Kmark

Hi! I have a 2008 Tahoe LS 5.3L V8 Flex Fuel with around 156000 miles that I'm having some starting issues with and I'm hoping I can get some insight on. I bought it used in March, was previously a DNR vehicle. Ran great at first, then a month or so later I noticed it smelled like gas, especially on the driver's side (not inside the vehicle, just outside of it). At some point after that, I'm not sure of the exact time line, but I noticed that it was cranking longer before starting, but still started on the first try. The gas smell progressively got worse, as did the cranking issue, to the point where sometime I would have to crank it twice before it would start. Then I realized that if I turned the key to "On" for a few seconds before I started it that it would usually start on the first try. Eventually that stopped working too but at this point my father in law had noticed how bad the gas smell was and insisted I take it to his mechanic.
The mechanic replaced the fuel pump module assembly in August, and it seemed to help the cranking issue at first, but it was short lived.
My husband, who is definitely not a mechanic, suggested that maybe it was because the battery wasn't good, so we got a new battery. And again, that seemed to help, but again, not for long.
Sometimes it would start right up and sometimes it would have to crank 3-7 times before it would start.
So in September my husband took it to his friend, who is a work-from-home kind of mechanic. To be honest idk what he did aside from connecting a tube that he said was disconnected, but I basically paid him to connect the tube and tell me "you still have to crank it a couple times but it's not as bad as it was"... So frustrating.
So again, I found that turning it "on" for 10 seconds before cranking it would usually at least start it on the first try. But of course that only worked for a week or so. Now it's doing a weird thing where I'll try starting it and it'll crank for 10-15 seconds then stop, I turn the key to off then retry and it'll seem to kind of catch and start but die right away, and it'll do that 2-3 times and then it'll finally start but it's a really rough start, I'm talking like it feels like it's chugging and grasping to start and almost shaking? the vehicle. Idk if shaking is the right word but idk how else to explain it. So of course I complain to my husband but every time he goes to start it, it starts. Sometimes it starts right up for me (rarely, but sometimes), sometimes I have to crank it only twice, and sometimes it does the weird scenario I described above.
I don't know what to do. I don't want to take it to the original mechanic because I don't think they're exactly high quality, I don't want to take it back to my husband's work-from-home mechanic friend and I definitely don't want to take it to some random place and be like "I have no idea what the problem is" because I feel like that's just screaming "take advantage of me please!"
Can anyone please, PLEASE help me?!?
I should add, it runs great once it's actually started, doesn't seem to be idling loud or rough or anything. The only other thing I noticed is after I got it back from my husband's friend, my AC is no longer working but I don't think that has anything to do with anything? (Although any suggestions on that would also be appreciated &#128522
Thanks in advance for any suggestions!!!

PNW NBS Z71

So, are you saying the gas smell you had before is now gone? What brand of fuel pump was installed? Lots of crap pumps out there, especially from Cardone. Should only be an AC Delco pump installed. It does sound like the fuel system is bleeding off and that is why it can take those multiple attempts to start. You may have an injector(s) bleeding off or a fuel pressure regulator causing problems. Or a line itself with a leak but if that is the case the strong gas smell should still be there. You will not smell the gas if is is an injector or the fuel pressure regulator. A mechanical fuel gauge should be attached at the fuel rail and see what pressure it shows with the engine off after sitting. The original mechanic should have given you a reason for replacing the fuel pump, did he? Did he tell you you had a fuel pressure problem. The backyard mechanic should have also gotten a fuel pressure reading. When I ran shops I never ever told a customer they needed something without telling them why. If you run the engine, with the mechanical attached, you want to see a good fuel pressure, You want to see at least 50-60 psi while idling and increase a little when accelerating. Then shut it off and watch to see if the pressure bleeds off, it should not lose more than 5 psi in the first 30 minutes. If it bleeds off then you have a leak as I mentioned above. Here is some info about the regulator:

In your case I believe the regulator is part of the pump assembly or is mounted on the end of the fuel rail.

There are two different problems that a bad regulator can cause:

Low Pressure

Most problems with fuel pressure are due to the pressure being too low. The inability of the fuel pump to increase the fuel pressure up to the vehicle’s specifications may have several causes:

• If the pressure is too low there may not be enough fuel reaching the engine for it to start. Or, if it does start, it may not run efficiently.
• A fuel leak is a cause of low fuel pressure; although this problem can often be identified without the need for installing a fuel pressure gauge.
• Other problems that can cause low fuel pressure include; a kinked fuel inlet line or a clogged fuel filter or strainer.
• A bad fuel pump in the fuel tank can also prevent the fuel pressure from reaching the required level.

