Hard Starting Due To Loss Of Fuel Pressure - Help!

brufener · April 22, 2007

I have a 2001 Suburban (5.3) that has been a solid vehicle. Last winter it began to have a hard time starting, especially when it sat for a long time. It would turn over fine, but acted like no fuel was present. After a few seconds of turning over, or if I left the key in the "on" position, it would start fine. After a few months one day the fuel pump wouldn't turn on so I figured the fuel pump was the problem. I replaced the fuel pump myself w/ a cheapy from ebay.

The hard start problem has gotten worse since then. If I leave the car turned off for even 15 or 20 minutes, I have to let the fuel pump run before cranking the engine or it won't start right up. Sometimes I need to turn it to the on position twice, or let it crank over for a few seconds before it will start. If I turn the car off, it will start right up immediately with no problems.

I swapped the fuel filter, and it helped for 1 day. I thought I might be losing pressure at the fuel filter connections, so I tried wrapping the threads in teflon tape but it seems like it is worse now.

Any idea what is wrong? I have no idea how to trouble-shoot a fuel system. Any advice is appreciated.

Thanks.

95Sierra2500 · April 22, 2007

Check your fuel pressure. 9 times out of 10 on these newer trucks, hard starts are caused by low fuel pressure (even 1 psi low). If I recall, key on, engine off should be 65+ PSI, and engine running should be 55 psi. This pressure is checked with a guage on the Schrader valve on the fuel line. If your pressure is low, then it's usually either a clogged filter (which you have already replaced), a bad regulator, or a bad pump. In my experience, it's usually the pump. Many have told me it's usually the regulator, but on my fiancee`'s Jimmy, the regulator (original) is still good, but I've had to replace the pump twice due to hard/no start conditions.

NealC · June 10, 2007

I have the same problem with a 2003 Silverado 5.3 liter. I was hoping it was just the fuel filter and replaced it. The pickup had been setting for quite some time and I did not follow the procedure for changing the filter so I expected a big "squirt" when I opened the line, but there was none. Replacing the filter did not fix the problem. The pickup will start up more quickly if I leave the ignition switch on prior to starting. If it has been running and I shut off the pickup, it will start right back up with no problem. So I am assuming (yes, I know, I should not assume) that there is a pressure valve that retains the pressure when the fuel pump is not running. Is this valve in the fuel pump? If so, I just will take the pickup in to the dealer and get a new fuel pump installed.

asilverblazer · June 11, 2007

Seems like the regulator could be slowly leaking off pressure.

RayRayGSXR · June 11, 2007

I too have the same problem, I have 2002 Yukon, and it started off... if it was left with under a 1/4 tank of gas and sat over night it wouldn't start. I noticed it progressively getting worse that if it had a little over 1/4 it wouldn't want to start, up untill 1/2 tank. But once you put gas in, it would crank right up. I replaced the fuel filter, fuel pump, spark plugs, & wires, now it even gives me trouble with a full tank. (A by the way: the mech. I took my truck to is trying to tell me that now it might not want to start due to the bosch +4 spark plugs I put it, which I think is bull....somebody back me up) so needless to say for all of us it seems to be a phantom problem. If anyone can help, I would really appriciate it.

NealC · June 12, 2007

Seems like the regulator could be slowly leaking off pressure.

Is the "regulator" part of the fuel pump?

guy with the truck · June 12, 2007

Hey guys im new here as of right now looking for answers to my own problems. I did have this problem last summer, Hard starting especially after long sits. on hot days (110*F in lake havasu) would be hard to start. had 70,000 miles on the truck. replaced the fuel filter and still had problems. well went to the local autozone ready to buy a fuel pump and the guy asked to see my truck. I said ok. popped the hood and started it, (took a while) he pulled off the vacuum line to the fuel pressure regulator on the fuel rail (driver's side 5.3L 1999) and it was shooting gas out it! the diaphram rotted. he had the same problem with his and didnt want to see someone else make the same mistake he did purchasing a whole new pump assembly. So im not sure if ythey are the same on the 2000-01-02 etc but check. start it see if gas comes out of if its wet replace it! it was $76.00 at autozone and a 1 yr warrenty. havent had a hard start yet!

asilverblazer · June 12, 2007

Seems like the regulator could be slowly leaking off pressure.

Is the "regulator" part of the fuel pump?

