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Old 11-14-2017, 12:12 PM   #1
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1984 34.5' Airstream 345
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Electrical and Fuel System Modifications for safety.

Having seen what happens when a Classic, or other Motorhome catches fire, I am worried, and feel we need some further discussion about prevention.
There is already a thread on fire suppression, but we can go there too.

To make this simpler to overview, reference, and comment, lets break this down in some areas for discussion.

Engine/Generator fuel fires.

The Fuel system on gas engines is a known weak spot.
The rubber/flexible gas lines from tank to engine/generator deteriorate over time.
This process is accelerated by modern fuel formulations that have added alcohol, which breaks down most rubber pipe even faster.
Compounding the problem is the common, additional rear mounted electric fuel pump, which pressurizes the fuel feed line to the engine, in addition to the mechanical fuel pump on the engine.
On 345 models, I have counted, and identified, at LEAST 15 separate pieces of rubber hose that need regular inspection, in the Engine, and Generator fuel systems. At least 10 of these are subject to fuel pressure of about 6psi or more. A minimum of 2 or sometimes 3 of these flexible pipes are subject to both electrical pump, AND mechanical pump pressure combined.
In addition to this, on many motorhomes, the electrical pump/pumps have no safeguards to shut them off in the event of an accident, or event.

Electrical System Fires
One Chassis Battery, and 2 House batteries as the normal setup.
On my '84 345 the is a manual mechanical rotary battery shutoff for both Chassis and House batteries, mounted inside the battery compartent.
There is no fuse or fusible link, or circuit breaker link between these main cables, Starter Motor, and the distribution system for power.
A failed cable tie, or accident could easily cause a dead short.
Distribution center for power is on the drivers side outer bulkhead. There is no protection for the posts, relays, and Isolator, from shorting in the event of an accident.

Additional Fire Concerns

Generator fires.
Refrigerator fires.
LPG Fires.
Cooking fires.

Anything I missed?
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Old 11-14-2017, 01:51 PM   #2
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On the fuel pump issue:
In the Chevrolet P30 Chassis manual, and in later models the 12v feed for the electric rear pump is tied to an engine oil pressure sensor.
Engine stops, oil pressure drops and cuts off power.
My motorhome does not have this, so i need to add it or something similar. There is a wiring diagram in the above chassis manual.

Maybe something similar could be added to the generator too....

On the main electrical cables, I am very concerned.
An electrical short on the main feed wires would be a runaway electrical fire in short order. The only way to stop it would be to unlock/unlatch the electrical tray, and twist the rotary disconnects.
This is in reality, a time consuming(at least 30 sec), action, if indeed even possible before the fire is already raging.

That scares the life out of me.

I have been reading up in my recently purchased books...
Automotive Wiring and Electrical Systems, Vol 1 and 2.

In vol 2, I read how the Author protected these wires, on a vehicle with rear mounted batteries, which is similar in concept, and wire distance to our motorhomes. He added a pair of 200a circuit breakers, wired in parallel, right on top of the batteries, to protect, and yet give enough capacity.
Since the vehicle he was working on had a 555CI supercharged Big Block with 1350hp, and stated that these paired 200a had no problem handing the high torque starter and systems on this vehicle.

A search of Amazon gave me a $15 to $50 price spread on 200A circuit breakers. Seems like cheap insurance to me for the chassis battery.

I have no idea if that would work on the house batteries, or what the current requirements are, and how to size the circuit breakers.
Also, keep in mind, the chassis and house tie together option for emergency starts!
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Old 11-14-2017, 02:17 PM   #3
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Electrically speaking-

Rear electric fuel pump: oil pressure switch feeding a relay (solid state is my choice) at the pump is a common mod on old hotrods. Add a momentary pushbutton at the dash to bypass for priming the line before starting.

Batteries: breakers are nice but I would stick with automotive, so they are rated for vibration going down the road. Also they can fail, where a fuse will not (or if it does it will fail safe)

All the breakers it came with are 30 years old, i would replace them for good measure.

I don't know anything about the distribution center you speak of, but I would think making sure everything is properly fused would take care of it.

Protection at shore power input is a must.
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Old 11-14-2017, 02:35 PM   #4
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Hi

I would suggest that a cooking related fire is more likely than anything you have listed so far. If you smoke, that would involve an even higher risk. You can dig into a variety of data sources for the stat's.

In the range of the things you are talking about, a lightning strike or wiring error on shore power is a fairly likely thing. You may or may not be fully protected from various faults that result. Oil pan / lube system fires do occur. I've seen at least two over the years ....

Lots of possibilities ....

