Never ending idling problems

[kxri318]

The fuel tank does not vent through the small line leaving the top of the tank and going up front when filling at the station. You are pouring a lot of liquid into the tank, the same amount of air needs to come out. Problem is, this air needs to be diverted away from the fuel coming in or it will start splashing and gulping, causing the station filler gun to shut off.

I am not sure how they vented your particular tank. On the f150's, the earlier models they filled the fuel through the large filler hose, and they had a small corrugated plastic hose mounted at the top of the large hose inside to direct the air out and away from the fuel going in. This didn't work that great, and the smaller hose was famous for falling down inside the large hose causing filling problems on these trucks (1980-86).

Sometime around 1987 they changed things around and it worked much better. They mounted a smaller rubber hose to the fill spout, and this smaller rubber hose layed on the inside the larger rubber fill neck hose. The fuel from the station nozzle went down the smaller rubber hose, and the air came back up the large fill neck hose and vented through a slot in the fill neck. This system worked much better than the older style.

Not sure how they set up the rangers, but it's going to be along one of those themes above.

I couldn't really see inside that well, but there's a big tube and WAY further down there's a smaller tube inside the big filler neck. There's a little rectangular thing right next where you put the gas nozzle on the piece that connects the filler neck to the outside but it doesn't move at all. I don't know how to describe the last part so I'll just send a pic.

 

[franklin2]

Guessing by looking at it, I bet you have a smaller rubber hose that is supposed to be clamped to a nipple on the other side of that little round door. So the fuel goes down that smaller rubber hose when filling, and the air comes up the large hose and vents out around that rectangle piece. I wonder if that rectangle piece is clogged with dirt around it?

Can you pry that little plate out of there with a small screwdriver? You can see when it's said and done and you put the gas cap back in place, it seals all that off from the outside. When the cap is in place, that is when the tank starts venting through the small line to the charcoal canister. It's like the new fangled gas cans you buy, the tank system is totally sealed to keep any vapors from going out into the atmosphere. But it does vent a lot outside when filling at the station. That is why some stations have a rubber accordion boot around the nozzle, to try and capture those fumes venting while you are filling.

 

[kxri318]

Guessing by looking at it, I bet you have a smaller rubber hose that is supposed to be clamped to a nipple on the other side of that little round door. So the fuel goes down that smaller rubber hose when filling, and the air comes up the large hose and vents out around that rectangle piece. I wonder if that rectangle piece is clogged with dirt around it?

Can you pry that little plate out of there with a small screwdriver? You can see when it's said and done and you put the gas cap back in place, it seals all that off from the outside. When the cap is in place, that is when the tank starts venting through the small line to the charcoal canister. It's like the new fangled gas cans you buy, the tank system is totally sealed to keep any vapors from going out into the atmosphere. But it does vent a lot outside when filling at the station. That is why some stations have a rubber accordion boot around the nozzle, to try and capture those fumes venting while you are filling.

The rectangular piece barely moves and when it does move, it also moves the actual metal circle covering the hole for filling gas. I think that's just a mounting point for the metal cover. I'm guessing that tube most of the way down the filler neck is supposed to be attached to the fill hole like you said.

 

[kxri318]

Not sure if this helps diagnose my running problems, but I did confirm it seems to slightly miss and run rough at higher rpms too and not just at idle, it's just not as noticeable. Earlier today I got on the throttle about half way and it missed HARD several times. Like shaking the entire truck hard. It seems to have some trouble starting too. It's not like its cranking and cranking, it fires right away but really struggles to get its self up to normal idle speed. I'm also getting about 12 MPG city and like I said earlier, plugs are pretty covered in unburnt gas. You can smell it's running rich from the exhaust

 

[franklin2]

Did you gap the plugs? They are not too wide are they?

 

[kxri318]

Did you gap the plugs? They are not too wide are they?

No, didn't gap them. They're NGK iridium ones but I don't know the exact model as I threw the box away soon after I put them in a year or so ago. I'd have to take one out and measure the gap. Pretty sure they're the right ones though.

 

[Josh B]

No, didn't gap them. They're NGK iridium ones but I don't know the exact model as I threw the box away soon after I put them in a year or so ago. I'd have to take one out and measure the gap. Pretty sure they're the right ones though.

Sounds like that would be a good idea

 

[kxri318]

Sounds like that would be a good idea

Just checked. They're NGK TR5GP's which according to NGK's website are 1mm gap or 0.0394 inches. This website here says 0.044 is normal Ford Ranger/Bronco II 2.9 liter Engines (therangerstation.com)

 

[franklin2]

Just checked. They're NGK TR5GP's which according to NGK's website are 1mm gap or 0.0394 inches. This website here says 0.044 is normal Ford Ranger/Bronco II 2.9 liter Engines (therangerstation.com)

Whatever they should be, they should be checked. You cannot trust the factory to gap them precisely and if they did, in shipping things can get changed sometimes.

 

[kxri318]

Whatever they should be, they should be checked. You cannot trust the factory to gap them precisely and if they did, in shipping things can get changed sometimes.

I checked one of them while I was out there and it was about 0.035". I'm just guessing as 0.033 had a tiny bit of wiggle room but 0.038 didn't fit. I don't have any feeler gauges in-between. I had to stack a few gauges

 

[Burnsy]

Does your throttle float shut completely when you let off the gas? Is the spring good? Maybe a gas/air ratio thing

 

[franklin2]

I checked one of them while I was out there and it was about 0.035". I'm just guessing as 0.033 had a tiny bit of wiggle room but 0.038 didn't fit. I don't have any feeler gauges in-between. I had to stack a few gauges

Good enough. They all should be checked unless it's a real pain.