Electric Fuel Pump Experience

[Kevin718]

This is a post to describe my electric fuel pump experience.

I am replacing the mechanical fuel pump due to vapor lock problems that I seem to experience at higher elevations. This problem has consistently showed up during trips to Big Bend National Park. After reviewing solutions to this problem, I have decided to try the electric fuel pump.

Determination of Flowrate Needed:
To determine how much flow was needed, I tried to come up with what I thought would be the worst case. And that is going highway speeds up a steep incline. This would be a worst case because this fuel consumption rate could last for a significant time. Therefore:
At 8 mpg:
70 mph = 8.75 gph
80 mph = 10 gph
85 mph = 10.625 gph

At 5 mpg:
70 mph = 14 gph
80 mph = 16 gph
85 mph = 17 gph

At 1 mpg:
70 mph = 70 gph
80 mph = 80 gph
85 mph = 85 gph

Therefore, depending on how fast you may be trying to accelerate, or how steep the hill is, the Jeep may need a large flow rate.


Fuel Pump Testing

Test Point Locations Used Below:
A = The outlet port of the fuel filter that goes to the carb.
B = The discharge port of the pump, which is located just behind the transmission cross-member on the driver's side.


Fuel Pump #1 - CarQuest, E8016S, Automotive Electric Fuel Pump
Pressure Regulator - Holley, P/N 12-804, 1-4 psi
Suction Filter - Deutsch, FF401

Test Point A:
Pressure (Port Blocked) = 1 psig (no matter how the pressure regulator was adjusted)
Flow Rate = 8 gph

Test Point B:
Pressure (Port Blocked) = 4.1 psig
Flow Rate = 21 gph

Driving Experience:
The Jeep would surge, as if running out of gas, during acceleration up a large incline.
Later, the Jeep would die while driving/coasting at slow speeds.
Pump was quite. Could not be heard in the cab.


Fuel Pump #2 - Holley, P/N 12-802-1, Blue Electric Fuel Pump, 14 psi
Pressure Regulator - Holley, P/N 12-804, 1-4 psi
Suction Filter - Deutsch, FF401

Test Point A:
Pressure (Port Blocked) = 4 psig (started at 5.4 psig, easily adjusted to 4 psig)
Flow Rate = 77 gph

Test Point B:
Pressure (Port Blocked) = 14 psig
Flow Rate = 123 gph

Driving Experience:
Minor short distance driving as of 8-14-06. No problems so far.
Pump is noisy and can be heard in the cab when Jeep is at a stop light.

I will add to this post after I have driven the Jeep at highway speeds and up the same large incline that gave the first electric fuel pump problems.

[Don S]

..
Kevin718;

Sounds like you have it whipped!
... I love the sound of my Holley Red Top. I can tell exactly that the fuel is being delivered to the carburetor. If a line was to have a big leak the Red Top would change pitch and tell me something was wrong.

... You didn?t mention the fuel return line. You did mention altitude and that is hard to really test in the state of Texas. There is nothing even 9,000 feet in the state. They have cities in Colorado 1,000 feet higher than that. There are places you can 4x4 higher than Pike?s Peak at 14,110 feet. Ouray is probably the very best site for testing Vapor Lock.
Some Links:

Add a Fuel Pickup line to a Tank

VAPOR LOCK 101

Vapor Lock Quick Check List

Have a good one and ?Jeep Jeep!? CUL.. Don S..

[Kevin718]

Don,

I did leave the stock fuel return line installed. I should point out that this line was not blocked when the pressure readings were taken at the outlet of the fuel filter to the carb.

Concerning the altitude / vapor lock problem, I am hoping this solves it. And it may. But I am also thinking that part of the problem is that the altitude compensation device on the 2150 carb is no longer working. Therefore the mixture may be too rich causing excessive heat under the hood and leading to the vapor lock. I have not investigated where I might get a replacement device (aneroid). I will have to find a way to check it here at sea level and then up in the mountains.

[Kevin718]

Additional Testing Results:

This evening I drove the Jeep at highway speeds while accelerating up a large incline. The engine did not surge. And I have not had any low speed stall problems.

So, it seems that the new fuel pump has solved the problems created by the low flow fuel pump.

Moral of the story I suppose is to test the installation whenever possible to make sure the system performs as you think it should.

[Junk Yard Genius]

Wouldn't a functioning return line been a lot cheaper and easier?

[Don S]

..
Kevin718;

... The shaft of the aneroid in the altitude compensators will often get gummed up and not work freely. A shot of Berriman?s B-12 worked well for the MC-2150 I had.