High Pressure

Fuel pressure that is too high can cause the engine to run too rich. Common causes of high fuel pressure include a bad fuel regulator or a clogged return line. Consequently, You will need to perform two different tests to identify the reason for excessive fuel pressure:

• The first test requires you to relieve the system fuel pressure; and connect a relief hose to the fuel return line. Place the free end of the hose in a container and activate the fuel pump. The fuel return line is blocked if the fuel pressure now meets specifications. Otherwise, the regulator may be faulty.
• The second test requires you to allow the engine to idle; while disconnecting the vacuum hose on the fuel pressure regulator for vehicles that are so equipped. The regulator may be faulty if the fuel pressure does not increase by about 5-10 psi.

Too high of pressure may result in over fueling of the engine. As a result, This can lead to a rough running engine; poor fuel mileage, and black smoke coming from the exhaust. If your regulator is going bad, your car could display several different symptoms.

Get your regulator checked if you notice any of the following;

Fuel Fouled

Spark Plugs Are Black

Remove a spark plug and examine the end of it. If it is sooty, it could be a sign of a bad fuel pressure regulator. If you find a plug in this condition, check the rest of them. A sooty spark plug could just mean the engine is burning oil at that head. If you end up replacing your fuel pressure regulator, you might also want to replace your plugs. You can try simply cleaning them and putting them back, but if your engine still runs poorly, get new ones.
Rough Running Engine

Engine Runs Rough

Speaking of poor engine performance; if you are idling the engine and it is not running smoothly; change your oil filter and check your pressure regulator to repair bad fuel pressure.

Another sign that your engine is suffering the effects of a bad regulator; is if you have trouble starting the car. It will fail to turn over a few times before it actually starts.
Black Smoke From Tailpipe

The Tail Pipe Emits Black Smoke

Having black smoke coming out of your tailpipe is a sure sign there is something wrong with your regulator.

Replace it.

The normal color of any smoke coming out of the exhaust should be white or gray; not black, so if you see the latter, there is definitely something wrong.


Gasoline Smell

The Dipstick Smells of Gasoline

Check the oil dipstick and see if you smell fuel on it.

If you do, it could be a symptom of a bad fuel pressure regulator, which has allowed gasoline to leak into the oil system.

If not repaired quickly it will cause the oil to lose its lubricating properties. As a result, damaging engine bearings.


Gas Out Tail Pipe

Gasoline Drips Out of the Tailpipe

Gasoline dripping out of your tailpipe is either the result of you overfilling your tank; or a bad fuel pressure regulator.

Most likely, the gas is leaking into the exhaust system; because the regulator is allowing it to pass into the lines.

As a result, Causing major damage to the catalytic converter.
Rough Running Engine

Engine Stalls

If the engine stalls when you press down on the gas pedal, check the fuel pressure regulator.

There shouldn’t be any hesitation when you press on the gas.

Even if you only notice a little hesitation; get your pressure regulator checked out because it may just be starting to go bad.
Wet-Fuel-Leak

Gasoline Is in the Vacuum Hose

If you are noticing any of the signs above; but aren’t convinced that the cause is a bad fuel pressure regulator; there is something you can do to be sure one way or the other. Remove the vacuum hose that attaches to the fuel pressure regulator, making sure the engine isn’t running. So, If gas is in the line, your fuel pressure regulator is bad. Also, if there is none in the line but when you turn the switch on; fuel drips out of the hose, it is bad.

Conclusion

Finally, We hope that this information we just provided for you helps you to understand how fuel pressure regulators work.

Kmark

Hi, thank you for your response!
Yes, the gas smell is completely gone.
​​​​​​As for the brand of fuel pump, I'm not positive because it doesn't say on the invoice, but when I googled the part number it came up as an Airtex.
To be perfectly honest, I didn't actually talk to either one of the mechanics, either my FIL or husband did so I'm not really sure if they checked the fuel pressure, I had ASSUMED they did but am learning that I need to stop assuming things. (Next time I see my FIL I plan on asking him about it though)
I also assumed that they would have checked or even replaced the fuel filter when they replaced the fuel pump (I have no idea if those two are even connected or related or what) but when I looked at the invoice I didn't see anything on there about it, and I know it wouldn't have been done for free LOL. So I suppose checking that out first would probably be the easiest thing to rule out, someone also suggested getting new spark plugs?

