Chevy 350 stalls

[bctbct]

Truck has been running fine, only use it 4-5 times a month. 1993 150k

Wed. I jump started my lawn mower.

Fri

Started truck, moved to yard, truck idled fine for 5 min and then died.
Restart was labored, but did get it.
Died again 5 min. later at idle when loading truck with branches.

Sat.

Starts, dies, restarts, dies.

Seems to take longer to restart now. When I give 25% gas it seems fine for 30 seconds and then the motor acts like it is missing and revs up and down in a rythmn and then died. Battery is now low.

I changed the fuel filter, had the alternator checked, fuel pump makes noise each time I turn the key. Now truck runs for about 30 seconds and then dies.

I am stumped, one thing I noticed was that the speedo was showing 10 mph when I was reving the truck. I wondered if perhaps there was a short somewhere, but if that was the case the battery should have been dead when I started.

Ideas??

 

[Christobevii3]

Have you ever replaced the distributor?

 

[bctbct]

Have you ever replaced the distributor?

no

 

[boomerang]

Check the fuel pressure. The revving up and down in a rhythm sounds like a lean condition. You combine that with stalling and a hard start condition and it very much sounds like a fuel pressure problem.

Don't replace the distributor unless you'd like to throw more parts at the car.

The speedo is a curious situation. Your short theory is off base somewhat. You could still have a short in a circuit that's not energized unless the key is on. I'll have to think about this one for awhile.

You mentioned jumping the lawn mower. It seems like a hell of a coincidence that the car starts acting up afterwards. Anything unusual happen during the jump?

No check engine light? If it's not on when running, does it come on at bulb test or with the key on?

 

[bctbct]

Check the fuel pressure. The revving up and down in a rhythm sounds like a lean condition. You combine that with stalling and a hard start condition and it very much sounds like a fuel pressure problem.

Don't replace the distributor unless you'd like to throw more parts at the car.

The speedo is a curious situation. Your short theory is off base somewhat. You could still have a short in a circuit that's not energized unless the key is on. I'll have to think about this one for awhile.

You mentioned jumping the lawn mower. It seems like a hell of a coincidence that the car starts acting up afterwards. Anything unusual happen during the jump?

No check engine light? If it's not on when running, does it come on at bulb test or with the key on?

No CIL when its running, the young man who helped me jump start may have touch the cables together when he was holding them attached to the truck, but I did not see a spark

Several years ago I had a spark plug wire shorting out somehow on the engine block and I noticed the guages would jump around...this is why I thought maybe a short?

The part that has me stumped is that it appears to run fine at idle until it just quits, that why I was thinking fuel problem and started with the pump and filter. Can I rent/borrow a fuel guage or am I better off having someone test it for me?

 

[boomerang]

I own one, so as far as renting I don't know. I would take it somewhere. There is more to it than just checking the fuel pressure. There is a procedure to follow that can tell you whether it's the pump, the regulator or even a blockage in the lines. It's also important to know what the correct pressure should be.

One thing you could do is try a different relay. Find where the fuel pump relay is located and if it's in an underhood relay center, there will be other relays there. Swap the fuel pump relay for another one to see if the problem is corrected.

If the engine loses oil pressure the fuel pump will be shut off. You most likely are not loosing oil pressure per se, but instead the oil pressure sender could be going bad. Worth investigating, but without a guage to check pressure, replacement will be your only option assuming the wiring is not suspect. Edit: There may be multiple senders. If the truck has an actual oil pressure guage, the sender for that may not also function to cut the pump off. Even if there is just an idiot light, there may be two switches. Obviously you want to be dealing with the correct one.

It sounds like fuel to me. It's the first thing I would rule out.

If you think you could have bad plug wires, raising the hood in the dark with the engine running will allow you to see any arcing. Does the car actually have a distributor? If so, you could take the cap loose and check the underside of the cap and the rotor. Look for cracks, signs of arcing and moisture. I still think it's fuel.

