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Cranks but wont start. Fuel problem?

102K views 21 replies 7 participants last post by  ak4life 
#1 ·
Well i hopped in my truck this morning to go to work, everything was normal. I started it up and let it idle for a second or two and then right when i was about to put it in reverse it just died like someone flipped a switch to kill it.

Continuous cranking would not start it so i hopped out and popped the hood.

I swapped the fuel pump relay with another one - Still didnt start
Checked fuses - Still didnt start (fuses looked good)
Checked the fuel pressure - Nada, nothing. No reading when the key is in the on position or while cranking. I also didnt hear it buzz when its supposed to be priming.

So my assumption is that its the fuel pump. The gas guage has been goin nuts for about a year and i was going to replace the sending unit soon.

It was raining pretty hard yesturday and there was a lot of water on the roads, could that have anything to do with the pump dying? The truck is lowered 4 in the front and 6 in the rear.

Im guessing the only reason it started was from the pressure built up yesturday right?
The fuel pressure regulator wouldnt have anything to do with this would it?

Thanks in advance for the help.

Engine is a 4.8 in a 99 nbs sierra 1500
 
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#2 ·
get a rubber headed hammer and have 1 person crank the motor and another bang on the fuel tank. Most of the time it will work to get it started thats when u know its the fuel pump. It may not work though and it still could be that. And also when you turn the ignition on have someone put there head down by the tank and see if they can hear the fuel pump. Worth a shot.
 
#4 ·
yes unless you can get your hands on a lift and drop it out that would be much easier. If its the first time its been changed it will prob be a bit a of a job. Especially if you drop it and u have a lot in the tank. And when your removing the actual pump be real careful nothing falls inside or u will have bigger problems.
 
#5 ·
i used a motor cycle jack to lower my tank, worked perfect. also to check to see if its the fuel pump spray some gas down the throttle body and see if she will start. i had a 98 and the fuel pump only pushed out 50 psi when it needed 58 to start if i didnt give it fuel to start it would just sit there and crank until i killed the battery. but once i got it started it kept enough pressure to stay running. so until i changed the fuel pump i took off my intake hose from the throttle body sprayed some gas down the throat and started it up. just thinking try it to see if that will get it to start at least this way you know your problem is 100% not getting fuel also change the fuel filter make sure its not clogged... also just a word of advice i changed my fuel pump 3 times, i bought one from advanced auto with a 2 year warranty, just do it right and get the one direct from gm and save yourself the time and aggrevation.
 
#6 ·
Yea I just filled the tank up the other day.

I'm not sure if the motorcycle jack will work (I do have one) because of my truck being lowered. And I do have a lift but I didn't set it up yet. Great timing :)

I'll probably end up taking the bed off and seeing if the pump is getting power first then change it that way.

I'll try the gas down the intake truck first though.

Thanks for the help so far everyone.
 
#7 ·
Ok, not sure what exactly I did but I played with the fuses and now it starts.

I was reading on another forum that the correct fuel Pressure with it running is between 55 and 62 psi is this right?

When it is running I get about 46 48 psi. Now when I take the vaccume line off the fuel pressure regulator i get 58 psi. Could the regulator be bad or do you guys think the pump is still bad/cause of the low psi. (no gas came out of the regulator)
 
#8 ·
sounds about right but it requires 62 pounds to start the vehicle and 55 psi to run the vehicle. thats what my problem was it would only push 55 psi when trying to start and stay there when running. but if its starting on its own it could be the regulator, try the cheapest route first its going to be trial and error brother.
 
#9 ·
Ok, so I ended up getting it working but in a weird way.

I pulled the fuse labeled ECM and put it back in and bam, starts right up and I can hear the fuel pump.

This worked for a few days but then it happened again and to get to work this Koenig I needed to pull the same fuse and put it back in

Also when I put it back in I see a small blue arc.
Any idea what can be causing this?
 
#14 ·
Ok, so I was on my way home and the second i got off the highway the truck died and the security light was flashing.

Could the security system be causing my fuel pump to shut off and then pulling he ECM b fuse resets it?

Do out trucks even have a security system?
I went to my local locksmith and he said the keys are just a plain b102 cut and that there was no resistance code or security chip in them. For my 99 anyways.

I ended up getting home but only by pulling the fuse and putting it back in
 
#15 ·
If you have a security light then you must have a chipped key. It may be "Passkey". Sometimes passkey gets muddled up and needs to be reset.

The reset procedure for passkey is as follows:

Turn the key to start briefly (do not allow vehicle to start) and leave key in run for approx. 10 min. until security light goes out. Turn key to off for at least 10 seconds.

Repeat this two more times.

After the third time turn the key to off for at least 10 seconds and then start vehicle. Reset procedure is then complete.
 
#21 ·
I have had similar problems, and yesterday this thread answered some of my questions... heres what happened to me...

I was on the highway and i started sputtering, so i pulled over all the way off and on to the side-street, and i had these problems prior to this happening, all of which i thought were un-related. My fuel gauge would flip around erratically sometimes, sometimes not, My cruise control would downshift A LOT and when it did it stuck down there tooo long and when it did shift it was a kick, not a solid smooth shift (I have a brand new 100,000 mile warrantied transmission), when i would drive on the highway for a while and i got back into the city, my truck would seem to be running really hard and i had excessive vibration in the cab (this is why i cleaned the throttle body with carb cleaner), and when i was at the gas station in idle it just sounded like it ran really hard in park. The new fuel pump (AC Delco) and filter (Same) fixed all of these problems.

I replaced the fuel filter and there was good pressure before i replaced it, but after i installed the new one (with correct flow) and tried to prime the pump by putting it to the on position, and heard nothing, loosened the filter again and no pressure no fuel. Replaced fuel pump and everything works perfectly.
 
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