2020 DF300 hard starts

[Captaintomc]

Zero issues with starting cold. After running for 20 minutes to an hour and shutting off the motor, the motor cranks and sputters but does not start. After 5 attempts the motor starts quickly. This happens on the same number of attempts after every period of running and stopping. (5 failed attempts - successful start - move to next location and shut off). The next morning when I start my day motor starts with no hesitation.

I hear my fuel pump when cycling the key, my primer ball although not totally solid does come right after a squeeze or two. I replaced a bad-looking housing and racor separator and problem still persists. Wondering if it is possible that the primer ball is the issue?

[redlowrey]

Do you know how to use a multimeter, and what is the day time temperature you are fishing in.

[Captaintomc]

Do you know how to use a multimeter, and what is the day time temperature you are fishing in.

Yes I can use a multimeter. Time and air temp varies between 8am-5pm, 50-75 degrees

[redlowrey]

Ok when you first turn the key on your computer will do a system test and it will look at the engine temp sensor voltage, and the inlet air temperature sensor voltage to calculate how much fuel it’s going to inject into the engine, and how much throttle opening.

As the temperature of the engine increases, the temp sensor signal voltage will decrease, if the signal voltage does not decrease with engine temp, it will inject the same amount of fuel as for a cold engine making it harder to start.

Each time the it splutters the computer will decrease injector pulse width and increase throttle opening you can see this live on a scan tool sds.

I would start with running the engine on the muffs cold hook up your multimeter on the temp sensor signal wire and monitor the voltage as the engine warmed up, it should drop below 1 volt at operating temp, start there cost you nothing but a bit of time.

[Captaintomc]

I’m unable to get a reading on my air temp sensor with the key on using my multimeter.

[Captaintomc]

When I probe the sensor it just Ohms out

[redlowrey]

Mate with the key on, you should be looking for a VOLTAGE signal, not resistance with ohms, when you get to the temp sensor there are three, two exhaust and one engine temp, that is the one I want to know what voltage it is with the key on when cold, and as the engine warms up what it drops to.