1998 Chevy Silverado Hard to Start

[dwilson]

Ok ever since i've had my truck the cats have been gutted and it ran fine (but the check engine light was always on). Just recently it started getting hard to start (usually only when the engine is cold). When I go to start it it just turns over (it sounds like its turning over fine) then I turn the key back off for about 4 sec and then try again and it turns over three or four times and "hits" like it's going to crank but it doesn't so I turn the key back off and wait 3 or four sec and try starting it again and it turns over a few times and then it starts up a spits and sputters for a second or two and then runs fine. After it finnaly starts theres a strong gas odor like it was flooded. After it starts it runs fine, when you stomp on the gas its very responsive and doesnt sputter at all. I few weeks ago theres was a code that said MAF sensor low voltage, I didn't replace the sensor but I cleared the code and it hasn't come back yet. I dont know if any of this could be related or not but the fuel gague flutters back and forth constantly and when I fill up the gauge goes about a fourth of a tank over the full mark. I'm sorry for this being so long but I wanted to be as descriptive as I could. I would apprectiate any help.

[ChevLoRay]

to the forum!

We're here to help.

The fact that you had a code that said the MAF sensor had an issue is a clue. I know you said you had it cleared but I wonder if you hooked up a scan tool, would it still read that the MAF sensor voltage is low?

My thinking is that code means that the sensor is dirty, but there are people on here who are "off the chain" when it comes to helping you figure this stuff and how to test it.

Let's see who jumps on this bandwagon. Feel free to check the archives on this forum and see if you can find some suggestions, too.

[ToughBowtieTruck]

Sounds like a pump dying. Even if check engine lights were on, the truck should still start fine in limp mode without that sensor hooked up.

Check for fuel pump/tank grounds also. Could be the source of the pump not building enough pressure and for the screwy fuel gauge . . .

These trucks with the Vortec engine run about 65 psi fuel pressure, and it sounds like the truck is having trouble building enough pressure to run the injectors correctly . . .

[dwilson]

I have hooked the scan tool back up and it didn't show a code for the MAF sensor(just the one for the oxygen sensor). I'm going to try and get a fuel presure test kit and test the fuel presure (I think advanced auta parts loans them out) and go from there.

[ChevLoRay]

This is what I like about the folks on this forum....someone has an answer or an idea about what might be causing a problem. As the moderator, I sometimes place myself in the "all-knowing" position, knowing I don't know very much at all about these....short of driving mine.

Hope you find your answers with the fuel pressure guage.

As for replacing the fuel pump, there are several posts on this forum that deal with that and associated things, like fuel filters and connections and little hoses, etc.

But, don't give up on us.

[dwilson]

Ok I just checked the fuel pressure and its at 49psi with the ignition on, the book says it should be at 60-66 so im pretty sure thats the problem. Now my question is how do I go about diagnosing the fuel system? (I can hear the fuel pump running when I turn the key on)

[munger]

this is a stupid question but when its hard to start is the tank almost empty because my dad has done that a few times with his 06 run it completly empty then it cranks and cranks then fires and dies then cranks and starts

[dwilson]

No it does it all the time.

[bwood]

I would put my money on a bad pump. The sender unit for the gauge is mount on the fuel pump assy also. A bad pump can still run, but age and wear can limit its ability to build pressure. If you want to verify a bad pump or regulator, its not that hard. You need to see if the reason for the low pressure is the regulator, check valve in the fuel pump or bad pump in general. You will need to locate the fuel system return line and block it off.

**Crimping the line off is not the recommended way to block the return line as it can damage the line permanently. Unhooking the line and installing some sort of cap/plug would be the best way.

Once the line is blocked off, turn the key and let the pump cycle. Turn the key off and watch your gauge. If the pressure bleeds off with the return line blocked off, the check valve in the pump is bad and there is no fix other than a new pump. If the pressure holds, carefully loosen the plug and let the pressure off and reconnect the line. Test again, if the pressure drops quickly it points to a bad regulator. But unfortunately the pump is the most common failure. The electrical connector on the pump is also prone to failure and should be checked before installation of the new pump and the parts store may require the purchase of a new connector to get their warranty.


As far as the MAF goes, CRC Chemical makes a MAF cleaner spray. NAPA carries it, its about $8 a can. Follow the instruction on the can. If you end up looking for a new pump, look for a Delco/Delphi (OEM) one.

[umwtnt]

Over the years dealing with dealerships and replacing many of these pumps, I work for a construction company as a mechanic, I have learned the fastest way to ruin a pump is to run the fuel level below a 1/4 tank of fuel. These pumps are cooled by the fuel covering the pump. If you constantly run the tanks empty the fuel pump overheats and you end up dishing out money for the repair. Sorry for no advice Just wanted to help get the word out.

[dwilson]

Thanks for the advice, I may have caused the problem (since im a teenager and dont have much money I constantly run it at or below a fourth of a tank). It sounds like i need to replace the pump.

[acepop]

did the fuel pump fix your problem? I am seeing the same issue.

[dwilson]

Yea the fuel pump is all that was wrong with it.