'96 80 Wont Stay Running (1 Viewer)

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Joined
Oct 5, 2018
Threads
17
Messages
94
Location
Southern California
Hey all,
So my '96, 195,000 miles, battery little less than 2 years old, my daily driver that I have poured a lot of money into in the last two years having the brake system what feels like everything else rebuilt or replaced (fuel system is untouched to my knowledge). Recent history: I drive it about 25 miles a day five days a week, with no problems, and did a 3" Icon Phase I lift back in December. Major recent repairs: Has had transmission rebuilt, brakes rebuilt with new everything including master cylinder and booster, new power steering pump, all new coolant hoses and PHH, blue fan clutch, all fluids changed, new plugs and wires. Very long term wish list: bumpers, knuckles service, delta front radius arms, and landtank lower control arms, oh and my lockers won't engage (but that's another story, actuators I think). I will admit I am a half banana mechanic, and have intentions of getting better at it, but kids and work have been all my time since getting the cruiser. I have a mulit-meter but don't really know how to use it yet (full disclosure here), and decent set of tools.
OK here's what's wrong

With COVID mess I've been working from home and I parked the truck a month ago and didn't start it until Tuesday of this week. Two days before I parked it my daughter left the rear dome light on and the truck was bit hard to start the next day but it fired up. Week before last I tried to start it and got one feeble rurrrr, then totally dead.

Finally this Tuesday a friend came over and we jumped started it without seemingly any problems at all, I drove it around town for more than an hour without turning it off, and it drove like normal without a complaint. This morning, four days later, I went to do some errands, and she started right up ok, so I left her running and ran inside to get a few last things. Five minutes later I jumped in and noticed the idle was really weak and as I thought that it sputtered and just died. Weird I thought. I restarted it which it did just fine and drove off, it seemed a bit sluggish but not too far from normal and about two hundred yards from home after driving up a small hill, it died again, no jerking just died. I coasted to curb and restarted it, again started up just fine, flipped U-ey and headed home, truck died again at stop sign. Restarted fine again and drove it home, seemed like I needed to keep it revved as I didn't want to let if fade and die again so I kept the revs up and got it home.

I looked at the emergency break down sticky and stuff about the fusible link etc. but just don't know with it starting up and running a bit?

I'd love to try and fix this myself and save the money and sincerely appreciate any suggestions. I don't know if something in the electrical system got fried during the jump start? (but why did it drive fine right after?) or if the fuel system is clogged? Thanks all for reading all of this,
Bob
 
I've never even heard of an ICV, I'll have to look that up! THanks
That's because it's called an ISC valve (idle speed control valve").
What is your battery voltage?
Are you getting the dashboard christmas tree lights?
 
That's because it's called an ISC valve (idle speed control valve").
What is your battery voltage?
Are you getting the dashboard christmas tree lights?
So I just ran outside and started it to check, so it started right up like normal, no lights out of the ordinary, the voltage guage on the dash was mid way between the middle and top at 18V so what is that 13V approximately. I let it run and it is weird the revs just begin to fall away slowly like a balloon running out of air slowly, the tach just fell slowly unitl it just dies. If I rev it , it perks up again for a sec but then starts to drop slowly again. any ideas? Thanks!!
 
So I just ran outside and started it to check, so it started right up like normal, no lights out of the ordinary, the voltage guage on the dash was mid way between the middle and top at 18V so what is that 13V approximately. I let it run and it is weird the revs just begin to fall away slowly like a balloon running out of air slowly, the tach just fell slowly unitl it just dies. If I rev it , it perks up again for a sec but then starts to drop slowly again. any ideas? Thanks!!
After it starts, how long before the idle starts to drop?
 
If the ISC was stuck then it wouldn't idle at all.
This sounds like fuel starvation.
I would certainly consider replacing the battery if it was drawn down flat and it is a standard flooded cell. They never come back from the dead.
 
If the ISC was stuck then it wouldn't idle at all.
This sounds like fuel starvation.
I would certainly consider replacing the battery if it was drawn down flat and it is a standard flooded cell. They never come back from the dead.
Thank you ok, its just an interstate battery, is there a better brand or type I should get instead? And any particular parts in the fuel system to start with typically? Fuel pump? filter? I should look in the archives . . . thanks again!
 
If the engine started normally then there should be sufficient battery power to run. As Jon stated once a battery has been flattened its lifespan is very limited but should not be your current problem. First thing you should check is that the intake tube is good condition. They tend to fail on the underside where the ribs seperate which allows unmetered air causing the engine to die. When the engine is revved it will overcome the problem until the idle falls again.
 
Is the "Check Engine light" on? What is the code if it is on? Usually an air tube, or other intake problem will set a code. The fuel system does not have any psi sensors in it and will not set a code if there is a fuel pressure problem caused by a bad fuel pump, relay, or filter.

After reading the repair list you have done, I would agree that you are a person who buys the best, and an Interstate battery is what you want. Now would be a good time to get a bigger one than the recommended stock size for the truck. I don't know the series numbers off hand, but a larger, higher cold cranking amp battery will fit nicely in the tray.;)

As for messing up a car when jumping it, just be sure the car that has the good battery is completely turned off when you jump from it. The good battery car's keys should be in your pocket. Basically, if the good car is running, and the dead battery car starts, the dead battery car goes into full charge amp output mode to make up for the dead battery. The good car can't handle the high voltage/ amps from the dead battery car, and can fry the good cars electronics. Not the problem in your case, but still a good habit to observe when jumping batteries. You will eliminate any chance of a problem.
 
perhaps this might be useful:

Not sure this applies to a '96, though.

