Bonco II intermitenly won't start PLEASE HELP!!!

[orion96]

Any suggestions would Rock

'88 Bonco II. This thing will RANDOMLY not start. Engine is crankin, it just won't turn over. It kinda sounds like you ran out of gas, but the tank is full. It will go fine for a week*, but then nothing. It doesn't seem to matter if it's a cold start or if I've been driving all day. When it does this, the best solution I can find, seems to be to just let it sit there for at least a couple of hours and sooner or later it'll turn.

Don't think it's the starter, 'cause the engine is actually getting spark and turning, plus I don't here that clicking sound. I'm just above neadrethal on the auto repair stuff, but it seems like a fuel problem. diaphragm, pump, ??? Sombody else suggested a modulator (?) or sensors(?), air filter?.

I've been to 3 different mechanics and they all say that they need to look at it when it's not starting. Trouble is that this the problem is totally random. By the time I have the thing towed there and they get to looking at it, it starts again. : (

[Truck]

My first suggestion would be to watch where you're going. She may not like your routine! (My 88 was terrible about deciding not to go home.)

Check the Dist. Module? (Also, a general computer check would be good.) My 88 finally gave up the ghost about 45 miles away from where we were moving that day! I replaced both and she's started fine since. (For most applications, the original MotorCraft would be the best choice for a replacement.)

[CraigRK]

Orion

I am not much above Neanderthal myself when it comes to this stuff, but here's a couple of thoughts which may or may not be relevant to your problem . . .

No 'clicking' when you turn the ignition on and no starting (but engine turning over & spark) suggests that the fuel pump, probably the high pressure pump, is intermittently not coming on to charge the fuel manifold. The problem could be as simple as a plugged fuel filter (pressure in the line still), the pressure sensing unit (the unit itself malfunctioning or just a bad/intermittent connection) or the fuel pump itself (again the pump itself or a bad/intermittent connection). I'd replace the fuel filter first (cheapest), and you may want to cut it open to see if it is plugged. If that doesn't work, try replacing the fuel pressure sensor then the high pressure fuel pump.

[orion96]

Thanks,
I'll give it a shot

[orion96]

Hey Craig,

The Bonco II finally got to the point that it would die any time it was put into idle. Changed out the fuel filter and for some reason the thing was purring like a kitten for a week. Problem solved? Apparently not. This afternoon...same thing. Checked the fuel pressure when I did the filter and it was approximatly 38 psi, which is what I believe it should be (of course this was after it had decided to start running again). The relay is also working fine. ???

Would a fuel pump just intermidently not work? Don't know if this sais anything about the pressure sensor, but the low fuel light has started to come on every now and then, even though the tank is full.

Any further help would be gratefully appreciated

Thanks, Rion

Originally Posted by CraigRK

Orion

I am not much above Neanderthal myself when it comes to this stuff, but here's a couple of thoughts which may or may not be relevant to your problem . . .

No 'clicking' when you turn the ignition on and no starting (but engine turning over & spark) suggests that the fuel pump, probably the high pressure pump, is intermittently not coming on to charge the fuel manifold. The problem could be as simple as a plugged fuel filter (pressure in the line still), the pressure sensing unit (the unit itself malfunctioning or just a bad/intermittent connection) or the fuel pump itself (again the pump itself or a bad/intermittent connection). I'd replace the fuel filter first (cheapest), and you may want to cut it open to see if it is plugged. If that doesn't work, try replacing the fuel pressure sensor then the high pressure fuel pump.

[CraigRK]

Hi Rion

I just got the email showing you still have a problem. (The email account that I have this site is linked to really sucks.)

The bad news is you still have the problem, but the good news is that you can be pretty sure you are dealing with a fuel system issue.

These are just some thoughts . . .

Here's one possibility I've heard of: Your gas tank is very rusted/corroded inside and is full of rust fines. The fuel filter plugs up quickly, preventing proper flow & pressure. Replacing the filter helped, until it became plugged again - far quicker than is normal. This is why I mentioned cutting open your last filter, to see if it was full if metal/rust fines. (Solution is to replace the fuel tank.)

Here's another: Your high pressure fuel pump is worn. It delivers the proper pressure only with a very fresh filter.

And similarily: Your low pressure fuel pump (inside the tank) is worn. It delivers the proper pressure only with a very fresh filter.

Another: The fuel pressure unit (on the fuel manifold) is malfunctioning.

And one more (probably not this): The lines running to your injectors have particulates in them, which may have been temporarily freed or displaced when you changed the fuel filter (backwash of fuel), but are now getting packed up against the injectors again.

As for the fuel level sensor, I think these are just badly designed units, as mine goes down, jumps back up etc.. Or the sensor could be having problems related to fines in the fuel tank.

Hang in there!

CraigRK

[Broncokid]

hey you might want to check your flywheel and replace it

[$BUCK$]

I HAD A SIMILAR PROBLEM WITH MY 88 BRONC RUNNING ALONG JUST FINE THEN WOULD QUIT WHILE DRIVING AND NOT START BUT WHEN IT WANTED TO. :cry AFTER READING OTHERS POSTS AND SEEING THEY HAD REPLACED FILTERS AND PUMPS TO NO AVAIL, :shrug I THOUGHT THE INERTIA SWITCH MIGHT BE DEFECTIVE. I FOUND THE INERTIA SWITCH ON THE PASSENGER SIDE FLOOR RIGHT UNDER THE DASH. IT WAS FRIED. I CUT THE SWITCH AND PLUG OUT AND TIED THE TWO WIRES TOGETHER. NOW SHE IS RUNNING JUST FINE! :rockon THE DOWN SIDE IS, DONT HAVE A WRECK! GAS WILL STILL BE PUMPING! GOT A NEW SWITCH AT THE FORD HOUSE BUT IT DOESNT LOOK LIKE THE OLD ONE. IT HAS A 3 HOLE PLUG AND MY OLD ONE ONLY HAD 2. ANYWAY U GUYS MIGHT TRY THIS IF U HAVE PROBLEMS WITH STALLING OUT AND NOT STARTING. :beer NOW I THINK I'LL GO HAVE ONE. CJY

[lobbdude]

I had the exact same problem with my Bronco II, 1988. The contacts on the inertia switch were coroded. conditions get just right, and the contact is lost, which shuts the fuel off(safety issue to stop fuel pump in case of a crash).

Try finding it and cleaning the contacts. If your vehicle hasn't been wrecked, the switch should be fine. If not, replace(or bypass at your own risk.

Cheers