Fuel? Smell

[Helirich]

Yesterday, my wife and I drove for a couple hours. Twice I had to brake reasonably hard and my wife said she smelled gas. She recently had Covid and doesn't have her smell completely back. I didn't lose my sense of smell and I smelled something, but I can't say for sure it was gas.

I read somewhere on here that if you have a fuel leak at the pump, sender or filler, you might smell fuel after braking because it will slosh hard to the leak spot. Today, I removed the tank cover and took the car for a drive. I hit the brake hard and jumped out to check the top of the tank. I couldn't see any wetness.

One thing that has me puzzled is the AC was on max. So even if the fuel leaked, I don't see why it should smell immediately. The outside air should not be coming in. Do you think my outside air valve is not closing tight? Is that a common failure? (I know it closes some)

The other idea I came up with is the accumulator leaking in the frame and that fuel sloshing forward on braking. Is that possible? I have recently had a couple hard starting issues. (That's why I suspect the accumulator.)

Any other ideas?

[iflights]

Yesterday, my wife and I drove for a couple hours. Twice I had to brake reasonably hard and my wife said she smelled gas. She recently had Covid and doesn't have her smell completely back. I didn't lose my sense of smell and I smelled something, but I can't say for sure it was gas.

I read somewhere on here that if you have a fuel leak at the pump, sender or filler, you might smell fuel after braking because it will slosh hard to the leak spot. Today, I removed the tank cover and took the car for a drive. I hit the brake hard and jumped out to check the top of the tank. I couldn't see any wetness.

One thing that has me puzzled is the AC was on max. So even if the fuel leaked, I don't see why it should smell immediately. The outside air should not be coming in. Do you think my outside air valve is not closing tight? Is that a common failure? (I know it closes some)

The other idea I came up with is the accumulator leaking in the frame and that fuel sloshing forward on braking. Is that possible? I have recently had a couple hard starting issues. (That's why I suspect the accumulator.)

Any other ideas?

You might try a new gas cap if you don't know how old yours is. Had a very similar experience with some gas fumes, not often, but frequent enough, and replaced cap. No fumes since.

[Helirich]

You might try a new gas cap if you don't know how old yours is. Had a very similar experience with some gas fumes, not often, but frequent enough, and replaced cap. No fumes since.

My gas cap looks as old as dirt. But I didn't notice any fuel around it either. I should probably get one though.

[Rich]

One thing that has me puzzled is the AC was on max. So even if the fuel leaked, I don't see why it should smell immediately. The outside air should not be coming in. Do you think my outside air valve is not closing tight? Is that a common failure? (I know it closes some)


Even though it is "closed" in MAX mode the recirc door is designed not to block all the outside air, only most of it.

It's not a failure. (DMC Technical Info Manual)

[Michael]

Also check your seal for the fuel gauge sending unit, (especially after a fill up), as well as the fuel pump seal of course.

[Helirich]

Also check your seal for the fuel gauge sending unit, (especially after a fill up), as well as the fuel pump seal of course.

I checked the fuel pump. It's very tight. The fuel gauge hole has just a plug. I removed it to check the O-ring and all looked good. I did feel it was easy to unthread. I threaded it on a lot tighter. (As tight as I could get it by hand) Should I use a pair of channel locks?

[Helirich]

Even though it is "closed" in MAX mode the recirc door is designed not to block all the outside air, only most of it.

It's not a failure. (DMC Technical Info Manual)

I guess that's so you don't suffocate? Are all cars like that? I would think the D would be the one car (rear engine) that wouldn't be much danger of carbon monoxide poisoning.

[Michael]

I checked the fuel pump. It's very tight. The fuel gauge hole has just a plug. I removed it to check the O-ring and all looked good. I did feel it was easy to unthread. I threaded it on a lot tighter. (As tight as I could get it by hand) Should I use a pair of channel locks?

Not too tight, you don't want to mess those threads up. The best way to tell if it's not leaking is brim the tank, and on the way home bring it to an abrupt stop a few times, then check the plug. If the weight of all that fuel pressing against it doesn't make it leak, you are fine.

[Helirich]

Not too tight, you don't want to mess those threads up. The best way to tell if it's not leaking is brim the tank, and on the way home bring it to an abrupt stop a few times, then check the plug. If the weight of all that fuel pressing against it doesn't make it leak, you are fine.

