Will NOT idle!
 

Ok guys, I'm out of ideas. I've been reading and researching for several days and I've tried many things but none have worked so far. Hopefully someone has an idea. This may get a little long but I think it is important.

The basic problem is that the truck will not idle after it cranks. It will stay running if I pump the accelerator, but dies quickly if I stop. But first, let me say that I have just finished putting the truck back together. However, I didn't disassemble any engine parts. So, ... I got the truck reassembled and after some coaxing I got the engine running smooth. The fuel was a couple years old but it was running fine. I was in the process of filling the radiator while the engine idled for about 30 minutes, watching the temp gauge and adding coolant when needed. I was also adding trans fluid since I lost quite a bit from disconnecting the trans cooling lines. There wasn't much gas in the tank to begin with so a few minutes later when I tried to restart the engine it wouldn't idle. I thought it was out of gas (pretty much on E). I put about 5 gallons of fresh fuel in it and after many frustrating minutes it still wouldn't idle. Since then I have:

• checked the vacuum hoses (which worked fine 2 min. ago apparently)
• researched the forums
• rechecked the spark plug wires (only a couple hundred miles on them)
• researched the forums
• checked the distributor cap (new with wires)
• changed the fuel filter
• rebuilt the carb (2 bl Motorcraft, stock)
• adjusted the choke (although it was running fine at that setting)
• researched!!!

The vacuum routing is pretty jacked up from the po but it's been running this way for past 20 years. The basics are there but nothing else. The carb bowl filled with fuel quickly both times it was empty so the fuel pump is working. The entire truck is stock except for the incorrect vacuum lines (that were just working fine). I'm out of ideas! Help please!

If you ran it out of gas and she'd been sitting for a while, try a new fuel filter. Had this same thing happen years ago and went nuts trying to find the trouble. I didn't check the filter because I had replaced it only a day or 2 before the trouble. I lowered the gas tank to work on it and the next day had the same trouble your'e having. Took 2 days to check the filter and find the trouble. Just a thought, sometimes the hardest problems have the easiest fixes.

When you rebuilt the carb did you put the float back right...Also did you check the idle screw...if you rebuilt the carb right then you need to readjust the carb...

It could very well be the fuel filter, but not the one that screws into the carb...there may be another, in the fuel pump itself.

Look at your fuel pump, is there a metal 'tomato juice' sized can that screws on to the pump body? As original...there's a cartridge fuel filter inside that can...it rarely gets changed because most ppl don't know it's there.

C4AZ9356B .. Fuel Filter-Cartridge Type (Motorcraft FG1A)

That is a very good suggestion Numberdummy. I haven't tried that because, like you said, I didn't know it was there. It certainly acts like a fuel delivery problem. I'll pick up another in-line filter as well. I'm not sure if it has the tomato juice size can or not. It looks more like two smaller skinny ones. I'll post an old photo I have in a few minutes.

Ok, here's a photo. It's the best one I have other than taking a new one tonight.

https://www.ford-trucks.com/user_gal...id=195062&.jpg

With the motor idling, take a can of carb spray and spray it around areas that can cause a vacuum leak, such as the carb base gasket, brake booster (if you have power brakes), intake manifold seals, etc. If the idle goes up, there is a leak there.

Recheck the float height as well. You might want to try a "wet-check" procedure which will be explained in the rebuild sheet if you still have it. Try adjusting the idle mixture screws - turn them all the way in and then back them out 1.5 to 2 turns. If you have to back them out much past 3 turns to get the motor to idle smoothly, you most likely have a vacuum leak.

What is the choke doing? You should start the motor cold and watch it open. If it's not opened within a few minutes, there is a problem there too.

First, I want to say thank you all for the input, your help is greatly appreciated!

I did that. Found no leaks. I had to be quick because the engine was dying by the time I rounded the door and sprayed carb cleaner IN the carb to keep it running and then around the various suspected leak areas.


I haven't done that. It may be next if the new, new fuel filters aren't the culprit.

Did that.

I'll try that.


The choke starts off mostly closed. I can only get it to run for a few seconds so I don't know what it does after a few minutes. I thought it could be a choke problem since it acts a little like it's 5 below outside but it seems to be in the correct position for cold startup.

Photo shows a replacement pump without the filter.

As original F Series trucks: Ford used the filter in the fuel pump from 1961 thru 1977.

It will continue to run if i constantly rev the engine. As long as I pump the accelerator I can keep it going (most of the time). The rpms must stay above 1500 (guessing, no tach) or it will die. It will also continue to run if I "supplement" the fuel with carb spray or starter fluid in the carb.

Would the carb settings change in 1-2 minutes with no intervention from me, between crankings? I thought that there must have been some trash get in the carb since the onset was so abrupt, so I decided to rebuild it with new seals and clean it (although I didn't chem dip it). It seems to me that nothing changed after the carb rebuild. It acted exactly the same as before. The float setting may need to be examined. With the engine off, the carb sprays two nice streams of fuel when I pull the throttle.

Can you put two inline filters on it? I was thinking of adding a transparent filter just prior to the fuel pump to see if its collecting a bunch of garbage.

if you left it sitting for a while you could have water in the tank. had that problem with a 1977 celica. it took forever to get it to run right.

Thanks for the input. While not impossible i guess, it is unlikely since it was inside an enclosed garage for the duration of the reconstruction.

Should I add more fuel to the tank to dilute the contaminants? It currently has only about 5 gallons or 1/4 of a tank.

we put denatured alcohol in the tank to get the water out. but we used it for about a month. there is some stuff at parts stores that does the same thing.