Can I get a full pour?!

[nosole]

I have a 2004 Suburban 1500 that has never taken a full tank of gas. I was consistently getting between 17-22gal per fill from empty and was so confused by the range that I looked at the tank capacity, and was completely blown away that the tank is supposed to be 30gal!! I acquired it at about 125k mi, and in the 45k mi or so since, the absolute most I’ve ever been able to get in there was 27gal, and that was only one time when I’d been riding the empty light uncomfortably long. Aside from that anomaly, I very rarely can fill more than 22gal.

I’m going to replace the pump and sending unit, so I’ll take a closer look when I have the tank out, but has anyone else experienced this problem or have any ideas what might be going on?

Thx

 

[Tonyrodz]

I have a 2004 Suburban 1500 that has never taken a full tank of gas. I was consistently getting between 17-22gal per fill from empty and was so confused by the range that I looked at the tank capacity, and was completely blown away that the tank is supposed to be 30gal!! I acquired it at about 125k mi, and in the 45k mi or so since, the absolute most I’ve ever been able to get in there was 27gal, and that was only one time when I’d been riding the empty light uncomfortably long. Aside from that anomaly, I very rarely can fill more than 22gal.

I’m going to replace the pump and sending unit, so I’ll take a closer look when I have the tank out, but has anyone else experienced this problem or have any ideas what might be going on?

Thx

How accurate is the fuel gauge? Might be reading incorrectly, making you think you have less then you really do.

 

[HiHoeSilver]

You have one of two things going on here.

1. Your gauge is off, as @Tonyrodz has mentioned.

2. You have an EVAP block. This could be the vent valve or purge solenoid stuck closed or the charcoal canister and/or its lines plugged up.

Does the pump ever click off while it's filling?

 

[corvette744]

If it has baffles in it i have seen some strange things with broken baffles in the tank.I have seen them lodged under the sending unit and others places,most of them bang when sloshing fuel around corners-but some don't.I would drop the tank remove sending unit and look around-if none of the other good recommendations don't work.

 

[retiredsparky]

I will throw out another idea based on the 24 gallon tank on my Tahoe. When the gauge shows empty and the light comes on it always takes about 18-19 gallons. So I tried driving it one time until I calculated that I had used up most of the gas (didn't want to run the pump dry). I pumped 23 gallons into the tank.

I suspect the manufacturers want some gas reserve to keep the fuel pump from overheating and they overdo it. A couple of gallons would probably be enough to cool the pump, but I'm no engineer!

 

[nosole]

You have one of two things going on here.

1. Your gauge is off, as @Tonyrodz has mentioned.

2. You have an EVAP block. This could be the vent valve or purge solenoid stuck closed or the charcoal canister and/or its lines plugged up.

Does the pump ever click off while it's filling?

I think it’s a function of both. I started another thread about my faulty gauge giving wacky readings, hence the reason for wanting to replace the pump/sending unit. But a faulty gauge has nothing to do with how many gallons the pump says I’m putting in (considering my weekly driving habits are very consistent and my sample set of 45k mi has given me a looong time to analyze and discount irregularities).

Yes, the pump always clicks off before full. Often multiple times. Some pumps seem more sensitive than others, but to give you an idea, I can typically fill an additional 4-20 gallons after the pump first clicks off. Yes, you read that right. At the most annoying times, I can only fill between 0.5-1 gal per pull of the handle starting at 5 gal filled all the way up to 20+. So I’m literally standing there pulling the handle 3-15 more times depending on how finicky the pump decides to act. Do you have any advice on where I might consult instructions how to diagnose said blockage/stuck solenoid?

 

[HiHoeSilver]

I think it’s a function of both. I started another thread about my faulty gauge giving wacky readings, hence the reason for wanting to replace the pump/sending unit. But a faulty gauge has nothing to do with how many gallons the pump says I’m putting in (considering my weekly driving habits are very consistent and my sample set of 45k mi has given me a looong time to analyze and discount irregularities).

Yes, the pump always clicks off before full. Often multiple times. Some pumps seem more sensitive than others, but to give you an idea, I can typically fill an additional 4-20 gallons after the pump first clicks off. Yes, you read that right. At the most annoying times, I can only fill between 0.5-1 gal per pull of the handle starting at 5 gal filled all the way up to 20+. So I’m literally standing there pulling the handle 3-15 more times depending on how finicky the pump decides to act. Do you have any advice on where I might consult instructions how to diagnose said blockage/stuck solenoid?

Check engine light on? Personally, I'd replace the the vent valve and the purge solenoid first. When you change the vent valve, you could check the canister and the lines. If the canister rattles, it's shot. Blow through the lines... the charcoal pellets like to clog them.
If you have a 12v power source, you can hook up the vent valve, blow through it, and take power on and off. It should open and close. I'd just replace it myself, it's like $20.

 

[nosole]

Check engine light on? Personally, I'd replace the the vent valve and the purge solenoid first. When you change the vent valve, you could check the canister and the lines. If the canister rattles, it's shot. Blow through the lines... the charcoal pellets like to clog them.
If you have a 12v power source, you can hook up the vent valve, blow through it, and take power on and off. It should open and close. I'd just replace it myself, it's like $20.

Nope, no codes thrown. But yeah, I like the sound of that. I’ll try all that and replace it. At this truck’s age, I really don’t mind replacing things because I wanna keep it running in good form for a while, so I’m happy to get after these things before they compound.

 

[nosole]

I went ahead and changed the vapor canister and vent valve, and then blew out the vent line from the tank to ensure no blockages. It helped for sure, but didn’t solve the problem completely. I tested it at a notoriously finicky pump (for me at least) and got 8 gal (as opposed to 2 gal) in my initial pour before it clicked off. And while I still endured short pours til full, I was able to max out the pump’s fill limit of 25 gal (something that previously would’ve been a rarity).

I’m gonna pop in a new purge valve too and hope that fixes it, but either way, I think that’ll be the end of my lil adventure here. Fingers crossed that it’s solved!

 

[swathdiver]

My '09 has a 31 and change capacity tank. The most we've ever put in it was 29 gallons. If we head to the pumps soon after the idiot light comes on she'll take on 25-26 gallons. That's a long tank and there is going to be a few gallons not quite usable I would think. I used to play the click game, forcing fuel into the truck after it clicked, now we just hang it up after a 10 second wait and one more pull of the trigger. Once in a while the pump will click from the get go, we move to another pump or station, it's not the truck IMO.

Never have run it out of gas. We have more than a few times driven over 50 miles after the light came on and the Tech-2 says 11% fuel remaining (level surface) the whole time.

Average fill over the last two years is 22 gallons.

Our Montanas have 25 gallon tanks and we've put 24-25 gallons into them before.