New member here with my first post.

I have a 1994 F150 5.0L 4x4 with 69,000 miles (yes 69K). I purchased the truck new and have had only minor issues (virtually none) over the past 20 years. Recently the truck has been hard to start after the first start of the day. It doesn't seem to matter if I try to restart after one minute, one hour or much more, it just cranks and cranks. In order to get the truck started I have to push the gas pedal to the floor as if the truck is flooded. It then runs rough for a few minutes but seems to clear up after a couple of minutes. It's throwing no codes that activate the CEL but I'm getting ready to check codes today regardless of the CEL not lighting. Yes it does come on before the engine starts.

I've wrenched on my own vehicles since I was 15 years old and prefer to do my own work, if I can. I hate to just throw parts at symptoms and prefer to figure out what the problem is and fix only that. However, I have very little experience with emission controls or EFI. In order to try and educate myself, I did some reading on FTE and other forums before joining FTE. After reading many threads like "My truck won't start" the symptoms were pointing me toward a defective fuel pump, fuel pressure regulator, ECT, PIP or TPS.

I'm going out in a few minutes to do a resistance test on the ECT and TPS to see if I can determine for sure, if one of these is the problem. The funny thing is that I just passed the state emissions test to renew my tags and came up clean as a whistle and as I stated earlier no CEL. The engine idles good and runs good. It's just hard to start after the first start of the day.
PS
Two days ago I put in a new set of Motorcraft copper plugs (old Bosch platinum plugs were black and one was wet). I also replaced the cap and rotor and yesterday I cleaned the MAF, ACT and throttle body and installed a new air filter. I also checked the static fuel pressure, the running pressure, as well as a leak down test. Test results were; 32 psi static (after three on-off cycles of the key at about 10 psi per on-off), 44 psi running. The system pressure rises about 5 psi after the engine is turned off and holds pressure for hours but does leak to 0 psi over night. I looked and looked but could find no reference stating whether the pressure should go to running pressure as soon as the key is switched on or if this is normal. It does jump to 44 psi as soon as I start to crank. I also checked the vacuum line at the FPR for signs of fuel and found none. I believe these tests rule out the following but please let me know if you disagree. Fuel pump relay, fuel pump, fuel injectors, fuel pressure regulator. Others??????
Does anyone know for sure if the fuel pressure in the rail should go from 0 psi to the static pressure with just one "ON" of the key or if multiple on-off-on cycles is normaly reequired?

Thanks in advance for your comments and help.

 

Did you check your throttle cable? It may be stretched. Have someone press the gas pedal while you are looking into the throttle body to see if it has the proper range of motion. If it works okay, I would lean towards the TPS.

 

Unplug the MAF. If it starts normal and runs normal then you have a bad MAF.

 

Thanks to those who replied but I believe I have found and cured the problem.

I went out this morning to pull codes but then realized that I would need to get the truck at operating temperature to do so. Since I didn't want to work on a hot engine, I decided to test the ECT (engine coolant temperature sensor) and TPS (throttle position sensor) before warming up the engine and pulling the codes.

I started with the ECT and when I took the voltage reading I got 4.85 volts. I believe it's supposed to be 5.0V but I suppose the meter has some error. The resistance reading I got at the ECT was 420,000 ohms. Yes 420k ohms. According to everything I have read it should have been closer to 55,000 ohms since it was about 55 degrees F in my garage and the truck had been sitting there over night and not run.
According to the chart I found on this site a reading of 420,000 ohms translates to a coolant temperature of about minus 350 degrees. I took the reading at least 4 times and even used a second meter to verify.

Since this sensor was obviously toast, I ran down to the local NAPA store and purchased and new, Echlin ECT. I took the ohm meter with me and tested the new sensor in the front seat of my car. I got a reading of 36,000 ohms which, translates to about 68 degrees F. Since the sensor had been sitting on a shelf inside the store this seemed about right so, I took it home and installed it. I retested the ECT installed in my engine and got a reading or 40,000 ohms or about 58 degrees F which also seemed correct.

After reinstalling all of the intake hoses I started the engine, shut it off and restarted it several times with no issues. I did not have to put the gas pedal on the floor (WOT) and it did not crank and crank without starting. Just bump the key and vroooooom!

I then let the engine run for about 25 minutes so it was good and warm and restarted the engine about 20 times in a row with no issues. Starts every time with just a bump of the key and idles as smooth as silk.
I was going to take the truck out for a drive and try starting, shutting off and restarting after putting on some miles but I looked at the clock and decided to wait until tomorrow. When I get back from my drive tomorrow, I'll post back on any problems, I'll also pull the codes and see if anything else comes up and post them for future folks who may have a similar starting issue.

 

Minus 350 degrees! Wow, that thing was dumping in fuel by the bucket fulls! Glad you got it fixed.

 

GREAT job educating yourself and finding the cause of the problem instead of just throwing parts at it!

And welcome to FTE!

 

Ya! Probably flooding on every start after the first start of the day and running super rich. The old spark plugs and the inside of the tailpipe were as black as my wife's heart!

I'll post back tomorrow after I drive the truck around for a bit but, from early indications I think I found the problem.

Many of my friends drive GM's or imports but, I don't care what anyone says! Ford makes a good truck! I'm still driving my 1956 F100 (was my father's) when the sun is shining.

 

. Yep, my first guess when I saw the title of this thread... temp sensor not telling the computer the engine has warmed up... so it's still in electronic 'choke' mode... dumping in excess fuel as if warm engine is ice cold...

 

In old school days cars doing this fix was to remove air filter open butterfly stick in a short screwdriver to hold butterfly open , jump back in car start, jump out replace airfilter, cap, butterfly nut, jump back in car drive like a scalded dog to homeroom tardy. Lol