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Fuel Pump Crossover

7K views 21 replies 7 participants last post by  Venom219 
#1 ·
My G8 runs out of fuel around 1/4 to 1/8 of a tank. I've checked and yes there's still fuel in the tank when it runs out. I researched and thought maybe the crossover tube had came loose. Just pulled the pump and tube was still attached to bucket and is attached somewhere on other side of tank. Not sure what else to check. Any ideas are appreciated. Thanks
 
#2 ·
That fuel remaining in the tank (based on your fuel indicator) should at least have caused the DIC to display the *low fuel* and or *very low fuel* status info. How many gallons of fuel do you add to your tank after reaching the 1/4 tank remaining level ? It should be at least 13 to 14 gallons. Knowing this would allow you to perhaps eliminate the 2 fuel tank level sending units, and give you an idea on how well the jet pumping action is working within the tank. When your down to that 1/4 level, there ought to be about 2 to 2 1/2 gallons remaining on each side (course that might be tough to tell by looking down into that dark cavity).
 
#3 ·
The time it died at 1/4 tank I put in one gallon to get to gas station, then put in 12 and it was full. The other time it died at 1/8th and put in 14 at the gas station. Do these cars use a jet pump? I read somewhere they just use the suction of the main pump to draw fuel over? Haven't found a definite answer
 
#4 ·
Jet pumping is the wording used in the service manual. Fuel rushing past a venture shaped device, creates a low pressure zone when passes by a specific area of it. That action pulls the fuel over from the drivers side to the passenger side, until both sides are balanced then it ceases. Once the fuel level drops to a given point in the passenger side, the action resumes to re-balance the 2 sides again. It repeats this action over an over until both sides are technically dry. If for some reason the transfer action ceases prior to reaching that totally empty status, I can see the pump only sucking up air from the shallow sump below it. Since you can get at that pump assembly so easily, you must own a car that has that slick access cover plate mod. Were you able to take a guess, as to how much fuel you think was still in that passenger side tank portion ? The Jet pump action must be working pretty good, at least down to the 1/4 tank level.


Or maybe you (or somebody) has messed around with the primary side fuel module, an components (within it) are a little out of wack from where things should be.
 
#5 ·
No one had messed with the fuel pump that I'm aware of. I've owned the car for three years and it just started happening this summer. It's got about 3/4 tank now so I can't say as how much is left. I was hoping the crossover tube had popped off or something but it hadn't. And no, no access cover yet. Just a little research and a Dremel to make the hole. Thanks for the replies
 
#8 ·
Sounds like your driver side pump is bad. It's just there to shoot fuel from the driver side of the tank to the passenger side main pump. Depending on your mileage you might want to change both while you have them out. We have some nice upgrades available if you are planning on doing any serious modifications or plan to run E85
 
#11 ·
What is the vehicle's current mileage? Is it driven mainly for relatively short trips i.e. around the corner and back, long commutes, or a combination of both? Since the car has only died twice at 1/4 and 1/8 of a tank, how much gasoline is normally kept in the tank? Discovered quite awhile ago, the fuel gauge on the G8 isn't 100% accurate which could be a calculated buffer. However, that's neither here nor there and it appears as if something is either on its way out, overheating, or shuts off after getting hot. The fuel pump is designed to pump fuel to the rail as long as it has fuel, power, and ground. Therefore, it getting down to 1/4 and 1/8 of a tank and possibly being unable to acquire gasoline is interesting. When the vehicle quit, was it a slow death as in sputtering or all of a sudden?
 
#13 ·
Any updates? Presume there is a correlation between the car dying twice and the amount of fuel left in the tank. Could it be the fuel pump relay (R12-instrument panel fuse block) upon getting hot shuts off power to the fuel pump? Of course, the notion would be more plausible if the car regularly quit regardless of how much fuel remained. There is a fuel pump fuse (F12) in the rear compartment fuse block which might be worth checking. Perhaps in the time it takes to add a gallon of fuel, an electrical component is given sufficient time to cool and resume operating normally. Long story short, was about to install a new fuel pump on a vehicle before discovering an intermittently malfunctioning relay was the culprit. Purchased a few used relays on eBay and problem solved.
 
#18 ·
No. Fill and run to less than 1/4 and refill. Car is driven pretty frequently and run hard. I did order the relay and will replace. No codes. Really at a loss as there are no clues as to the problem. Even if I replace the relay, I won't know if it's fixed unless it dies again.
 
#19 ·
Current mileage? Could have swapped it with a lesser used, fully functional relay. If it happens again, would wait a few minutes then try to restart the car before adding fuel.
 
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