Running an EPA eliminated 6, I was advised to add a bit of diesel to the gasoline, and it helps reduce float bowl percolation. I use 5% diesel or about 0.9 gallons per 17 gallon tank. No idea what it will do to a "modern" computerized engine, but in my old gal, there are no I'll effects. Just a thought.

 

No sure what the theory would be, I just tried it plugged and then not plugged and that's what happened. Try it on yours and see what happens.

 

Sorry, I forgot to grab a pic of the other end of that line. The larger of the two lines in that photo goes directly to the carb, no solenoid. At one point I had it capped off (in between remove the old line and installing a new one), but I don't remember if that made a difference or not.
Would a canister purge valve help with this issue?

 

I would cap it off again and try it, just to make sure we are not barking up the wrong tree.

 

The Purge Valve is to purge the charcoal canister of trapped hydrocarbons.

You have a few different things going on here. All related to fuel available today. Today's fuel have a lower specific gravity and a lower evaporation point and a much higher evaporation rate.

Some time this can be solved by increasing the specific gravity, increasing the evaporation temp and lower the evaporation rate by adding a heavier hydrocarbon such a diesel fuel. It can be mitigated by keeping the carb cooler either by insulating it from engine heat either by means of a spacer and or a heat shield or allwing more airflow around the carb to keep it cool.

Since your issue seems to be related to sitting none of the carb cooling solutions will work. As the heat from the engine is literally evaporating the fuel off.
And with the engine off there is no carb cooling is happing from the venturi effect of the carb pulling in air, so insulating it from the engine will do nothing as after you shut it off the carb will eventually heat soak to the surrounding and contact temps.

So you practically have 2 solutions increasing the specific gravity, and increasing the evaporation point and reducing the evaporation rate of the fuel. Or adding an elec pump.

I personally would opt for the elec pump. The best recommendation for an Elec pump for this (and for all stock and lightly modified applications) Is the Facet pt# 40106 Kit pt # FEP12SV
These are OEM quality (and are used by many OEM in other applications) and will last decades Unlike some of the other Elec pumps out there (cough cough Edelbrock) yes not the cheapest but one of if not the most reliable.

This pump will lift 36" move 35 GPH at a pressure of 4.5-7psi (perfect for most North American origin carbs including the 2150). See below.

Mount the pump to the frame of the truck near the engine (to minimize wire runs) and rubber hose from the pump to the carb. Be sure to jacket the hose anywhere it could rub or chafe.
This will do two things keep the fuel cooler (you are not driving it through a metal fuel pump bolted to the engine) and it will replace any fuel that has evaporated off in the carb as soon as you turn the key to on/run.

This will solve your hard start issues and like most if not all vapour lock issues.

To power the pump (these pumps draw almost nothing) one of the best places to pick up the power is the red wire at the ignition module You can tap into this before the ICM with no issues. This circuit is only powered in run, since you have a carb once the bowl is filled the carb the engine will start and run even without the pump running in start.

Ideally, you should add an inertia cut-out switch inline (between the power source and pump). These are mounted button facing down. This will ensure the pump is shut off in the event of a collision where the fuel system could be compromised. One can be scrounged from your local u pull it (be sure to take a few inches of wire and the connector) and it can be screwed to the inside of the driver fender near the ignition module.

Below is the Ford-style inertia switch is the simplest and really the most reliable of the inertia switches.
This can also double as a theft deterrent as a quick smack to the outside of the fender opposite where the switch is located will usually trip the inertia switch so no matter how hard someone tries to start your truck it once the float bowl is empty it won't run till that switch is reset.

Once you have installed the pump, to start the truck after it has been sitting you will turn the key to run and wait for the pump to bog down (yes you will be able to hear it) indicating you have full fuel pressure and that the carb bowl is full. Do your accel pump shot, then start the engine.

As for your carb bowl vent cap it off, leaving it open provides a path for dust and other garbage to be sucked into the fuel bowl when the engine is running.

 

Wow! That was very thorough and helpful. I capped the fuel bowl vent to confirm that we're on the right track. I'll give it a day or two and see how it does. If that fixes it, then I'll start planning out the electronic pump and get that installed soon. Thanks for all the help!

 

Wow matthew we agree on something. I love those little pumps, I just put one on my diesel. It sits there and sounds like a little woodpecker under the hood. We had one on a old dump truck, and while everything else broke, that little pump kept pumping.

