I had a nice running car, failed emissions, tuned it up, ran nice, changed O2 Sensor, idled horrible, but drove strong. Went to start the next morning, just cranked, never started. Changed Fuel filter, checked wires, coil tests fine. I assume TFI module, am I correct? Could it have failed after idling poorly?

When I pulled the module, and did resistance tests, the numbers were consistently lower ohms...is that a bad module. I have a new one coming in the mail, but I want to know what else I should consider in the meantime. Thanks

 

If it is a TFI module, or any other type module, you usually do not get any warning. It turns into a no start condition and that is it. I had one go on a Crown Vic while going down the highway, it gave no prior symptoms, it just quit.

 

I just replaced the module, got a known good used Motorcraft one, and I confirm I do have spark. Still no start. It is trying though, and coughs good! I smell fuel, but does that necessarily mean that I am getting enough fuel to start? Thanks

 

If you cranked the engine very long trying to get it to start with a bad module it could have fouled the plugs. Did you have spark before you changed the module? If you did there is a wild goose chase in the making. Like mantta said, you usually don't get any warning with a module. If the fuel pressure regulator got stuck or a MAP sensor failed it would also cause a rough idle on an engine that otherwise runs well.

 

I did have spark before I changed it, and even after I changed the O2 sensor before that. What would cause it to suddenly stop starting after I had driven it only 12 hours previously?

Could the plugs have gotten that fouled in a 2 hour period to make it not start?

The plugs were two days old, I suppose I can take each out and check them for fouling

 

Can you hear the fuel pump run for a couple of seconds when you turn the key on? If so the fuel pump is good. If not, it isn't necessarily a bad pump, maybe just a quiet one. Of course, that's assuming it is an EFI truck. What exactly are we working on? I don't want to give you troubleshooting info for a carbed truck if it's EFI. If it's EFI you should be able to hear the fuel pump relay click on and off when the key is cycled to run, if you don't hear that the relay is probably bad. Will it start if you hold the pedal to the floor and crank? If it will, it's getting too much fuel. Where are you checking for spark at? If you checked it at the coil, you could have a problem in the distributor cap or rotor. If you checked it at the plug end of the plug wires it should be good.

 

If you have an EFI engine there is little known relay called the EEC Relay ( Electronic Engine Control ) this little baby provides power for the computer. If the relay is bad ( bad or high resistance contacts ) the engine won't start or runs and just shuts off whenever it pleases, a real thrill when you are in the middle of an intersection It mostly shows up as an intermitent no start. I have had the one on my truck go bad ( full of water and rust and yes the engine ran with it that way ) and the one on my wifes 93 ford. The relay is located on the drivers side fender pannel in the engine compartment. It is a single relay about 1.5 x 3/4 of an inch sq. It is located near or on the bracket that holds the 3 large wire harnesses from the engine. I believe it is the only seperate relay there. If you find it rap it with a screw driver and see if your engine will start, this might not be the problem but it can't hurt to look.

P.S. the relay is only $15 or so from Ford

stractor

 

The car has new plugs, wires, cap, rotor, fuel filter. TOday tested the relay by swapping in a new one, no change. I do indeed hear the fuel pump click on. I see spark when I pull a plug wire at the plug, and place it against metal. I also see a spark when putting one of the plugs at the end of the spark plug wires outside of the cylinder head. I smell gas, I am at wits end...I even tried starter fluid, no luck!

Could it be a low flowing pump...I bought a pressure tester, but at $40, I might as well buy a new pump and replace it instead since the tester canteven be returned.

Truck is an 88 Bronco EFI 4.9L, and doesnt start any which way now

 

I pulled out and cleaned that relay alredy. No change. I guess I could replace it also. It was not cracked or rusty or anything though

 

Try replacing the distributor. My truck did the same thing, ran outta power and then just died and would only cough. I replaced the module, rotor, cap, and coil and they didn't work. I pulled the distributor and when I got it out, the drive gear fell off the shaft onto my hand. I sheared the pin and it would turn just enough that I'd get spark to the plugs.

 

What part of the relay did you clean?? As I remember it is a sealed relay and you can't get inside to clean the contacts and that is where the trouble will be if the relay has a high resistance contact or a burned contact. You could check the in and out of the relay with a voltmeter with the key on to see if they are the same voltage. It was just a thought as it drove me crazy trying to find the no start problem, with the water inside the relay. I happened to test it by hitting it while the engine was running and the engine idle speeded up, so I replaced it and no more start problems If the ford computer gets less than ten volts it won't work.

stractor

 

I cleaned the contacts, and checked the wiring of the relay. I think I will buy a replacement tomorrow to try. I cant believe it would be the distributor...I mean the car ran only hours before.. I have been thinking of setting the igntion timing from scratch to see if something screwed up here.

Also, I kept priming the fuel pump to see if that mattered, and it didnt. I pressed down the shrader valve on the fuel rail to relieve pressure, and there was only a trickle of fuel...not a burst. Is that significant? I didnt have the engine running prior to this (obviously) so I dont know what kind of pressure should be there. Does this sound like a fuel problem to anyone...and if so, why didnt starter fluid work?

 

You should have 55 or so pounds on the fuel rail fitting with the key on and the pump running. How did you prime the pump ? Isn't yours in the gas tank ? You may or may not have any residual pressure when you turn the key off. If you have good check valves in the fuel pump (s) you will have good pressure at the fitting with the key off but that will bleed down over time (hours) If you have a bad check valve in the pump(s) like I do , you will have little or none. Get yourself a fuel pressure gauge kit at Auto Zone or the like and measure the pressure , They cost only $15 or so. Also pull the dist cap and see if the rotor turns when you crank the engine. Grab the rotor (NOT WHILE CRANKING THE ENGINE) and see if you can turn it The post about the broken dist drive pin is a good one, it is only a 1/8 pin that holds the gear to the dist shaft , shear that pin and the gear will turn but not the dist or the oil pump connected to the lower end of the dist shaft. Shearing that pin could happen at any time.

stractor

 

sometimes its good to do a quick run down of the simple things.

Is the exhaust clogged somehow? Did some stupid furry animal crawl up there?

Is it flowing air in well? Pull off the filter box cover and see if a rabbit jumps out, you never know.


When you push in the shrader on the fuel rail, was that with the key in the "on" position? Try cranking for a few seconds, then hop out and push it in. It should spray, not trickle. If its a trickle, it could be the fuel pump, something messed up with the fuel lines or the filter. Again, something coulda gotten in your gas tank and clogged up that filter.

 

This is where we stand: new fuel filter, new air filter, new breather, new plugs, cap, rotor, wires, O2 sensor, PCV, vaccuum lines. Known good ignition module.

Yesterday:
Tried different fuel relay, and ECU relay, no difference.

Today:
new fuel pump, not sure if the old one is definitely bad, but I have noticed alot more fuel at the shrader now.

Didnt start! Still have spark!Definitely have fuel now, as I pulled my plugs, and each of them were soaked in fuel now. Cleaned them off, still didnt start

Removed distributor. Everything is solid there, no end play, PIP insulation is not cracked or "mushy" Contacts for Module clean, no corrosion, wires solid, no corrosion, Coil had proper 0.5 Ohms across terminals. Re-installed module, cleaned, and re-dielectirc greased it.

Started to find TDC on engine, but it was super cold out, and I didnt have my remote starter with me. For the 4.9L does the crankshaft pulley have a notch that I am using for timing, or should I look for a scribed line in the pulley? I have found both. Also, all I see for timing marks on the engine is way down, and it looks like " 14 10 6..." Is that it, or is it the marks way above the pulley that have "10 8 6 4 TDC?"

Next, I am blowing up the truck. It drove so well before this darn emissions problem!