I am experiencing a Hard Start Problem intermittently, the only common symptom is it appears to be more common after it has been running and warmed up. Initially I was told my fuel pump could be weak, so changed that, new fuel filter, new plug wires Belden 7mm, plugs AC Delco, Rotor and Cap, Readjusted the timing, New Distributor last year, at times will roll over to where I stop and try again, most times it then fires right up. Friday afternoon it threw a code for the first time(Mass Airflow Sensor) K&N Air Cleaner Removed and saw what looked like a very small piece of the air cleaner on the bottom of the Tube removed it ( about 1/4 the size of a Pencil eraser head, Code cleared and I hoped good to go. Yesterday it was longer than I am accustomed to, was beginning to think it wasn't going to start. Removed Air Cleaner again, nothing found, wiped off surface of MAF Sensor, replaced air filter, started several times all good, started up this morning drove about 40 miles came home, unloaded some things and went out to move it in the driveway after about 10 minutes and it cranked and cranked all over again, No Code. So, I am willing to replace the MAF Sensor but at almost 200 bucks I'm searching for advice. This Truck is pretty close to mint, never seen a winter all mechanicals are up to date, Pull a 26 foot travel trailer and that's about it. When running it's smooth 88,000 miles, plugs that I replaced looked a tad rich, other than that I'm poking and hoping. Fuel Pressure is fine as is oil pressure. Have owned truck for 13 years.

 

What was the code? Diagnosis can go a few different directions depending on what it was.

Take the air intake tube off and inspect the throttle body for excessive carbon buildup around the plate and in the IAC valve bore. If cleaning is needed, pull the TB off, remove IAC and TPS and clean using carb or brake cleaner and compressed air. Install with a new gasket (even if the old one remains in tact).

You should really ditch the K&N filter and install a factory intake. The K&N filters are fine for racing/off road applications but on vehicles with MAF sensors, the oil typically coats the sensor and skews the readings. There is MAF cleaners but even using that, the oil will start collecting on the sensor as soon as the engine starts again.

 

Believe it or not I've have been thinking about that, I kept the factory Intake, Experienced the same issue when racing go karts, sucking the oil from the pre filters. Thank You for that, will reinstall the factory one tomorrow. Hope I haven't set myself aback trying out the K & N, I'll clean the MAF Sensor and move on. will Let you know. After all, it's not a race truck but, a very nice truck. I believe the diagnosis was MAF Sensor, it was a brand new Mac Tester. I'll ask again tomorrow for sure.

 

Reinstalled Factory Intake, Cleaned MAF Sensor, Throttle Body, Seems to Run Smoothly although I have a friend who believes the MAF Sensor may be compromised by the oil as it is electrical, if the problem persists then replacing it I guess is the next step, thanks.

 

2 quick tests that can be done with the engine idling and at operating temp:

1) Using the handle end of a screwdriver, lightly tap on the MAF sensor housing. If the engine stumbles as long as you’re tapping on it, this suggests the MAF signal is good.

2) Unplug the MAF sensor. If the engine stalls, the MAF is fine. If it only stumbles but then recovers, the MAF may be faulty but first you’d want to verify the wiring and connector terminals are good.

The yellow wire is the signal back to the PCM.
The pink wire should have battery voltage with the key on, engine off.
The black/white wire is grounded at the top of the right cylinder head. There is a splice in the harness where other components share that ground as well. I’d recommend using an ohm meter or test light and wiggle testing the harness to verify it’s in tact.

 

Well, a bit ahead I guess, replaced the MAF today and it appears to still crank excessively at times. Time as you say to begin checking the wiring. Just went out and attempted to start it cold after new MAF, rolled over for the longest time, then started right up the next 3-4 times. I'm confused.