For any of those that dont like a wordy post please skip to the end of the post for the questions I have listed in bolded blue color....

Recently I plumbed a larger gas tank in Ethyl The Tool Truck (ETTT). Yesterday was not cool. Ive operated the truck 3 or 4 times since Ive plumbing it and electric fuel pump that is part of this new plumbing. I have wired an on/off switch so I can choose to run it or not. Prior to this addition only the original style mechanical fuel pump that has a special windshield wiper vacuum chamber delivered fuel to the engine.

Yesterday I got on Interstate 5 north from my Delmar Heights onramp at 9am. The usual morning busy San Diego commute traffic was there. Its ok it brings speeds down to around 50 mph where my truck is happiest. I made it about 6 miles to the Birmingham exit. Currently there is a bunch of extensive freeway improvement/addition/widening happening starting at that exit and progressing north for 3 more exits. The Birmingham exit currently has those temp concrete 4 foot high wall barriers on the exit to add the additional lane they added. It redirects folks at a sharper angle than usual but it did add a lane. That was great because I was now blocking the other one. I just made it off the freeway onto the exit by maybe a couple of feet out of the freeway lane when my engine stopped. 200 yards approaching that exit I was struggling to keep the engine running and was proceeding at 5 miles an hour. If I tried to accelerate at all the engine wanted to shut down. I was basically traveling a bit above an idle. Thankfully I made it onto the exit and there were no freeway construction crews there yesterday to further congest stuff. The apron before that exit is removed now also due to all the construction. If my truck had died in the lane it would have been a real calamity. I really did not like lifting the hood right there with me just clear of the freeway lane on the exit to see what was what but.I could not get the engine to start. I was forced to go see what the heck was up.

My Oil bath air cleaner etc set up that is on a COE isnt conducive to see what is going on in the carb (see the pictures of the air cleaner/air cleaner fixture etc). I determined that it was a fuel problem because it seemed it might want to fire. I knew my new tank had gas in it and that my old tank had a full tank of fuel. I had pinched off the rubber gas line from it that is connected to the mechanical pump inlet because I was trying to use the electric fuel pump and the added 45 gallon tank to see everything was good with all of that (See the picture of how that was pinched off.) I also clamped it because the electric fuel pump was filling the 2nd tank up. That original tank leaks out of the fuel sending unit when it is too full. The first time I used the electric pump and did not have that tank hose pinched off I had a huge gasoline leak out of that original tank when it filled from the electric pump pushing fuel into it..

On that exit, I removed that hose clamp pinching the gas tank hose and my truck started up as if nothing had ever been wrong. I took my good fortune and got the flake out of there. At the Top of the exit(yes it went from level for the freeway lane to an almost instant 5% incline to exit onto Birmingham.) is a Chevron gas station with a surprisingly large back of building asphalt covered area. This area of San Diego is high dollar real-estate so this mostly wasted space was a welcome surprise for my 30 foot truck to easily sit in out of the way of the gas station pumps and any other stuff. Two trucks my size could fit side by side there with plenty of room for anyone to drive past etc.

I crawled under the truck at the passenger side behind the rear of the cab to see if I could hear the electric fuel pump mounted on the frame there chattering away. It is in place just in front of the 45 gallon barrel gas tank that I just plumbed. I heard nothing. I felt nothing from the electric pump. I found the ground wire connector to the pump disconnected from the stud on the pump. Both this and its counter part positive came with this Summit Racing pump. These are a press fit connector that looks great with a very nicely done thick rubber insulator cover. I pushed the connector back on and noticed it didnt seem to click in place over the negative post. Now that I was focused on it, it didnt seem to grab at all. I decided to try the positive one also and found it to just be the same loose fitting thing. Neither one snaps in place at all.

