Now it will not start

94Beater · #1 07-02-2008, 12:05 PM

Ok, here is the rundown
Truck has been sitting for a few months. Battery was out, I had to change the transmission on it, etc, etc.
Any way I got everything back together and triy starting it - NO GO.
It will turn and start if I've sparyed carb cleaner down the TB - OK Problems with fuel delivery - Probably bad fuel pump.
Got the fuel pump replaced yesterday.
Yeah baby it started but only for about a minute or so[:'(]
It would not start again. I checked fuel -it goes in.
Before I got it back together I've changed spark plugs, wires, cap and rotor.
When it ran it sounded fine, except sputtering a little at higher rpm.
My guess is that one of the sensors is out

WHICH ONE[sm=confused06.gif]
TPS
IAC
MAP Sensor
maybe Oxygen Sensor [sm=smiley29.gif][sm=smiley29.gif]

Any input appreciated

94Beater · #2 07-02-2008, 07:04 PM

[&:]C,mon guys I'm not talking building a space ship I just need to get this truck running.
I guess you know my symptoms - now give ma clue of how to diagnose the problem.
I got fuel delivery OK
There might be an issue with spark - How do I trace where the fault is?
I've changed cap, rotor, wires, spark plugs and even coil.
AND IT RAN OK (for about 1-2 minutes)
Tried putting little gas in the TB - NO start
Could faulty sensor cause the truck not to start??

SRT_Sizzle · #3 07-02-2008, 07:49 PM

It could definitely be a sensor, but I have to ask... have you checked the injectors to see if they've fouled?

Timb75 · #4 07-02-2008, 08:19 PM

You drained the gas before you tried to start it right? If not there is a good chance you gummed up a line or injector.

94Beater · #5 07-02-2008, 10:40 PM

I did not drained the gas. I've added about 8 Gallons of fresh fuel plus the whole Sea Foam bottle to the tank. Plus the whole fuel pump assembly/pickup is new.
All 8 injectors would have to fail at the same time, otherwise I think I should get at least some kind of a misfire with a at least one good injector.

94Beater · #6 07-02-2008, 11:50 PM

OK, lets try different angle.
What would be the symptom of:
1. Faulty IAC Valve
2. Faulty TPS Sensor
3. Faulty MAP Sensor
4. Faulty Oxygen Sensor

dhvaughan · #7 07-03-2008, 12:16 AM

ok, several things.

1. i've seen people post that a dead battery can really screw up things with these trucks, so if yours is weak, put it on charge and get it up to 12 volts.
2. you can probe the TPS with a digital multimeter. throttle closed is about .6 volts and wide open is about 5 volts (i think). tps has a lot to do with fuel delivery.
3. IAC is only responsible for idle, and only when your foot is off the gas and throttle plate is closed. so if you press the gas pedal a little to open the plates, the IAC is out of the picture.
4. i don't know about MAP.
5. O2 sensor only comes into play when engine temp is up and the pcm decides its time for closed loop mode. o2 sensor tells pcm how much unburned fuel is in the exhaust and pcm tweaks fuel mix lean/rich. at cold start up, i don't think this has anything to do with your problem.
6. i'd check for spark by removing a plug, connecting the plug wire, grounding the plug to the block/head/bolt and having someone crank on the motor. bright blue popping spark is good, no spark is bad.
7. i'd try to start it by having an assistant crank on the motor and dribbling a small amount of gas or starting fliud down the throttle body.
8. i'd test fuel pressure the shade tree way, by pushing in on the little valve on the fuel rail (while key is on). gas squirting out under high pressure is good. don't smoke while doing this or #7.
8. you said transmission has been out. there is a crank position sensor on the back of the block, passenger side, in an impossible to get to place. its possible to mash the wire to this with the transmission. i don't know how to test it.
9.keep going back to the basics. all the truck to needs to run is gas, compression, spark, and timing.

master tech · #8 07-03-2008, 12:27 AM

I would drain the fuel tank and remove the tank too, You may have some bad fuel or sugar in the tank or some kind of crap. And also blow out your fuel lines too.

Sixtysixdeuce · #9 07-03-2008, 12:55 AM

Once it stalls, are you loosing fuel or spark? Obviously this is not a mechanical issue, or it wouldn't start at all. Check your relays-could be heating up and failing.

94Beater · #10 07-03-2008, 01:15 AM

Thanks for all the replies,
Battery new - checked 12 V OK
TPS - will try to do the test this weekend
IAC - I don't think so
MAP - leave it alone
Oxygen sensor - now here I'm having little question. O2 sensor goes into play when the truck warms up. Well truck was running for about a minute or so just about enough to get warmed up, then I try to rev it up and it sputtered, blew black smoke from the tail pipe and ran like S__T. Felt like it ran on 2 cylinders and I could smell the sulfur in the unburned fuel. This is when I shut if off and was unable to start since.
Crank positioning sensor - I was very careful not to damage it, and it looks OK
I'll try rest of the tests this weekend
Thanks again