Hi, I own a 1986 Ford F150 2wd 302 pickup... first year EFI.

Brief history:
I went to start the truck up last week, heard a grinding sound, shut the key in the off position, and the truck still continuted to run...

So, I replaced the solenoid and got a new battery for good measure as the one I had in was over 5 years old. I put a new alternator in it roughly a year ago.

The truck is running reasonably fine, but it stalls out constantly at low RPM's. When I pull up to a stop light, turn corners, change gears, etc.. however, it isn't consistent in stalling out every time, but it is frequent enough to cause me to drive with one foot on the gas and the other on the brake to keep the RPM's up.

Does this sound like an external voltage regulator problem? Or perhaps something worse with the EFI?

The truck has had some serious mickey mousing done to it before I ever owned it, for instance; the EFI changed and my emissions are no longer even hooked up, the timing has to be set slightly off and not in exact position or it will stall out...

Any help with anyone who may have had similar problems and possible solutions would be very helpful

 

I am trying to get this problem fixed asap... anyone with some info would help me a lot right now.

 

Alright, Diggs;

Since you haven't gotten any other replies yet, I'm going to give it a go. Maybe if we keep the thread near the top of the first page we can attract the attention of someone more experienced.

Since you titled the thread stalling problems I'm going to guess replacing the starter solenoid solved the run-on-with-the-key-off problem and what you need input on tracking down is the cause of the stalling. (Correct me if I'm wrong!) (At any point -- not just about this... )

Now, lets see if we can give that more experienced someone some more information to go on. Does it stall as you are braking to the stop light, as you are sitting waiting for the light to turn, or when you mash the gas to pull away? Have you pulled the trouble codes from the computer? If so, what code numbers did you get? Did the stalling problem appear immediately after the work you did on the starting system, or was it doing this before? Finally (I don't know how much difference it would make, but it might help to frame the situation), which transmission does your truck have?

Hopefully, after you come back with details, it'll start ringing bells for people and you'll start getting more input. Good luck.

 

HI, thanks so much for replying

First off, admittedly I am not as automotively adept as I wish I was, and as much as the majority of you on this board. I try to learn what I can as I go with the truck so I can maintain it as much as possible without taking it to a garage. So I appreciate the help and please bear with me as I try to explain what I can and do know.


Yes, the solenoid and battery replacement did indeed fix the problem with the truck running even with the key in the off position.


The truck stalls at low idles; when I am braking at a stop, slowing with the brake to turn a corner, or putting the truck into Park and Reverse, etc. "Mashing the gas" has never caused me any problems, aside from the occasional speeding ticket...


I have had the problem with the truck stalling for years whenever I put it into Park, before I even turned the key off. I learned to live with it.
I also have had the problem with the truck occasionally stalling when after driving at high speeds (usually highway at 120 +) and having to put on the brakes quickly where it stalls, and I have had to sit for about 10 minutes because it would not start up right away because it was flooded. Again, I just learned to live with it.
The current problem where it stalls out on me at low idles constantly has become extreme ever since the solenoid and battery installation last weekend.

I have no idea even where to begin with that one...it is beyond my "know" and capabilities.
Perhaps you can explain more to me if you are of a mind to?


It has your standard C6 automatic transmission.

I have currently 327,000 km and counting.



However....today I went down and adjusted the throttle linkage about three turns clockwise with the help and suggestion of a friend, and it seems to have helped considerably with the truck idling in Park, sitting at stoplights, changing gears....

like I said, I am learning as I go...I am hoping this helps to eliminate the problem all around, and will know for sure after this week of driving to and from work, etc, if this is indeed the cure...

BUT, if you happen to think there is more to this problem, or that I am looking at something worse coming on, please let me know. I hate the idea of having a greater problem (like no transportation) that could be fixed now...

Again, thanks for taking the time to read and replying

 

I dont know if this will help any but maybe a new set of plugs and wires might help some. Also try a bottle of STP carb and fuel injector cleaner.

 

WEll my friend...i think that you are probably having a fuel problem...seeing how when you get gas it stays running...that tells me it isn't a firing problem....i would definately check the fuel pump to see if it is working properly and in order...i would also add injector cleaner just for good measure...this same thing happened to my f-250 diesel...and it turned up to be the injector pump...but since you have a carb that makes a big difference...make sure also that your fuel tank is clean of trash and debris....if your truck has sat for any amount of time with half a tank of gas moisture can form on the walls of your tanks...thus creating rust...thus creatin debris...which could run through your fuel lines into your carb...which would clogg the jets...let me know how it goes....

matt- f-250 diesel 6.9 liter 420

 

Just added fuel injector cleaner.. I add it about every 5 fillups now. New plugs (Bosch platinums) put in two years ago...last year tune up they were still in great shape....going in for this years soon and will see...

So far so good...It is an old truck... it isn't going to get any better... I just want to make sure it runs as good as it can while I have it.

I don't have a carb... my truck is EFI...

I was under the impression that when your fuel pump went... It just went and that was it. My pumps are intank too.. so that is something I am hoping doesn't go any time soon either...

 

Hi Diggs,

I see you got some more replies! The reason I asked about the computer codes is that I also think the stalling is fuel system related, but in a slightly different way. Dirty injectors can give you stalling, but they also tend to make your engine run like crap pretty much all the time. It doesn't sound like you have power and acceleration problems, so I'm thinking it will be something else. I suppose it could be your fuel pump, but what little experience I do have says you are probably right about that one. I've had four electric fuel pumps go out on me over the years and none of them presented like what you've got going on. All mine basically just bought the farm. When I turned the key to run and listened... nothing. No whirring sound from the fuel tank. and , of course, no fuel pressure followed by no start. (A couple of them went from whirring to growling before they croaked and one of them started playing possum intermittently, but they died within days thereafter.) So, again, I think it is something else.

It is your computer that controls how your engine runs. Specifically, the computer controls the air-fuel mixture at different RPM and loads. To do that, it relies on a bunch of sensors to give it clues about what's happening. If one or more of those sensors fails the computer can't do it's job properly at one RPM or another. I think you may have a failed sensor. With most of them, the initial failure will cause your "check engine" or "service engine soon" or "emissions" light to come on... for awhile. After awhile, the computer stores numerical code in it's diagnostics memory and stops turning on the light. If you can check the codes, you may be a step closer to solving the stalling problem.

"How do I check the codes?" This is the part that is hard for me to describe. There is a pair of connectors in the engine compartment (In mine this is on the passenger side fender, near the battery.) that you plug a jumper wire (even a paper clip will work) into to cause the computer to output the codes when you turn the key to run. But I can't show you what the connectors look like. You need a book for that. The Haynes manual for your truck calls these the diagnostic link connector (DLC) and the self-test input connector (STI). There is a diagram on pg. 4-16 and and photo on pg. 4-17. The procedure is described step-by-step and there is a chart telling the meaning of the codes.

What I most want to get across is that you don't need a special scanner or tremendous knowledge base to check out the electronic workings of your truck. You need a book, a paper clip, and a pen and paper. Start with the book.