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89 BII Will not run

WNYBroncoBill

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City, State
Western New York State
Year, Model & Trim Level
3X88-90 Bronco II
Help!

My 89 BII quit running while driving it yesterday. It started losing power then eventually the RPMs dropped off until the engine quit. I towed it home and immediately checked the fuel pressure (38 PSI at the fuel rail). The fuel pump is only 2 months old. The way it stopped running this time reminded me exactly of how it quit when the pump went bad two months ago.

Today, I changed the TFI module, tested the coil (.6 OHM drop across terminals, and replaced the coil to distributor wire.

If I try to start it, it runs at low RPM for about 10-15 seconds then quits. It doesn't matter where the throttle is positioned and during this time it runs rough as if only on a few cylinders.

Where should I look next?

Help is appreciated!

Bill
 



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I posted this about my BII. 46 people read this, can't anyone post a response to help me? I have posted many responses to help others. This is I believe a common problem with BII's, but I don't have an archive of these problems?

Today, I checked fuel pressure again, 38-40 psi at the fuel rail. It will fire if starting fluid is sprayed into the induction system at the butterfly valve. It only fires, doesn't run with this test.

Spark is good out of the coil, timing light on a plug wire is consistent with a good spark.

Fuel pump and filter changed on April 2, about 2000 miles ago. BTW it was an Aerotex pump not a Delco or Bosch.

Please help with ideas.

Bill
 






Wish I could help you. But I'm not good with FI motors. Now if it was Old School carb, that would be different. With that said, if it's getting spark, compression and fuel it should start. I'd take a plug out, attach spark plug wire if possible. Lay plug on metal part of engine and have some one crank it over and see if spark jumps the gap. Also when you take the plug out after you try to start it, do you smell gas or see that the plug has gas on it? Have you checked compression?
 






Today I tried a new FI pressure regulator. That didn't do any good either. I put a timing light on the coil wire and there is spark there. Tried the same with a spark plug lead and there is spark there also. Tested fuel pressure again and it is 38-40 PSI at the fuel rail. It cranks and sounds like it has compression. It tries to run on a cylinder or two for a few seconds.

Not sure where to go next. One friend told me that it is probably the Airtex fuel pump, but it seems to be getting the correct pressure. I am going to try a new fuel filter just in case there is a blockage in the filter. That was changed a few months ago when the fuel pump was replaced.

The fuel doesn't seem to be contaminated, no presence of water in a sample taken at the fuel rail.

I don't know where to go next.

Bill
 






Did you check your throttle position sensor? I'm reaching a bit here because I haven't worked on an EFI-IV engine in about 5 years, but that's the first place I'd look. Also check your IAC. There are instructions on testing, but as it will run (badly yes) for a few seconds, try to disconnect the TPS and see what happens. Ditto the IAC. just do one at a time though. I know vacuum leaks can sometimes result in higher idle speeds, but check for all your vacuum lines too. You have good fuel pressure (I'd still say it's a bit low for my liking, but IIRC it's still in the acceptable range) but maybe the wires on the pump are not seated correctly either? Intermittent contact...
 












ZPN BY,

Thanks for the reply. I will try the TPS disconnect. Not sure what the IAC acronym stands for, is that the MAP sensor?

I will say that when the vehicle failed, it acted exactly like it did 2000 miles again on my way back from Greenville, SC. Going along fine in 5th gear, started to lose power for 10-15 seconds then quit running. That is when the Airtex pump and filter were installed by a local shop there. It ran fine for the 13 hour non-stop trip back to Western New York State.

Bill
 






Not the TPS, disconnected it makes no difference.
 






I had a couple of Explorers that drove me nuts trying to find out why they would do this and that. Bought a shop manual that showed exactly how to test each sensor using nothing but a voltmeter/Ohm tool. If you don't have either, I'd get them and start testing each and every sensor. Also used to have a stock B2 that every once and awhile would just cut off. Found out it was the main wiring harness in the steering column. Had to remove the plastic steering cover that bolts around the shaft. When the engine was running all I had to do was to slightly move the connection and it would cut off. Found out that this is a common problem. All I had to do was to wrap a zip tie around it so it would not vibrate loose.
 






A friend that runs a repair garage and ex-Ford shop mechanic tells me to replace the fuel pump again with a Bosch or Delphi pump. Even though the Airtex pump is only 2000 miles old, he tells me they are nothing but trouble.

I'm hesitant to do this since the BII has about 21 gallons of fuel in the tank and the new Bosch pump is around $170. Plus the pump is putting out 38 PSi at the fuel rail.

That's why I'm trying everything else.

Rookieshooter, I have the Ford shop manual, the Haynes and the Chilton manuals!

Bill
 






Bronco II Repaired!

Finally, it is running again. It turned out to be a faulty distributor - possibly the Hall Effect pickup inside the distributor. No signal was getting to the new TFI module.

I purchased a new distributor that included a new cap, rotor, TFI module. After installing it, the Bronco II runs fine again.

Bill
 






That is great news. Had me stumped.
 






Rookieshooter,

I now know more about the Bronco II fuel and spark delivery systems than I would have ever wanted to know. Could come in handy as my son and I have 4 of these 88-90 Bronco II's

Bill
 






89 BII timing issue?

I'm back, same problem. I gave up on it last summer and put it in storage. I now have it home again.

