Hoping one of you F-150 experts can assit me with a running issue with my newly aquired 84 F-150 (300CID).

The truck runs fine for about 20mins. but soon after that it will start to buck and carry on and loses power drastically (Foot to the floor and only going about 15-25mph) and will satrt to run fine again for about 1min or so then it returns! If I need to stop while it is acting up it will stall but does refine after a few cranks.
I'm not sure what the issue is because it is carbed and very foriegn to me (i'm use to working on my fuel injected 2.8liter Fiero GT).

It almost seems as though it is running out of gas but the the strange part about it is that is that when stopped I smell a heavy gas oder when I aply the throttle. This would lead me to believe it is flooding. It runs fine when I first start driving it (only after about 20mins. does it start acting up)!

The previuos owner said it had a new manual choke installed by his garage aswell as the ignition module.

Anyone have any idea's about this issue! What things should I check...It sure seems fuel related but wanted some people firmular with this vehicle to give there expert opinions on it before I blindly start troubleshoting it!


Thanks for your insight!

 

Guessing... from what you describe, you are probably correct about it flooding. Sounds very much to me that the float is sticking allowing far too much fuel into the engine or far too rich. I would first check the choke to insure that it is working properly with the hand settings (Full open/Full closed). If choke seems to work okay you can move to the carb bowl. AT ENGINE IDLE, remove the side carb bowl screw (put a rag down on the intake first) the fuel should just drip out of the fuel bowl at the screw hole. If it pours out or squirts out, there is a float adjustment on the top of the fuel bowl. If you can not adjust the fuel with the float adjustment, time for a rebuild.

 

OOPS MY BAD....

Just noticed 84 4.9.... Sorry about that!

1984 was the transition year, 4.9L and 5.0L were fuel injection engines. The 5.8L and 7.5 were still carburated.

 

'86 was the last year for the carb'ed 300. '87 was the first year for EFI 300

 

84 propably as TFI-V with feedback carb. If he is lucky he has a Durspark.

It is has the Feeback Card and TFI-V. Then I would recommend switching to Duraspark 2, and getting rid of that headache.

 

OOPs... Once More ....

I'll gently bow my head in disgrace and keep with what I am most familiar.

Guess ya learn somethin' new every day :-)

 

Please excuse my ignorance on this but this is the first ford truck i've owned and a far cry from what I am use to working on.

Anyway.......
what is the difference between the 2 systems "TFI-V with feedback carb and Duraspark 2" (how can I tell the difference between them)?. I haven't even looked under the air filter yet. I'm pretty mechanically inclined and not affraid to tackle most jobs (comes from owning a car that no garage is willing to touch...DAMN FIERO) so if given some idea's I would be more then happy to tinker with them.

**********My thinking on the probelm at hand......
It seems time related concidering it only does it when the engine is run for a given amount of time (ie. 20mins.). Could the module be causing this? In the Fiero world this is the first thing that would be checked because of the hot engine compartment and they are heat sensitive...not sure if the Ford trucks are known for ignition related issues!
On the other hand I do smell fuel (super rich exhaust when I pull up to a stop sign.....even when it is running fine) which leads me away from the module theory and points me towards the fuel delivery system! But then it only acts weird (stumbling and loosing power) after 20mins. I also noticed the temp gauge really never comes up to operating temp. (2 notches above "C").......I'm really at a loss here!

If this is the TFI-V how hard is it to swap over to the daraspark system and what donor vehicles should I keep my eyes open for and what parts do I need from the donor vehicle?

What is the difference between the 2 systems?


Sorry for all the questions but i'm trying to soak up all the info I can to help me know alittle more about this beast!

Thanks!

 

Go to "The Ranger Station" web site and go down to ignitions and click on the two articles on Duraspark. They are very detailed articles on the converstion from the TFI system to the duraspark system.

You can tell if you have a TFi system if you do not have a vacuum advance on your distributor and you have a 4" long plastic module with a five wire plug attached to the distributor.

Your '84 was a transition year and you may already have the duraspark.

You can tell a duraspark by looking at the distributor and you will have a vacuum advance and you will have only a plug with four wires on the side of the distributor. You will also have a 6"x6" square box mounted on the drivers side fender or fender well. This box will have two plugs one plug with a red & white wires and one plug with the wires running to the distributor.

 

thanks for the reply and info...I will head over to the artical(s) mentioned and have a look see at my distribitor!

Thanks for the info!

 

Ok I have checked the engine compartment of the ford!

It seems as though I already have the daraspark system (a control module looking thing with wires coming off it on the lower part of distribitor assembly)! So what next????????

ALSO.....
I noticed upon visaul inspection that the large tube that goes from the underside of the air cleaner housing (not sure where it goes to) is torn loose from the hose clamp that secures it to the air cleaner! Could this cause problems or is it simply an air inlet tube???????

What are your thoughts now that it is confirmed that this has the daraspark system.

Also please note that there is no control box on the driverside fender well wire wires going to the module. The wires from the module (located under the distribitor run through a wire loom and I believe connect to a unit on the passenger side fender well!

Thanks for your continued suport on this problem!

 

Does you distributor have a vacuum advance modulator (A devise on the side of the distributor with a vacuum tube attached)

If you do have the vacuum advance - it's the duraspark system.

Your description - module on distributor - makes it sound as though you have the TFI

The tube off the air cleaner is a hot air bypass used for cold weather starts and warm-ups.

 

I have a 5.0 302 that has a carb. Were all engines made with the TFI?

 

You might have a clogged catalytic converter.

 

it sounds like you have a clogged fuel filter. Check right up there by the carb and there should be a filter there right before the line goes into the carb. I just had that prob happen yesterday on me in my 81 f-150

 

sounds to me like you choke is closing tight on ya...............it is temp sensative, and it sounds about right it runnin good for 20 mins then fudging up...............go to electric choke, i had the same problem and it fixed it..............good luck man