As Vladen said above, the biggest problem with glue injection is that you don't really know where the glue is going. If it is a luan layer, chances are the water based adhesive they use to make the luan has desolved. To fix it by injecting glue would require getting glue between each and every layer.
I would consider removing the cabinet on the inside and cutting a section out, being careful not to damage the outer skin. This is easier than you may think as the last layer is allready delaminated from the skin. Then rebuild with new luan back to the inside. The wall would be solid and the repair hidden by the cabinet. Consider a fiberglass layup on the inside to restore structural integrity.
A small cut out (6 inch by 6 inch) would tell you what you are really up against and should not weaken the wall.
For a previous post with Delam around the gas fill, Spilt gas and diesel is very destructive to the foam core, glue and to the plyed wood if it gets in. Especially the diesel as it does not evaporate easily if at all. I found in mine the manufacturer didnt consider this at all when it came to sealing the port up so as to prevent this. In general I'd keep a rag handy and soak up any spillage fervently to prevent the likely damage.
I agree with those reccomending epoxy over solvent-based construction glues, or the moisture-cure polyurethane Gorrila glue. Epoxy is more gas and oil resistant than the others. The Composet product (www.delamrepair.com) is a 2-part epoxy designed for marine and vehicle use. It is much, much thinner than what you find on the shelf anywhere else. It wicks into porus materials, including micro-fractured Filon skin and luan. Safe for styrofoam too. Their kit goes comes with syringes to direct the flow of epoxy. Not going to fix everything, but works wonders on some delam cases.
It probably will not hold when the sun heats it up. You need to clean it off and start fresh by cutting in from the inside or outside.
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