Fuel pressure regulator is on the fuel rail at the rear of the engine.

GatorFan · June 12, 2007

I agree, it sounds like the regulator to me as well. I bought mine from the dealer and it came with everything you need to replace it. It cost me around $70 and was an easy install. Make sure you have plenty of rags around to catch the fuel that spills out when popping the regulator off the fuel rail.

The whole process took about 10 minutes to install and I have not had a problem with hard starting since.

Good luck!

NealC · June 13, 2007

Well, I will give it a shot. Thanks, guys. I will post after I change it out and see if it works.

NealC · June 20, 2007

Well, I was going to replace the fuel regulator but then I had another problem. I turned on my pickup, the radio was on, but no music. I had problems with the ignition switch before so I thought I would just take it into the dealer. Then the brand new battery went dead. I jump started it and took it to the dealer. Well, they said it was the fuel pump. They stated when it started, it pressure was low and it was the fuel pump leaking the pressure and not the fuel regulator. Here is the kicker, $500 for the fuel pump because now Chevy has both the pump and the sender unit as one and $400 for labor. Then he suggested flush the fuel lines for $140. He hasn't even looked at the ignition switch yet.

Well this guy has only 40,000 miles but it is 4 1/2 years old, so no warranty. Last time I take it to the dealer out of warranty. By the way, it was O'Rielly Chevrolet in Tucson.

I think I am going to find a pre 87 Chevy pickup so I can work on it.

asilverblazer · June 20, 2007

That's why I'd try the regulator first... If you are working on it with the door open, the battery could easily run down, even a new one. If it is the fuel pump, you can put it in your self, unbolt the bed and slide it back. Much easier than dropping the tank. And a lot cheaper than 400$.

NealC · June 21, 2007

Next time, that is what I am going to do.

I was concerned about getting to the ignition switch so I went to the dealer. I asked on this site about the switch and it was not going to be an easy process. I need to get another pickup so I can work on one when time permits and I still have something to drive.

opasno · August 24, 2007

Hey guys im new here as of right now looking for answers to my own problems. I did have this problem last summer, Hard starting especially after long sits. on hot days (110*F in lake havasu) would be hard to start. had 70,000 miles on the truck. replaced the fuel filter and still had problems. well went to the local autozone ready to buy a fuel pump and the guy asked to see my truck. I said ok. popped the hood and started it, (took a while) he pulled off the vacuum line to the fuel pressure regulator on the fuel rail (driver's side 5.3L 1999) and it was shooting gas out it! the diaphram rotted. he had the same problem with his and didnt want to see someone else make the same mistake he did purchasing a whole new pump assembly. So im not sure if ythey are the same on the 2000-01-02 etc but check. start it see if gas comes out of if its wet replace it! it was $76.00 at autozone and a 1 yr warrenty. havent had a hard start yet!

I'm having the same issue, but when I pull the vacuum line on the pressure regulator, no gas spits out. The pump went out on me a few months back, and I have changed that, changed the fuel filter, just this regulator left. Thinking of changing it out but I can only get it at the dealer, and they want $180. Wanted to make sure that this is it, because its not spitting out any gas..

Westlotorn · August 30, 2007

I have not worked on the 5.3L, I own one and had a 6.0L with no issues.

In all your notes I did not see an important one. If they start fine after leaving the key on a few seconds that tells you they are taking more time to build pressure. WHY is the question.

Put the pressure gauge on the system and turn on the key. Take a reading and then with the key off watch the gauge for a few minutes.

Pressure should hold or lose very little pressure in 10 minutes or so. It should not drop fast. GM has specs for the amount of drop over time.

If you have a leak it could be an injector, the regulator or the pressure side of the pump lines. Could be a leak internal in the tank between the pump and the top of the pump hanger assembly before the fuel actually exits the tank but after it is pressurized. It could be an external line between the pump and the engine leaking. You did not mention fuel smell so I suspect it is internal wherever the leak is located.

When you let your key stay on before starting you are covering up for this leak.

Good luck with this issue.

low2kchevy · August 30, 2007

i had starting trouble on my 2000 5.3 and checked fullsizechevy.coms forum and everyone said fuel pressure regulator, if you pull the vaccum hose off of it and gas drips out the regulater is bad and needs to be replaced, i did it to mine and sure enough gas came out so 45 dollers later for the part at auto zone now truck starts like new hopefully that helps