Bob
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Old 11-14-2017, 10:18 PM   #5
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I'm talking about 1980's thru 1990's Airstream Classic Motorhomes, not trailers.

Many have been lost to the fuel line failure, and many to Electrical fires.
Evidence of one example, is a recent, and powerful reminder, which prompted me to start this thread..

http://www.airforums.com/forums/f42/...nt-162052.html
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Old 11-15-2017, 02:21 AM   #6
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1984 27' Airstream 270
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On my house batteries, I have the fuses at the batteries in the box and I moved my battery switch under my dinette (over the battery box)

Chassis battery is unprotected.
With my TBI install, the fuel pump only turns on for a few seconds if it does not detect the engine running.
For fuel, I ran steel lines of larger size to and from the engine, no rubber except a short section of the return line at the engine.
Generator is still the stock install.
The point about cooking is valid because you have propane and a propane leak can be more explosive than a gas leak.
One other thing I experienced was a battery explosion in the box. I assume it was hydrogen buildup. only damage was acid on everything.

http://theouterlimits.ws/projects/airstream/index.html
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Old 11-15-2017, 04:16 AM   #7
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Quote:
Originally Posted by uncle_bob View Post
Hi

I would suggest that a cooking related fire is more likely than anything you have listed so far. If you smoke, that would involve an even higher risk. You can dig into a variety of data sources for the stat's.

In the range of the things you are talking about, a lightning strike or wiring error on shore power is a fairly likely thing. You may or may not be fully protected from various faults that result. Oil pan / lube system fires do occur. I've seen at least two over the years ....

Lots of possibilities ....

Bob


Iíve always been nervous about the gas stove. Iím going to convert it to a two burner induction cook top.
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Old 11-15-2017, 07:37 AM   #8
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I never saw those rims pop up on E Bay after that fire.......Just saying... Regards,Bob
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Old 11-15-2017, 07:54 AM   #9
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I, for one, am excited about the propane stove. I currently have electric in my house and hate it. Can't beat cooking with fire.
Propane leak detector below the stove and carbon monoxide detector above are probably good ideas. And a fire extinguisher within reach is a must. Don't cook things that might flare up. (Grill that steak outside)

Also, fuse that chassis battery, even the cheapest of cars do it. Starter malfunctions aren't uncommon.
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Old 11-15-2017, 10:46 AM   #10
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Electrical and Fuel System Modifications for safety.

Our 310 has what I guess is the standard setup, mechanical fuel pump on the motor and electric fuel pump back near the tank. A toggle switch on the dash controls the electric pump, donít know how standard that is. I find that I am able to leave the electric pump turned off unless I am in the mountains. Having read this, I have a better reason to keep doing that.
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Old 11-15-2017, 11:05 AM   #11
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That's how mine is too, and I don't even know if the feed is fused, so I want to get that sorted out.
On a side note, but it is relevant, I had an issue with fuel pressure being 8 or 9 psi with both pumps on, after I replaced the mechanical pump, and did a test. I believe the system was designed for 6psi max, and I had a leakage, flooding issue out of the top of the old carb.
I added a Fuel Pressure Regulator into the line going to the new carb, and set it at 6psi.

On the subject of fuel line, this is what I used when I did my hoses.

https://www.gates.com/products/autom...fuel-line-hose
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Old 11-15-2017, 12:44 PM   #12
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From my thread, here is what I found when I looked at my starter motor cables last year...
These need to be inspected, especially if you have headers that radiate more heat than the cast manifolds do. A heat shield for the starter motor is a good investment, as it protects the wires and starter too.

I drove 1600 miles like this, not knowing, and this was 30" or so downwind of a weeping chassis rail hard line to fuel pump rubber line...
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Old 11-17-2017, 07:48 PM   #13
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I'm actively looking for that front fuel pipe I mentioned, but in searching my picture archive I found these pictures of the original or older rubber fuel lines....

Note the weepage!!!!
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Old 11-17-2017, 08:18 PM   #14
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Here is another gem...
My Airstream smelled of gasoline in the bedroom, under the bed, at all times, but strongly when I filled her up..
So, FYI, the fuel filler neck has a 2" rubber hose to another metal pipe that goes through the floor.
There is also a 1/2" breather hose in the same area.
It is hidden by a vac formed cover which is mastic'ed to the wall and wood floor.
My mastic was loose and cracked.
Inside that, both fuel pipes were perished, cracked and weeping gasoline into the wood floor...

From there, the filler and breather pipes go down to the fuel tank...

This is the lower half of the 2" diameter fuel filler pipe....
Note the staining on the upper part, where it was cracked and leaking at fill up and if full sloshed.
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