Image Unavailable, Please Login Image Unavailable, Please Login Last week I started my Testarossa, took it for a drive and noticed the gas level dropped pretty quickly. from a full tank to about half. I fueled her back up, brought it home, and parked it. I made nothing of it because I figured maybe I missread the gauge when I started the car. Two days later I went for a much longer drive. Surprisingly, the gauge only went down about a quarter tank, which didn’t seem bad at all compared to the shorter drive before. This morning I backed it out of the garage to warm up. When I came back outside, there was a huge puddle under the car. At first I thought it was oil, but it turned out to be gasoline dripping steadily. I shut it off, restarted it, and the dripping stopped completely. I put the car on my lift, pulled the steel plate, but couldn’t find any signs of fuel leakage. Took it to the gas station, filled it up, brought it back home, started it on the lift, still no leaks visible… So now I’m stumped. Has anyone ever run into this issue where the car leaks a bunch of fuel and then suddenly… nothing? Any common culprits on these cars I should be looking at?
Gasoline dries up quite quickly when in small amounts and evaporates easily in a hot environment. Was the puddle under the car more to the right or to the left ?
I have had leaks from the fuel pressure regulator, enough that the fuel began to pool on top of the engine, but not enough to create a puddle like that. See if any fuel is puddling on top of the engine. Stains will also show a potential leak source. I would wait until the car is cool, turn the key on to pressurize the system and look for leaks with a flashlight. There are fuel return lines that deliver excess fuel back to the tank - see if the hoses are deteriorated. As well, there are fuel tank vent lines on the back of the rear bulkhead - they are generally petrified after so many years. Check them too.
Ezio, easy to determine where your major leak is coming from. You said you removed your undercarriage protection plate. Put it back up on the lift and do not start the engine. Too dangerous. Pull both fuel pump relays. Pick one side, let's say the 7-12 bank, and jump the 87 and 30 relay contacts (on the right side FP relay socket). That side fuel pump will run and will fully pressurize the 7-12 system and return fuel to the tank. Quickly observe to see if that side is leaking and be prepared to quickly remove the jumper if it does. Catch dripping fuel if you can. If no leak on the 7-12 bank, then do the same to the 1-6 bank (on the left side FP relay socket). Steve M will jump in if this is unfamiliar territory to you as he has done for all of the TR community. By now pretty much all of your fuel system components and hoses on a '90 Testarossa should have been replaced. Once you determine the leaker, you should evaluate the replacement status of everything else. Remember the braided stainless hoses are just plastic inside and the plastic becomes very brittle with age and heat. The rubber hoses returning fuel to the tanks will become petrified, as well as the fuel pump suction hoses and the fuel tank crossover hose will become petrified. The fuel pressure regulators will piss fuel out their little rubber vent line spraying across the top of the engine when their internal diaphragm fails. Ask me how I know, so preventative replacements are critical. EDoug
Thank you! I’ll try that. After putting the car on the lift and trying to see where the fuel is leaking from, there are no signs of leakage. Insane! I have to look further into this.
Ezio, two observations. Does that water heater in front of your Testarossa have a lit pilot light. If so, can it be turned off during your investigation as it is not smart with leaking gasoline. The color of gasoline leaking down onto the concrete looks dark because it washes the chassis coatings off on its leakage path. EDoug
Looks like it coming off from up the fuel tank. So I'd check that fuel return hose and the nipple its attached to.
That is a TON of gas. You have to have a bad line or loose connection somewhere going to that passenger pump to filter, or further.
I’ve located the issue… see attached image. From what I can tell, this appears to be the fuel return line, as it’s positioned at the top of the tank. I lost approximately three-quarters of a tank in under ten minutes due to the failure. It looks like this component had already been repaired once before, and that repair has now failed. I was unaware of any prior repair work, but it appears that during a previous service at the dealership, the line may have been damaged and temporarily fixed with adhesive or sealant… Now, recommendations for a proper and permanent repair without having to take the tank out!? Image Unavailable, Please Login Image Unavailable, Please Login
Thank you for this, you were correct, the spot where the fuel was leaking is because the fuel took the coating completely off the undercairrage where it was leaking.
