1986 5.0 Rebuilt, have spark and fuel pressure, no start

[homer302]

Not reading all the posts because as well all know, all it needs is air, fuel and spark. Let's think a minute, your car won't run on its own. BUT if you manually add fuel to it (Ether) then it runs. I believe we have solved your mystery. You are missing fuel for some reason because when you add fuel it runs. It doesn't seem that complicated but like I said I did not read every post.
So, what is fuel related that can stop an engine from starting? low pressure for sure, bad injectors but it would have to be more than 2 bad, probably be 3 or 4 to keep it from even starting. A V8 will run on 6 cylinders for sure, maybe 5. It will start at least. Clogged filter/line maybe? I do not know the root cause but you figured out what the problem is already. How are you adding the Ether? is the intake tube unhooked and you are shooting it in the throttle body?
Again, can't be a ground because it RUNS when you add fuel. Either the fuel is not making it where it needs to be or the computer is turning the fuel down/off for some reason.

[homer302]

How did you check for spark? Are the plugs wet with fuel?

I don't know the answer to your specific question but I know it has to have spark somehow because he continues to say it runs on Ether. If that is true, (and I can't say it is but he says it is) if the plugs, TFI or coil were bad all the Ether on the planet would not make it run. I am not sure why any of those were replaced. If it will sit there and continue to run so long as someone shoots a spray of Ether in it and it never shuts off this a fuel delivery issue. It could be a fuel sensor that is reading incorrectly and believes there is no pressure even when there is but you should only concentrate on sensors for the fuel system. Is the inertia sensor hooked up? I know you said it would run when you sprayed Ether but has this car EVER run in your possession or did you buy it like this?

[jdrtexas]

I first checked with a timing light on 4 different plug wires. Then I pulled one spark plug and grounded it and got a good spark. The plugs are not wet with fuel.

[jdrtexas]

I'm right with you. Next I'm going to pull the return fuel rail line and make sure the fuel is cycling through the rail. I can't believe all the injectors are bad. I did clean them all back in December in an ultrasonic cleaner and then carefully replaced the pintle caps and o-rings.

If that doesn't work, I have a new Motorcraft MAP sensor coming in Friday and will give that a shot. Not sure I understand how a MAP sensor would prevent it from running or least trying to run, since ether will allow it to fire up...?

[jdrtexas]

Sorry, forgot to answer how I get the ether in, the intake is off and I'm shooting it directly into the throttle body.

[homer302]

Did this car ever start and run right since you owned it?

[erratic50]

Absolutely, yes. Just my experience.

[jdrtexas]

No, the car has never run since I've had it. When I bought it I was told the fuel pump was bad, but it did run on ether. The long story short, went to replace the fuel pump, pulled the tank and decided since it was a SSP, to pull the axle just to check, found issues with the ring gear and here we are today, completely rebuilt axle, transmission and engine. Bought this in November of 2017, so I never got the opportunity to actually drive the car.

[Haystack]

The pip uses the tfi module to tell the computer when to fire injectors. You can in fact have good fuel pressure but have it not run as long as either of those (or a wiring issue) is bad.

Thats why I linked to the no start trouble shooting guide. It tells you every wire and sensor you need to run and how to check it quick and easy.

[jessesandy]

Did you test the injectors after rebuilding them ?
Sounds like there is pressure up to the injectors and no error codes. (?)

Rig up a tube to squirt carb cleaner into the injector and some wires to a battery. Just power on a second at a time and look for a nice spray pattern.

BTW, that is an Acura injector.
!!! Someone please comment if Ford injectors are not happy being clicked on for a second directly from the battery.

[Haystack]

I still don't see how pulling the upper intake to pull out the injectors to hook it up to an external battery source is better than just seeing if the injectors work in the car with a test light it really is a five-minute thing

[KevinVarnes]

I still don't see how pulling the upper intake to pull out the injectors to hook it up to an external battery source is better than just seeing if the injectors work in the car with a test light it really is a five-minute thing

He did say he checked #1 and #5 and he was getting a signal to fire at both injectors. I guess the question is, assuming the injectors are getting the properly timed signal to fire are they actually spraying fuel?

