Got this truck from a kid that let it sit for several months. I have done a tune up (spark plugs, wires, dist cap n rotor, fuel filter), oil change, replaced rear fuel pump, coolant temp sensor. I have also done a smog pump delete. The problem I am having is a hard start after warmed up. First thing in morn (regardless of outside temp) it fires up perfect. After driving it for 10 or 15 min, it gets harder and harder to start the longer it sits. The next morning it cranks up no problem. I have check for ignition with a timing light, no problems there. I checked the fuel pressure the other day. I disconnected each fuel pump to make sure I could test each one individually. each tested the same. the fuel pressure slowly leaks down, regardless if i am using the new pump or old pump. i thought i might have a leaky injector. my question is though, if it is a leaky injector, why would it fire up instantly after it sat for a while. The other odd thing, is that after sitting for a while, if i hold the accelerator down for about 7-10 seconds, it starts much easier than if i just try to start without touching the accelerator. once again, first thing in the am, it fires up no problem, no accelerator pedal needed. No codes. it does run rich....so there's that. thoughts?

 

A warm start no start, do you mean "no crank no start" or "crank no start"?

 

I apologize....crank no start after warm.

 

You can try to easiest ones first. In the morning, get the voltage of your battery with a voltmeter before starting, get a helper and watch for the voltage drop during starting, what are the 2 readings? Do the same on a warm start, does the voltage drop too low below 9V?
Higher temperature = higher resistance = higher voltage drop. If your cranking voltage when it's warm drops too low it can be a possibility. The fix is to buy new or clean your battery cable terminals both B+ and ground.
You said something to do with your accelerator then why not have a look at the throttle plate movement.

 

Thank you for the ideas. I will try them tomorrow. The only thing that I keep coming back to is this.... After testing the fuel pressure (both pumps test the same), it leaks off over the course of time. I thought I might have a leaky injector (stuck open or broken). However, i am not sure how that would explain the truck starting just perfectly first thing in the AM.

 

You should really get a fuel pressure gauge and verify the fuel pressure at the fuel rail when it will not fire up and start.

Depending on if you have the REQUIRED (35-45 psi) fuel press we can eliminate that and verify if the problem is ign related.

You cannot go by , "There is fuel coming out of the schrader valve".
You can use your timing light to verify there is spark at the plugs when it will not start. NO FLASH= NO START..

Let us know what you find, thanks.

 

Yes...the require PSI is good during operation and just after turning off. I have used a gauge to check that. Over the course of the next several minutes, you can watch the PSI slowly decrease while sitting. For example....An hour after shut off, the PSI was 20-22.

Yes, the timing light does show spark. I tested this when I thought it might have something to do with a sensor. So all is well there.

I have already changed, and then checked (ohms and voltage) according to ambient temp, the coolant temp sensor.