Warm engine starting problems

[logsaw]

Low mileage truck from Minneapolis but with underside rust problems. I have replaced the TPS, IAC, fuel filter, fuel pump and a sensor in the hose right after the air filter. Remaining problem? It will start just fine after siting for an hour or two, but come out of a store and it is hard to start....turns over for like a 15 - 30 second period and will finally start, blowing an amount of white smoke. It will start easier during the warm start if I touch the gas pedal slightly. With a fuel gauge hooked to the rail, the pressure is around 35 psi at both the initial start and the start after warm up. What be the problem? Thanks,

 

[Haywire6000]

Next time this happens unplug the Mass Air Flow and try to start it. If she starts right up that's your issue.

 

[tomw]

You might have a failing coil or pickup that opens when hot. Check for spark the next time it will not start. You may get white smoke or vapor just from the fuel being evaporated in the cylinder and being pushed out the exhaust.
tom

 

[logsaw]

The Mass Air Flow sensor (also replaced 1500 mile previous), per your instructions the next time it would not start, seems to be out as there was no difference.
So we are probably down to a spark problem. So we have 1) camshaft position sensor, 2) ignition coil, & 3) ignition control module that could be faulty. The only way I can test spark is by holding the plug with an insulated pliers?? Probably should get a spark testing light. What procedure should be followed here with just the voltmeter I have? Or what tooling and procedure should be followed. Or should all these parts simply be replaced at 140,000 miles?
Thanks, Jay

 

[tomw]

Take a spare spark plug, remove one of the plug wires, and install on the spare plug. Ground the shell or threaded part of the plug and crank the engine over. If you have spark at the plug, you can generally expect the other plugs have spark also.
The individual parts, such as pickup and module can be tested also, but you have to have some equipment along with a procedure. I don't have one handy, but there are posts on the web on testing the modules, for sure, and likely the pickup as it is a very simple device.
If you don't want to pull the plug wire at the spark plug end, you can use a spare plug wire and plug it into the coil end in place of the plug wire, again grounding the outer metal of the spark plug while testing.
tom

 

[logsaw]

I have the problem corrected. I unbolted the mail coil pack from the metal mount, found an undue amount of rust and corrosion, cleaned that all, bolted the coil pack into place again and we start fine. From my slim knowledge of these engines, it appears the coil pack was losing ground when the engine was warm. The truck came from Minneapolis with a healthy amount of rust. THANKS FOR ALL YOUR SUGGESTIONS.