That's pretty much what I did today and couldn't duplicate the smell or see anything with the cover removed. When it happened, we had allready driven a fair bit. (Maybe 45 min) That's why I thought of the accumulator. But as I recall, it is not over the close plate. It would seem like it's leaking somewhere over that plate and when you hit the brakes it shoshes forward and the fumes get picked up by the AC. The car does not leak in my garage. When I fill it, I always fill it half way up the rubber fill tube. I never see a leak than.

On the accumulator, we went to lunch after driving for an hour and a half. Of course the car was hot and it was sitting in the hot sun for our lunch. (1 1/2 hours) We went out and it was hard to start. This is the first time it was hard to start since I got it on the road. I know the accumulator is to help with hot starting, but do you consider a car sitting for an hour and a half "hot start"?

Anyways, it did start after several long cranking sessions. Then it ran as normal for the rest of the day. Today it took just a bit longer than usual to crank up from dead cold. The accumulator is one of the few things I have not replaced in the fuel system. But I still don't see how it can leak in the frame. I need to jack the car up and check it out again.

[Michael]

Accumulators can go bad but in all probability it's something else. A good way to check rest pressure is to remove the air filter housing and press down on the metering plate. You should feel some resistance. It's better to have a fuel pressure test kit to watch it. I don't know what the manual says but I would imagine about 1 to 1.5 hours would be approaching the limit to hold rest pressure.

Also on your fuel smell, there are some hard lines around the accumulator (and soft lines too) that can leak. The access point to those lines are practically right under your nose( under the center console) and it doesn't take a big leak to smell it in the cabin. Not saying the fuel cap isn't the problem, it would the first thing to try and if it's old, it needs to be replaced anyway.

[Bitsyncmaster]

My car will hold rest pressure for 3 hours. If I tried to start it at 3.5 hours on a hot day parked in the sun it would not start. Now if I tried to start it at 4 hours it had no problem because the engine had cooled off enough.

That is why I put the 3 hour rest pressure extension into my RPM relay. But for that to work you must hold rest pressure for 1 hour or more.

[CFI]

I guess that's so you don't suffocate?

Cars aren’t airtight, if that’s what you’re referring to. Airplanes aren’t either, btw:)

[JBaker4981]

As others have said.... and I restate starting with the simplest thing first... replace your old gas cap. There is a high probability that this is the issue.

I was in the same boat within the first few weeks of owning my DeLorean and smelled gas in the interior and simply resolved it with a new gas cap from DGo (https://www.deloreango.com/us/gas-cap.html)

[Helirich]

My car will hold rest pressure for 3 hours. If I tried to start it at 3.5 hours on a hot day parked in the sun it would not start. Now if I tried to start it at 4 hours it had no problem because the engine had cooled off enough.

That is why I put the 3 hour rest pressure extension into my RPM relay. But for that to work you must hold rest pressure for 1 hour or more.

I had thought a hot start was 10-20 min. After that I figured it was considered cooled. If your accumulator is bad, can you not turn the key on and off a few times to get the pressure back up?


As others have said.... and I restate starting with the simplest thing first... replace your old gas cap. There is a high probability that this is the issue.

I was in the same boat within the first few weeks of owning my DeLorean and smelled gas in the interior and simply resolved it with a new gas cap from DGo (https://www.deloreango.com/us/gas-cap.html)

I took the gas cap and wire brushed the metal and cleaned the rubber. I also took some scotch bribe to the filler neck. It doesn't look old now and the rubber looks good. It has circular lines in the rubber. Is that a stock cap? It does fit tight.

I do feel it has to be something that sloshes. Obviously, any opening in the front of the fuel tank is suspect. But the fact that it only seems to happen on long drives has me thinking of something else. I know that AC water can sit on top of the close plate. I had that problem and fixed it. So if fuel leaked on there slowly, it could build up and slosh forward with brakes. Micheal reminded me of the accumulator location and I don't think it would leak on top of the plate. Maybe the fuel pressure or return lines. But aren't they hard lines with no joints through there? I wonder if the leak could be right at the fuel line to tank hose connection. Maybe the leak is running down the hard line and I didn't notice it. I guess I will pull the access cover again.

It can't be leaking much because I get pretty good mpg'.

The other wild idea I have is that it's not fuel at all. My wife says it's gas, but her normal great sense of taste/smell has been dulled by Covid. In my case, I never could smell very good. I definitely smelled something when she said it, but I thought it smelled like pool chlorine. I've never takin apart the AC box. Could water or bleach sit in there and slosh forward on braking to make a smell?

[Bitsyncmaster]

The prime does not force fuel though the injector lines. That is where the problem occurs. You would need to press the air plate to get fuel to flow though those lines.

