Problem at the gas station - 308 gtsi

That is strange. Have you checked the "Check Valve" on the fuel pump? it may be overloaded with a full tank? the bucking and backfiring to me indicates an electrical pump issue... there is a fuse on the check valve relay in the trunk - right hand side when standing at the rear of the car.. under the carpet.. you need to remove 4 bolts - and flip it up side down to see the fuses wiring... but my first guess is the check valve is old, malfunctioning... or .... I dont know.

good luck - chasing these things is a pita.

 

It sounds like an evaporative emissions system problem to me. I don't know how much of a system that car would have had, but I seem to recall even the later carb cars had charcoal canisters. You might be getting liquid fuel in one and then sucking it back in, driving the engine hopelessly rich.
You can try to work around the problem by trying two things: try only filling to ~3/4 tank, and try filling slowly. If one or both of those resolves the concern, it will help you focus your solution.
An examination of the system components can point to a hose that might be damaged or pinched, or a valve that might be stuck.

 

The fuel accumulator can cause the starting issue when warm.

All you can do is replace it.

That might solve a good part of your problem.

And yes the FI cars had charcoal canisters. My '81 does. Passenger side behind the shock tower.

 

Good point that could explain the issues after re fuel

 

Jason, does it act the same way if you drive it the same distance as you would to go to the gas station and then shut it off for only as long as you would during refueling?

 

Are you putting ethanol blend fuel in there? The carb 308s are more sensitive to this (no question mine is) but I've heard of issues with all sorts of older injected cars

 

That's a big reason why I was asking if the problem arises under the same circumstances, even if he's not adding fuel. Vapor lock is something that comes readily to mind when you live in our climate.

 

could it be a fuel pressure issue. Removing the cap releases/changes the pressure in the tank and therefore the system?

 

Sounds like a great plan. Let us know what you find.

 

On an '81 308 ???

 

The plot thickens!

 

Cool --- So at least you've ruled out the possibility that your car was simply neurotic and in need of psychotherapy

 

Try adding fuel and leaving the cap off,drive a bit .Venting issue?Mike

 

Jason,

This is an effective way to rule in / out a venting or tank pressure issue. However, I would leave the cap on and just loosened (no seal) though --- to prevent any major spillage out the filler neck.

If the problem persists during this experiment, then you likely have another issue. My guess would be a weak / failing fuel pump.

 

Other than the fuel pump, there is one other possibility I can think of --- though it would be very unusual.

If the fuel tank on the driver's side (the fill side) is loose in its mounting (it is held secure by steel straps), it could be possible that when full, the additional weight is allowing it to sag or displace in a way that is compressing / distorting the fuel supply hoses or even pinching / shorting the electrical wires for the fuel pump --- as these are all adjacent to that tank.

Again, although this is unlikely..... stranger things have happened. And, it would fit with the symptoms you are experiencing. Might be worth a quick look.