Suburban not starting with Less than 1/4 tank


#1

I am getting the check engine light and the code is reading several issue with the EVAP system. Recently when it has been registering close to a quarter tank or a less than a hundred miles the car will die when going down the road or will just not start. I go and get a gallon of gas and put it in the tank and it starts up fine. Is this the fuel pump leaving me or could this be a result of the Charcoal canister, canister vent solenoid valve wiring, or all the other EVAP “stuff”?


#2

Just because the guage says you have some gas left doesn’t mean you actually do.


#3

Fill the tank at the 1/3 mark for a while and if problem does not happen again just keep doing that.


#4

Good ideas above. Here’s something else to try.

As gasoline is used, air is supposed to be allowed into the tank. Otherwise the tank gets a vacuum in it. It may be the evap system problem is creating a vacuum in the tank, and when you buy new gas, you are allowing fresh air into the gas tank which eliminates the vacuum temporarily. A big enough vacuum in the tank could prevent the fuel pump from delivering fuel to the engine.

Next time it happens, instead of putting a gallon of gas in, just open the gas cap, and maybe press on that little circular thing where you’d put the nozzle so it moves out of the way for 10 seconds or so, enough time to allow air to get into the tank. If it starts after doing that, it’s a pretty sure sign you have an unwanted vacuum in the tank. In any event, I expect you already know this, but with EVAP codes present, you need to find out what the problem is and fix it so the CEL turns off. Otherwise you won’t know if something really serious happens b/c the CEL will already be on. (Don’t drive unless the gas cap is fully on of course.)

You might search this forum for “evap system” problems to get an idea what the cause is. A lot of times it seems like evap code problems turns out to be the purge valve is malfunctioning.


#5

I’m leaning towards the pump, for these reasons . . .

When the level is low, the pump may not be fully submersed in fuel, and I would expect it to run hotter. I’m no engineer, but I know that the fuel cools the pump to some degree

And if the pump is running hot, I would expect the chance of failure to be greater

How old is the truck?

I’m asking because we have tons of GM trucks in our fleet, and in most cases, the fuel pump quits before the 10 year mark, sometimes well before


#6

I too believe a fuel pressure test is prudent; I too am leaning towards the pump.

When the tank us full, the pump is assisted in pumping the gas by something called “head pressure”, which is actually just the weight of the gas helping push the fuel up the pump’s pickup tube. When the tank runs low, and the “head pressure” disappears, a weak pump can be unable to pump the fuel by itself with sufficient pressure to keep the engine running. Your symptoms are not at all unknown with a weak fuel pump.


#7

Here’s another vote for a weak fuel pump.