Anybody a mechanic?

A

Andrew Holley

Well-known member
Having problems with my Avalanche, 2002 135K mileage.

Tuesday night, I drove home on fumes (empty tank), on the way to work on Wednesday, filled the tank up and put 140 miles on driving around for work. Thursday morning drive to work, head across town (10 miles) truck chugs in a parking lot, try to get on the highway and it chugs then dies on the on ramp. Couple times got it running for a couple seconds then it dies.

Have it towed home and pushed in the garage, turn the heat up to 80 and took the other car back to work. Figuring it's either water in the tank, fuel pump not working or relay. Go to the part store, would have to order the pump get it in a couple days and not cheap. Guys there (don't know how much they know) says it's not the fuel pump relay, probably the pump (again expensive, go figure they recommend that). Buy a new fuel filter and a can of heat.

Tonight after work, change the fuel filter, as I unscrew the down side of the filter, the gas is still under some pressure (pump is working?) and it starts and run for a minute or two, then chugs and dies, almost like it's running out of gas. The heat I added has had no time to mix with the gas, so if there is water in the tank the heat should be asbord by tomorrow morning.

Second thought that just came to me is the cadalyic converter is plugged, however, there are two of them, so both plugged? Does burn some oil, but not alot.

Plan as of now is let it sit until tomorrow, try starting it again. If it doesn't run, borrow a fuel pressure tester and see how much fuel pressure I have, low pressure pump needs to be changed, enough pressure I have to start over.

Engine light never came on.

Any other ideas?
 
I'm not a mechanic, but my first thought was fuel filter. You said that you addressed that - I'm not sure, but is there only one filter in the fuel line? Second thought is the water in the fuel. Also, you have addressed this, but with that Ethanol crap on the market out there, you can't be over-cautious.

From your "chugging" description, it seems that it is almost certainly a fuel or air problem. Did you check your air filter and breather lines?

Beyond that, I would start suspecting injectors (if your fuel pump checks out) or vaccuum lines.
 
Take it to a good GM mechanic. If it's a fuel pump, hang on as it isn't going to be cheap.

I might try some fuel treatment/deicer in it first. I keep stabil in my GMC and stabil marine in my outboard tanks including my new E-Tec I just had put on my Grady White.

140,000 is a lot of miles on a fuel pump also I used to change fuel filters on my old suburban every 40,000 miles. With today's generally crappy gas I would suspect a fuel and not an air problem.

Sorry your having trouble right here at the most expensive time of year.

Merry Chritmas anyway,
Harry
 
Andrew,

Sounds like you're on the right path to start. Check the fuel pressure first, even though the pump seems to have pressure (fuel filter pressurized) it might not be enough. Running low isn't good on the in-tank pumps, this time of year it shouldn't be a problem (the fuel in the tank keeps them cool), but it might be getting weak with the mileage.

Doesn't sound like a catlytic convertor problem. Usually when they're plugged the truck would idle but labor when revved to higher rpm, not die. If the fuel pump relay wasn't working it wouldn't run at all.

Good luck!

Jim S
 
I am definately going with water in the fuel. Especially up there with all the cold temps and condensation etc. I'll bet it just hung up in the system. I wonder if it could be in the fuel return line and going back into the tank? In any case my bet is that it'll work itself out though it seems like it's taking a long time to me.

Put some good fuel injector cleaner in too....you may have a tremendous buildup of guk.
 
the fuel pump is easy to check, sit down by the rear tire about where the fuel tank is and have some one else turn key on, you dont have to try to start it, just turn it on. you should be able to hear the fuel pump cycle on. it'll run for a few seconds then stop once preasure is up. if it makes a weird noise or is sparatic in operation that may be your problem. if you dont hear it run at all, you should take the plug off the pump and check for voltage. if you have voltage, bad pump. no voltage, its a wiring issue possibly pump relay. both GM trucks i owned in the past had fuel pump issues at around 125,000 miles. if its not a fuel pump issue i would think its probably contaminated fuel(water, sediment, gunk, etc.) and if the problem is that bad and it were me, id pull the tank and clean it out. if you run into anything else, email me. amldetermined@yahoo.com ill help ya any way i can. best of luck!! im on duty today till midnight so if you need anything today email is austin.lay@navy.mil.
 
135K miles isn't high mileage now days, & I'm not familiar with this engine, but I'd ask my mechanic if any chance this is an engine timing problem (started, running at idle but can't take a load).
 
Oxygen sensor. My old 3/4 ton Sierra did the exact same thing. Cheap fix. Like my father used to say, start with the cheapest stuff first
 
Last night added two bottle of heat, this morning before blowing, started it, when I turned the key, heard the fuel pump run for 10 seconds or so, started right up, ran for about two minutes, chud/labored some (lost some rpm) then died. Not a good test, but ran to the tail pipe, plenty of exhaust.

Hearing the pump, it's getting voltage, suppose it could have weak pressure.

With the storm we have, not sure I am going to make it to the shop to borrow a fuel pressure tester.

Just thought of the oxgen sensor, two months ago, engine light came on, took it to Checker, they lent me the tester and one of the four were bad, won't tell me which one and they were sixty a piece. Didn't have my wallet with me, nor that much cash that day, next day the light went off, and I forgot about it. However, if that is the problem, shouldn't the check engine be on? If they fail, does that send too much gas and floods the engine or very little gas and it dies? Sounds more like it is dieing of lack of fuel than choking and flooding, plus I should be smelling some fuel.
 