[Ron]

The other wild idea I have is that it's not fuel at all. My wife says it's gas, but her normal great sense of taste/smell has been dulled by Covid. In my case, I never could smell very good. I definitely smelled something when she said it, but I thought it smelled like pool chlorine. I've never takin apart the AC box. Could water or bleach sit in there and slosh forward on braking to make a smell?

Maybe, brake fluid? ...hitting exhaust?


The prime does not force fuel though the injector lines. That is where the problem occurs. You would need to press the air plate to get fuel to flow though those lines.+1
OT, but I still think you should make a unit that activates the CSV if the RPM Relay (87b) shows the engine is not rotating and it sees the WOT activated, say, three times within 5 seconds and held. It could help with very cold starts too...

[Helirich]

Maybe, brake fluid? ...hitting exhaust?.

Not sure what that would smell like, but I doubt it could migrate forward to the AC pickup.

[JBaker4981]

I took the gas cap and wire brushed the metal and cleaned the rubber. I also took some scotch bribe to the filler neck. It doesn't look old now and the rubber looks good. It has circular lines in the rubber. Is that a stock cap? It does fit tight.

I do feel it has to be something that sloshes. Obviously, any opening in the front of the fuel tank is suspect. But the fact that it only seems to happen on long drives has me thinking of something else. I know that AC water can sit on top of the close plate. I had that problem and fixed it. So if fuel leaked on there slowly, it could build up and slosh forward with brakes. Micheal reminded me of the accumulator location and I don't think it would leak on top of the plate. Maybe the fuel pressure or return lines. But aren't they hard lines with no joints through there? I wonder if the leak could be right at the fuel line to tank hose connection. Maybe the leak is running down the hard line and I didn't notice it. I guess I will pull the access cover again.

It can't be leaking much because I get pretty good mpg'.

The other wild idea I have is that it's not fuel at all. My wife says it's gas, but her normal great sense of taste/smell has been dulled by Covid. In my case, I never could smell very good. I definitely smelled something when she said it, but I thought it smelled like pool chlorine. I've never takin apart the AC box. Could water or bleach sit in there and slosh forward on braking to make a smell?

Man, I really wouldnt beat around the bush with the gas cap. Just replace it. My old one looked perfectly fine but the slightest imperfection will result in fuel vapors being released.

For the AC Box, there is a drain that goes through the chassis from behind the center console that drains out water. This has known to become clogged easily as it is a very poor design. Once this drain is clogged, it will eventually back up to the point where your entire AC box will be leaking onto your passengers feet in addition to your passenger floorboard. So with that said, unless you constantly have water in the floorboard, dont worry about the AC Box.

[Ron]

Not sure what that would smell like, but I doubt it could migrate forward to the AC pickup.Are you saying that it is definitely coming from the AC vents?

[CFI]

I had thought a hot start was 10-20 min. After that I figured it was considered cooled.

The hot start problem is caused by fuel vaporizing in the lines after the engine has been shut off. This takes some time to accomplish. Generally speaking a hot start issue shows up 1-3 hours after engine shutdown.

[Helirich]

Man, I really wouldnt beat around the bush with the gas cap. Just replace it. My old one looked perfectly fine but the slightest imperfection will result in fuel vapors being released.

For the AC Box, there is a drain that goes through the chassis from behind the center console that drains out water. This has known to become clogged easily as it is a very poor design. Once this drain is clogged, it will eventually back up to the point where your entire AC box will be leaking onto your passengers feet in addition to your passenger floorboard. So with that said, unless you constantly have water in the floorboard, dont worry about the AC Box.

Did you just buy a cap at the zone? I think mine is OEM and I'd kind of like to keep it that way. Probably will order a new cap next time I order fro DMC.

I'm aware of the drain tube. I had to fix it and clear it allready. I did use some bleach, but I don't think it could be in there now.


Are you saying that it is definitely coming from the AC vents?

Yes, both times I had the fans on full blast and the smell was almost immediate after braking.


The hot start problem is caused by fuel vaporizing in the lines after the engine has been shut off. This takes some time to accomplish. Generally speaking a hot start issue shows up 1-3 hours after engine shutdown.

Interesting, on aircraft engines we have hot start issues too. On them, it seems like if you start it in five minutes, no problem. If you wait fifteen minutes, sometimes it's a big problem. Of course that's how long the fuel guys always take at the airport. If you wait 30-40 minutes, no problem. A lot of airports have battery carts just for such issues. (It easy to kill a aircraft battery.)