It helped me when the '93 didn't want to idle at all after the battery had been disconnected.
 
Is the "Check Engine light" on? What is the code if it is on? Usually an air tube, or other intake problem will set a code. The fuel system does not have any psi sensors in it and will not set a code if there is a fuel pressure problem caused by a bad fuel pump, relay, or filter.

After reading the repair list you have done, I would agree that you are a person who buys the best, and an Interstate battery is what you want. Now would be a good time to get a bigger one than the recommended stock size for the truck. I don't know the series numbers off hand, but a larger, higher cold cranking amp battery will fit nicely in the tray.;)

As for messing up a car when jumping it, just be sure the car that has the good battery is completely turned off when you jump from it. The good battery car's keys should be in your pocket. Basically, if the good car is running, and the dead battery car starts, the dead battery car goes into full charge amp output mode to make up for the dead battery. The good car can't handle the high voltage/ amps from the dead battery car, and can fry the good cars electronics. Not the problem in your case, but still a good habit to observe when jumping batteries. You will eliminate any chance of a problem.
Thanks, no no check engine light on, it popped on once when the truck died at the stop sign but when I restarted it yesterday after limping home there were no unusual lights at all! Would intake issues throw a code?Thanks, and I'll look into getting a new battery, another interstate!
 
Serious intake manifold leaks will cause the computer to throw a "lean condition" code. The tube everyone talks about is a very common place for a leak to happen.

Take the tube off and look at it very closely. They usually break due to oil change shops opening up the air filter without removing the tube at the same time. They man-handle it and bend it upwards cracking the old brittle rubber tube.

A definitely red-neck half ass test for the IAC is to tap it ever so lightly when the car is idling. It is nothing more than a tiny motor that turns a "plug" that lets air into the engine. If the motor inside is going bad with a rough spot on it, tapping it will get it to move again. And your idle will change. If it does change with the tapping, the IAC motor is most likely got a bad spot in it. Tap with your finger. Even the back of a screwdriver can crack the plastic IAC housing.
 
Serious intake manifold leaks will cause the computer to throw a "lean condition" code. The tube everyone talks about is a very common place for a leak to happen.

Take the tube off and look at it very closely. They usually break due to oil change shops opening up the air filter without removing the tube at the same time. They man-handle it and bend it upwards cracking the old brittle rubber tube.

A definitely red-neck half ass test for the IAC is to tap it ever so lightly when the car is idling. It is nothing more than a tiny motor that turns a "plug" that lets air into the engine. If the motor inside is going bad with a rough spot on it, tapping it will get it to move again. And your idle will change. If it does change with the tapping, the IAC motor is most likely got a bad spot in it. Tap with your finger. Even the back of a screwdriver can crack the plastic IAC housing.
Nice, thanks I think I will look into getting a new intake tube as mine is original, I wish there was a repair guide to 80s with lots and lots of pictures! Thanks I am still wondering if I should have the fuel pump and filter changes as well?
 
As for messing up a car when jumping it, just be sure the car that has the good battery is completely turned off when you jump from it. The good battery car's keys should be in your pocket. Basically, if the good car is running, and the dead battery car starts, the dead battery car goes into full charge amp output mode to make up for the dead battery. The good car can't handle the high voltage/ amps from the dead battery car, and can fry the good cars electronics. Not the problem in your case, but still a good habit to observe when jumping batteries. You will eliminate any chance of a problem.

Where have you heard this? Why would you run the risk of disabling BOTH vehicles when jump starting?

The good car CAN handle the amps / load from the dead car, because that's what the system is designed to do. The alternator / generator on the dead car has a regulator that SHOULD limit the charging from that vehicle and will therefore not damage the good vehicle.

Also, if the good car is running, your are SUPPOSED to rev the engine to about 2000 RPM to increase the amperage and voltage output of the alternator. If you leave the good car off, you ONLY get whatever power is in the battery. It may not be enough.

If you're dumb enough to hook it up backwards, it will damage one or BOTH vehicles whether it's running or not. Then you have TWO dead cars on the road.

This is why I NEVER trust anyone to hook up to my vehicle except ME. I confirm the markings on the BATTERY, I do NOT go by cable color.

When hooking up:
You should always connect the cables to the DEAD car first. (FOLO)
Connect the cables to the GOOD car second.
Connect the positive cable first on both the good car and the dead car.
Always connect POSITIVE to POSITIVE, regardless of cable color. (This includes positive ground systems.)
Connect the negative cable second on both the good car and the dead car.
Always connect the NEGATIVE to NEGATIVE, regardless of cable color.

When disconnecting:
Always disconnect the GOOD car first. (Last on, first off. LOFO)
Disconnect the NEGATIVE cable first
Disconnect the POSITIVE cable second
Disconnect the cables on the dead car.
Disconnect the NEGATIVE cable first
Disconnect the POSITIVE cable second

Always make sure when handling cables that the clamp ends are kept away from each other, whether you are working on the good car or the dead car.
The reason you hook up the dead car first is because there is always a spark when the connection is made. On the older Lead Acid batteries, Hydrogen is released during charging. This is especially important when DISCONNECTING, as the dead car will have an "envelope" of hydrogen around the battery and the spark CAN ignite it and explode the battery.
 

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