Hard Start after Warm- Help Diagnosing


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Joined
Feb 24, 2026
Messages
5
Points
1
City
Sussex
State - Country
NJ - USA
Other
1989 E-150 4.9L
Vehicle Year
2005
Vehicle
Ford Ranger
Drive
4WD
Engine
4.0L
Transmission
Automatic
Total Lift
0
Total Drop
0
So I replaced my spark plugs and wires about 3 weeks ago, truck runs great for a week and a half. Walk out to start it after 5 min drive to post office and it won’t start. I put a new ignition coil in it, test drove for 20 mins, park it and it starts back up ok, runs ok for a day and doesn’t do it, thought I fixed it. Go on a 30 minute drive, go to start after and it has a really hard time. Finally starts after cooling down for an hour, and drives home fine no problem. I want to try a Coolant Temp Sensor, TPS, crank sensor(don’t think this is it).

But instead of throwing parts at it I’m wondering how f anyone has suggestions to diagnose this. I’m wondering if the spark plugs/wires is related and I should just change out the wires(from rockauto) or it’s coincidence. Would love to keep this out of the shop and do myself, but I unfortunately am not great at diagnosing at all. There’s no codes, I have to check if my OBD 2 does live data.

Don’t think it’s a cranks sensor, CEL goes off when cranking after hot. Engine does not start on Flooded Engine Test. Read this on some other forums to try.
Any help greatly appreciated
 
Assuming you're talking about the '05 in your profile?

Leaking fuel pressure regulators are kind of the 1st thing to rule out on any EFI vehicle for hard warm start/no warm start/extended cranking when warm. Not sure how that works on a returnless system like yours though.

Clear Flooded Engine won't work on many of our trucks because of the "stretched" throttle cable/collapsed spring problem requiring the zip tie mod (google that.) If the throttle isn't fully open because of the cable issue, the computer won't know that it's supposed to cut power to the injectors.

I guess I'd try starting fluid the next time it happens, shoot a bunch into the intake and see if it fires. If not = potential no spark issue... if it does, then I'd be looking at wiring/grounds/corroded fuses/maybe a failing fuel pump.
 

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