StaticInMyHead

I have a 1992 GMC C1500 with approximately 118000 miles on it. Just recently, the truck started acting up. I tried starting it one morning and it had trouble idling. It is fuel injected, but it acted almost as if it were carbureted and idle inconsistently. It would go from 1100rpms to 400rpms, and often it would just die because the idle dropped too low. Ever since then, which was about 4 days ago, the truck has run horribly. I stopped at a store to run some errands and when I tried to start the truck on the way out, it refused. I walked to the nearest Auto Zone and grabbed some starter fluid - it started fine and idled with no problem. So I proceeded to continue my errands. Then I found out the engine speed was limited while in gear. In any gear, it will choke out at 2600rpms and bog down if I try to accellerate and push it past 2600rpms. It happens in 1st through 4th gear; I haven't tried it in 5th because 2600rpms in that gear is about 85mph, but I'm sure it would do the same thing. I have a somewhat limited knowledge in the automotive area, but I think it is something to do with either the fuel filter or the fuel pump. I originally thought it might be the coil, but the fact that it started up with ether would seem to rule that out. Any suggestions?

On a side note, I'd just like to comment on the place I bought my gas at.. A Frys Marketplace was built recently with a gas station in the facility, so I've been getting about 50% of my gas there. The gas I got before the issues with the truck started happening never showed up on my debit card and the account status says it was never deducted from the account. Coincidentally, a friend of mine also had to replace his fuel filter recently; he gets at least 80% of his gas at that station. Is there a problem with the fuel at that station, or am I jumping to conclusions?

manic

Does the check engine light come on when this happens? Or does the
check engine light stay on? If yes to any of those questions, you need
to pull a code. There will be a code stored in the computer as to what
the problem is. Could be maps senser, throttle control senser, could be
a injector, if its not throttle body. If the check engine light does not come
on or stay on you can pretty much rule out a senser.

StaticInMyHead

The check engine light only comes on when I turn the key to the 'on' position before I'm about to start it. After I start it (if it starts), the light turns off.

Midnight Tech

Are you sure it's not a Nissan?
All kidding aside, I've just had a similar experience on my 86 Nissan truck....and a faulty air flow meter or associated circuit will give the exact same symptoms right down to the RPMs being limited.
I'd get the truck to someone with a scan tool and see if they are any trouble codes in it....and see if you can find someone with a spare air flow meter the same part # as yours to try on your truck.

StaticInMyHead

Well, now that you mention it, I did change out some parts on the truck for performance ones a while back. About three months ago, I replaced the air intake with an Airaid performance filter and intake, and I added a throttle body spacer. I'm not sure if that has anything to do with it, but it makes me suspicious now..
Also, as an update, I just bought a new fuel filter for it and the symptoms remain the same. My thinking is, if it was in fact a problem related to a dirty or clogged fuel filter, whatever damage that could have been done would have be done by now. Either the pump stressed out and overheated and began acting up because the filter was clogged, or the filter let some debris flow to the injectors and now the injectors are clogged. What does everyone think?

Spacemonkey6401

You could pop off the air cleaner and see if the injectors are spraying a nice fine mist, or if it's dripping into the intake.

Air problems seems likley, if you did that changing and your computer isn't reading it right and getting the right mix, you could have problems there.

You already replaced the fuel filter, I'm guessing the external one. Is there a whine noise from the gas tank? Chevy fuel pumps have a definate whine to them when they are going bad.

StaticInMyHead

Well it ran fine for like three months with the intake and the spacer; I don't understand why it would be acting up now. I wouldn't think that the intake would make enough difference to need a change in fuel:air ratio...I barely got any performance boost out of it. The fuel pump hasn't become any more audible than it was before. I can only hear it while it pressurizes the line with the key in the 'on' position right before I start it, and thats if I listen closely. I'll definitely be looking at the fuel injectors though. A friend of mine who is a chevy mechanic said he would take a look at the truck tomorrow; hopefully, he'll give me a definite diagnosis so I know what to fix.

manic

You mentioned a spacer, and its not throwing a code "check engine"
I suspect a vacuum leak. When you start it and it starts idling rough,
pop the hood, get that starter fluid, start spraying around the the
throttle body, if you have a vacuum leak the starter spray will
clog it, evening out your idle, then you have found your problem.
You can also use wd40. Leaks like this are hard to find, that is why
a spray is the best way. Check plugs wires, distributer cap, rotor bug
as well...

StaticInMyHead

Well, I can't even start it anymore, so checking for a vacuum leak is impossible now. It barely makes an attempt to start with the starting fluid. Three vehicles in 17 months has got to be a record somewhere..

Spacemonkey6401

Is it getting fuel at all?

StaticInMyHead

No, the injectors definitely aren't getting fuel. I'm pretty sure now that the fuel pump is dead. Now the fuel pump isn't audible at all, and there's not even a slight drip from the injectors when I try to start it. The last thing that I can think to do is unhook the fuel filter and see if any fuel sprays out when I turn the key on. If not, then I know for sure that the pump is dead. I'll have that update tomorrow.

Midnight Tech

If it is the fuel pump Static, are you gonna try to change it yourself? I've seen a couple people take the bed loose and jack it up rather tham lowering a full tank of fuel just to put that pump in. Just make sure that the tank is clean and there's a new pickup sock on that pump before you button everything up.

StaticInMyHead

Yeah, I've had several suggestions to raise the bed rather than to drop the tank. I don't have a vehicle lift, so I'm sure the bed raise idea would be a better choice anyway. But, I'll more than likely be taking it to a mechanic. That is, after I get the final diagnosis that it is the fuel pump for sure. No more guessing what it is and in the end spending twice what I should have had to...

StaticInMyHead

Ok, I disconnected the fuel filter from the line that leads back to the pump and turned the engine over. I'm assuming there should be a pretty big gush of fuel out of the line since it is usually pressurized; however, when I tried it, there was nothing at all. So it has to be the fuel pump.

Midnight Tech

Sure sounds like it Static....make sure either you or your mechanic gets a well-known brand so you don't have a comeback problem....also check the wiring on the inside of the hanger/sender assembly...it is known to give problems.

Spacemonkey6401

True, raising the bed is an easier way, but i'd suggest dropping the tank, and draining all the fuel out, or taking the bed off and getting all the fuel out somehow. I'd put good gas, petro, in from a place that you normally get it from, and not Fry's.

If you leave the fuel in, you might run into the same problems. I'd also throw on a new external filter, to make sure you get all the stuff out.

jumppack03

sounds like your inline converter on your exhaust.When they start to clog and go bad it causes your car(truck) to idle strange ,as if it couldnt breath right.Which is exactly whats happening.if u know what ur looking at underneath the car , bang on the converter lightly with the handle of a large screwdriver.If it rattles and sounds as if something is rolling around in there u might have found ur problem.

daamon_vexion

that wouldnt explain the loss of fuel tho..

JamesO

http://www.autozone.com/servlet/UiBr...3d80087951.jsp

Before you pull the fuel tank apart, make sure you do not have some electrical problem?

JamesO