1994 B2300 2.3L (same as Ford Ranger) with 345K miles, Manual Transmission.

I start my truck in the morning (cold start) with no issues, it starts right up. Then, I drive it for like 5 mins, the engine is still not fully warm-up yet. I turn off the truck and re-start, for some reason, it will take few cranks to start up again. If I drive my truck til the engine is fully warm-up. Then, I turn off the car and restart with no issues at all. No CEL to indicate any issues. I changed out temp sensor, O2 sensor, ICM, sparks plugs, sparks wires, coil packs, IAC, fuel pump, fuel filter, fuel pressure regulator for other issues I had few months back. I have not noticed this problem until lately, because I usually start the car in the morning and run the engine fully hot and will not notice this restart issue.

Please advise...

 

Have you tested fuel pressure after a short cold run & restart?
Have you tested under load battery voltage on that short cold run restart, or had a parts store Load Test your battery & or perform a voltage drop check at the battery cable connections across the battery post clamp connections & where they connect to the engine & the under hood power distribution box & body to engine & battery ground connections?

 

Thanks for your reply. I want to ask you something about my spark plugs.

I measured the resistance, most are 10K Ohms and one has 13K Ohms. I measured it when it is cold. I read some posts, they said it should not be more than 5K Ohms.

Any advise....

 

We don't know which spark plugs you have. What does the spark plug manufacturer say the ones your measuring are supposed to measure?
Are these the plugs specified by Ford for your year model engine?

 

They are CHAMPION plugs (3408, Platinum Power). They are made for my truck. Can't find the spec as far as what the resistance should be. The resistance seems to be too high...

 

Just my opinion but Champion plugs are not very good plugs,,,i will not use them !!! Just google the year and engine of your truck and get Motorcraft plugs or AC Delco .Ford recommends Motorcraft plugs !!! But your truck so use what you wish ..

 

I just ordered NGK since they are made in Japan and should have better quality. They also have pretty good review and should be good enough for my truck. Just curious, Spooktn, do you have some sort of measurement for the spark plugs you have in your truck? I want to know the resistance.

 

no sorry i have never checked resistance i just gap them to spec and put them in

 

I google many sites, all of them pretty much say 5K should be the normal resistance value.

 

Pawpaw,

I replaced all the spark plugs with NGK copper V-Power (basic). All were tested with 4.1K Ohms prior to installation.

The issue remains, it starts right up when engine is cold or fully warm-up. The only problem is in between cold and fully warm-up, it has hard time to start. I checked all possible ground points with a multi-meter. Connection to the battery terminals are tight. I even re-sanded the Pos and Neg terminals, just in case.

Where is the fuel pressure test point? If I have a fuel pressure issue, why I would start up in the cold at all???

Please HELP ....

 

There is a schraider valve on the fuel rail,,,it kind of looks like a tire valve stem except it is medal not rubber ,, you should hook a gauge to it and should have around 50 psi give or take a little,,,,see what gauge reads running and not running and turn off truck with gauge still on and see how long it takes to leak down 5 or 10 psi and let us know what you find

 

The fuel pressure regulator is under hood on the fuel rail. It's a round can with a vacuum line attached. Pull the line to see if it's wet inside with fuel, if not, the regulator diaphragm is likely ok, so replace the vacuum line & perform a KOEO & KOER fuel pressure test.
KOEO = 35-45 psi. KOER, vacuum line attached, 25-35, vacuum line removed & plugged = 35-45 psi.

Use, borrow, or Come by a scan tool that can read live sensor feeds on your OBD-1 diagnostic system, like a Actron CP9145, etc, so you can monitor live data like fuel trim. O2, MAF, IAT, ECT sensors live PID's to the computer, to see how their behaving with temp & have the scan tool scan the engine computer for any pending, or set trouble code clues & post All code Numbers, as they can help focus a trouble shoot.

Seeing as how the problem seems to be Temp sensitive, it could be something as simple at the IAT, or ECT temp sensors giving the computer corrupt readings that's causing the computer to lean out fuel trim in that temp range, or you have a fuel pressure problem in that time frame, or maybe a old lazy O2 sensor, or one with a faulty heater that's causing the O2 sensor to be slow in coming to operating temp, so it could be slow to switch & cause the fuel trim to be lean on a not fully warmed up engine restart.
Carry your pressure gauge with you & perform a pressure check when its in one of its stubborn no start fits & hook up the scan tool to get a trouble code scan to see if the computer has a good trouble shooting clue for us when its reluctant to start.

 

Thanks for your quick reply. I had few similar thoughts like yours. Therefore, I already changed out O2 sensor, fuel pressure regulator, fuel filter, IAC, coolant temp sensor. These items don't cost a lot, so I went ahead and changed it one by one. However, problem remains...

Will a fuel pressure tester from Harbor Freight do the job????

 

Yes the Harbor Freight fuel pressure tester will work. I had to apply plumbers PTFE tape to the hose thread fittings to prevent fuel weeps on mine.

 

May I ask one thing about the ECT sensor when the engine is cold (60F). I measured it last night, it's around 34K Ohms. Does it look right?