1996 (Aug 1995) Ranger XLT 2wd 3.0 Crank no start when outside temp is about 75-80F or warmer. No CEL when first turning the key on. Doesn't seem to be holding fuel pressure after shutdown. Runs great when it starts. Starts fine when the motor and air temp are cool. Will usually restart when hot within a few minutes of shutting it off. Starting fluid works sometimes when it won't restart after driving. Only DTC in 7 years is PO1445, so I cleaned the PF sensor, the PF valve, and the electrical connectors and replaced all of the fuel vapor hoses from the tank to the charcoal canister to the intake manifold since they were getting old. Also has new IAT and CKP sensors, fuel pressure regulator, fuel pump, fuel filter, air filter, and MAF sensor.
I've tried too many things to remember before I realized it might be air temp related. I'm ready to start troubleshooting from the beginning again. At 6 a.m. this morning it was 70F, truck had sat all night and fired up instantly, drove for 20 minutes and then parked in the shade. It restarted a few minutes later. At 9 a.m. it was 80F, crank no start! Also happened last summer, just started again this year.
I'm going to start checking sensor grounds, voltage, and/or resistance.
Went outside at 7:30 a.m this morning. It was 72F @ 88% rh. Crank no start, no CEL with key on. With the key on, there was zero fuel pressure on the fuel rail. Starting fluid did nothing. I didn't hear the fuel pump come on this time, which is very unusual. Seems like high humidity might be part of the issue.

 

how did you check the fuel pressure? but the pump did come on, did you ck pressure then? did it pop at all with starting fluid?

 

If it doesn't fire up, I'll occasionally depress the Schrader valve on the fuel rail and it does nothing but maybe
go psssst for a second or two. I haven't checked the pressure with a gauge when it's running because it runs so well. There hasn't been pressure at the gas cap when I open it since I got it in 2018 (had the PO1445 then so I changed the purge valve and sensor but not the old hoses which fixed the DTC for a few years before it started acting up again last summer,)
For the latest episode this morning I didn't hear the FP relay click or the fuel pump come on and I was drenched in sweat so I gave up. Starting fluid did nothing at all.
I think I need to check the connections at the fuel pump and the relay. I've had the bed off a couple of times so that is doable.
There is misinformation online about this particular year truck and engine. Like that there is a standalone fuel tank pressure sensor (seems to be part of the fuel pump assembly) or that the charcoal canister is under the bed behind the fuel tank when it's tucked under the battery.
I would expect it to be a pressurized fuel system. The fuel pump is new this year.
I'm ready to try anything at this point. FYI I was a certified mechanic in 1991, but I only worked in a shop for about a year.

 

humm, is it OBD 1 or 2? when you do the 50/50 test with starting fluid, if it pops that means you have spark of some kind. i see where you are thinking its a fuel problem but it should try and run with starting fluid. so it could be a spark issue. id try and pull a plug wire off a plug and put in a plug that you have laying around. ground it to the motor and have someone try to start the truck. see if it sparks, ck youtube there might be some videos how to do this. so you are looking for spark. you are trying to find out if you have a fuel issue or spark issue.

 

I have a spark tester and a helper (for the weekend at least).I replaced the spark plugs in the spring, coil packs and pigtail last fall. We'll check for spark and run down the wiring from fuel pump to evap system, FP relay, and PCM. And the fuel and vapor hoses. I have the wiring diagram and PCM pin out. Will also check the coils and connector, and the camshaft position sensor wiring.

It has 270K miles, wasn't maintained well from 1996 to 2016 when my dad had it, was abused for another two years by a nephew who would put anything combustible in the fuel tank when he was broke. It's been driven a few hundred miles on 91 octane 50:1 two cycle engine fuel before I got it.

When it won't fire up the CEL isn't lit when I turn the key. If I run the jumper from the FP relay to the PCM ( I forget which wire) the CEL lights. The PCM is aware of the problem, but not telling me anything.
So, if the fuel pump relay isn't clicking the fuel pump isn't being energized. Can the PCM cut spark or fuel delivery or both but not give a DTC? Would a bad MAF or IAT not trigger a DTC?

 

ok so guessing its OBD 2?

 

something else i thought of, once with a friend we tried to start his car. it had sat for quite a while. it turned over pretty good but didnt start. i tried staring fluid, no go|? so we were thinking spark, we charged the battery some more and it fired right up. the news was voltage was too low i think.

 

Yes, first year OBD- 2.
Battery charged overnight last week.
I remember in about 1988 that my buddies new Camaro had a fancy electronic ignition that required a minimum voltage to fire but would still turn over if the battery was a little low.


I just read a post called Hard To Start that might be the answer. He said that on that era Ford the IAT and the coolant temp sensor work together to control the fuel ratio. That sounds like they take the place of the choke on a carb engine which explains a lot. It acts just like a partially closed choke. I have a new coolant temp sensor but I'm waiting on Teflon tape to be delivered so I can swap it out.
A lot of the sensors and parts I've replaced on this truck were the original OEM part. I changed the original water pump at 235K. The impeller was almost completely gone. The original coolant temp sender crumbled as I removed it. The OEM cam position sensor failed at about 200K. It came out in pieces.
Like I said above, it was neglected then abused before I got it.

 

theres 2 temp controls ones for the ECU other is for the guage. thay are different ones a sensor other a sender. theres lots of info about these. also you might not want to use tape. they need to be grounded to work.
so was there spark?

 

Had no KOEO CEL (indicated no communication with PCM) . No fuel pressure, so no spark. Quickly checked the 5 or 6 fuses and relays involved (PCM and FP relays ) Swapped a spare diode into the PDB and she fired right up. Intermittent heat related electrical component failure. No DTC exists on a first year obd2 ranger for this. It's not even a computer but more of a series of rules in a box under the hood. Break the rules and the engine might crank all day but the PCM is not allowing spark. Free fix after literally years of this being an issue. Been in the shop a few times for crank no start but they never found this. I got my diode at the scrapyard.

I