I have a 1991 F150 Custom with a Jasper 300 straight 6 engine, and everytime I run the truck and the engine is warm and I stall somewhere it doesnt want to start, it will turn over and crap but It wont start, any ideas what it could be?
thanks

 

I have the same prob starts and runs good gets warm and spits sputters boggs down and dies let it sit awhile starts rite up and runs till it gets warm again i cant figure it out to save my life

 

do u have duel tanks an is it carb or efi if its efi its the with duel tanks its the fuel pump under the bed that pumps from the tanks

 

its duel tanks bolth pumps are n the tank back tank does not work front pump sounds fine doesent run constant ive been all over the truck and cant figure it out

 

it is efi ive hookt it up to get the codes out of the computer and all it gave me was one for the efg valve or censor

 

there another pump after the 2 tanks that bring it all to one fuel line

 

sorry its a ele switch that can go out bye pass that and run just one tank an see if that fixes your promble if it does then u know where your promble is

 

where is the ele switch and where is the third fule pump i here so much about

 

its not a pump its its a switch right after the 2 tanks

 

and that would meke it die after it gets warm and haft to sit awhile before it will run again

 

yea i had that same promble wit my 88 f150 wit a i6 an it worked 4 me

 

I had that problem with mine last sept, it turned out to be the throttle positioning sensor-(TPS) it would be cold, start it up, and it would race a bit, drop down to regular rpm, then crap out, wouldnt start up again till it got cool enough. I went nuts between the TPS, and the IAB or( idle air Bypass located on the side of the throttlebody).
anyway, it wasnt the IAB, -you should be able to pull your codes with a paperclip if you cant get a hold of a code reader, -go to Fordfuelinjection.com it may help out..good luck.

 

quisp and quake, did you get a TPS reading on your scanner? just curious

 

the only code im getting is 33 egr valve position(EVP) sensor or pressure feedbackEGR(PFE)SENSOR INDICATES EGR valve is not opening. Or EGR valve position (EVP) sensor or pressure feedback EGR (PFE)sensor indicates EGR valve not seated (closed) properly i changed both with egr valve and the sensor off of a 92 351 just to see if it would do any thing different but it does the sam thing

 

And EGR that dose not open will not cause an engine problem, just burn more gas.

But an EGR valve that is not closing internally can cause the problems you are describing.

Take it of the manifold (2 bolts , and a Pipe nut, ) Apply vacuum to the valve or sometimes you can move the diaphram with your finger tips. Look at the valve in the chamber and make sure it moves freely up and down.
You may just have some exhaust carbon built up in it, wedging the valve operation.

But if the valve was stuck closed ,and not opening at all , you wouldn't even notice anything with your engines running condition. It would just burn a little more gas then normal.

It only operates at cruzing vacuum. Not at full throttle or idle (it's compleatly closed). It operates at highway speeds.

The exhaust gas that is recirculated back into the cylinder again, is pretty much an inert gas (it wont burn), therefore the space it now takes up in the chamber , chemically shrinks the cylinder, requiring less air and fuel ratios. This is how we keep getting a lot of the fuel economy out of cars. In addition to reducing cubic inches. It dose have a leaning effect........Most "racers" do not have an EGR and just block the hole off with a plate. I have done the same to my 5.0 (Pictures in Profile) And have never had a problem out of it since. It's not a problem because it is not there to be a problem anymore.
Yes it run's richer , but this richer fuel ratio has a lubracating and cooling effect internally.
The O2 still sniff's out the exhaust gases and controls the injectors to what the engine needs, constantly during operations.