[Ron]

Yes, both times I had the fans on full blast and the smell was almost immediate after braking.
Got ya! - I didn't mean that the brake fluid was necessarily hitting the exhaust, just thinking about any other 'vents' (like the one by the battery, flow through,...) since you already checked the tank area and was still considering the accumulator.
I'd say migration would be about the same WRT the rear brakes...

Throw a bottle of florescent dye made for gasoline in it (before you jack it up;-)

[CFI]

Interesting, on aircraft engines we have hot start issues too. On them, it seems like if you start it in five minutes, no problem. If you wait fifteen minutes, sometimes it's a big problem. Of course that's how long the fuel guys always take at the airport. If you wait 30-40 minutes, no problem. A lot of airports have battery carts just for such issues. (It easy to kill a aircraft battery.)

It’s not a fair comparison. The injected Skyhawks I flew could fill their fuel lines via the electric pump. You also have complete control over fuel mixture. Priming the DeLorean will not fill the fuel lines. In the thousands of hours I have in fuel injected Skyhawks, I’ve never had a hot start issue, no matter how long or short we let the plane sit after shutdown.

[Helirich]

ItÂ’s not a fair comparison. The injected Skyhawks I flew could fill their fuel lines via the electric pump. You also have complete control over fuel mixture. Priming the DeLorean will not fill the fuel lines. In the thousands of hours I have in fuel injected Skyhawks, IÂ’ve never had a hot start issue, no matter how long or short we let the plane sit after shutdown.

I was not suggesting that the hot start issues were related. I've had hot start issues on carborated engines. What I think happens is a cold aircraft engine has much reduced compression. So the starter can crank it easily. A warmed up engine has full compression that the starter can only swing through a few times before it stalls the starter motor. If you don't get it started in those first few turns, your done. (At least with the onboard battery) A engine that was just shut down usually starts in those first few turns. But if it's sitting for 15-20 minutes, it takes a bit more.

I will say airplanes start easier than helicopters because the weight of the prop helps carry the rotation through the compression stroke.




A question to anyone.
What is the recommended procedure when it won't start? Is there any reason to push the throttle? I mean, there is no direct connection to the plate. I guess there slightly less resistance to the air sucking it down.

[Bitsyncmaster]

I was not suggesting that the hot start issues were related. I've had hot start issues on carborated engines. What I think happens is a cold aircraft engine has much reduced compression. So the starter can crank it easily. A warmed up engine has full compression that the starter can only swing through a few times before it stalls the starter motor. If you don't get it started in those first few turns, your done. (At least with the onboard battery) A engine that was just shut down usually starts in those first few turns. But if it's sitting for 15-20 minutes, it takes a bit more.

I will say airplanes start easier than helicopters because the weight of the prop helps carry the rotation through the compression stroke.




A question to anyone.
What is the recommended procedure when it won't start? Is there any reason to push the throttle? I mean, there is no direct connection to the plate. I guess there slightly less resistance to the air sucking it down.

Using some throttle will help keep it running after it fires. I rarely have to do that if my car has been sitting for a few months.

When I was flying airplanes (all carburetor equipped) It would always start quickly because of the prime with 3 shots. I know some owners that had starting problems with fuel injection on hot engine starts.

[Michael]

Comparing DeLoreans to airplanes is like comparing DeLoreans to airplanes.

[CFI]

What I think happens is a cold aircraft engine has much reduced compression. So the starter can crank it easily. A warmed up engine has full compression that the starter can only swing through a few times before it stalls the starter motor. If you don't get it started in those first few turns, your done.

I think a more likely explanation is that a cold engine has more resistance than a warm one, and fuel vaporizes better in a warm engine.

I’m not sure what kind of plane you’ve flown, but I’ve never “stalled” a starter motor, nor had one quit after just a few turns.

[Helirich]

Comparing DeLoreans to airplanes is like comparing DeLoreans to airplanes.

That's because airplanes are the "white sheep" of the family. Helicopters are much closer comparison.

[CFI]

When I was flying airplanes (all carburetor equipped) It would always start quickly because of the prime with 3 shots. I know some owners that had starting problems with fuel injection on hot engine starts.

Carbs tend to start better when hot, fuel injected tends to start better when cold. However, the hot start procedure in the POH for late model 172s works like a charm. The trick is knowing when it needs the procedure (oil temp out of green arc is usually what we used), and not overpriming it to the point that fuel is dripping from the cowling.

