I've been having all sorts of intermittent problems with the feedback carburetor and emissions control system on my 1986 f-150. normally it'll run like crap for a while and then for no reason straighten itself out and run great for a while. Even when it's running great it's still getting 9-10 miles to the gallon, so I'm assuming it's in "limp home mode". Last week I had to go pick up some stuff which required going across the Mississippi River bridge. Just as I was getting onto the ramp to come home it started running horribly and I was afraid I was going to get stuck on the bridge with no shoulder so I just kept going. Ended up having to floor it, and it was choking and bucking and going about 15mph. I tried letting off the gas but it wanted to die, even though it seemed for all the world like it was getting way too much. Long story short I got off the interstate and was just trying to get to a parking lot or someplace safe when it finally conked out. I put it in park and it started smoking and someone ran over and said "hey man, get out, your trucks on fire". Sure enough underneath the bed (see picture below) something was on fire and dripping down. I think it was the underneath overspray stuff from the old rhino liner on the bed, but not sure. If you look where the arrows are you can see flames up there, too:



Hit it with an extinguisher before the FD arrived so good as far as that goes.

Crazy thing is, that's under the bed, right? Well I have a plastic folder that I keep my proof of ins and all the receipts and things that sits under my seat and the floor of the cab also got so hot that it melted that, too:



Took it to two mechanics and neither of them knew their backside from a hole in the ground about the feedback carb or any of that stuff, so I'm about to go pick it up.

Here's my question: I'm tired of playing around with old broken parts from the junkyard. I just want to strip the carb, emissions control system, all of it, and replace it with brand-new stuff. I don't care if it's the same feedback carb stock set up, or change everything to the Dura spark system, or anything else that will work with the motor, but I want it to be dependable. I'm sinking way too much money and time into parts that are already 20 years old and not working well. Honestly, I wouldn't mind just dumping a crate motor in it, but I don't think the block/pistons and stuff that you would get brand-new in a crate motor are the things that are causing my problems, so I don't think that would fix anything if it just goes right back with my old crappy carb and vacuum tubes and what not.

Any suggestions?

 

So Dr tell us is it a 2 stroke or 4 stroke motor you got in that thing.........oh wait it is electric right? (hint what motor/trany you got in it?)


Good to hear it only melted a few things and did not..........
Back in the old days that melting (and fires) was caused by bad cats over heating then heating the metal floors and setting the rugs & seats on fire.
Dave ----

 

Sorry, I had set up a signature with all the truck info in it, don't know what happened to it. 4.9/300 I6, C6 Trans.

[EDIT] Now the signature is back... ?!?!

 

Just messing with you on the motor.


If I had a feed back system and had issues I would go with a <81 carb and DSII system.
Now I hear there could be issues getting the wiring for the DSII so I would also look into a HEI dist.


Then I would look into the cat(s) if plugged and maybe remove them if not needed or new if I did.
Dave ----

 

I would guess that it was getting too much fuel, and that overheated the cat convertor under the truck, and it caught some old oil and debris on fire, and also melted your floorboard stuff. The cat is probably ruined now.

The most common cause of this is dirt in the fuel system. The gas tanks on these trucks love to rust out where they sit up against the frame, and these rust flakes get pumped up to the carb. The filter gets clogged, but most of them have a spring that will let the fuel pump push the filter back when it gets clogged and then all the dirt goes into the carb, and sticks the float needle, and it overflows with fuel, pouring fuel into the engine.

You can pull the fuel filter and dump it out in a container and see how much junk is in it. If it's full of dirt, you can bet that is your problem. A new fuel tank doesn't cost that much. You can get it running again, and then you can convert it over. You may have to pull the carb apart and clean it out.

 

Here's some info I forgot to list; it has a new tank, new fuel pump, new fuel filter, new fuel line, new sparkplugs, and rebuilt carb.

 

Yup the exhaust loaded up with un-burnt fuel form the ("did not work even new, EPA required bull-crap carb)"
I stripped 51 lbs of emission crap off my 351, (yes 51 lbs!) went with a Edelbrock 4-v non EGR intake and 4-v carb, Purrs kike a kitten and pushing over 15 mpg.

 

Ok, so far it looks like two votes:

• DSII
• Edelbrock 4-v non EGR intake and 4-v carb

Any other suggestions?

 

I suggest rounding up a older 1 barrel carb off another six. The 4bbl setup on the six is expensive, and it requires some modification, you might have to run a header, not sure about that though. And you will have to run heat to the bottom of the carb somehow, and redo the throttle, fuel lines, etc. You can run the 4bbl, but it requires some commitment to get it on there.

 

The guy with the 4 barrel suggestion is running a 351 V-8. I think his suggestion was, in essence "get rid of the feed-back carb system".

 

You are correct, sir, say good by to the feed-back, (if you can in your state)

 

Yes get rid of the feed back system but even with a 300 six he could still run a v4 intake & carb.
I would not go that route just get a 81 or older carb for the 300 six.
Dave ----

 

Ok, I'm sold so far. Dump the feedback monster, and get an 81 or older carb. Two questions:

1: There are no salvage yards within driving distance that have any 7th gen F-150s. I have an email alert set up is one shows up, but they haven't had one in almost a year. I'd like to just get a new one and not have to worry about it anyway. What is the name of the carb I should buy?

2: Would this mean switching to the DSII? Either way, what changes do I have to make when I swap out the carb?

 

I would do this in small steps. I would first see what is wrong with it now. If it's the carb, then you could go ahead and get another carb, but leave the ignition on it for now, put the new carb on, and get it running.

Here's a carb for a late 70's truck with a 300. I like the manual choke.

https://www.summitracing.com/parts/u...rd/model/f-150

 

You don't have to look just at F150's and pre 81 300 six motor be it F or E (vans) from 150's to 350's.


For my 81 F100 w/300 six, Auto Zone lists it as a Carter YFA
United Carburetors Carburetor 7-7587 - Read Reviews on United Carburetors #7-7587



On the DSII switch yes. Because the TFI dist. has no timing advance for better performance, advance comes from the computer, and you have removed the computer controlled carb the computer goes in to limp mode so you can drive it to a garage and get it fixed.


Now you don't have to go with the Ford dist. and control module (CM) and wiring. Looking AZ using my 81 to look up parts They list a rebuilt for $40 and a new for $80 then you need the CM at $30.
Then you still need wiring, I hear Painless has one for $$$ or you can try and find one in a JY but as you are finding out not much out there.


Because of the above information and what others have posted on using the HEI dist. on a 300 six I think that is the way I would go.
Ebay list them from $130 w/o wires to $160 w/wires.
ford HEI 300 | eBay


On the carb & HEI dist. for best price look at local stores, might be hard for the HEI, Ebay and Amazon
Dave ----


edit: As Franklin said and I hinted you don't have to do the dist at the same time but to get the best performance you need to do both at some point.