The fuel is supposed to stay INSIDE the engine...but in this case it didn't.

Not sure what happened exactly. I went out to lunch and when I went to start the car it didn't start right away. I thought maybe it was flooded, so went to "clear flood" mode and it did start but died right away. Lots of cranking and I heard a loud POP and started seeing heat waves coming out of the back of the hood. Then I saw FLAMES coming out of the back of the hood. I turned off the ignition, grabbed the fire extinguisher (required by the National Council of Corvette Clubs for high speed driving events) and jumped out of the car. Fun now starts as I'm having trouble getting the hood open. I spun out several years ago in an autocross and I think it tweaked the frame because ever since then my hood won't open on the passenger side unless I pull up on it while pulling on the hood release. I tried to adjust it a while back but never got it fixed. Anyhow, finally got the hood open and there are flames shooting out around the rear runners. I pulled the pin on the fire extinguisher and looked for a trigger to pull. No trigger. I finally figure out that there's a lever on the TOP and press that. Success. Spray around the flames. They go out. They come back. More spraying. They go out. They come back. Finally run out of extinguisher but the flames are now very small. Somebody runs out of the restaurant with a fire extinguisher and a few second burst puts it out for good.

I'm looking at the engine with powder everywhere and can't really see any damage. Pretty amazing. Then I notice a vacuum line for the fuel pressure regulator has come off and the plastic is melted. I concluded that the fuel pressure regulator diaphragm ruptured and blew off the vacuum hose and sprayed fuel on the engine. Don't know what ignited the fuel. Maybe the heat from the EGR valve and pipe. Maybe a spark in the distributor.

While I was waiting for the tow truck it occurred to me that it would be a good idea to pull fuel pump fuse so it wouldn't run when the ignition was turned on. I figured there would be some steering involved. Good thing I thought of that because the first thing the tow truck driver asked me was to put it in neutral so he could pull it onto the flatbed.

Took some pictures when I got home and noticed stains around the gaskets where the runners attach to the plenum. I thought the pop was the fuel igniting, but it seems to have been a backfire. I don't remember this car ever backfiring in the 25 years I've had it, so? New theory is that the backfire blew out the fuel pressure regulator diaphragm. I guess it's possible the diaphragm ruptured and fuel got pumped into the plenum through the vacuum line where it exploded.

Can't really see any damage Oops, just remembered that the plastic lens on my Accel fuel pressure gauge is melted. I did notice that the EGR switch wire insulation is a little rough. OK. OK. OK. I couldn't stand it. I HAD to know. So I went down to the garage and ripped it apart. That powder went EVERYWHERE. When I took the plenum off fuel poured out of it (!) Stupid security Torx bolts on the fuel pressure regulator. Why did they do that? Years ago I bought a cheapo set of "every bit you could possibly want" and the hole in the T-10 bit was about 0.0000001" deep and it wouldn't go into the bolts. I had to use vise grips on them to get them out. The diaphragm was ruptured.

The wiring all looks OK, though it's slightly singed. The only real damage I saw was some of the vacuum lines were melted. The one going to the vacuum check valve was melted into two pieces. Pretty amazing (I said that before...). The funny Y-shaped piece is melted but looks like it might actually be intact. It's lying on top of the fuel rail and you can see that it is distorted. Check it out:

 

Wow you were lucky to get away with such little damage, did the hood survive no paint bubbles from overheating the paint?
I had the oil pressure sender fail on my vette spewing oil all over the extractors (while i was doing 100kmh!!!)
melting some wires and bonnet latch cables,and damaging the hood paint lucky for me i had two fire extinguishers in my vette and extinguished the fire quick smart.
As you noted the powder one makes a mess without putting out the fire, the Halon one put it out instantly ..... i should have used that one first hey (they are now banned for damaging the ozone layer)
Well put it all back together, you will most likely have 2 fire extinguishers in your vette from now on
Your vette lives to lay down some rubber another day
now have a well deserved cold one to celebrate saving your vette

 

Wow, glad you and the vette are OK.
Seeing this reminds me I need an extinguisher in the vette.

 

I bought one a few months ago. Hope I never need it.

 

Glad it wasn't worse. Good thing for the fire extinguisher.

 

I fastened one to my pass. lower seat frame, out of the way, but easily accessible for just this reason. C4's are getting older, I figure an engine harness and some wiring repair, etc...is cheaper and easier than a whole new(er) car. Glad you, anyone else was not hurt. Car can be fixed thanks to your quick reaction and being prepared.

 

Good thing you're okay.
jeeeez .... looks like a snow storm hit it. I can't laugh, really. I've got a situation with a hood latch now that I'd hate to keep me from getting to the engine if the need ever arose.
I'd better get my hands on a couple of extinguishers for that special bonding moment if it happens to me.

 

This is the reason I have a can of Cold-Fire in the car instead of a powder-type extinguisher.

You got off lucky, I'd say.

 

What is "a can of Cold-Fire"?

Thanks, Kim

 

http://www.firefreeze.com/coldfire.htm

 

I'm really glad I had that fire extinguisher in the car. Who knows what would have happened without it? I don't race this car any more (I use my '03 for that now). Several years ago I got fed up with the junky plastic bracket I had and replaced it with a metal one. The old fire extinguisher didn't fit the new bracket so I bought a new one. Good thing.

In retrospect, I think I remember the pop coming from under the car. The restaurant guy told me there were flames under the car (I never saw them). I think the fuel ran down the back of the engine and ignited on the catalytic converter or exhaust pipe.

