways since the fuel gauge was not working. I bought a FP from Autozone, put it in and no start. I could hear the pump working so I pulled the pump out and saw that they sold me a broken pump. The fuel line from the pump up to the top of the assembly was missing. Had to bring it back and by a new one from Napa. This one looked to be much better quality, it is a Carter. Put the new pump in and some new plugs. It started right up no problem. I drove it around quite a bit that day without any issues.

Today I get in to start it and it just sits there cranking away. I can hear the pump kick on but the engine just wont catch. I was thinking about getting a code reader to grab the codes off the ECU next eventhough there is no CEL.

Any suggestions?

dr.mediocre · June 8, 2007

I would look at the pickup coil in the distributor or the crankshaft position sensor.

g0speedracer · June 8, 2007

I just checked the codes. Nothing there. Does anyone know how to test the crankshaft position sensor? On my Audi I can measure the resistance across pins 1 and 3 but I have no idea what the resistance should be on the GMC. -Thanks

g0speedracer · June 15, 2007

So after inspecting the distributor I found that it does not have a pickup coil. The only sensor there is a camshaft sensor. Apparently, the truck has a HVS ignition system:

http://www.autozone.com/az/cds/en_us/09008...irInfoPages.htm

The truck seems to start fine during the day but for a couple days now when I go out in the morning it does not start. I then wait until the afternoon and it starts right up. The original problem all started when it stalled out on a rainy day. Could it be that the moisture is affecting it?

Drunken Sailor · June 15, 2007

Well, you know compression is good, and fuel should be good now, so we're down to spark. Another pointer in this direction is that it's happening when it's wet. Are your cap + rotor and wires good? If they are leaking, they will arc to ground when wet and you will lose spark. How about the plugs? Are they old and fouled?

g0speedracer · June 15, 2007

Plugs, cap, rotor, fuel pump and filter are all brand new. I did not replace the wires because during my testing I pulled the plugs and checked for spark. I had spark on all the cylinders but the plugs looked pretty dirty so I replaced them. Could the ECU cause these problems? I would think if it was a sensor I would see some kind of code on the reader even if the CEL is not on.

g0speedracer · June 15, 2007

Is there a chance it could be the ignition relay? I went to start it this morning and it just kept cranking. I let it sit for about 15 minutes in the sun with the hood up, tried it again and it started right up. I then pulled the ignition relay and tried to start it. With it pulled it seems to have the same symptoms. I tried putting the relay in the freezer for a bit and it still worked. I may just pick up a new relay anyways since they are so cheap.

jhm · June 15, 2007

I suggest new wires. I replace them when changing plugs.

g0speedracer · June 18, 2007

I bought a new relay and it did not fix the problem. The strange thing is that it only happens first thing in the morning. If I let it sit in the sun with the hood up for a bit it will start right up. I may just bring it in tomorrow and have the shop figure it out.

Rolandd · June 18, 2007

change your wires. They are probably oe and are done.

dreman · June 18, 2007

I recently replaced the cap, rotor, wires and plugs on my '99 GMC Sierra 4.3. I did all that hoping it wasn't the fuel pump, but the fuel pump was the problem. However, after I changed the pump, it started but ran poorly above idle. It turned out to be the cheap distributor cap and wires. New AC-Delco parts fixed it.