Altitude (High) Power Loss
... I have driven three late model Fuel Injected 4x4s over Imogene Pass and my 4v (4 barrel carburetor) 401 Wagoneer has been over it 4 times.
All engines lose lots of power at high altitudes but if the carburetor and engine are tuned for a particular altitude the old vehicles do not lose much more than the FI models. It?s not that noticeable with the big V-8s like the 401 and a 4.7 WJ Grand Cherokee but the lower HP engines even with the latest FI systems the loss is noticeable.
Barometric pressure will decrease 1? per 1,000 feet Greatly effecting
Vacuum idle settings

... A decrease of Horse Power of about 4 % per 1,000 feet is due to a reduced supply of Oxygen and ambient (barometric) air pressure. The best answers for high altitude performance is a supercharger or turbo charger and/or a very good power to weight ratio.
With carburetors as you gain Altitude the fuel ratio will get richer and carbon up the plugs and that causes the engine to start missing bad at the lower RPMs. The link below covers that topic?
CARBON & FUEL ADDITIVES
A very slight advance in timing can help but I don?t bother with it.
Carburetor Jet size decreases could be reduced about .001? per 1,000? feet from where it was tuned for. Some times slightly reducing the float level will help but could add to a vapor-lock problem. A very large loss of power can be caused by leaks in the vacuum systems.

Have a good one and ?Jeep Jeep!? CUL.. Don S..

[68wagoneer]

I have a Holley red top, used to be a blue but it failed and they gave me a red under warranty. 3/8" feed line off tank to filter (oversize) and then to pump. From pump up to 1 input on regulator is 3/8" line and then out of regulator same size at steady 4 psi to carb. Other regulator line has 5/32" line back to tank for return. One thing to keep in mind as I learned from racers. These pumps are way over rated for our trucks... unless your running 400+ hp and a 750+ cfm carb you don't need that much fuel. Hence the return line, keeps the pump moving fuel and keeps the pump cool say if your idling at a stop light or wheeling downhill in low gear... you ain't burning much fuel. If the pump ain't moving fuel it gets hot, quick. This causes 2 problems right away. 1- The pump can actually heat the fuel coming in to it to the point where it boils off into a vapor compounding the situation. 2- Carb's don't work well when supplied with vapor or fuel in a liquid/vapor mix. Anyway I ran the original blue for sometime with no return line and had a myriad of problems. When I put the return line in with the new red, ain't had a trouble 1 since. All the gas you want to burn
is going to the carb, uphill/downhill/high speed/low speed/idle, etc.
Mike

[Kevin718]

Electric Fuel Pump Learning:

The fuel pump is still working well, but I learned that this pump will run out of gas sooner than my mechanical pump did. My fuel light had come on, but it was at the point where the fuel gauge would swing quite a bit from accelerating to braking. So there was enough gas in it to slosh around.

As I was driving to get gas, the engine would stumble when driving on a level road at a steady speed. And then it died and I could not get it restarted. Using the bypass switch, I ran the pump and did not hear any gas moving through the lines.

Luckily I was near a gas station. Filled it up and everything was fine. Its just odd that the pump "ran out of gas" when I have been in this situation before and the mechanical pump did not run out of gas.

I think contributing factors to this problem may be:
1. The electric pump was not designed to pull gas, and the instructions say to mount the pump low so that it develops a siphoning action to supply it with fuel.
2. The electric pump moves so much fuel so fast that it could easily empty the suction line if the gas were to not cover the pickup.

So, I will just have to remember to fill up earlier, and carry a gas can with me everywhere.

[scantar]

Hi Kevin,

A while back I had electric pump problems that I attributed to lots of other things until I began to systematically eliminate them. Turned out that in the end, it was the wiring that was the problem. The power I had originally used was not a constant 12v When I pulled power straight from the battery all the pump issues disappeared and now everything is as it should be in the universe.

Steve

[Kevin718]

Update:

It seems the electric fuel pump has solved my vapor lock problems as I had no trouble on my latest trip driving at an altitude of about 6000 feet. Here are a couple of pictures of the installation:

Holley Blue Top Electric Fuel Pump:




Fuel Pressure Regulator / Relay / Bypass Switch:



Now the only problems are:
1. I need a pushbutton inside the cab to prime the carb.
2. This pump is noisy. I need to find out how to keep it quiet.

[Kevin718]

Yes, the wood is temporary. I need to make a metal plate for this.

[Gambler68]

would be simple enough to make or mod a small sheetmetal enclousure with a 12 vdc computer cooling fan to vent/cool it. Would protect it and quiet it.