Hey! it's been a while since I've been on this board but nowI have a problem. I have a 1993 F-150 4x4,5ltr.V8 with duel gas tanks.
here's the problem, The engine won't start altho there is fuel pressure in the fuel rail. You can hear the pump pressurize but no fireing unless you crank the heck out of it. I can get it started this way and after it is going in runs normaly. The computer has set codes,21,24 and 33. I have changed the coolant temp sensor .(not the one going to the dash). any thoughts?

Steve

 

If you hold the pedal to the floor and then try to start it, will she fire up easier?

 

Check your fuel pressure regulator and the spark. Check your TPS (throttle position sensor). Remove the spout and check your timing. Clear codes and re-read see if any change. Had to crank the heck out of my 460 when the regulator went south. Once replaced all was well.

 

Next time give it a shot of starting fluid,that should determine if it's fuel or spark.

 

Codes 21 and 24 usually mean that you tried to collect KOEO codes on a cold engine and the outdoor temp was below about 45 degrees. These codes are normal and somewhat expected in this circumstance. One of the ways the computer tests the ECT and ACT sensors is to check them for "in the expected range", which means a warm engine.

Code 33 is a memory code for "EGR valve not opening". It is unlikely this has anything to do with your starting problem.

You say you have "pressure" at the fuel rail. Is it the correct pressure? How fast does the pressure bleed down? If the regulator or one of the injectors is piddling fuel, you may have a flooded condition during initial crank. If the pressure is too low (as from a weak fuel pump or a leaking check valve), then the pump will have to run for a while to build up adequate pressure.

If you don't have a suitable guage, you can run a couple more tests to try to narrow it down. Cycle the key from on to off to on to off about 5 times, then attempt a start. Does it start better or worse? If better, your initial pressure was too low and the cycling is brining it up. If worse, it is likely the regulator or an injector is leaking.

In addition to the "clear flood mode" Popa Tim suggested, try depressing the accelerator pedal about 1/3 of the way during crank rather than just leaving it alone. If it starts better this way, you might have a dirty or sticky IAC -- and it is not opening fast enough to admit sufficient air for starting.

And as Tex94F250 suggested, check that you are getting spark during initial crank (bad grounds or weak Hall effect pickups can give you no-spark or weak-spark as the battery voltage drops due to the current draw of the starter). Check the spark quality when it is running. Is it a good healty snappy spark, or is it barely firing? An engine can run fine on a pretty bad ignition system, but have trouble starting.

 

Ok,that is a lot of stuff to remember while typing this but here goes.
I have a spark at the coil and at the plug wires. The fuel pressure in the rail bleeds off with just a little spurt when I depress the shcrader valve.
I suspected the fuel filter might be clogged but I couldn't get those quick disconnect fittings off.
Will the IAT sensor that is in the intake plenum cause the engine not to start?
How do you test the fuel pressure regulator,and where is it?
I tried some ether last nite and it didn't even fire. Also tried cranking the engine with the throttle at different positions.
How about the ingnition switch? That crome thing turns a little independently of the key sometimes.
Steve

 

I am having the exact same problem with my 95 F150 302. The truck ran fine the last time I drove it, sat for a day, hasn't started since. I have feul pressure at the rail, 39lbs when the pump primes. I have changed the plugs, wires, cap, rotor, TFI, and ignition switch while trying to troubleshoot this. I have good blue spark from the coil. I have 12v on the injectors with key on. I have tried pressing the gas pedal to various levels while cranking. Visually inspected as much of the wiring as I could. Made sure all fuses both in the dash and under the hood are good. This is killing me. I can't even get it to pop while spraying ether in it. Please, someone help.

 

I'm giving up.. ...calling the dealer today!

SteveSr

 

You know the mantra -- an engine runs on fuel, air, compression, and spark. One of those things is missing, that's why she won't start.

Spark at the coil is good, but you need that spark at the plugs. Pull one plug wire off, use an old spark plug to verify spark gets from the coil, through the distributor, and all the way out to the spark plug.

A bad IAT or ECT sensor can cause the engine to fail to supply enough cold start enrichment for starting in cold weather. The engine should at least pop or cough, and should start with a shot of ether, if this is the problem. It is fairly rare that this causes hard no-start issues, unless the temp is -20 degrees.

12 volts at the injectors is good, but you need those injectors to be opening during crank. Use a test light to verify that one side of the injector stays at 12 volts while the other side flashes (is grounded periodically by the computer) during crank.

39 pounds at the rail is good, but how fast does it bleed down? It needs to stay above 32 or so for 30 seconds after the fuel pump stops.

The tool to remove the fuel filter connections costs only a few dollars at any auto parts store.

The fuel pressure regulator on a 302 is at the back of the engine. Follow the fuel lines up past the bell housing to where they tie into the injector rails. The mushroom shaped thing with the vacuum line on it is the pressure regulator. To test it, test the fuel pressure at the Shrader valve. Also, remove the vacuum line and cycle the key a few times. Any fuel present at the vacuum connection indicates a failed diaphragm.

Check the static ignition timing.

Check the compression. Usually you can find such things as a blocked exhaust system or a jumped timing chain, as well as internal engine damage this way.

 

Hey!
I decided to give it one more shot,I changed out the IAT sensor Friday nite and that didn't fix it. So I went back to the ingnition,put an old plug on the coil wire and I had a spark but it looked kinda whimpy. I got an old coil that I had in the garage ,probably from my old "84" F-150 and rigged that on and .....WHOO HOO!!!!! it took right off!! So I guess perseverance does pay off sometimes!!
Thanx for all the advice!

SteveSr