I have a 91 f150 with 302 & am having problems. the truck will die when you stop for red lights occasionally and or sputter when taking off from a stop. it is also extremely hard to start, will start after cranking on it several minutes, and acts like it is flooded when it does start. seems worse on cooler days, or rainy days. i have changed the iac which helped a little with the stalling but not the hard to start problem. any help would be greatly appreciated.

 

put some gas in it

 

i don't need comments from the peanut gallery buzzsaw

 

I'm sure others may have better (more experienced) advice, but I would try to determine if you are having fuel issues. When you run into a hard to start time, try spraying ether in it. If that suddenly fixes your problem... then you can trace your fuel supply... depening on your setup, if dual tanks, depending on year, there can be a handful of things that could be restricting the fuel (and might be intermittent).

One thing I did once on a prior truck, b/c I got sick of opening up the intake (to spray in it), was punched a small little hole in intake. That way I could quickly pop hood, put little spray tube from ether/carb clear and give it a quick blast. If you are trying to to this drill solo (with no helper) you can use all the time saving you can get. Can easily cover the hole with electrical tape during normal use. Kind of ghetto, but effective.

 

Sounds like an injector problem,I have an ASTRO VAN I just tore down with central muti port injection that was doing the same thing. That 91 probally has multi port injection and has a bad injector or two.
dmattingly

 

'90-up has the better fuel system (no pump on the frame), but check fuel pressure with a gauge anyway. Click my black Bronco below & look in the EFI Fuel Pump album for more info. The diagram of the FDM includes instructions on forcing the pump to run for testing.

I'd also 1) rewire the relays, 2) pull the codes, 3) test the ignition system per the procedure in Haynes, & change the fuel filter.



Unless the filter has NEVER been changed, it's not likely that there's any problem with the injectors.

 

91 ford f150 with 302,to date i have changed the following but not helped it any. iac valve, fuel filter, coolant temp sensor, distibutor cap, rotor, plugs, and wires thermostat, checked all vacumn lines, and cleaned entire throttle body. still very hard to start and will fall on its face on a fast takeoff, it will sputter and die.

 

Changing parts that aren't bad only gives you more unknowns in the system. Stop swapping stuff, and start TESTING (including all the new parts). It's cheaper, and you learn more about your truck.

BTW
There are 2 coolant sensors - which did you change? The all-brass one with a threaded post terminal, or the one with a 2-wire plastic connector?

 

steve i changed the coolant sensor on the front of the intake beside the distributor

 

steve when i changed the iac it seemed to help a lot with the stalling and dieing. also after sitting overnight if you depress the valve on the fuel rail it will not spray a lot of fuel, more like a dribble, this is the same on front or rear tanks, too

 

That's for the gauge - it has nothing to do with how the engine runs.That doesn't matter. The ONLY way to test fuel pressure is with a gauge with the key on, either with the engine running, or with the test connector jumpered.