EEC-IV bronco II
Elder User
Joined: Feb 2004
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From: Ocean Park WA
A hairline crack in a valve seat will cause the leak only under pressure (Engine running at all). Industrials are real prone and it will not show under normal automotive test procedures. We've only been able to do it by MAGNAFLUX.
New User
Joined: Feb 2006
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Bronco II starting problems
hey guys...need some help and my local Ford place can't help. My 86 Bronco II hasn't ran since Dec. I hooked up the code reader to it and all it threw was a code 21. I have changed the plugs, wires, fuel pressure regulator, starter solenoid, and I know the timing is good. I have good fuel pressure and I have spark-good spark. I know that I have little to no compression in cylinders 1 and 5, but it ran fine when I bought it with that same problem with compression. All I can get the thing to do is crank..it won't fire over. It started up and got me 4 miles right after I changed the spark plugs, but then I wound up having to get jumped and followed all the way back home. Any ideas?
Postmaster
Joined: Dec 2001
Posts: 3,742
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From: UT
Originally Posted by Bronco2Babe
hey guys...need some help and my local Ford place can't help. My 86 Bronco II hasn't ran since Dec. I hooked up the code reader to it and all it threw was a code 21. I have changed the plugs, wires, fuel pressure regulator, starter solenoid, and I know the timing is good. I have good fuel pressure and I have spark-good spark. I know that I have little to no compression in cylinders 1 and 5, but it ran fine when I bought it with that same problem with compression. All I can get the thing to do is crank..it won't fire over. It started up and got me 4 miles right after I changed the spark plugs, but then I wound up having to get jumped and followed all the way back home. Any ideas?
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Joined: Dec 2002
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From: Racine county, WI
Originally Posted by Bronco2Babe
As far as I know...I know the system is getting fuel. Any ideas as to the reason for that particular code or what it means?
Can you tell us a little more about this "jump" you needed? You made it 4 miles, then what? Did it sputter at all, loose power fast, loose power slow or did it just die? Were there points in those 4 miles you thought it was going to die? Once dead was there no power to even turn it over or did the battery go dead after trying to restart it for a long period of time? Have you tried recharging your battery in your attempts to restart it since?
The low compression, how low is it? The more real numbers and info you can give us the more likely you'll get good help. We need info like what is your fuel pressure? You can have all the volume in the world but without pressure it won't fire correctly. I know from experience that everyone here is happy to help but to be totally honest you aren't giving us much here.
New User
Joined: Feb 2006
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I plan on doing another compression test today...will post that when I get those numbers. When I was having the problems with starting, it would surge a little, but if I kept the idle up I was fine...How do I check the injectors to make sure they are firing? Also, I had a friend check the fuel pressure...how can I do it myself?
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Postmaster
Joined: Dec 2001
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From: UT
KOEO 21 is easily set when the test is performed on a cold engine (a likely scenario considering the engine doesn't want to start). A CM 21 accompanying the KOEO 21 could indicate other problems with the coolant sensor (ECT). ECT is a basic thermistor and is easy to check with an ohmmeter.
As far as you can tell there is adequate fuel in the fuel rail. If the fuel injectors don't "fire", then that fuel doesn't get into the combustion chamber and the engine doesn't start. The fuel injectors make an audible click.
Have you put a fuel pressure gauge on the fuel rail? What is the pressure? A little tinkering I've done suggests you need at least 25 psi for the engine to run. There may be pressure there, but it may not be enough.
As far as you can tell there is adequate fuel in the fuel rail. If the fuel injectors don't "fire", then that fuel doesn't get into the combustion chamber and the engine doesn't start. The fuel injectors make an audible click.
Have you put a fuel pressure gauge on the fuel rail? What is the pressure? A little tinkering I've done suggests you need at least 25 psi for the engine to run. There may be pressure there, but it may not be enough.
New User
Joined: Feb 2006
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Well, there was more than 25 psi in the rail. My friend/mechanic informed me that when he went to do another compression test today, I have a leak in my head on the passenger side....yeah. Hopefully $350 and rebuilt heads will fix it.
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