I just scratched my head did this truck just make it the last 1/8 mile before the exit crawling on the minuscule stream of fuel that might have made it past the crimp of that 3/8 fuel hose? This engine just WANTS to run just about no matter....A couple of years ago I was experiencing an erratic idle sometimes. One night I lifted the hood and saw quite a light show. The coil wire nipple for the distributor cap was completely broken away from the cap and that broken away nipple part was just sitting there on top of where it should be part of the distributor cap if it were not cracked all the way through. This truck had been running with a freeway speed sometimes miss like that for about a week. I could lift the coil wire and the nipple for the cap was still secured in the coil wire boot while the jagged edge that was broken off of the distributor cap was exposed....This truck had no business running then either!
I wanted to replace the press fit wire end with an eyelet connector but this fuel pump has knurled non threaded positive and negative studs requiring a press on connector I cut the rubber boot insulation off reduced the size of the diameter of that clip on connector so I had to force it over the fuel pump's positive and negative studs. Now the pump works again. I forgot to put that clamp back on the original tank's exit hose and I had a massive gas leak again a few minutes later. Im gonna disconnect that original 20 gallon tank from the engine and use it to hold diesel for the onboard generator soon so for now it will be clamped off..
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Is there any problem running the electric pump while the mechanical one also is pulling gas from the newly plumbed tank? Why didnt the mechanical pump pull fuel from my added tank when the electric pump lost its electrical supply? there is a drawing included of how I routed the plumbing.

gas tank routing plumbing.

COE special air cleaner contraption no easy way to see carb and if gas is flowing with it in place.

hose from original gas tank to the mechanical fuel pump inlet is clamped closed.

Mechanical fuel pump this truck uses.

Fuel regulator view.

 

Gary:
I think punctuation, coupled with deletion of run-on sentences and cohesive paragraphs might assist others in solving your problem.
Your narrative is just too difficult to parse out and analyze.
This is constructive criticism only, nothing sinister intended.

Regards, Mark.

 

I couldn't open the diagram on my phone but to answer your question you highlighted in blue. Fuel pumps are good at pushing liquid but typically inefficient at pulling liquid. Gravity was usually designed into the system to make it easier. Especially true if a mechanical fuel pump had an operating pressure of only a few pounds. If it was arguing with any sort if check valve on the inlet side it would likely struggle as well. You are trying to use the electric pump as a transfer pump from an auxiliary tank only? Is that correct?

 

It looks like the electric pump is, all at once, trying to fill a second tank (through its outlet), push through a mechanical fuel pump then check valve, and fill the carb directly? That's a lot of work for that pump and you have at least one redundant circuit. When you have the second tank un clamped you are also trying to fill and drain it at the same time. And even with the check valve after the mechanical pump you are still fighting the pressure from the electric pump at the T to the carb.

This routing doesn't make logical sense and your best bet is to start by simplifying it and running a single line to the carb through either the mechanical pump or electric pump. If you want to have a transfer setup I would use the electrical as a standalone transfer pump and run the mechanical to the carb from there. As-is I don't see the point in even having the mechanical pump circuit if you're blocking off access to the second tank due to it leaking

 

thanks Ill shorten/ and otherwise fix it.

 

Also if I don't get completly through your drawing, I had a second tank in one of my cars. Easiest way is:


mechanical pump gets fuel from 1st tank (your originail)
electrical pump adapted to your second tank fills fuel into first tank.. (could be connected electrically to sending unit or manually via switch).

with that kind of way you loose a lot of headache.

 

Thank you sir. The electric pump is transferring gasoline from a tank I recently added. That new 45 gallon tank is now the MAIN tank. I will soon be using the other tank(20gallon) for a diesel generator that is also part of this truck. I will be removing any hoses lines and the like from the engine bay for that original 20 gallon tank. My objective was to use the mechanical pump as the main pump. The electric pump is a back up. I mounted it very near the 45 gallon tank so it can push fuel. I want to hit the switch for the electric pump to start the truck on those occasions when it has not been started in a few days. This truck with fuel in the carb bowl starts on a turn over of the engine. When there is no fuel in the bowl from a few days of not being used it requires much more starter action than I like.

This truck has an elaborate cover for the air cleaner over the carb which is a PITA to reinstall when its removed. I dont want to drill a hole in that cover so that I can dump gas or spray ether into the carb on those occasions when fuel has evaporated from the carb bowl. I dont want to remove the mechanical pump. I like the look of it hanging on the engine and eventually I want my windshield wipers to be reconnected to it. If it were not for the wipers depending on this mechanical pump, I wouldnt be adverse to make its lever not touch the cam and have it hang there just for looks. At this point I think the electric pump may be better for my needs.. I dont like the prospects of having the mechanical fail Ive had 3 replacement pumps now in 5 years. My truck weighs 14,000 lbs, My knees dont like me to try and push it....(that's a joke...nothing is moving this truck if its not functional except gravity and another rig pushing or pulling it.)

