I have owned this truck for about 2 years, it has 112,000 miles on it, it recently has been hard to start when the engine is cold, i would crank it over for a minute at a time, then it might start the 2nd or 3rd try, and sometimes, no start, then let I would let it sit for a hour or so then come back out and it would fire right up like nothing ever happened, then some times it would fire first try right from the beginning. Now it wont start at all, I have replaced all spark plugs with new ones, made sure the Gap was correct, .44 thou.
replaced control module on drivers fender, replaced fuel pump relay and ECC relay, I am getting power to the coil, and seem to be getting power at the plugs, maybe its just me but it possibly looked weak, it has dual tanks and I did try switching tanks to see if one of the fuel pumps where bad.
Dont know what else to try? Any help would be great

 

You should have a good blue spark if you ground a plug and crank the engine, but usually an engine will run on less than optimal spark, just not as well.
Did you replace the rotor when you did the plugs? It might cause a no start conditon and even if not the cause of the problem, should really be part of a general tune up.
Without some test equipment we are kind of shooting in the dark here, but there are a couple of things you can try.

If you cycle the key on and off several times and then try to start it does it start or fire?

Is there pressure at the rail? After cycling the key if you press the schrader valve (looks like a bicycle tire air valve) it should spray fuel out fairly strongly.

Have you tried taking off the air cleaner, holding the throttle open and spraying some starting fluid into the intake, and then trying to start it normally?

I don't know if you have experience with starting fluid, but a large towel is handy to smother the odd flames that don't get pulled into the intake on occassion. Having a fire extinguisher around is never a bad idea either. I've never needed one, but wouldn't want somebody to burn down their truck following my suggestions.

If the engine starts, or tries to with the starting fluid then you most likely have a fueling issue.

If you can get somebody to turn the key for you, you can put a funnel in the tank filler and hear the pump run. It should run for a second or two when the key is first turned to prime the system and then stop. The pump should run constantly while cranking or when the engine is running.

If the pumps are running like they should then I would check the fuel filter next. If you look at the fuel that comes out of the filter you can often see dirt in it, and if you let some sit on your hand you can sometimes see water puddling as well. If the filter is good you should be able to blow through it with no restrictions after dumping the fuel out.
I would replace it while you have it out as part of your tune up, but if its blocked or partially blocked there is a good chance it is your problem, or part of it.

If the pumps don't run, then the cause of that will have to be found and corrected.

If the starting fluid didn't make any difference, then another path will have to be followed as well.

Just let us know and we can go from there.

 

Hey, Thanks for the response
I have not checked the schrader valve yet, good Idea, Cycling the key once or several times doesnt seem to have any affect,
I also did not replace the cap and rotor, It looked to have been replaced somewhat recently before i bought it, and I have only put about 2,000 miles on it in the two years I have owned it, but I did inspect both of them, and they looked good to me, I also took a little emery cloth to the contact points of the rotor just incase there might have been some corrosion on it from not getting drove alot. I currently have my battery on the charger tonight so I can start trouble shooting tomorrow with full juice. I bought a can of starting fluid and will also check to see if Im getting fuel pressure at the rail.
Im also going to recheck my spark tomorrow with a spare plug grounded out versus just pulling the coil wire off the cap and trying to watch the spark jump.

I will give updates after I try these things.
Thanks again for the help

Also I was reading something about a no start situation that ties in with your Check Engine light not lighting up when you first turn the key on. Mine does not light up, but I cant remember if it ever did? the bulb might have been burnt out already.

 

Do you hear the fuel pumps run for one second each time you turn on the key?

You can also rent a NOID light from an auto parts store and plug it into one of the fuel injector plugs and then crank the engine. This will tell you if you are getting power to the injectors and a grounds from the computer.

You may have a bad computer or you may be missing power and grounds to the computer.

 

Okay, so I put my Battery back in with a full charge. I also bought and installed a new Neg. battery cable because the one that was in there was fully maxed out tightened around the the terminal and when I went to spread it back out with a screw driver, so I could re tighten it, it cracked. Both the small and large neg. cables are properly attached to the vehicle as they are suppose to be.
Then I pulled one of the intake pipes off the throttle body and while squirting starting fluid in, had someone turning the ignition over and it started for a second, so I ruled out a spark issue, next i checked the schrader valve on the fuel rail for pressure, switching back and fourth between the front and rear tank, cycling the key multiple times and trying to start the truck and found no pressure, I also took the fuel caps off and stuck a funnel down the fuel spouts while cycling the key, starting at the full OFF position and heard nothing from the pumps.
Once again I have switched out the fuel pump relay already, and I seriously doubt both pumps took a "S H # T" at once, so what else could it be keeping my pumps from pumping fuel? I'm lost.

Thanks again for all the help so far.

 

Ground pin #6 of the self-test plug and turn on the key.
Do the pumps run all the time the key is on?
If they do not run now have you reset the fuel shut-off switch?



/

 

The next step would be to ground the #6 pin on the self test plug. Just jumper it to pin #2 on the same plug.

There are several posts about this on these forums, but here is a photo on another site that should help you locate the plug and identify the terminals you need.

Fuel Injection Technical Library » How To Run a Self-Test

The plug is under your hood on the drivers side inner fender. It may have a cap on it labeled eec self test. Number 6 is the bottom on the right side, and number 2 is the top on the right side if you are looking at the plug with the flat side down and the angled side up like it is shown in the first photo.