[jdrtexas]

Yes, injectors #1 and #5 are getting signal to fire, can't say if gas is getting sprayed. From looking at what a MAP sensor does, it certainly appears that a bad MAP sensor can cause the computer to send a signal to the injectors not to spray fuel.

Useful write-up on Ford MAP sensor:
http://troubleshootmyvehicle.com/for...e-map-sensor-1

[jdrtexas]

So the saga continues....I also have a 1991 LX 5.0, I swapped the BAP sensor from the 91 onto the 86. Still no start. I then put the MAP sensor from the 86 onto the 91 and the 91 fired right up and idled no problem. Still no codes on the scanner. So the MAP sensor isn't the issue. Starting to think either some unexpected obstruction in the fuel rail or its time for a set of injectors.

Also, the new distributor would "sway" slightly front to back when the engine turned over....very weird. So I put the original distributor in and it didn't move a bit when the engine turned over. I then checked the injector harness again with a light and the injectors are getting signal, so the original distributor shouldn't be the problem....

[Haystack]

Sorry I missed the post talking about injectors. I find it pretty unlikely that Ali fuel injectors failed at the same time when I was 16 I was doing an engine cylinder balance test and I randomly unplugged injectors and I managed to get the car to run on only two working injectors my opinion is now you need to see what kind of fuel pressure just getting out of the pump you can buy a cheap crappy Harbor Freight fuel pressure tester for about $15 what I do is I unplug the filter and hook the rubber hose straight to the filter with a hose clamp it should be somewhere in the 60 to 80 psi range I have had cars run as low as 40 PSI anything lower than that the fuel pressure regulator won't be working properly

[jdrtexas]

I will swing by HF and pick one up and check the pressure at the filter. I am getting 38 pounds at the rail and will pull the return line just to make sure the fuel is cycling through the rail.

Thanks

[Haystack]

Actually, if you have 38 psi at the fuel rail, that should be plenty to run. I remember I did have a cruddy airtek parts store pump that only put out 27 psi. It was enough to start the car, but bogged baddly when you tried to drive it.

I think next is to verify spark and the coil. Since you got the fuel pressure and codes, you can pretty much rule all of that stuff out.

Sometimes a weak spark will run on starting fluid but not gas.

Not trying to be mean, but this is really starting to get interesting.

[jdrtexas]

I'm not insulted in the least, I appreciate the feedback and advice! I'm rapidly tapping out on ideas!

I think I have good spark, I confirmed spark on the wires using a timing light and then pulled a spark plug and grounded it and saw a good strong spark. When I pulled the spark plug, it was dry and didn't have a smell of gas. I also replaced the coil, just to eliminate that possibility.

[erratic50]

Just for informational purposes I’ll comment on the question about the map. The map sensor is critical for fuel map calculations — literally the fuel required for an engine to run!

if it malfunctions then fuel delivery fails to be at a level that will produce a running motor.

If the other car runs with the map then it is a known good one.

My next instinct is the rotor inside of the distributor and the coil wire. Mainly because I’ve had both of those fail and cause no code no start issue also. Just following my nose on this one — there is a no start thread that is great!

[jessesandy]

Spring for the $19.99 fuel pressure test kit. The brass fittings and high pressure hoses and metal adapter fittings/hose clamps make it safe to leave it connected as long as you need to and monitor that variable at all times.

Curious for more details on the ether. Does it just fire up, race real fast and then die out ? Did you say you could keep it going for some time ?
And, just trying to start normal it just cranks with zero signs of trying to start ?

[Haystack]

I did this same thing, almost in the same order with my dads e-250 460 van.

I basically decided it had to be spark related, yet it passed all the tests. I decided to make sure all the spark plug wires were fully seated, when I pushed down on the coil wire, it fell out of the boot and was obviously corroded really badly for a long time.

I think we are getting back down to basics...

You haven't seen the car run, except for on starting fluid. No codes, but getting the all okay from the computer. Not a bad map sensor, but you are getting both 38psi at the rail (within spec) and injector lights, meaning both the pip and dizzy are at least getting a signal.

I think we are either to a compression issue (unlikely, but possible) or a bunch if bad fuel injectors.

