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2000 Suburban will not idle or accelerate

My 2000 Chevy Suburban with 5.3l engine died today, it had been running great now I can’t get it to idle and pressing the gas does not increase the RPM’s. No warning signs, went from normal to bad in an instant.



The truck has about 105K no check engine light.



After it stalls I have to wait a few minutes to start it again and it will immediately not hold idle.



With the key on I pressed the value on the fuel rail and got a squirt of fuel so it seems to be getting to the engine.



Help!

Well, let’s see. We’ll have to start throwing darts at the board. A lack of idle is frequently from a problem with the idle air control valve. This lets air in when you don’t push on the accelerator pedal and if it sticks closed the car will momentarily start but then stall shortly after for lack of air. The problem there can be mechanical or electrical.

But you say that pressing the gas does nothing which then suggests a different sort of problem. Check the throttle cable, spring and plate and see if everything is operating normally.

Getting fuel to squirt out of the fuel rail doesn’t tell you anything b/c the fuel pressure has to be in the correct range for the vehicle. So the only way to check the fuel pressure is with a gauge. Get one or get someone who does.

A better description of what exactly happens when you turn the key would help.

A description of basic maintenance history would also be good - e.g. do your plugs, wires, distributor (if so equipped), air filter, and fuel filter all have 105K on them. (Oil changes are irrelevant to this issue).

Response above

How would I check the fuel pressure is the engine will not run very long?

I’ve had the truck for about four year, purchased it with 60K. Normal maintenance has included regular oil changes and air filters. Fuel filter has not been replaced.

I don’t think my truck has a distributor, the plug wires are very short and each connects to it’s own module.

Plugs and wires are new, I changed them this afternoon after the incident occurred because I had them in the garage and figured it couldn’t hurt. Made no difference.

I removed the snorkel from the air cleaner to the engine and observed the flap opening and closing with the throttle.

When I turn the key the engine will start but the idle is low, it will stay steady low for about 15 seconds then start to cycle lower until it eventually stalls. Pressing the gas or opening the throttle manually has little effect, it still stalls.

Hope this helps

The fuel pump is electric so the pressure is there whether the truck runs or not. Over a period of time with the engine off it may very likely drain down and lose pressure, but if you just do a few key on-key off cycles (key on to the position where the dash lights come on) - listen for the hum of the pump (2-3 seconds) - do that several times and it will pump up the pressure. You can hook up a gauge and have an assistant do the key on/off.

Better yet, the truck will run briefly, so hook up a gauge, have someone else start it up and watch. If you don’t have the specs you can probably get them from Autozone’s online repair manuals. Just go to their site, register, and plug in your car’s info.

If I were you checking the pressure is what I would be doing next. If it is lower than minimum specs I would replace the fuel filter and then check again. If its still too low with a new filter, then I’d be looking to replace the fuel pump.

…and the key about the throttle plate is that it moves when you push the accelerator pedal - not just that it moves. Make sure you don’t have a cable problem.

Would low fuel pressure trigger a trouble code? If so wouldn’t the check engine light be on?

The throttle plate only moves when I press the accelerator, when the peddle is released the plate is closed solid.

Does this problem in any way sound electrical?

The symptoms of low fuel pressure might eventually trigger a light, but the fuel pressure is not monitored by the computer - it would only show up in other codes having to do with fuel/air mix.

The problem could be electrical - like the electrical fuel pump motor is no good - or like the electrical power to the fuel pump is not right. The problem with saying “electrical problem” is that it doesn’t refer to anything. Most every functioning component of your car requires electricity.

You could also have poor spark, a problem with CKP or CSP sensors, a huge vacuum leak, low compression or whatever.

Your next step is just to check the fuel pressure.

Fuel pressure is 20psi, I believe it should be 40-60. I’m going to change the filter and see if that affects the pressure.

What next?

Tom

What should the fuel pump sound like when the key is turned on and the pump runs for 2 seconds? Should is be a smoother sound of a thumping/pumping sound?

I suppose fuel pump sounds could vary - ?

But it should just be a hum - no thumping.

The fuel pressure is your problem so see what happens after the filter. If the filter isn’t clogged then you just need a new fuel pump.

I tried for a couple of hours to get the fuel filter off, one side finally turned the other was not moving. I soaked it in liquid wrench for a couple of hours, gave up. I had the truck towed to a local mechanic who I’ve used before. I’ll post the outcome if anyone is interested.

Tom

Most everyone is always interested, so by all means please do let us know how it went.

Just got the call, replaced filter no change in fuel pressure needs a new pump. I was quoted $900 parts and labor for the pump and relay using a GM OEM pump assembly. Does this sound about right?

Fuel pump replaced, all is well…

Thanks for the support