It doesn't have any power (most of the time) every once and awhile it has a spurt of power then back to just running rough and stalling. It fells like the timing is not correct - although I have timed it and it is just where it should be.

Replaced the TPS and the sensor connector. No difference. Does the TPS sensor need to be pre-loaded to the position of the throttle body lever?

I changed the ECM module located in the right passenger kick panel. Found one from an identical BII (89 with A/C, 5-speed) same Ford part number. This made no difference.

I have changed the spark coil, plugs fuel pressure regulator and swapped a MAP sensor.

Is there a common place in the wiring harnesses that a problem has occurred? I wonder if there is a short in the TFI input or the SPOUT output?

I really need to resolve this problem. Any help is appreciated.

Bill
 






If you want to keep it, I'd recommend that you get a code reader ($20 Innova on amazon) and a full set of shop manuals from ebay.

Info dump coming :)

Do a test for vacuum leaks, mine had a gasket between the lower and upper intake go bad. No engine power at all. It actually idled just a bit rough but if you tried to drive it felt like it had 5HP total. Those gaskets dry out and get hard and brittle. When it went bad it was not a gradual thing, it was good and then BAM! bad.

Check everything electrical on the vehicle, lights, signal, etc... One of those not working might give a clue to a short or bad ground somewhere.

Water leaks from the drip rail can run down to the PCM in passenger kick panel and cause issues. Can cause connector issues. Probably not an issue as you have replaced the PCM and were likely to have seen any problems.

Check and clean all of your grounds. The one from driver cylinder head to the firewall can be left off if the heads or engine is replaced. Make sure that is there or a suitable replacement is in place.

Clean the throttle body and throttle cables to be sure the throttle plate isn't sticking.

If it has an aftermarket radio pull it and check the wiring job. Mine had been done who knows how long ago and 80% of the connections were bare, luckily for me the only thing that fried when the wires shorted was the radio

It does sound like a fuel problem, check the harness to the injectors. You might have some clogged injectors or the line going to the injectors.

Any one of the engine sensors could make your engine run badly. One of the BroncoII or Ranger sites has good article on how to test them. The IAC can be cleaned and checked easily, the ACT is pretty cheap and easy to replace, the ECT can be tested but since your BII wont run long enough to get hot the test will be incomplete but if the cold values are wrong you'll know it's bad, 02 sensor can give you fits and so can the MAP sensor.

The Innova will test the TPS for you.

Have you replaced the plug/coil wires? They can arc to the block/chassis and if the coil wire does it will barely or not run at all. A simple way to test is start it in as dark a place as you can and look for the arcs.

Oh just remembered, the relays on the passenger side, I had a BII that got water in/on one of them and that caused a random no-start issue. That was long long ago I don't remember exactly which one it was. might want to check the connections there too.

I hope that helps.
 






Have you replaced the plug/coil wires? They can arc to the block/chassis and if the coil wire does it will barely or not run at all. A simple way to test is start it in as dark a place as you can and look for the arcs.

I would check the coil as well.

Have you been buying cheapo gas? If the answer is yes then look at the fuel pump and filter. Injectors may be clogged or unplugged.
 






JerryC and BroncoIIPower,

Thanks for the replies. I will try them this week. I did replace the coil and ignition lead. I have a rebuilt ECM coming tomorrow from Advance. Decided to spend the $100 just to make sure it isn't a bad one I got from the wrecking yard.

The intake vacuum leak is where I will check first. That is the way it quit running. Just shifted into 5th gear at around 50 MPH and there were a couple of pops and it quit running. It never ran again at all until I replaced the distributor and TFI module, now it idles very rough and has absolutely no power.

I will check the ground also, perhaps run a new one when I'm changing the ECM.

This 2.9L ran perfectly till it just quit. The engine was rebuilt about 40K ago at a shop in Fort Mill, SC. Everything replaced with OEM Ford parts. The owner built it for his son to get through high school and college, so he did it correctly. Ran perfectly on the 13 hour trip back from SC.

I will let you know....

Bill
 






Bronco II Running Again

All who helped and responded,

It is alive and well. Not 100% yet, but 95% there. Problem turned out to be the new aftermarket distributer. One of the first things I did to try to get it running. It did run after the new distributer, but would not advance.

I tried several ECM's (including a rebuilt unit from Advance) nothing made and difference.

Finally obtained a used distributer from B&R Auto Wrecking in Corvellis, OR. In stalled it on Tuesday and now it runs almost perfectly. Still a little skip hesitation in the mid-range RPM's, but it might be wires or a bad injector. I have a wiring set coming tomorrow morning. Hope that does it!

Now, on hard acceleration, the check engine light flashes, vehicle runs OK, but has a little roughness at that range.

What is your bet? A bad wiring set or a bad injector? Why does the light flash?

Thanks,

Bill
 






If you get a check engine light you definitely should pull the codes.
 



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Changed plug wires today. New Belden 8MM wires. No difference, still has the mid range slight skip. If you floor the gas pedal it runs smooth but the check engine light flashes very quickly. Let off a little and the light goes out.

Wondering if there is a bad injector? How can I diagnose a FI problem without changing the injectors? Could a slightly plugged injector cause the slight skip and the check engine flashing? Is there feedback from the injectors to the ECU?

Could it be a knock sensor? Where is it located?

Thanks for previous ideas.

Bill
 






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