86 Bronco fires but dies immediatley
- Thread starter OHMY
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
BigWrenn
New member
One thing you can check is the cap and rotor on the distributor for carbon arcing/wear. I had a similar problem and that was the main cause.
fig1072
New member
If you have changed wires or caps make sure your firing order is correct.
Seabronc
New member
Is this additional information to a previous post. If so it should be attached to the same topic.
I moved it for you. Don't open a new topic when you are discussing the same topic. Also, you haven't responded to the questions already asked.
Did you change anything before this happened? Like plugs and wires? If so, are you sure the wires are correct? It sounds like a timing problem. What engine is in the truck, 300, 302 or 351? EFI or Carb?
Add your truck vitals in your signature.
>-
Last edited by a moderator:
Put new spark plugs in, checked cap and rotor they are fine. Have not checked firing order. What about vacume line?
302 EFI,
BroncoJoe19
Active member
What about vacuum line? Did you check it?
Pull Diagnostic Trouble Codes (DTCs) From your onboard computer.
Your engine and transmission are computer controlled.
The computer uses sensors to tell it a number of different things and it controls actuators that push or pull mechanical levers (kinda). If one or more sensors aren't working properly, the computer goes "blind" and doesn't know what to do. If the computer can "see" but one of the actuators is broken and therefore can't follow the commands of the computer; the engine won't run correctly. The computer is preprogrammed with set values for each of its sensors, and each of its actuators. It will run a self check of all systems, like the space shuttle; it will compare its set value(s) to the value(s) it recieves from its sensors, and actuators. If any sensor or acutator is out of the "normal" range the computer will generate a "code." It will generate some codes on the fly, and others will be stored while you are driving. There is a simple method to "pull codes" out of the computer for one to use for diagnostic purposes.
Earlier versions of On Board Diagnostics OBD 1983-1995 can flash the error code to the dash board and can be pulled in one's driveway without any special tools.
Later versions of On Board Diagnostics OBDII some 1995, and pretty much all 1996 and newer, require one to use a code reader or scanner tool.
Some auto parts stores will scan your engine codes for FREE, you may want to call around. Some will scan OBDII but not the older (prior to 1996) OBD systems.
SO here you go...
How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway
Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more
Checking for vacuum leaks.
Some of the sensors and some of the actuators either read the amount of vacuum, or use vacuum to move controls, therefore it is important to the proper functioning of the engine that your vacuum system is fully intact. Otherwise one may get codes falsely indicating that there is a problem with a controller/actuator, or a sensor when in reality it is caused by a lack of vacuum.
Look at your rubber vacuum hoses (they are about 1/4 - 3/8 inches in diameter, if they are dry rotted or cracked, replace them. IF they slip on/off of their connectors too easily, they may have stretched out a little bit, cut the ends off, and put them back on.
You may listen for a leak. Sometimes using a cut off piece of garden hose is a good aid to listen with. Sometimes a cardboard tube (like from gift wrapping paper) is helpful. Just remember that whenever you stick your head inside a running engine compartment, that you are not wearing any loose clothing or jewelry that can get caught.
Another suggestion is to use a spray can of carb cleaner and spray around the bottom of the intake manifold, and the base of the throttle body assembly. IF there is a leak, you should hear a change in your engine.
Keep a fire extinguisher handy, or use water instead of carb cleaner (it works, but not as well.) Be aware that if you use water and the wires get wet and it runs worse... your wires may be bad, and the water is allowing them to arc instead of jump the gap of the spark plug.
Another suggestion is: to take a propane torch, turn it on (but don't light it) and move it over the vacuum hoses and connections. The engine RPM's will increase if there is a leak and the propane gets sucked in.
Also check the PCV valve, hose and grommet
Pull Diagnostic Trouble Codes (DTCs) From your onboard computer.
Your engine and transmission are computer controlled.
The computer uses sensors to tell it a number of different things and it controls actuators that push or pull mechanical levers (kinda). If one or more sensors aren't working properly, the computer goes "blind" and doesn't know what to do. If the computer can "see" but one of the actuators is broken and therefore can't follow the commands of the computer; the engine won't run correctly. The computer is preprogrammed with set values for each of its sensors, and each of its actuators. It will run a self check of all systems, like the space shuttle; it will compare its set value(s) to the value(s) it recieves from its sensors, and actuators. If any sensor or acutator is out of the "normal" range the computer will generate a "code." It will generate some codes on the fly, and others will be stored while you are driving. There is a simple method to "pull codes" out of the computer for one to use for diagnostic purposes.
Earlier versions of On Board Diagnostics OBD 1983-1995 can flash the error code to the dash board and can be pulled in one's driveway without any special tools.
Later versions of On Board Diagnostics OBDII some 1995, and pretty much all 1996 and newer, require one to use a code reader or scanner tool.
Some auto parts stores will scan your engine codes for FREE, you may want to call around. Some will scan OBDII but not the older (prior to 1996) OBD systems.
SO here you go...
How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway
Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more
Checking for vacuum leaks.
Some of the sensors and some of the actuators either read the amount of vacuum, or use vacuum to move controls, therefore it is important to the proper functioning of the engine that your vacuum system is fully intact. Otherwise one may get codes falsely indicating that there is a problem with a controller/actuator, or a sensor when in reality it is caused by a lack of vacuum.
Look at your rubber vacuum hoses (they are about 1/4 - 3/8 inches in diameter, if they are dry rotted or cracked, replace them. IF they slip on/off of their connectors too easily, they may have stretched out a little bit, cut the ends off, and put them back on.
You may listen for a leak. Sometimes using a cut off piece of garden hose is a good aid to listen with. Sometimes a cardboard tube (like from gift wrapping paper) is helpful. Just remember that whenever you stick your head inside a running engine compartment, that you are not wearing any loose clothing or jewelry that can get caught.
Another suggestion is to use a spray can of carb cleaner and spray around the bottom of the intake manifold, and the base of the throttle body assembly. IF there is a leak, you should hear a change in your engine.
Keep a fire extinguisher handy, or use water instead of carb cleaner (it works, but not as well.) Be aware that if you use water and the wires get wet and it runs worse... your wires may be bad, and the water is allowing them to arc instead of jump the gap of the spark plug.
Another suggestion is: to take a propane torch, turn it on (but don't light it) and move it over the vacuum hoses and connections. The engine RPM's will increase if there is a leak and the propane gets sucked in.
Also check the PCV valve, hose and grommet
BroncoJoe19
Active member
You may also check your fuel PRESSURE. With an EFI, you should have approx 35 psi. There is a shraeder valve on top of the engine on the fuel rail where one attaches a fuel pressure guage. If one jumpers the fuel pump test pin to the ground, the pumps will run continuously for testing purposes. BTW.. in an '87 you have two pumps, a high pressure one on the driver's side frame rail, and a low pressure in the tank.
Last edited by a moderator:
