Hello everyone. Well I started a post on here a while back about fuel problems. Let me give a little history. 1992 F-150 super cab XLT. 302 w/166000 miles. E4OD, 4x4. Got the truck in rough shape. I gave it a complete tune up. New plugs, cap, rotor, wires, oil and filter, air filter, fuel filter, tranny fluid and filter, diff fluid (both axles) and transfer case fluid change. Now it was running not quite right after all of this. I changed the wires 1 at a time, so the wires are in the same firing order. I decide to run the codes to see what I get. Came up with egr position sensor, (which I changed along with a new EGR valve), Engine coolant temp sensor, ( I changed this as well. The one on the intake). I repaired the ERG tube which had broke at some point. New lower intake gasket, and I made sure to hook up the vaccum lines. I did a fuel pressure test on the rail. Got 35psi on rear tank 32 on front. I checked for spark which I got. I got fuel. The engine just cranks and cranks. I even set the firing order 2 ways. Old firing order of: 15426378 and the new firing order of: 13726548. The po said the engine had been replaced so I am not sure of the year of it. I just don't understand how I have fuel, spark and air but it doesn't start. I was hoping that it would be my daily driver for this winter, but right now it's sitting in my driveway. Anyone got any thoughts as to where I should go from this point? I really like this truck, but I'm tired of the aggravation of it not starting.

 

Maybe check the timing?

 

try starting fluid.

 

theres a simple way to look at any gas engine,all it needs to run is gas,fire and compresion. then it all needs to happen at the rite time,so it sound like ya have all 3 bet its a timing problem or fireing order issue

 

Thanks for all the replies everyone. So are the firing orders right? Early and late 302s? I tried them both but it still just cranks and cranks. Gonna check to see if base timing is right. Then what is it set at? 10BTDC?

 

did you try starting fluid?

 

did you use aftermarket plug wires? or Motorcraft ones. I've had bad luck with aftermarket ones

 

As stated try starting fluid, The reason they are saying this is to see if it will ignite when that is sprayed into the throttle body. Have a helper try shooting it in while you are trying to start not alot. I usually give it a good burst and then try to start it, if it acts like its going to start then you have seperate issues. Could be low fuel pressure etc.

I would look into timing, check and make sure the distributor module, usually on the fenderwall is good. Mite be sparking but not all the time, and not the right amount. ALSO.
I have had green corrosion on connections, work on cleaning off, or wiggling the connections between the dstributor and wiring harness, and the connection that goes into the coil. IT is amamzing what can happen when you bump wires, they may look ok, but try checking those connections. I have seen it happen a few times.

 

Take out the plug on #1 cylinder. Turn engine 'till pistons top dead center.
Remove the cap and make sure where the rotor is pointing is under #1 wire / tower. You might have all the wires off by 1 or more positions.
Once you got #1 in the proper place, you can put the rest in the correct order.

 

The FO on the 92 was (IS) 15426378. An aside, but make sure you keep #7 and #8 separated by #5 and #6 wires as long as you can. Otherwise, when you do get it running, it'll run like poopy. Trust me, been there, done that.

Now, have you checked to see if the injectors are firing? Rig up a light bulb to hook up to one of the injector connectors. See if it strobes while you're cranking. If not, they ain't turning on. But, as several said before, try a little starting fluid in the intake. If she cranks but dies again, you have fuel to the rail, but not into the intake ports, which could actually be good news. If the truck is still Speed Density with the original ECM, on a 92 it is bank fired, meaning it actually fires 4 injectors at a time, twice per revolution. The pulse is half what it needs for one revolution. If it looks like the injector harness has been modified, someone may have put a later ECM in with SEFI (sequential), which will fire only once per revolution. Either way, if you don't get a strobe when starting, the injectors aren't firing. This could be a bad ECM, or much simpler, a bad TPS (Throttle Position Sensor). I keep seeing this same problem in here, and keep saying, if the TPS says WOT during start, the injectors WILL NOT fire. Check the TPS voltages. You'll need a sharp probe or straigh pin in the wire. Something I HATE doing, but with the molded connector, I haven't found any other way. I can't remember the colors, so maybe someone else can chime in with that. Turn on the ignition and one wire to common (ground) should have about 0.6 V on it with the throttle at rest (throttle position signal). Another should have right at 5 V on it (source voltage). The third will be ground or signal common. If the ground on the TPS breaks, or the TPS breaks inside mechanically at WOT, full voltage will be applied to the wiper, and simulate WOT. The only drawback to the TPS is that the throttle body has to come off to repair/replace it. Good time to clean the EGR and the backs of the throttle plates.

