Hello all, I've had a problems getting my 1985 F150 starting for a while now.
It's a 2WD inline 6 flareside, single tank.

Also...i'm a total novice when it comes to stuff like this...so be gentle with me

About 2 years ago I had the bed removed and figured it would be a good time to check why the fuel gauge hasn't worked in about the last 20 years (it was my dad's truck, he's very lazy). So, I pulled the in-tank pump and saw that the float had deteriorated away.
I replaced the whole unit and the pump and float all worked. A rare win for me and this truck.

Then, over a year ago I got frustrated on how hard it was so get started. So, I took it to a local mechanic. I explained that I want it to start up when I want it to start up. He suggested just throwing a new carb in there. We did and it worked fine for about 2 weeks. Then, after it sat for a week or more, it once again was very difficult to get started.
Almost impossible if you don't have a nice full can of starter fluid.


So, here we are now...

I went out today and tried to get her started because it's been a few weeks.
I'll pop the hood and squirt some starter fluid directly into the single barrel carb. It'll turn over and sound like it's starting with that big rumble and then it seems to die immediately once the starter fluid is burned off.
It's almost as if the carb isn't getting fuel.

I crawled under the truck and had a look around. I basically see the original plastic fuel line that runs up the frame. It then connects to a metal line that snakes its way into the fuel pump. From the fuel pump, up to the carb.
Everything is original and worn, but doesn't seem to have any leaks.

So, I've got a new'ish fuel pump in the tank on the one end and a new carb on the front end...everything else in between (I believe) is original.

Any suggestions out there as to what I can start with to try and troubleshoot my starting problem?
I thought the first step for me would be to maybe swap out the fuel pump?
And, I have no idea where the fuel pump relay is located...or if there even is one!

Thanks in advance.
JT

 

JT, we have a few things going on that done make sense
All 80- 86 factory flare sides only had 1 16 gallon front tank.
Only us guys that add a rear tank with all the factory dash switch & fuel valve, wiring & fuel lines have duel tanks.

No on to the real part.
You said you dropped the tank and You should not have an in tank pump. You would have a sender with a float & pick up that goes almost to the bottom.
Is that what you meant?
Because of no electric pump you wwill never find it.

Then you say you looked over the fuel line and it was a mix of plastic & metal?
I don't think they use plastic on the 300 six till they went with EFI.
In any case I would start at the tanks and work forward to the pump replacing the hard line either with metal or plastic (I like metal) and any rubber hose you find.
Should have rubber at the tank from the sender to the hard line that runs down the frame.
I would also replace the pump as I don't think it was to much $$ when I replaced mine.
If there is a rubber hose at the pump to metal line to the carb (don't think there is) replace it and any rubber hose going to the carb.
Now would be a good time to replace the fuel filter.

All of that should not run to much dollars and most likely need replacing from what you posted.
Once replaced pull the air filter off the carb and plug any vacuum lines you disconnected.
Hit the throttle once did the choke close? If not you need to look into why it did not and that would make it hard to start any time but when up to temp.

Do all that and get back to us on what you find or if you need more help.
Dave ----

edit: On the rubber hose it is 5/16" I tried to use 3/8" at my pump and was trying to pull gas from a can on the fender well and it would not. I even replaced the fuel pump and that is when I found out about the line size.

 

Have you ever messed with a weedeater or a lawnmower starting them up? If you have, you know they have a choke on them, and you have to set the choke, and once they start you have to turn the choke off or fiddle with the choke till the weedeater or lawnmower is fully warmed up, and then it runs ok and you can use it.

Your truck engine is the same. It has a choke on the carb, but it's automatic. You should check to see if it's working. With the engine dead cold from sitting overnight, take the air cleaner off, look at the top of the carb, there should be a metal door on top. This is the choke. Go inside and push the gas pedal all the way to the floor and then let it up. Go back out and look at the choke door. It should be completely shut. If it's not, then that is part of your problem and it needs to be adjusted.

