Got what I think is a new one. My 944 burst into flames yesterday in the driveway as I was trying to restart it. Got the flames out with what I hope is minimal damage. Need help with fuel system problem

Here is the history - sorry if it is a little long. Car has been running great. Parked car the other day for 20 minutes. Came back and it would not start. Sounded totally dead despite constant cranking on the engine.

Yesterday, I went through all of the normal items. DME relay was good. Had good spark. With plug out the pistons pumped out mist with obvious fuel in it. Loosened the boot to the air intake a squirted a little gas directly into the intake (did this before to track down a DME relay problem). With throttle full open and 10-15 seconds of cranking, the car finally starts and spews out clouds of white smoke for about 30 seconds before finally clearing out.

Appeared to idle OK but a little rough. At this point I am totally perplexed. I assumed if the situation was a no-gas problem, the engine would cough and run for a few seconds from the small amount of gas added and then die. The car is now running - although a little rough. So, I drive it around for about 15 minutes to see how it is performing. Suddenly, it starts to run worse and will not hold idle without extra throttle. I shot back home and parked the car in the driveway. I spent 10 minutes clearing a space in the garage to park the car so I could do more investigation.

Lucky for me I never got the car into the garage or I might have burned down my house. While cranking the engine at full throttle to try to restart it, the car burst into flames. The boom was loud enough for my wife and son to come running out of the house. Flames shot out from under both sides of the car. It was pretty exciting. To my surprise, the electrical is fine and the engine will still crank - although I did not try to start it. Air conditioning belt melted and a fan blade got a bit burnt.

It was obvious to me that I had a gas leak and decided this morning to try to figure it out. I jumped the DME relay so that I could hear the fuel pump spin and look for fuel leaks without the ignition on. I heard hissing at the fuel regulator and smelled gas. The vacuum line connection at the back of the fuel regulator was spitting out a fine spray of gas right down on to the top of the engine.

Thus, I think I finally understand the root of the problem. The regulator failed and was allowing raw fuel to be pumped back into the air intake causing too-rich air/fuel mixture to allow the car to start without long, full throttle cranking. When it did finally come to life, the white clouds were the extra rich mixture being burned off until the car could run OK despite the additional fuel being sucked in through the vacuum line.

The pressure at the vacuum line connection at the rear of the regulator must have been great enough to force out the spray of gas. When I parked the car in the driveway after driving around for 15 minutes, the engine compartment had become saturated with gas and gas fumes from the leak. What luck!!!

Here is my question for the experts. Does all of this make sense and has anything like this ever happened before? Did the pressure regulator failure occur in a normal manner or is it possible that I have another problem that caused the regulator to fail? I obviously want to fix this right. I don't want to assume I just need a new regulator and have it fail again due to some other problem.

Thanks for any help you can offer.

 

Regulators are known to fail from time to time, usually filling the vaccum hose with gas when they do. If the vacuum line isn't a tight fit, it can leak like yours did. You're lucky you caught it in time!

 

Oh, and welcome to rennlist!

 

change the vac line and the FPR. they are known to fail.

 

and check ALL of your fuel lines! Do that while someone cranks the car.

 

+1!!

The way the fuel lines run, the heat from the exhaust rises up and bakes 'em. They dry out and eventually split. If you haven't replaced them (all 3 - supply, return, and *especially* the little one that goes from the damper to the rail) do it now.

 

Thanks for the info Tom. I assume that the same problem can happen to the damper, so I am going to replace that too along with all three of the rubber lines and vacuum line connectors.

Mike

 

Here's something else you might consider, have the local hose/hydralic shop add long barbed ends to the fuel hard pipes and Reg/Damper. 300 psi hose is like a dollar a foot from a spool, the stock replacement is HOW MUCH? Mine acommodate three 1/2" clamps, just to be sure. I can change all three hoses in 5 minutes for $4. And 'FlyBoys' sells nice heat reflective covers for $40.

 

Should I be able to remove the vacuum line from the fuel pressure regulator and damper without depressurizing the fuel system? Will it be dry? Is this a good way to check if they ok, need replacement or should I invest in an air/fuel gauge?

 

Should be dry unless the diaphragm broke

 

A/F gauge (wide band ) or fuel pressure gauge? Two different things. I'am adding this with a tap for a sending unit.

http://www.pauertuning.com/index_fil...ssuregauge.htm

 

Can you post pictures?

 

wouldnt hurt to change the tank-to-pump hose either, it takes about a minute and it is one of the most exposed hoses on the car.

 

Any pics??

 

This kind of nightmare is exactly why I replace all of the old easy/cheap stuff BEFORE it fails. The FPR and damper were two of the very first things I replaced. Simple risk avoidance.