I have a 1991 f150 4by4 with a 302 efi, when I bought this truck used it started fine but as time went on it became more difficult to start, you have to pump the pedal as if it were a carb and at some point it will fire up and when it does you smell gas and it puts out a lot lot of smoke. I just rebuilt the engine and this issue was there before it was rebult so I know it's not internal,the engine has a new coil, ignition module,cap,rotor,plugs,wires,tps,iac,correct timing and all vacume lines are good as well as all intake gaskets and it still is reluctant to start and yes it is geting spark while you are trying to start it, soooo any help would be great thanks.

 

Week Fuel Pump

 

Are you getting any fault codes?

Not sure if your model year has the MAP or MAF sensor - perhaps a problem with the airflow measurement? One problem with the MAP is a hole or other leak in its vacuum line.

Holding the pedal to the floor is supposed to kill the injectors - useful during flooded conditions.

 

I have not tested the fuel presure yet and the truck does not have a mass air flow sensor. What do you think about the fuel regulator?

 

Measuring the fuel pressure should help towards determining a fuel pump, filter, obstruction, or fuel regulator issue.

Essentially, the fuel pump should be able to quickly reach the target rail pressure - typically somewhere in the 25-40 psi range. Monitoring the fuel pressure after the ignition is cut off should determine the health of the regulator - should be just a few PSI drop over the first couple of minutes.

As I'm interpreting things - you have a fuel to air imbalance - whether that means the fuel or the air is out of balance remains the challenge to troubleshoot.

It's difficult to troubleshoot these issues without actually being there, thus the varied opinions from others based on personal experiences and insight - some leaning towards the fuel side, others leaning towards the air side.

Basically, when one can't figure out what it is, have to resort to figuring out what it's not. It's a challenging problem, but there is a solution. Good luck, and keep us posted!

 

I feel like its a fuel issue, if you remove the plugs and turn the engine over therewill be a cloud of gas that comes out of each plug hole or if you leave them in and turn it over then remove them they almost drip with gas, this can't be right! Then when it does start it runs rough for a couple of seconds.

 

Wde3477 offers up good solid info! Test the fuel pressure, paying close attention as too how long the pressure is maintained after the engine is turned off. If injectors are leaking, pressure drops immediately. If pressure regulator is leaking, pressure drops immediately. The easiest to test is the regulator. Put a vacuum gauge to it and see if it holds vacuum. Short of removing injectors from cyl heads and then reconnecting to fuel rail and turn on fuel pump, I can't off any other suggestions with out spending money. As you describe, wet plugs and vapor present out of spark plug holes, you have to be dumping fuel. Good luck and keep us posted as to progress.

 

Well I put a new presure regulator on today and it did not fix the problem,I am thinking that there might be a blockage in the return line, so tomorrow I will open up the return line and see if I can blow air through it.