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Fuel pressure regulator. If the pump is working, it could be the regulator that is causing the problem. I would check online bulletin boards and ask the problem there. I've had great success when my Dakota gets itself into trouble. also worth $80 or so would be to take it to a GM dealer and have them put it on the diagnostics machine. This will then tell you what is wrong and if you can then fix it yourelf.

Other options. Some of the auto parts places will let you rent tools. Some of them rent the diagnostoc tool and you can diagnose it yourself. Final thought. I know that on my Dakota, if I turn the key in a certain sequence, the truck self diagnoses itself and then the error code flashes on my odometer. I can then look up the error code online. I've used this one quiet a bit. Most recently, my check engine light has come on. I do the key thing and a number codes flashes. I look it up online and it means small vacuum leak. I go to a dakoto board and search and sure enough, there is a common problem to check with that error code. I have an easy project this weekend. Well, it should be an easy project.

Mark W
 
Andrew, I have a '02 Silverado w/ about 130K and the service engine light came on two days ago and it turned out to be the either the o2 sensor or moisture in the connectors. I was fortunate enough to have the auto mechanics school shop next door to mine so the diagnostic was easy. Thiose scan tools will do almost everything except replace the parts. I had to replace the fuel pressure regulator in mine about a year ago, the symptoms were hard starting. The regulator holds pressure to the injectors and mine was leaking down overnight. The guys in auto cleared the codes and I'm waiting to see if it was moisture or probably the 02 sensor. They told me the 5.3s had a bit of history with those. I know less and less every day. Good Luck BTW I think you are on the right track also.
 
Andrew,

On the off chance that it is a computer problem I wonder if reseting the computer would help. Could be it got all screwed up at some point and is sending the wrong signals. I have recently heard that taking both cables off the battery and shorting them together will reset the computer. Never tried it myself.

Pete
 
If the computer already has the code stored in it, then it might not cause the check engine light to come on again. Quickest way to clear out a computer with diagnostic codes is to take both the positive and negative battery cables off and touch them together(not to worry it's not hooked up). Clears all codes out. Did it to the Mercedes because I needed to figure what was going on (read:eek:2 sensor)

My 2 cents is that it isn't the pump or regualtor because your car starts in the morning and then after running for a minute or so it dies. The pressure within the fuel system is at it lowest first thing in the morning because it has been sitting all night. This is why everytime that you turn the key to the on setting the fuel pump buzzes for a few seconds to pressurize the system. Usually you know when you fuel pump is starting to go bad by the constant loud humming while you are driving. Normally you won't hear any humming/buzzing, only when the key is in the on position before starting. I bought a fuel pressure reg for my truck but never put it on. I am not sure how common they are to go bad on these engines. Mine is a 350 cid 99 Yukon

My guess is that is is the o2 sensor because they come into play after the car has started and that is when you are having the problem and that's when they tell the computer what it needs it to do in terms of gas/air mixture. If a mechanic already told you that this is a problem, I would go ahead and replace anyway. You could buy two and replace and see how the truck runs. If there is not change then put the old ones back in and take out the other two and go from there. Shouldn't take more than an hour of your time. Still cheaper that a fuel pump, but at 130,000 its day is coming too.

I had a problem with my Yukon not starting at all then not starting throughout the day, to occasional stalling. If it started first thing in the morning you were good to go all day. If it didn't you could wait a few hours and it would be fine. Went through 4 fuel pumps in 30,000 miles in three years. Kept telling the dealer that it wasn't the fuel pump. They said that there was no pressure in the line. Smarty pants(me) said how about checking the wiring harness to the pump. Because it's an electrical problem and it's not the pump. Long story short, that was it and 3 years later not one problem.

At least if its the o2 sensors you can do it yourself pretty easily. Fuel pumps are not bad either just expensive.

Cheers,
Mike
 
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3 years ago my fuel pump died in my 93 suburban it just quit and would'nt start
I got lucky and coasted into a parking space right infront of my house. That truck is still running strong with 280,000+ miles.
I just replaced the fuel pump in my 2000 I thought it was the [font=Verdana,Arial,Helvetica]fuel pressure regulator because like Toms my truck was having a hard time starting. It turned out the fuel pump was on its way south the auto shop teacher in my building took care of it the pump and filter cost some place around 345
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Rob, I thought when the pumps ran until the failed completely. Didn't think they gave out slowly, however, maybe they do?

My wife's Ford was recently having some problems, turned out the fuel pump relay failed. Won't turn the pump on. Wondering if the pump gets turned off and it's coming back on? Maybe something wrong with the relay.

The fun of this is gone.
 
Take the relay out, bang it a solid surface a couple of times. Not hard, just tap a few times and re-install. This has worked more than once on my old Porsche. I have some sunroof relays that muck up once in awhile. I take them out, bang on them, reinstall and the sunroof works again for the season. Been doing this for some time now and haven't repalced one yet.

Mark W
 
Andrew I don't know on you vehical but check to see if you have another fuel filter, near the engine. My chev had two one on the gas line on the frame and another near the engine. If I remember it was screwed in by the carb. You should have enough pressure by both. My experience the fuel pump either works or not. If you hearing it it works. Hope that narrows it down.
 
I just talked to him he said he could hear it turning slow - its running good now
who knows maybe the filter was clogged he changed the filter and the fuel pump
 
Most likely a bad pump. Only way to know for sure is to check volume and pressure. Pump can run but not put out enough pressure to atomize the fuel. Running tank low is the worst thing you can do. We sell them day in and day out.
 
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