Just connect them with a short jumper wire and turn the key on and see if the pumps run. If they do you can start the truck most likely. I drove mine jumpered like that for a few days one time.

If the pumps run then you most likely have a computer problem, but possibly a wiring/connection issue.

Its fairly easy to pull the computer out and have a look inside it. There are capacitors in there that sometimes burst and cause various problems.

Anyway, see if the pumps run when jumped and we can take the next step, or if you are in a hurry you can read lots about the issue on this forum.

 

Subford is better at this than I am - has his own photos too

 

I would suggest grounding pin #6 to a good ground (NEG post of battery) first.
If they run with the key on then remove the ground and short pin #6 to pin #2 and turn on the key.
If they do not run now (2-6) and they ran with the ground wire to a good ground and pin #6 then you have a wiring ground problem.

 

Thanks everyone, Ill try that and get back to you guys. Also, where is Fuel cutoff reset button, and where is the computer located that runs the fuel injection and pumps?

 

Fuel pump inertia switch is on the inside firewall on the drivers side, easy to find.

Its also easy enough to check, but if your pumps run with #6 grounded then you know that the inertia switch, relay, and associated wiring are all good.

I initially had a longer post on my earlier reply about jumping the test terminal, but when I submitted it there was a problem and it was lost. So, my reply was shorter the next time.

Subford already covered the difference between a straight ground and using the signal return circuit as a ground. The signal return circuit can be thought of as an internal ground in the computer.

I wouldn't pull the computer until you have checked to see if the pumps will run with pins 2 & 6 jumped. If they do, then I would pull it for a look.

If the pumps don't run when jumpered then you have a ground/power issue.

The computer is under the driverside kick panel. Just pop it off, one of those plastic push in things roughly in the middle of the panel and then push it upwards to release the slide pins and it pulls out. I don't remember if you have to take the plastic threshold piece off first or not. Both my pieces are off and in the rear tool box waiting on some rocker repair.

There is one bolt with a small bracket holding the computer in, but before you remove that I would go out under the hood and remove the connector there first. It may have a plastic shield on it, just pop the shield off and you will find a bolt, keep loosening the bolt until you can pull the connector straight out easily.

This is a good time to inspect the sockets in the plug to make sure none of them have worked their way backwards.

Then just go back inside the cab, pull the bolt/bracket and the computer will come out. Might have to wiggle it a bit because there is a seal where it goes through the firewall.

There are a few small screws holding the cover on the computer, take them out and pull the cover off and inspect the components on the circuit board. The capacitiors are known to burst and leak.

If you or somebody you know are handy with electronics it is possible to repair the computer if the damage isn't too bad. Otherwise you can get a replacement at most parts stores, Advance, Autozone, etc....

 

The inertia switch on my 95 5.0 is under the passenger side kick panel.

merhlin

 

Okay, so I ran a jumper wire between pin 2 and pin 6 on the test plug and it fired right up, ran for 2 minutes flawlessly, then died as quickly as it started. I rechecked the connections at the plug and also rechecked the wire itself to make sure it didnt have any defects, and tried again, No start, the front tank that I am currently running off of has just under 3/4 of a tank and the rear has just under 1/2, so then then I unpluged the jumper wire from pin 2 and and jumped pin 6 to the Neg side of the batt. and tried again, no start.
How depressing, I thought I was so close to figuring out what I needed to replace to make this truck run.
Its not my primary vehicle, or even my primary truck, but I like to have all my vehicles turn key ready if the time arrives, Know what I mean?
Also, when you guys are referring the the Kick panel, are you talking about the panels on the underside of the dash or the ones in front of the doors by the floor?
Once again, Thanks alot for all the help so far!

 

I understand what you mean about having all your vehicles functional. My truck isn't my main vehicle either but I keep it running or within a couple of hours of running just in case.

Kick panels are the ones on the side in front of the doors on both the passenger and driver side.

There is a very good chance the computer is still the problem. They do odd things when they go bad. Sometimes they run the pumps all the time, sometimes they don't run the pumps at all, sometimes the pumps work fine but the injectors won't fire.

Mostly we wanted to see if the pumps would run when jumpered, the truck running can be looked at as a kind of bonus.

When the capacitors burst they can leak onto the circuit board and eat into whatever tracings or components the fluid touches.

It is possible for the computer to be damaged in such a way that it wouldn't run the pumps, and when the pumps were jumpered it ran the truck for a couple of minutes and then another circuit already weakened was broken by the higher current generated.

Its also possible for there to be a problem with the pump system that forcing the pumps to run by jumpering them caused the problem area to fail. If this happened, it also caused the problem to show itself and can now be found easily, be it a ground or a worn pump, switch, wiring, or relay. But if one of these are the case, then the pumps won't run when jumped right now.

So, long story short, do the pumps still run even though the truck doesn't?

 

No, I can not hear the pump running. I was thinking about going down to the local Pick N Pull and seeing if I could find a computer, Thats not what I am going to permanently go with but for a fraction of the cost of a new one I can do some trouble shooting, and even return the part if not needed for yard credit without hassle.
Im wandering what years might have the same computers and also does it have to come out of a 7.5L or would a 5.8 or even a 5.0 work?
Does the donor truck need to have dual tanks also? because that would rule out vans as a possibility.