So does having a bad fuel pressure regulator mean that the entire pump needs to be replaced again?

My friends husband works as a mechanic and bless his heart, he said he would look at it next week for me, so the fuel pressure regulator and the injectors, and any possibly kinked hoses, are added to my list of possible problems that he can check out, thank you!

I wanted to add that I've been driving it all week and although it's still cranking longer than it should, it has started on the first try every time. But I feel like, and maybe this is just in my head I don't know, but I feel like as my tank got down to a little under a quarter tank full, that it was taking longer to start. And after I thought about it, the times that it started really roughly, my gas gauge was at about the same spot: 1/4 tank full. Coincidence?
Also, the last time it started roughly, I hadn't driven it in 3 days so idk if that had anything to do with anything either.
Regardless I'm hopeful that it can get figured out, it's awfully embarrassing being in a crowded parking lot, or anywhere public, with a vehicle that struggles to start.
Again thank you so much for your input, it's much appreciated!!

PNW NBS Z71

I ran shops and a fuel pump replacement without giving fuel pressure readings on the old pump and not replacing the fuel filter at the same time, is a big no no. Just like kids in math have to prove their work, so should a tech with a customer's vehicle. Plus, should also give new fuel pressure readings with the new pump and would have been smart for them to check the regulator. If is at the end of fuel rail, then is easy to check but if part of the pump, then no reason to check because is part of the pump replacement. My feelings about aftermarket pumps is clear. The "plugging back up/in" of the tube by the mechanic friend may have taken care of the fuel smell problem. The fuel pressure hold test, after the new pump has been installed, will tell you if the pressure is bleeding off. The condition of the spark plugs is needed as well.

Kmark

Hello again, unfortunately I still have not had it looked at again, friends husband and family are all currently self isolating...
So a couple things I've noticed this past week while driving it: it definitely is harder to start when it gets to around a quarter of a tank full; and there's definitely something weird going on with the gas gauge. After filling the tank I drove it maybe 60 something miles and the needle didn't budge from the 'F' position, hubby drove it maybe 30 miles and when I got in the next day the needle was down to less than 3/4 of a tank. By the time it got to slightly less than 1/4 full I only had driven about 240 miles, which just didn't seem right, and when I went and filled it, it only took 14 gallons which means I should have nearly half a tank left. Could this have anything to do with the cranking issue or is this a whole other issue that I now have to deal with?

PNW NBS Z71

No, the reading will not have anything to do with the cranking issue but it does point at the fuel pump assembly that does have the float for the fuel gauge and also may be having a problem picking up the fuel in the tank when it gets low. When I ran shops I always told my customers, and anyone else that would listen, to consider the 1/4 tank reading as empty. I never ever let my fuel tank get below 1/2 tank because the fuel pump build heat and the fuel around it cools the pump. If you run the vehicle low on fuel you are allowing the fuel pump to run hotter and shortens the life of the pump. The pump should be replaced with this: https://www.rockauto.com/en/moreinfo...41040&jsn=1694, has the pressure regulator and filter built in the assembly. When the tank is dropped and the pump replaced, the tank should be cleaned out. Bet there is debris in that old tank.

Kmark

Just out of curiosity what do you think it should typically cost to do all that, labor and materials?

PNW NBS Z71

That always depends on the shop you take it to. See if you can supply the part and make sure they know you are not expecting them to warranty the part. Make sure they know it is a quality AC Delco part and not a piece of **** like a Dorman part. Depends on their shop labor rate but is likely a 2.5 to 3 hour job. They should also be allowed to do the diagnostics before the work to back up what has been said here.

Kmark

I was just curious because after clicking the link you sent me for that fuel pump I was a little shocked at how much cheaper it was than the one I paid for, especially if the one you recommended is actually better for my vehicle than the one they put in.
I hate to have to replace the same part twice but I'm thinking that's just what I'm going to have to suck up and do.

PNW NBS Z71

That link is the Rock Auto price to you. All shops will mark up the price they charge you from what they pay for it. Typically in the 40% to 60% increase area. Some shops even double the price they pay. That is why I said to try and find a shop that will allow you to supply the parts. I ran shops and worked in shops for 35+ years and it was rare that I allowed a customer to supply their own parts. The shop that does any work on any problem should be able to back up what they say is needed by showing you their diagnostic/testing process.