As for the sensor you replaced down on the manifold, it had one wire, right? That was just the temperature sensor for the gauge. The ECT is up on the coolant tree where the heater supply hose leaves, and has a two wire connector on it. Signal common is also at that connector, and may be the better place to connect one lead of your meter to prevent shorting out the ECM's sensor source voltage and damaging the ECM. I too have a '92, and have come to know it intimately. Your gauge will work nicely, but you haven't fixed the ECT yet (if it's actually broken). A failed ECT won't stop the truck from cranking. It WILL crank, albeit run very rich in 'limp mode', and probably smoke black.

Whatever you do, do NOT take it to a stealership for a 'tune-up'. I have learned that most stealerships don't even have the equipment for OBD-I diagnostics any more, and all you have to work on your vehicle are kids that know words like Nintendo, Atari, Sony, but wouldn't know a spark plug if it bit them on the a$$. Real mechanics don't work for dealers.

 

It could also be the TFI module on the fender. If it's not telling the computer that the coil is firing it won't pulse the injectors.

 

Ok, sorry for the late reply. Gotta plumbing nitemare in the kitchen to fix and work on top of that. Ok, I tried the starting fluid. Nothing. Just cranks. I pulled the #1 plug to check the timing. It's dead on. The plug was wet and smeeled like fuel, but I'll try the bulb in the injtector harness to see if I get a stobe. As far as I know, nothing was modified on the engine. It was just a direct swap with another truck. I remember though the other night when I was checking for spark from the coil to the plug, It was a fat orange/blue spark. More orange than blue. I know on my '77 it's nice and blue. And yes, it was the guage sensor I replaced. Duh, I shoulda known better. I'll check the injectors and the TPS voltage tonight and report back. Is the ECM the computer by the way? Someone else mentioned that in another post. Wierd if it turns out that way. Good one day, bad the next.


Update: Ok, I checked the injectors ( 1 per side) and I gotta stobe on both. So, I think the injectors are firing. OK, the TPS. Not sure if I did the test right but here's what I got: on the harness side Brown/White wire 5.04v White/Red 0.03v White/? 0.02v. On the Sensor side: Red 5.04v Green 0.03v Black 0.00v. I pushed my lead into the back of the connector and moved the throttle by hand to see if I had any voltage changes. I didn't. So, is the TPS bad or the ECM (computer?)?

 

if no start with starting fluid than you have no spark.

 

The green wire should have around .6 to .9 volts. Sounds like it may be shot, or just misadjusted. Next test on the TPS, with your meter connected to the green wire on the sensor side, ignition on (no start), move the throttle from idle to WOT, and see if the voltage increases smoothly from base voltage to 5 volts at WOT. Analog meters work better for this to see if the pot (position sensing potentiometer) is "noisy" or erratic. If erratic, replace it. If the voltage doesn't change, make sure the connector pins are clean, especially the one the black wire on the sensor side connects through. If it cannot pass current back on the black wire, the wiper (green wire) will normally float up to the source voltage (red wire, 5 volts) and indicate WOT to the ECM (Engin Control Module, computer, yes). With the wiper voltage that low, it may not be feeding enough fuel for idle. Something sounds amiss with the TPS, but that may not be all of your problem.

One of these days, I'm gonna measure the actual resistance of the TPS at idle and WOT positions and post that info. I did it when I replaced mine, but didn't write down the data, so I won't hazard a guess. I'm getting old and have CRS (Can't Remember S***)

 

It ran before you did the tuneup? Did you remove the distributor? Maybe you didn't install it correct timing wise?