Ok guys. This is a tuff one. Back story. Truck is 1996 F250 460, 136,000 miles. Always taken very good care of. So started having a hard start problem. Truck has always fired right up first try. But 3 weeks ago it started to take 2 or 3 tries sometimes and other times fired up 1st try. I have a buddy whos parts manager at local ford deal so i get ford parts at very good discount and labor rate for me there is to hard to pass up to let them deal with certain stuff on truck. I called down there to booked apt. to have a tune up done, and replace all fluids and alignment. On way to take truck in it started having what i call like a hickup here and there. Maybe 3 times on way into shop. Told the service writer. She said they would look into it while truck was there. Well as it goes, they didnt find anything. Truck never acted up for them. Picked truck up. Seemed fine, drove to work in morning everything was good, but on way home truck started doing it again. Called dealer asked to bring truck in and she said sure. In mean time, spoke with buddy whos parts manager and he said he would drive the truck a few days to and from work to see what its doing and give mechanics an idea of whats going on. Well he had it a week, truck he says didnt do anything wierd. Now he doesnt live to far frkm the dealership so i told him he has to drive it farther. He says he would try it and he still never had truck act up. I pick truck up this last Saturday morning to get a xmas tree and with the whole family in it the truck started doing it thing again. This time it actually died as i was waiting forna parking spot. Took 3 times to get it started and finally did. Buddy happened to call asking about truck and told him its still acting up. He said hes not sure what to do.
so there is no check engine light on. No codes and its an obd1 truck. I got into my hanes manual and started to try and get ideas of what to check and decided on replacing Coil. Did that, drove truck around, didnt act up. Then next day went to get gas because its a 460 and truck wanted to die when i pulled into store and seemed to sputter here and there. Not sure what to do. This will take some old school mechanics and im not sure i have that kind of knowledge to figure this out. The IAC is a year old with about 6,000 miles on it. Just did tuneup. Replaced coil. No engjne light no codes. The truck acts up on both tanks, hot or cold, sometimes fires right up, other times takes up to 3 times. Truck acts like it wants to die, but catches itself. I can here the fuel pumps running. I am stuck. This is an intermittent problem so even harder to diagnose. Any ideas or direction would be greatly appreciated. Thanks again for reading.

 

Does it do it on both tanks? Or just one?

 

It does it on both tanks.

 

I replaced the coil. Do i need to disconnect the battery after i put new one on so the computerbcan relearn everything, similar to when you replace the IAC?

 

No, not for a coil replacement.

 

Didnt think so. But you never know i guess. Lol

 

How long since fuel filter was replaced ? This is a fuel injected truck ? Does it have just the two in tank fuel pumps or does it have the third helper pump in line? I would try and install a fuel pressure gauge and route it up under wiper to read while driving to see if a pressure problem.

 

Yes. This is a fuel injected truck. Filter was done maybe 2,000 miles ago. As far as i know, its just the 2 in tank fuel pumps. Havent seen a 3rd pump. I thought about trying that idea for a fuel pressure guage. I wanted to buy an aftermarket one for my pillar, so i can always keep an eye on it so ma uh be its time to do that

 

A 1996 truck would be OBD 2.

 

Well I'm not one to start throwing parts at a vehicle until something sticks, but I do believe you need a baseline as far as knowing plugs, filters cap rotor etc are in good shape or recently replaced. The troubling part is having a cold start issue as well as your dying while driving which would be when the truck is warmed up? With this in mind the only common issue would seem to be fuel pressure, but having two tanks with their own fuel pumps their only common item would share fuel line and fuel filter. As cheap as a fuel filter is I'd replace it and I usually write mileage on filter with a marks alot being careful not to wash it off with fuel. At that time you can survey the fuel line after two tank lines join for a third pump which was on high altitude trucks and most extended or crew cab trucks and it was a helper pump. When it's in the loosing power or dying mode go to the specific tank your on and crack the gas cap and see if it's got excessive pressure when you open, if so try leaving it cracked or loose and see how it drives. Otherwise we're back to reading fuel pressure while driving. A actual fuel pressure test gauge has enough line to have tied into fuel rail and run under side of hood around to mirror tape it on or under backside of hood and stick under wiper so you can read. Just close hood to safety catch so doesn't pinch line. If your going to run a actual fuel gauge on your truck, I wouldn't mount it inside the cab in case of a line failure. Mount it to the cowl and purchase one of those bullet housings to mount it in. Other than that, how long have plugs been in and what type? Autolite or motorcraft only in my Ford products. Cap and rotor ok, are plug wires OE, not wanting to throw money at it I'm just asking here. Next have you physically taken the ISC motor off and cleaned the bore and pental with carb cleaner, clean the throttle body as well. But I usually spray tb with carb cleaner and then with throttle held wide open by vise grips or screw driver I'll take paper towel and long needle nose pliers and swab tb out to wipe up excess carb cleaner and the sludge just cleaned out.
I'm sure this will give you something to check, keep us posted and good luck.

 

Federal emission F250HD/F350 trucks over 8500 GVWR stayed OBD-I through 1996/97. California emission F250HD/F350 trucks were OBD-II.

 

Ya. When i purchased the truck i just assumed it was an obd2 truck. I even purchased a code reader from summit to just have for the truck. But code reader was delivered, i went to gonplug in just for the hell of it and couldnt find the port. Well thru research i figured out what the previous post says. In 1996 not all truck were obd2. Lol i was confused.

 

Ya. As to the post about typical tuneup parts. All that was just done at the dealership with all ford parts. Thats all i ever use. My best friend for 37 years is the parts manager there so all parts are a good price for me. Plugs, wires, cap, rotor, all fluids throught the truck were done. 2 weeks ago. As for the 3rd helper fuel pump. The trucnk is an extended cab and ive been all over the underside of that truck and ive never seen a 3rd pump. But then again, ive never looked for one either. I will do that and see if i can find it. I was originally thinking fuel related when 1st had issues. I will try that guage idea. Thanks for all the ideas and help. Will post my findings as soon as i can crawl under that truck.

 

Please define "No codes". At the very least you should get System Pass Code 111 for the KOEO tests and the same Code 111 if there are no stored codes. If you ran the KOER tests and everything passed you would also get Code 111 System Pass.

 

Yes. Sorry. I get the pass codes. For both tests