sorry if this has been posted before, frankly i dont have the time to search through all the forums for this specific issue. i recently purchased a 1990 f-150 5.0 v8 xlt lariet. drove it for about a month with zero issues, even made the trip home with it... 3hrs plus. recently ive had issues with it in the morning, it will be rough...almost sputtering like its not getting the right mix. once its warmed up an ran for about 20 min shes good to go for the rest of the day. its just when she sits for about 8 hrs or so that this issue occurs. however the past two days its been running a lot rougher, its an all day issue not just a 20 min issue. the past two times ive put gas from base in it which contains 10% ethanol. i know a truck that age ethanol shouldn't effect it but in my opinion it might be the culprit. i do have dual tanks and i plan on putting just straight gas in the rear to see if it makes a difference. i have not done anything maint wise to this vehicle yet, but i do plan on it...(major tune-up, fuel filter spark plugs etc.) its just rattling my brain how it drives perfect one day and so crappy the next. in my opinion its not getting enough of one thing, fuel or air. im just looking for some quick and semi easy places to start...any help will be appreciated..

 

OK so I've changed a few parts. Fuel filter, plugs/wires and dist. Ran good for a little while, 30 min. While it was in the driveway anti freeze started spilling from the block heater. No big deal swapped that out leak tested it refilled fluids. Cranked it to check for leaks and started right up and idled like a truck off the assembly line. Started it three more times with no issues, very easy to turn over and fired right up. Later that night, tried re starting very hard turning over which wasnt at all surprising... ^^^^ (previous post). I've tried cranking it about 5 more times today allowing the fuel to settle of course and now absolutely nothing. A couple of times it sounded like it wanted to but just didn't have the gumption. I'm going to test for spark tomorrow and fuel pressure this weekend. Fuel pump does kick on when the key is turned. Anything electrical I could be missing?? The rpm guage will flicker every once in a while when I try to start it. I'm pulling my hair out, this drove perfectly not more than 3 weeks or so ago.

Thanks for your time,
Rick

 

Perhaps there is some sort of residue in your fuel tank. Everything would be fine until it floats up into the fuel pump inlet, which could be one possible cause of the problem. If the truck had previously set idle for a long time, that could be a cause. I recently pulled the tank of an air compressor which sat idle with gas in it for years, and what was inside was not pretty! Non stabilized gas will gunk up a tank on fairly short order....

 

Ya I'm with you on the whole gas thing, the guy i bought it from used it for hunting etc. Wasnt his daily driver. which is why I need to get my hands on a pressure tester. I put about a gallon in the rear and it was still doing the same thing. Once I test pressure I'll see what it reads and hopefully rule that out. I'm gonna check the tfi and coil pack with a multimeter and see what I get from that. Along with the spark. Fuel+spark = go go go...unless of course something with a connector that might be fouled..let the head scratching continue

Thanks

 

I'm actually having the same issue. Except I replaced the fuel pump and filter around December.

Runs fine sometimes. Every once in a while it'll stall after starting, but driving down the road it'll stutter and sputter. Usually clears up when I press into the pedal a little bit, so I'm thinking injector issue.

 

Ok here's the plan for the day once I leave work. It occurred to me that after I installed the block heater it started up fine 3 times. I had the battery disco'd for about 3 hours. Just a habit of mine to disco it whenever I'm doing something that requires me to be under or on the engine. After digging through fourms for the better part of the day I've discovered that by discoing the battery it will clear codes if any. So first thing I'll do is once again discobthe battery for 30 min or so and see what the outcome is. Depending on that I'm going to unplug the MAP and see what that does. I really don't think fuel, spark is the issue...I'm still open to suggestions however. With the issue being so interminnent and acting the way it does I'm leaning towards eletricial...TFI,EGR, ignition coil or MAP...luckily I've got a buddy who's got a 92 with same motor...wonder how hell feel about me borrowing dome parts to eliminate some ideas.

 

I had a similar situation.
Fuel press regulator leaked occasionally when I pulled the vac line off. but I digress.
I promised myself that when I got it running, if ever, I would unplug stuff one at a time and see if they really cause trouble.
so I unplugged the throttle position sensor and it still started and on to everything else I could unplug and eliminate as a problem.
Not real science and may cause damage somehow but I was sick of looking at 30 different things and testing them as best I could
when it wouldn't start.
and yes, I replaced lots of good parts so I got another identical truck and a spare set of almost everything suspect, distributor, coil, and on and on.
Oddly enough, with all the electronic stuff, it really does come down to spark and fuel.
I'd rather have a fuel pressure gauge on the dash than a tach.

 

ps - a good fuel pressure reading does NOT tell you volume of flow.
My fuel diverter (tank to tank diverter) has a super clogged filter in it so even with good pressure, it simply did not have good flow.
That diverter says 'do not touch' and the Haynes manual say to servicable parts and NO mention of a filter at any parts stores., but the bottom sediment bowl unscrews with an oil filter wrench.
Easier to check fuel pressure and flow first however.

Guessing that @ 10 miles per gallon, it should pump at least a coffee cup of gas in 1/2 minute?? 100 litres per hour?
I really don't know.

 

to recap:

BOTH front and rear fuel pumps kick on
disconnecting the batt and waiting 30 min did nothing ( worth a shot)
after disconnecting the TB air hoses i went to manually turn the butterfly valves and encountered some resistance (more than normal) so that made me think that the TB isn't opening enough to get the correct air.

i mashed the gas while attempting to start and it fired up, i had to stay on the pedal or it would die. so back to the forums, i discovered what the TP sensor is all about and read through a few posts and all the symptoms sounded like mine. for a second i thought i had it figured out. i sprayed the connectors with contact cleaner and attempted a start. it started without me working the pedal, it didn't sound 100% however. i checked it with a multi-meter and got the correct readings. ( which bummed me out) i wanted hard evidence to change SOMETHING!! I've been noticing some buildup in my air-box (oil) could a TP sensor check good but still have some build up in there and causing my issue??

also if i were to spray some starter fluid in the TB which port should i spray?? the upper OR lower, i got a little hesitant after reading the can...LOL i never really need to use the stuff, but i want to see what outcome it will produce.

 

got it started and drove around the block today! i re-checked the volts on the TP sensor, sprayed some throttle body cleaner down her throat and fired right up. i had to do that a couple of times however, one concern. i noticed a little bit of smoke coming from the left part of the engine when i pulled in the garage. opened the hood and noticed an oil/fuel mix coming from underneath the air-box. searched FTE and am only hoping it's the PCV valve and NOT what everybody else has said. any thoughts/inputs???

not feeling all that confident right now...

 

I am thinking it's not JP-8.............and this could be a serious blow-by.........time to try a new FORD Motocraft PCV, then compression/leak down if not resolved......

 

i'm going to check for suction at the pcv valve ( although it looks like a bitch to get to) see what that tells me than more than likely install a new pcv valve. as far as the leak down/compression test goes...that's wayyy out of my league. never attempted before. something to accomplish in my garage? special tools?

funny you mention jp8, wouldn't happen to be a crew cheif in the military???

 

Former two-seater (E) air-to-mud driver.................

 

Nice! Worked Cs at Eglin than Es at Mt. Home. Now lucky enough to be a Minot working 52s....(sarcasm)

 

Pulled PCV valve, it clicks....and I've got suction from the line......one thing after another....