 

Don't talk to strangers, look both ways before you cross the street, don't take wooden nickels and tip your bartender. Now that we have the advice out of the way we can get on to the trouble shooting. I'm going to take your word for it that you have an electric in tank pump, you changed it out, I didn't. If you do have an electric pump and it came from the factory that way, you'll have a fuel pump relay and an inertia switch. Look for a relay near the power booster under the hood. My 85 had a plastic holder mounted in that area that the relay stabbed into the bottom of. The inertia switch should be in the passenger footwell near the transmission tunnel up by the firewall. Might be hiding just behind the carpet if you have it. Should have a reset button. If you find it, try resetting it.

Before doing anything I'd confirm a no fuel issue. Take the fuel line loose at the carb and try and crank the truck, if you have fuel, then it'll be a carb issue. Either stopped up with debris or a stuck needle, something. If no fuel, check the inertia switch, see if you have a switch on your oil sender on the driverside rear of the engine. Then look for the fuel pump relay.

 

First of all...thank you for the detailed response!
See comments in BOLD below.

Ok, so the proper width for a rubber hose is 5/16, 10-4

 

Thank you Dave...comments below.

Ok, noted. The door is usually closed when I pop off the air cleaner. I usually flap it open to squirt a shot of starter fluid down there. I'll give it a close look today and fiddle with it, make sure it's opening and closing.

 

Thanks for the reply and advice...

 

Here's what I got, relay fits inside this box/holder, wires hang out the bottom, think the connector was green. Yours may be different. Now, if you get fuel shooting out, that doesn't mean your pump is good, just good enough it should start. You can have a weak pump not push enough fuel to keep up with demand and cause drive ability issues, but even a weak pump should fill the bowl enough to at least start it. Also, have you looked into the carb and actuated the throttle to see if any fuel runs into the carb? It's hard to see on my carter 1bbl, got to look at just the right angle and point the flashlight just right.



Truck is pulled apart down to the cab, this is the holder, right next to the fender

This is what the(an) inertia switch looks like, several different styles, this was on my 85. wires come in from a firewall plug on the passenger side. Mounted to firewall near trans tunnel on passenger side

 

Thanks for these photos, I don't have ANYTHING similar to that on my firewall. I've got a few photos I'll attach here in a few min.

 

I can't see any way this truck has a in tank pump. Even if someone modified it, they would most likely put an external electric pump, not one on the sending unit in the tank. And if they added a external pump, 99% of the time they would not add the inertia switch or any of that.

 

The Saga Continues...

So, I replaced the fuel filter this AM and cut it open, it was orange and gunky on one end. Almost looked like tar.
I installed the new filter, tried to start her up...no dice.

While I was trying to get it started, I noticed a few odd things...


Before squirting some starter fluid into the carb, I noticed this random hose laying there under the carb. This is shot from the drivers side. Red Arrow points to the tip of the hose which wraps all the way around to the passenger side and should obviously be attached to something.


Here is a y-connector where that loose hose originates from. It's under the carb on the passenger side and wraps all the way around to almost the rear of the carb.


AND...while poking around looking for where my new lost hose attaches to I noticed this little guy just sitting out there...nothing attached to it. I DO NOT thing the hose I found attaches to this, because it's literally just above the y-connector. Is this something I should cap off? Anyone have any ideas what's up with this lonely guy?

 

In the picture below, that steel line there going to the side of the choke, does that go down to the exhaust manifold? I think it does and that mystery open nipple in the picture goes to the other end. That steel line sucks warm air from the exhaust manifold into the choke to open it up. It needs clean air for it's supply, it gets it from a hose attached to that nippled which leads to the inside of the air filter area where the air is filtered.

 

When you pull that choke door open, can you peak down in there and watch while you pump the throttle open by hand? Each time you do that you should get a strong stream of fuel going into the engine. If you do, that is just as good as the starter fluid. You can pump the gas a couple times and then see if it will fire off.

If you are not getting a good strong stream of fuel, there is something wrong with your accelerator pump in the carb. Or you do not have any fuel in the carb.

 

Hey Dave,
In the tank there is a fuel sending unit. I probably mis-typed earlier, very sorry for that confusion.
Looked almost identical to this: https://www.carparts.com/details/For...E&gclsrc=aw.ds

 

I'll give this a shot in about an hour.
Thanks,
J