I have not been actively working on cars for over 10 years. There are a few others here whose opinions I would trust. Hopefully you get some other opinions.

 

[bctbct]

looks like I better take it to the shop, thanks

 

[kornphlake]

My Chevy Blazer with a 4.3L (same as a 350 minus 2 cylinders right?) showed similar symptoms before I got rid of it, I took it to a shop and all they did was replace the battery. The engine would crank and start, it would even run but the gages would bounce around and acceleration was sluggish, like the fuel filter was clogged even though it was only 6 months old. I'd already replaced the fuel pump and relay previously as they'd gone bad 6 months earlier. Replacing the battery solved the problem, at least for the two weeks I drove it before selling it.

I couldn't understand how a battery would crank the engine but not supply enough juice to keep the engine running, the shop insisted the alternator was working fine and the battery just wasn't holding enough charge. I'd had so many problems with that vehicle I wasn't convinced that just replacing the battery was going to fix the problem so I went ahead and sold it while it was running. Like I mention, a new battery did fix the problem at least for a couple weeks. It's cheap and easy to test a battery, it may be worth while before taking the truck to a mechanic.

 

[bctbct]

thanks Korn I will try that, my battery has free replacement thru the end of this month.

 

[SpatiallyAware]

My bet is simply a bad battery from a vehicle that is rarely started. Most likely the first good cold started all of this

 

[funboy6942]

Change out your in line fuel filter. Usually attached to the frame under the drivers side.

 

[bctbct]

Fuel filter changed, alternator checked, battery checked and charged...still dies.

damn, knew this was a clunker 4 mos. ago, never become emotionally attached to a vehicle.

 

[kornphlake]

If the charging system and fuel delivery are in good shape I'd start looking for a vacuum leak, if you have an electronic idle air control I'd figure out how to test that and confirm it's working correctly, the throttle position sensor may not be functioning properly too. Good luck, Chevy engines are pretty simple as engines go and there's a ton of good info on line on them, once you've got the problem narrowed down it should be pretty easy to fix. One advantage to American made vehicles opposed to imports is that for a given model a high percentage will have the same problem or problems, so repairs are well documented. Imports may have fewer problems overall but they have more unique problems so finding information on repairs is often more frustrating.

 

[exdeath]

Should still have it checked with a scanner even if there are no codes, to monitor vitals like O2 feedback and injector pulse width, idle control counts, air flow, spark advance, throttle position, etc. to identify anything that might be acting up and causing the computer any difficulty in maintaining idle right when it starts to die out.

If you can coax a no start situation via repeated stalling and flogging, it makes it easier to find. Then it comes down to fuel + spark at the combustion chamber.

Regardless of computers, or electrical problems or anything else, ultimately one of those two things is going to be interfered with.

Fuel is pretty simple; is there pressure and injector signal? Hear and feel the injectors ticking? Does fuel pressure rise instantly when you pull the vacuum line off the regulator? Does it stay steady when revving? What does the needle do when it starts to die? Sudden loss of fuel pressure for example could be as simple as a faulty relay that shuts off after it warms up.

Spark isn't as cut and dry; it can be there but still not be good enough. Something that can show waveforms is almost a must unless you're content to throw cheap regular maintenance items at it (cap, rotor, wires, plugs, coil, etc) until you get it. You can still inspect individual parts for signs of arcing, wiggle things, etc. Even take a spray bottle with water and mist various components and connectors like around the ignition module, coil, distributor, etc. and see what happens. Pull a plug wire and stick a screwdriver in the end and hold it close to a clean ground point; does the spark behave differently when the engine is about to die (color, length it can jump, etc). Older systems that aren't OBD2 compliant aren't always capable of detecting misfires among other things, and won't make it easy by turning on a light with a nice error code.

 

[bctbct]

Thanks for the input everyone, turns out it was the ignition control module $173, cheap fix