 

Yup those cube pumps are dead nuts reliable and will last just about forever. Ya they are not cheap but will outlast some of the cheap ones 100 times over. And unlike the centrifugal or postive displacement pumps, there really are no parts to wear out. as all that is in them is a foot valve and plunger valve a coil and a circuit board. Any time someone talks about going electric fuel pump this what I recommond.
For whatever reason though the 24V ones tend not to last as long as the 12V ones. I think Facet did not build enough cushion space in the volt rating for the circuit board as many 24V systems can spike up to 28V or even 32V with some of the prestolite alternators

 

Gave the fuel bowl a few days and cranked it with only some hesitation. I did it again this morning after giving it 2 days and it fired right up. That was definitely it, so I'll keep that capped off and plan to install the electric fuel pump. Thank y'all so much!

 

[QUOTE=matthewq4b;19900389]The Purge Valve is to purge the charcoal canister of trapped hydrocarbons.

You have a few different things going on here. All related to fuel available today. Today's fuel have a lower specific gravity and a lower evaporation point and a much higher evaporation rate.

Some time this can be solved by increasing the specific gravity, increasing the evaporation temp and lower the evaporation rate by adding a heavier hydrocarbon such a diesel fuel. It can be mitigated by keeping the carb cooler either by insulating it from engine heat either by means of a spacer and or a heat shield or allwing more airflow around the carb to keep it cool.

Since your issue seems to be related to sitting none of the carb cooling solutions will work. As the heat from the engine is literally evaporating the fuel off.
And with the engine off there is no carb cooling is happing from the venturi effect of the carb pulling in air, so insulating it from the engine will do nothing as after you shut it off the carb will eventually heat soak to the surrounding and contact temps.

So you practically have 2 solutions increasing the specific gravity, and increasing the evaporation point and reducing the evaporation rate of the fuel. Or adding an elec pump.

I personally would opt for the elec pump. The best recommendation for an Elec pump for this (and for all stock and lightly modified applications) Is the Facet pt# 40106 Kit pt # FEP12SV
These are OEM quality (and are used by many OEM in other applications) and will last decades Unlike some of the other Elec pumps out there (cough cough Edelbrock) yes not the cheapest but one of if not the most reliable.

This pump will lift 36" move 35 GPH at a pressure of 4.5-7psi (perfect for most North American origin carbs including the 2150). See below.

Mount the pump to the frame of the truck near the engine (to minimize wire runs) and rubber hose from the pump to the carb. Be sure to jacket the hose anywhere it could rub or chafe.
This will do two things keep the fuel cooler (you are not driving it through a metal fuel pump bolted to the engine) and it will replace any fuel that has evaporated off in the carb as soon as you turn the key to on/run.

This will solve your hard start issues and like most if not all vapour lock issues.

To power the pump (these pumps draw almost nothing) one of the best places to pick up the power is the red wire at the ignition module You can tap into this before the ICM with no issues. This circuit is only powered in run, since you have a carb once the bowl is filled the carb the engine will start and run even without the pump running in start.

Ideally, you should add an inertia cut-out switch inline (between the power source and pump). These are mounted button facing down. This will ensure the pump is shut off in the event of a collision where the fuel system could be compromised. One can be scrounged from your local u pull it (be sure to take a few inches of wire and the connector) and it can be screwed to the inside of the driver fender near the ignition module.

Below is the Ford-style inertia switch is the simplest and really the most reliable of the inertia switches.
This can also double as a theft deterrent as a quick smack to the outside of the fender opposite where the switch is located will usually trip the inertia switch so no matter how hard someone tries to start your truck it once the float bowl is empty it won't run till that switch is reset.

Once you have installed the pump, to start the truck after it has been sitting you will turn the key to run and wait for the pump to bog down (yes you will be able to hear it) indicating you have full fuel pressure and that the carb bowl is full. Do your accel pump shot, then start the engine.

As for your carb bowl vent cap it off, leaving it open provides a path for dust and other garbage to be sucked into the fuel bowl when the engine is running.



Will adding an inertia switch to a 1985 F150 302 EFI that’s having the same issues work on the EFI configuration? Yes, I have a ‘Y’ in the 8th position of the VIN.

 

The diesel added to gas has been tested and does not work at least for the person that posted the test so you can forget that part.
Me I will stick to the factory fuel system as it works for me and the little bit of issues I get is not worth it to change.
The other problem is I have duel tanks so no good way to run just 1 electric fuel pump so even more work to wire up 2 fuel pumps and having it work with out problems down the road.
But that's me
Dave ----

 

The EZ fix is an electric pump.