[Helirich]

I think a more likely explanation is that a cold engine has more resistance than a warm one, and fuel vaporizes better in a warm engine.

I’m not sure what kind of plane you’ve flown, but I’ve never “stalled” a starter motor, nor had one quit after just a few turns.

Not following that first line. The cold engine starts easier. More resistance would make it start harder.

I've only flown a handful of planes. (Ive flown just about everything helicopter, I'm ATP) But I've stalled lots of starter motors in both. (Never did it in a turbine though, lol)

[Helirich]

Using some throttle will help keep it running after it fires. I rarely have to do that if my car has been sitting for a few months.

When I was flying airplanes (all carburetor equipped) It would always start quickly because of the prime with 3 shots. I know some owners that had starting problems with fuel injection on hot engine starts.

So back to the question, no benifit to throttle while cranking? (Only after it fires) When I had my incident at the restaurant, it didn't fire at all for awhile.

[CFI]

Not following that first line. The cold engine starts easier. More resistance would make it start harder.


A cold engine will always require more energy to start than a a warm one, but that does not mean that it starts “harder”. The injected engines start just fine in sub-freezing temps, but I guarantee you that the starter worked harder to accomplish that. Heck, even the POH recommends pulling the prop through a few cycles to loosen everything up during winter ops.

There a reason preheaters are poplar in the Northern States.

[Bitsyncmaster]

So back to the question, no benifit to throttle while cranking? (Only after it fires) When I had my incident at the restaurant, it didn't fire at all for awhile.

As long as your curb idle is set correctly than I see no reason or benefit to using the throttle while cranking. That would also cause advance as soon as it started on a hot engine.

[David T]

Getting back to the OP's original problem, if you are getting a fuel smell out of the A/C it is because something is leaking in the top of the fuel tank area. On one car I saw, the OEM fuel sender leaked at the rivets. Some silicone sealer and all was good again. This fuel smell problem always seems to occur when you fill the tank up to the top. Because of the high pressure, you may never see a tiny leak but because it is so small, the fuel atomizes as soon as it escapes and becomes fumes. Go back and recheck everything. If it is a hose problem it will always smell. If it is not a pressure leak it will only be noticeable when you have more than 1/2 tank of fuel. It certainly could be a bad fuel cap or the neck where the cap attaches is bent preventing the cap from sealing properly. I had to replace my cap because the rubber gasket got hard and didn't seal well anymore. The Delorean fuel cap is kind of special, you will have trouble finding a replacement that works. Get it form a Delorean vendor. The neck is soft enough that if you lean on the fuel nozzle while fueling you can bend the neck.

[Helirich]

Getting back to the OP's original problem, if you are getting a fuel smell out of the A/C it is because something is leaking in the top of the fuel tank area. On one car I saw, the OEM fuel sender leaked at the rivets. Some silicone sealer and all was good again. This fuel smell problem always seems to occur when you fill the tank up to the top. Because of the high pressure, you may never see a tiny leak but because it is so small, the fuel atomizes as soon as it escapes and becomes fumes. Go back and recheck everything. If it is a hose problem it will always smell. If it is not a pressure leak it will only be noticeable when you have more than 1/2 tank of fuel. It certainly could be a bad fuel cap or the neck where the cap attaches is bent preventing the cap from sealing properly. I had to replace my cap because the rubber gasket got hard and didn't seal well anymore. The Delorean fuel cap is kind of special, you will have trouble finding a replacement that works. Get it form a Delorean vendor. The neck is soft enough that if you lean on the fuel nozzle while fueling you can bend the neck.

On the two occasions that we smelled the fuel. First was after 30 minutes of driving and the tank was almost full when we started. It was not a panic stop, but it was a fast deceleration from 65. The second time was more than an hour later (driving time) on the way home. Again, fast deceleration from 65. I did not fill the tank in between, so the tank was not very full.

When we got back to town, I filled the tank and drove 7 miles to my house. The next day, I removed the tank cover and tried to make it leak. (Several fast stops from 70) Couldn't smell a thing and could see any wetness on the tank.

[MrChocky]

As others have said.... and I restate starting with the simplest thing first... replace your old gas cap. There is a high probability that this is the issue.

I was in the same boat within the first few weeks of owning my DeLorean and smelled gas in the interior and simply resolved it with a new gas cap from DGo (https://www.deloreango.com/us/gas-cap.html)

Yes, and quoting this one more time because it's important. *Also* check, (as already noted), your accumulator lines. They are very likely original.