I bought mechanical pumps that are said to have seals and other parts built into them that are supposed to support the gasoline chemical make-up that is common today. Mechanical pumps and other parts that lasted decades before dont last at all now so I want a back up for my mechanical fuel pump. This mechanical pump is 3 years old and has maybe 20,000 miles on it. If it were to fail it was my hope to be able to flip the toggle switch that activates the electric pump and use it. Soon my fuel pump plumbing will be simplified when I disconnect the 20 gallon tank and take its hoses and route them to the back of the truck for the diesel generator to use. I will also remove the one way check valve that is on the inlet line from the mechanical fuel pump to the carb before it "T's" into the electric fuel pump once the 20 gallon tank is disconnected from this system. .

My drivable Fords.

 

Thank you. I want to keep the mechanical fuel pump functional as the main fuel pump. My vacuum operated windshield wipers (will) need it to work otherwise I would just use the electric one. I plumbed it this way to have both tanks function until I was sure all my JUST added on stuff like the tank and fuel pump were in place and worked. I need this truck to start and run. I dont have a regular place to work on this 30 ft 14,000 lb truck. When I do work on it I want to have it drive as soon as possible. Some of this plumbing reflects the need to be able to immediately drive using one or the other pumps, or gas tanks. Now that I am sure the 45 gallon tank is plumbed well, that the electric fuel pump is wired in and hung well, I will disconnect the 20 gallon original tank from the system. I wasnt sure the truck would run with all of this new stuff so I wanted to be able to block off the new stuff and effectively use the old original design to drive her until I figured it all out. Clamping that hose off has the effect of removing the 20 gallon tank I see what Ive added works for the most part. I see I need to remove my one way check valve and one of the fuel delivery line circuits. I over thought, over built a way to block the flow of fuel from each of these pumps. I guess in a few words...your points are dead on.

 

A second tank on a big truck certainly isn't a terrible idea. The design just has to be "Murphy-Proofed" because at some point something unexpected happens. Switches,,solenoids, valves and check-valves can fail. Cheap aftermarket (low quality) fuel pumps will get you too. I've been on the side of the road on wreckers calls sorting it out over the years. Before that sometimes I was the victim a time or two.

 

Gary, I love your trucks and I'm glad you're using Ethyl for your work truck. But another piece of advice for long threads is to use paragraphs. The just break up the text and make it easier to read.

 

Yes all of that is why I am adding all of this. If system A gives me grief and fails, I have a back up in the other system. I am working out the bugs right now. I would like to know why I had to experience the on the freeway just make it to the offramp experience....I could do without that

 

Yes good point Abe Every once in a while my brain misfires and posts like that one happen. I bet if they did one of those brain scans while that was occurring it would be quite a light show.....or maybe it would be rather blah and not much life would be showing...I have gone back and edited it.... let me know how the correction fared.

Using Ethyl works out fine. Sometimes I have some interesting and what should be considered scary situations. Im never scared in the handful of times they have happened. Im of course concerned and as careful as I can be while cars are whizzing by at 70 mph....but I was calm and knew I would make it off of that exit fine. When I think back and reflect on what I experienced I then really know I am blessed. I have the phone numbers for 3 tow services that can handle Ethyl and am prepared to do that if need be. So far knock on wood each time something similar to yesterday happened I was just enough out of real harm to allow me to pull a similar rabbit out of my hat and escape what could develop into real danger and ALSO not have to pay or wait for a tow truck....I guess the man up stairs is in charge of all of this stuff also.....that.s probably how I stay so even keeled while its going on....????

 

If you want to run the mechanical and electric pump to supply fuel to the carb depending on the situation a couple of additional suggestions:

Power the electric pump with a switch so you only use it when the mechanical is not in service or you are priming the bowl.

on an older motorcycle there is typically a petcock that allows you to switch between 2 different fuel lines. The main line and a reserve. You just manually rotate it, the center position is typically off and reserve and main are to each side. I bet they make an electric one these days or you could set one up with solenoids yourself, but that is a reliable and fool proof way to achieve what you want. Switch on the electric pump and rotate the petcock to open the feed line from the electric pump and that closes the feed to the mechanical pump. Turn off the electric pump and rotate it the opposite direction for the manual feed.

Cool truck.

 

ill have to look into that petcock siggestion to see what might be available I appreciate the complement on my truck

 

Here you go. I forgot about the marine applications for the petcock. The marine guys almost all run 2 tanks but this can be used for one tank and to switch between feeding the electric or mechanical pump.

Lots of choices out there but this is what I was referring at west marine. Looks like it would be perfect and allow for a nice clean install.

https://www.westmarine.com/buy/west-...65?recordNum=2