Hello all,
I work at a repair shop in southern Kentucky.
I was just put on a project we have.
1989 Ford F-150 with 351 dual tank and automatic.
it has a jasper engine.
originally it idled at 4000 rpm and died.
we have replaced distributor, IAC, cap-rotor, plugs and wires.
had the computer refurbished locally and flashed.
NOW, it won't start just cranks.
I have good spark at coil, and coming out of distributor.
we get 35-40 psi of fuel pressure.
if I continuously crank, all I can manage to get is one small backfire.
it also will not fire up with spraying in the intake to start, so I know its not a fuel issue. I have already installed the disty correctly and confirmed correct running of plug wires.
BUT heres the thing.
I have fuel and its VERY strong, I am thinking... that the issue is not enough air and or spark to go with the large amount of fuel being dumped.
I have not been able to locate, but does the truck of a crank sensor or anything along those lines ? or anything anyone can think of as to WHY I have everything I need to run, but not a running truck ?

thanks for any help.
sorry its such a long post... but I wanted to give all the information I could.

 

The engine uses the distributor as the crank position sensor you are asking about. The 351w firing order hasnt changed unless a 302 cam is in place. The coil can go bad on the truck as that seems the last thing yet to replace, if the wires are not run to the cylinder that is suppose to be firing then you will have no fire at the cylinder. Best thing to do is to set the dizzy at number 1 and confirm that the number 1 cylinder is at TDC and go counter clockwise on the cap through the firing order confirming that the cylinder has the right wire to it. Also remember that number 1 is the passenger front then back to cylinder 4 on the back of that bank, then number 5 is driver's side front back to 8 on that bank.

 

Have you Checked the timing?

 

Yes, I set the timing today.
module on disty and rotor are new. engine is a Jasper rebuilt, with about 25k on it.
disty cap is new. plugs are new, wires are new, IAC (idle air control) is new
battery is new, starter solenoid is new.
fuel pressure is 35-38 PSI, but does not start even with spraying fuel into intake.
computer was sent out-refurbished and updated.

This truck has been at the shop for a month.
they stuck me on it, after everyone else has torn it apart and put it back together again several times.

the only thing I have not checked, is pulling the fuel rail, and seeing if all the injectors are squirting.

it REEKS of gas under the hood after trying to start, and MOST of the plugs are dripping with it.

compression is 125 on all cyls.

 

Try another set of plugs in it. From your description it sounds like they are fouled, if you're positive you are getting spark to them.

This is just a guess, but say the original problem was a spark problem. With all the new parts installed it was solved. But in the process the plugs were fouled beyond being able to fire.

I've run across a couple cars at the shop I work that had me troubleshooting for hours. All it ended up being was fouled spark plugs.

 

compression seems slightly low to me, maybe the fuel and continuous cranking has washed the cylinder walls. Try squirting a small amount of ATF in each spark plug hole and let it sit for a couple of hours before trying to start again.

 

I thought it was a little low myself, my probe sits at 225 psi across both banks dead nuts even.
but this doesn't even TRY to hit. If I crank for an extended period of time, I'll get a backfire when I stop.
I am kind of drawn to the computer, they sent it out... had it flashed and whatnot, how am I supposed to know if its any good. I am wanting to get one from a junkyard and try it.
I've heard 351 computers from that age have.... issues.
looking at the plugs, they don't look that bad.
if they were fouled or comp was too low... it would still, catch a little bit... this is just free cranking.

one other thing, the starter solenoid on the fender... has 4 ports for plug ins, only 3 are being used... it feels wrong to have the port labeled I blank.

 

That must be an old style starter solenoid set up for a different ignition system. It won't hurt a thing not having that extra terminal hooked up to something. Have you tried to pull the codes from the computer? A lot of times that can give you an idea of the computer's health.

When you crank the engine, does it sound like it has compression, or does it sound like it's just free wheeling? I would try the ATF just to see if it makes a difference. You know you have fuel, you know you have spark (although it might not be at the right time), the only thing left is compression.

 

Pull the vac line to regulator & see if it is full of gas first.

 

I don't know what they did to the computer, but the EEC processor from this era is not "flashable".. it's doesn't even have flash memory, so unless they replaced it with another it's probably toast.

 

Here's my two cents. Sounds like the injectors are being fired by the computer as you seem to have lots of gas in the cylinder, so gas not a problem. Unless you have a rag in the intake some where there should be enough air to at least get it some kind of ignition. Air is almost never a problem for starting an engine. Last, spark. If you pull a couple of plugs one at a time and crank the engine with the wire on it you should see it spark. You will have to ground the plug against the engine or body. If you have all three, then the problem is down to two things. If compression is bad enough it won't fire. I have no idea what the compression would be to make that happen, but I'm not buying that's the problem. Do you know when the last time this truck ran? My guess is that if you have spark and fuel, then the timing is off. If the timing is off enough and or the spark plug wires are incorrectly wired it won't fire, not a bit. I have seen this problem posted in here before where the engine would crank and crank and just nothing. They got the timing right and it ran just fine. The timing doesn't have to be off much for the engine to not start.

Conasnski does make a good point in that you can't flash that computer, so I have no idea what's going on there. But, ignore that for the moment and look at the basic components you need for combustion. Air, Spark & Fuel. If you have all three, the computer is doing enough to at least get the darn thing to fire up.

 

Codes?

My friend's Crown Vic with a 302 had many of the same symptoms, and I could almost get it to run by pulling off the air filter and tube so that I could place a piece of cardboard over the throttle body and control the air intake myself. It turned out it was the MAP sensor was bad. Replaced that and good to go.

Jason

 

I'm not saying that's for certain the problem, but it won't hurt anything to try the ATF trick to get enough for it to fire. I've had first hand experience with this same type of problem and that fixed it. Crank all day, with plenty of fuel and plenty of air. I'm pretty sure the compression we tested was lower than what was tested in the truck here, but if every other idea has been exhausted, trying it isn't necessarily a bad idea.

Another thing to try is to crank it with the throttle held wide open. The computer shuts off the fuel injectors cranking at WOT to clear a flooded engine.

 

I beleive it would be in the spark. if you have that much fuel and the plugs are soaked in it then your not getting spark and correct me if im wrong but arent you supposed to have the engine at operating temp. to get an accurate reading with the compression check. I dont beleive compression is the issue. Im with conanski I believe the computer may have an issue...(although my 87 f250 ran with a eec out of a ford sable for a while). you may have to much fuel although those nubmers sound right for pressure. what kinda shape are the injectors in again maybe the eec has them all wide open Im leanin on the eec dude.

 

the atf trick or use oil instead of atf would be a good idea to try. take the plugs out and put about a teaspoon full in each cylinder. this is called "pickling" the engine and just might seal the rings and raise the compression enough for it to start if everything else checks out. I had an old ford truck I had to do this to if I left it sit to long without starting it.