DANGER!!! Warning to anyone with gas tank mounted higher than carburetor!!!

I drove my roadster pickup over to my sons house, across town, and parked for an hour in his really steep driveway.. When I left his place, the RPU hiccupped when I left his place---I thought--Hmmm---Must be flooded a bit from being parked in a real steep incline. It seemed to clear allright, and I drove down to the first intersection. Then it quit!!! I could smell gas quite strong, and it turned over fine, but no spark. I waited 15 minutes and tried again---same thing.. Caught a ride home and got my Ford Ranger and my towbar and went back across town and hooked up the car and towed it home. Waited an hour and tried to start it again. This time, it wouldn't turn over at all. Charged the battery for 2 hours and it still won’t turn over. I hear the sarter solenoid kick in, then just a grunt, and nothing else!!! I pulled the plugs. Engine was totally hydrauliced!!---With gasoline. I pulled the p***enger side rear plug, and gasoline ran out of the cylinder. After getting a good visual on where my fire extinguisher was, I tried the key---all sparkplugs out. It shot gasoline clear across the garage from just about every cylinder!!!--Darned old intake must have been right full of gasoline
I know what happened. The gas tank is higher than the carburetor. I don't think that is unduly weird, because there are a zillion hot rod pickups running around North America with tanks in the bed, higher than the engine, and they all seem to work allright. Will the tank gravity feed thru the mechanical fuel pump?? Damn right it will!!! I pulled the gas line off the carb, and it was constantly flowing, with the truck setting in my yard on the level driveway. So, I deduced that the float needle in the carburetor was stuck wide open. It might have something to do with having parked in my step sons steep driveway, or it could just be coincidental. The gas is flowing thru the carb, thru the intake manifold, and filling up any cylinders that are setting there with the intake valves open.. I siphoned all the gas out of the tank, and connected a rubber drain line to the fuel line which screws into the carburetor---that drained any residual gasoline that was still in the fuel tank into a five gallon gas can on the floor.
I decided that I had better change the oil---OH My God!!!---I got 2 gallons of oil mixed with gasoline out of the oilpan!!!!
This is the first hotrod that I have built with the gas tank higher (in the bed) than the carburetor. I did a little research, and found that on trucks with dual gas tanks there is an electric solenoid valve available. With no power to the solenoid, it defaults to tank #1. When you want to switch over to tank #2, you flip a switch which supplies power to the valve and shifts it to tank # 2---as long as the solenoid is energized.. I bought one of these “switch over” valves, ($56.00) and plugged the port to tank #1. I plumbed the port which would normally run to tank #2 to run to my gas tank in the back of the roadster pickup, and ran the wire from the solenoid to the “switched power” side of my ignition key. Now when the RPU is just setting, with the engine not running (key shut off), the solenoid valve closes and no gasoline can gravity feed from my tank into my engine. When I turn the key on to start the engine, the solenoid valve energizes and lets the gasoline flow. I don't know how much gasoline has migrated thru the exhaust manifolds and into my mufflers, and there is no way to tell, because when I had the exhaust system built I welded the mufflers in place. Once I get everything ready to start, new oil, rebuilt carb, and safety shut-off valve wired up, I may have a real set of flamethrowers!!! One thing for sure, I won't be starting it inside the garage.

 

You got lucky!!! A friend of mine had a leaky carb, didn't hydralic lock the engine, (more misfortune for him). Trying to start a fresh engine, spark traveled down a sloppy dist. shaft, ignited the fuel in the oil pan, blew him about 30 ft. Also blew off/distorted every piece of tin on the engine. Got lucky though, didn't get hurt, just s****ed up a bit. Cost hiom a lot to replace all of the tin though. Yes, he did fix the carb leak.

 

An electic fuel pump that is wired hot all the time will do the same thing. I like the way you fixed your truck.

 

A buddy of mine in high school had a '64 Galaxie with a 390. He went to start it one morning before school and he heard a bang and smoke poured out from under the hood. The tin on both valve covers had bowed out from the explosion. Similar to what happened in brianangus' situation, the fuel pump went out and leaked fuel into the oil pan. Not too familiar with Fords, but was told the pump was the culprit. My friend too was lucky nothing else happened.

 

your a JOHN FORCE wanna be...

sad way to make 2 cycle gas..

man be careful that fuel flushed out all your engine bearings too and will soften gaskets ..

i would topoff each cylindar/over fill enginewith oil and turn over engine by hand to try to get lube where it should be


if you do" fire it" up you had better have a oil pressure gauge !
and i would drain that oil and re filter it again and then do it real quick after that

 

fill the engine up to the top of the manifold with oil. let it sit a couple days. turn it over by hand. rotate it both ways. drain. repeat procedure. drain. fresh oil, filter, and break in like you would new motor. good luck.

 

Thanks for the head's up Brian. My tank is a lot higher than the pump. I'll definitely watch where I park.

 

The FIRST thing I done on the T-roadster I bought last year was to put a shut off pet**** and then a filter at the outlet of the fuel tank.

It just seemed like common sense to me to shut off the fuel.

Ford did it on the T's and A's. Motorcycles do it. Most race cars do to.

It safe, but more importantly to me it makes maintainence easier.

Frank

 

The Ford pick up 2500 Diesel(about 88 ) had an electric tankswitch/valve who would be very suitable in this situation!

 

The tank in the bed of my daily driver is in the bed (36 gal ss tank) but it draws the fuel out of the top with a tube going in from the top. So far it hasn't siphoned fuel out when it shouldn't but I have thought about putting in a shutoff valve.