One thing that could possible still point to a bad tfi/pip, if you can get it to run on starting fluid and watch the injector pulses, it might show an intermittent function in pulsing. Where you had another gt to test the map on, am I correct in assuming you could pull the dizzy as well? A simple swap of the dizzy could prove or disprove a functioning part with 5 mins worth of work.

Basically, the pip is a hall effax (sp?) Sensor. It reads pulses with a magnet. These pulses are caused by the gaps as the rotor spins around. The number one cylinder is bigger or smaller (I forget which) and signifies number 1 as well as when to fire injectors and the speed the engine is running as the computer sees it.

Lets say it is only picking up that signal intermittently, it may think the engine is spinning much slower. This would sorta unsync the injectors.

You would think that a random correct timing would still fire, but what do I know. It would explain good fuel pressure, functional injectors and a lack of codes, with good spark, and should be pretty quick and easy to figure out if you can swap parts between the cars.

[erratic50]

What about the old “timing is off a cog or two so I moved the wires a notch” BS shade tree mechanics sometimes do. If it was that way to begin with would you notice when you put it back that way?

Put the engine at TDC. Pull the cap. The rotor should point directly to the firewall (#1) or if you are 180 degrees off it will point directly forward (#6). If it doesn’t, pull the dizzy and fix it.

Check your timing with a timing light while cranking it. It will run anywhere between about 20 degreees btdc and 15 degreed atdc although it will run best at 10 degrees btdc to 14 degrees btdc.

An HO motor follows a 351W style firing order. Make sure it’s all correct

The other thing - if you’re turning the key on and off a lot and it’s priming the pump you could be flooding the motor. Pull the plugs and verify gap. Crank the motor without plugs in it with the fuel pump unplugged so any excess fuel is pushed out of each plug hole.

Hold the throttle at WOT and pressure test each cylinder. If there aren’t over 100 treat with Seafoam directly down the plug hole overnight and retest.

good luck!

[jdrtexas]

OK, great info guys, let me make sure I give useable answers...

The engine was completely rebuilt (I did the rebuild and only used either Ford parts or quality aftermarket, no China junk). New Ford Spark Plug wires, new coil and the engine will run on ether, so I don't think it is a spark issue.

Yes, the engine will run as long as you spray ether in, once I try to crank it on gas, the engine just turns over, doesn't even try to fire.

When I put the original dizzy back in, I left the original TFI on, still same situation. I then put on a new Motorcraft TFI, no change.

I've checked the timing, pulled #1 plug, turned over to compression, the rotor was pointing to the #1 tower on the cap and I was damn near right on TDC on the marker (you know how it goes turning the motor over trying to hit the compression stroke). So I think my timing is in the ballpark.

Also, when I pulled #1 plug, the plug was dry and didn't smell like gas.

When I'm turning the engine over, I have a big shop battery charger attached helping the battery with all the engine turn overs.

Thanks guys, I really appreciate the group effort on this!

[erratic50]

All roads lead to fuel. Check voltage at the injector. Check ECU ground.

On a hunch - extend the ground lead on the motor down to the K member with a 2nd lead and bolt it down. I say this because the grounding straps go bad. Remove the fender mount ECU ground, unbundle the 4 wore in 1 wire out mess, solder in a sizeable wire (around 8 gauge) wire from the bundle to the battery. Add a loop connector to the end and use a nut to sandwich the loop between the negative post nut and a this new 2nd nut.

Double check your ECU relay and your ignition switch.

Verify your fusible links are intact and passing power properly.

[jdrtexas]

OK, pulled the return line today and confirmed there is good flow back to the tank. Bought a better fuel pressure gauge and the pressure at the rail is 41 pounds.

I also checked the TPS and it was .84 volts. Could the low TPS voltage somehow cause the injectors not to fire? The noid light confirmed signal, but don't know if the computer could reduce the signal to injectors??

I found a set of NOS injectors and bought them. They should be in later this week.

I pulled the upper intake and pulled a couple of injectors. There is plenty of fuel on the top of the injectors, but doesn't look like there was any fuel in the pintle cap area. And it looks like I forgot to cap the vacuum port on the back side of the upper take that connects the same port that goes from the front of the upper intake and connects to the charcoal canister on the passenger side of the engine compartment. I don't think that would cause the problem...but anything is possible at this point!