Several years ago I had a blown head gasket and I cleaned the plenum, runners and manifold very well. Now I see stains all over them, which apparently is a combination of the fuel and the powder from the fire extinguisher. Here's a pic of the plenum (it's clean now):



The ruptured fuel pressure regulator diaphragm (I just ordered a new FPR because I didn't trust the aftermarket diaphragm -- this is obviously a critical part of this car):



The melted vacuum lines:



The top one goes to the vacuum check valve. The bottom one goes to the A.I.R. valves and the fuel pressure regulator. The rubber elbows are really hard, but AutoZone has replacements. The Y joint is molded on so I'll have to use rubber hose to connect the plastic lines. I already have a roll of the plastic vacuum line from when I replaced one on my EGR solenoid (also available at AutoZone).

I replaced the Accel fuel pressure gauge about 6 months ago because the lens kept falling off the old one (the new one is a different design, so that can't happen now). I just ordered another one. Kinda $$$$, but I want to know what's going on in my engine.

The tape on the wire harnesses in that area is a little singed around the edges but otherwise intact. I have a roll of harness tape, but they are so hard to get to that I think I'm going to leave them as is. This type of thing is right on the edge of my pain threshold, so I might just fix them while it's apart and I'm waiting for parts. The problem is that I'm about 95% done with the 700r4 I'm rebuilding and I got the one part that was holding up completing that project today. We'll see how it goes...

 

Found lots more melted vacuum lines. Every plastic vacuum line is damaged somehow, even the one between the two A.I.R. solenoids. Apparently the fuel flooded the intake manifold and ran down the front and rear of the engine.

The really irritating one I just found is the one that goes into the wiring harness behind the distributor and goes to the A/C system. That one is just a stub off the vacuum check valve. So the distributor will come out and we'll see what we will see...

That fire extinguisher powder is a big problem. I vacuumed up as much as I could. I had to blow some off with compressed air. That created a cloud that I tried to blow away but some got in my lungs. Nasty stuff. Not good.

 

Hey Cliff, that line is inside main harness and enters cabin at main connector on passenger side. You could dig it out at firewall entrance and patch in a new line from there.

 

Thanks, Agent 86. I see it in the picture. That's very helpful.

I took out the distributor tonight and I didn't see where the vacuum line goes (before looking at your picture). I did know that it went into the harness. I never really looked back there before so this is all new to me.

I just found out tonight that the vacuum line to the heater water valve is about a foot long and ends in a melted glob. I have never followed that one either so I have no idea what the route is. It looks like I'll have to pull the wheel well off to see what's happening in that area. Another opportunity to learn something new.

Sorta reminds me of something I read years ago. It was a little "saying of the day" thing that would come up when you turned on the computer. The one I liked the best was "You have the ability to learn from your mistakes. You will learn a lot today". I learned most of what I know about this car by figuring out how to fix problems...

 

for what it's worth, my limited, basic firefighting training emphasized discharging the ENTIRE contents of a fire extinguisher to prevent the type of reigniton you experienced.

sorry about the fire...happy it wasn't worse

 

Glad you were able to contain the fire. I had a similar experience a few years back with an underhood electrical fire my extinguisher that I had in the car at the time didn't work either but some local cops saw what was going on and helped out to get things under control.

Looks like the "bolt on" fuel pressure gauge's "glass" is busted in the pic above any chance the gauge failed and may have in turn released the fuel?

 

The lens of the fuel pressure gauge is plastic. I just put the new one on tonight.

You can see where the vacuum hose blew off the fuel pressure regulator. Fuel went everywhere. It flooded the intake manifold and ran off both the front and rear. It apparently caught on fire when the fuel hit the exhaust pipe on the driver's side. The brake master cylinder balance switch wire is the most damaged of the wiring. I just replaced it a few months ago because I somehow broke the connector. Those connectors are discontinued and I had to put on a used one.

Tonight I discovered that the vacuum check valve on the back of the engine is damaged. One part is melted and the passage is closed off. I searched through the parts book and couldn't definitely pin it down. It appears to be Delco 15-5421, but everywhere I looked shows it as discontinued. Auto Parts Tomorrow showed it for $5.33 and Sears for $34.95, so it pays to look around for these parts. A price doesn't mean anything if you can't buy it...

 

I found a new vacuum check valve at AutoZone for $3.99. Dorman Vacu-Tite 47150.

I replaced most of the vacuum tubing tonight.

I discovered that the vacuum tubing that goes to the heater water valve is melted at the firewall feedthrough. THAT's going to fun to fix. I unbolted the feedthrough last year while chasing problems and with about 200 wires going through it, it's almost impossible to move it very far.

The vacuum tubing from the check valve is melted but looks intact. I tried sucking on the tubing but couldn't tell for sure.

I took the fuel rails apart and removed the old fuel pressure regulator. As I was removing the O-rings from the FPR, one of them fell on the floor and disappeared into the twilight zone. I looked for quite a while but couldn't find it. I hope the new FPR comes with O-rings. It's supposed to be here tomorrow afternoon.

 

WOW, that was too close! Glad it didn't do more damage.

While you've got it all apart, my suggestion is to replace all the O-rings, hoses, and gaskets that are in contact with our gasoline/ethanol mixture with non-rubber ones. The ethanol is eating the rubber. Do the whole fuel system, from pump to runners. This was recommended by a guy in one of my car clubs.

Best of luck.

 

Where do they sell this Fire Freeze/Cold Fire? I think it's a good idea to carry one in the car. You know, "just in case".