 

It won't siphon untill someday when your float needle sticks, then **** will happen real fast!!! This is the fourth year of driving the roadster pickup--3 years trouble free untill now---brian

 

Great tip, good heads up, Im building a pickup now, I'll definetely check this out.

 

After reading this, and contemplating a lot. I think I will go the extra bucks and put 1 under the bed of mine.

 

I think I'd be investigating an electric solenoid to shut off the fuel supply unless the ignition is on.

 

THANKS, since I am right in the middle of my RPU build, your heads up came just in time! The solution that you came up with is the way that I will go man! I have also enjoyed your tech post, this guy from Texas is very thankfull for your input!!

 

Buddy of mine had a model A roadster pick up with 3 97's and a fork lift fuel solenoid that shut the fuel off when he turned off the ignition. That was years ago and I remember him telling me that the way things were going, we would soon be paying $1.00 a gallon for gas.

 

thanks for headsup also ,just came in from garage .building rpu guess what thinking tank in bed! ill have to take care of that!

 

This exact same thing happened to me about 4 weeks ago! I had driven at lest 1000 miles before this particular day and never had this problem. Then same thing - battery seemed like it wouldn't turn the engine ... etc, exactly like you said. After draining and putting in new oil right where it sat, started it and have driven several hundred more miles trouble free - oh and I added added a manual fuel valve. First I had ever heard of such a thing. My tank is higher than the carb ....

 

I'm glad nothing broke!

Manual fuel valve on the Model A tank is what I have to prevent the strombergs from swamping my engine. I shut it off when I'm not driving.

 

old cars with the tank in the cowl or motorcycles also suffer from this if you don't watch it... it's also a good reason to use a good fuel filter, occasionally a piece of trash will stick one open...

 

I have one that I run with a return line at the pump. I ***ume it keeps excess pressure off of the carb. But I would like to put in a manual shut off valve on it, so that it won't flow on it's own if I decide to work on the fuel lines or carb. And if you get a leak in the line it will empty your tank all over the ground. Not fun! My father in law had a fuel pump leak internally which pumped his crankcase full of gas. It didn't blow up or anything like that but it did quit running, and that's what they found.

 

how close to the carb did you mount this shut off valve?? just wonder about the gas, in the line, between the valve and the carb. might be enough to cause a problem. certainly could take a minute to start if the gas all ran into the engine and the carb and line was empty. just curious. glad you brought this to everyones attention. i've never heard of this one before but it makes perfect sense.

 

In my T tub I am running the stock tank in the cowl because I have a Chevy ll 4 banger. I used one of the electric solenoids available from Mac's just at the tank outlet. Also running an electric fuelpump. Works good so far. Had to end up putting on a fuel regulator though with the electric pump. Too much gas for a 4 banger. Pat.

 

I put the valve at the rear of the car near the tank. ***uming that the carburetor is working properly, when you shut off the key any gasoline in the carb and gas lines will remain "static". It can not run into the engine, because of the needle and seat in the carburetor. It can not run back to the valve, because the valve is shut. Next time you go to start the car, there should be no difference because of the fact that the valve is in there. The valve is insurance against that one time when the carb float needle sticks open and the whole damn gas tank fills up your engine, like happened to me.

 

From my experience with this problem on race cars, I would check compression to see if it bent a rod when you tried to turn it over with the cylinders full of fuel. I have seen this happen several times and had it happened to me once. My engine builder told me it is the number one cause of engine failure, in his opinion. It is amazing how easily it happens, but I guess when you consider the gear reduction between the starter and ring gear, it becomes clear how it happens.

Jay

 

I'm just curious is your fuel outlet at the bottom of your tank or does it come in fromthe top I have seen a few cars do this when they try to use the stock model a tank and don't install a fuel shut off valve. You are lucky you didn't blow up the neighborhood by turning over the engine without plugs

 

Very interesting information to tuck in the back of the head. Thanks for taking the time to post the details.

 

Top outlet tanks will siphon gas out.
That's how the fuel gets to the pump - in most cars - whether electric or mechanical.

Making sure the carb is higher than the tank is important and a shut-off valve of either kind is a good safety feature.

When I pull the carb I shut the fuel off back by the remote filter near the tank - which also stops fuel flow to the filter so you can change it without dumping gas.

With the shut-off valve closed, the fuel line and filter are still full of gas and if you let the carb end of the line hang down it will siphon fuel out of the line.

I have the fuel line set up so you can break the line about head height and it's right on the edge of siphoning there.
For that reason and if the carb line will be off for a while I have caps that fit on either the fuel line or the bulkhead fitting on the fuel line splitter.
A nice safety feature if the car will be unattended for a while.
I carry a couple of these caps in the roadster toolbox as well.

Here's a pic of the fuel line splitter which is a handy gadget and makes swapping between single quad and dual quad easy.




Running a drag race style bottom outlet tank is a less than desirable setup on a street driven car.

 

Brian, is there room under the bed to set a tank?

A custom tank would probably be required, but I see a lot of pickups with the tank between the frame rails and the filler accessed through a panel in the floor.

Speaking for myself, I'd probably put the filler someplace I could access it in case I had the bed full of stuff.

Big PITA if you have to unload simply to fill up.

Watched a guy unload most of his trunk on a nicely built 34 coupe - that was on the edge of being overly smooth - just so he could remove the inner carpeted panel that hid the trunk and then fill up.

 

Thanks Brian, particularly for the tech on solving it. Those of us that have owned bikes have lived with this issue for years.

Does anyone run a bike style tap in the fuel line, would be a good security device too.