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Discussion Starter #1
Here's my story...

First off, i've got a 86 5.0efi. I fill up my tank the other day, drive home, and park overnight. Next morning, rough start. She would start but wouldn't stay running without feathering the gas. Now she won't even run. Starts up fine and dies, even with accelerator to the floor. I can hear it priming when i turn the key. So i check a few things and replace a few things, trying to track down the problem. I've got spark, connections are good, dizzy & rotor are fresh, batteries charged, coil is <6months old so i'm pretty sure it isn't an ignition problem and i narrowed it down to a fuel/exhaust issue. So far, i've changed:

Fuel filter
Fuel pressure regulator
IAC
TPS

I took the throttle body off and cleaned it till it looks and feels new. I'm pretty new to broncos and working on cars in general so i need some help as to where to go from here. I pulled codes this morning and the only code I got was a 22, MAP sensor out of range. I checked connections and they look good so what's the problem? I'm hoping it isn't the in-tank fuel pump because that seems to be a b*tch to replace. maybe the high-pressure pump on the frame? any way to test it?
 

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I scrape on both sides
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just because the connections are good doesnt mean the map isnt fried, also do a check for any vacuum leaks
 

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Roller rockers are gay
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well, i'd say the map sensor is shot.
 

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Clogged injectors. Filled up tank. Lets say bad gas or even some build up got in the fuel lines and got to the injectors. I mean its not likely but hey anything can happen. Or map sensor
 

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Yeah, even with a good vac leak it should still run. Best thing is pull a plug and crank it to make sure you have good spark. And I'm not very knowledgeable on the efi but can you crack a fuel line near the injector to check for fuel?
 

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Roller rockers are gay
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Yeah, even with a good vac leak it should still run. Best thing is pull a plug and crank it to make sure you have good spark. And I'm not very knowledgeable on the efi but can you crack a fuel line near the injector to check for fuel?
no. it must be checked with a fuel pressure gauge. the efi needs a certain PSI to work properly. it it's too low, it won't run.

i'm still saying the OP has a dead MAP sensor, or a loss of vacuum source to the MAP sensor (i.e. vac hose is crushed or collapsed).

or he has a wiring issue. i doubt its bad gas. a dead MAP sensor will cause a hard start, no idle condition.

if it pukes black smoke, and misses something fierce when throttle is given, that's a good sign of a bad map sensor.

also, OP, check your fuel pressure regulator. just for the hell of it. pull the vacuum line off the regulator and smell it, if you smell gas, it's junk.
 

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God I love carburetors.....
 

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Roller rockers are gay
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**** carbs
 

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Discussion Starter #10
Forsure, thanks all...looks like napa has a MAP sensor in stock so i'll pick it up tomorrow and post an update on how it goes
 

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yo,

DTC 22 or 126 indicates the Manifold Absolute Pressure (MAP)/Barometric Pressure (BARO) sensor is out of Self-Test range. Correct MAP/BARO range of measurement is typically from 1.4 to 1.6 volts. Possible causes: circuit open between sensor vehicle harness connector and PCM. circuit shorted to VREF, SIG RTN, or GND. Damaged MAP sensor. Vacuum trapped at MAP/BARO sensor. Unusually high/low barometric pressure. Kinked or obstructed vacuum lines (MAP). Basic engine (valves, vacuum leaks, timing, EGR valve, etc.). High atmospheric pressure. Damaged PCM. VREF circuit open at MAP sensor. SIG RTN circuit open at MAP sensor. The pinpoint test directs you to check the voltage to the MAP sensor. With the MAP sensor connected, use paper clips to back probe the MAP connector so you make contact with the terminals inside the connector by inserting the paper clips into the bak of the connector. This allows you to get voltage readings while the connector is plugged in. The other option is to use straight pins to pierce the insulation of the wires. First check the voltage of the outer two wires of the MAP connector by connecting a voltmeter to the clips or pins you have inserted. You should see 5 volts with the key on. This is the power to the sensor. The BLK/WHTwire provides a ground called Signal Return (SIG RTN on EEC), it will show 0 volts with the black probe on negative battery terminal. The 5 volts VREF (ON EEC) (Reference Voltage) is supplied on the ORG/White wire. The Signal the computer reads is on the middle wire, DK BLUE/-Lt GRN (MAP on EEC). The correct MAP/BARO range of measurement is typically from 1.4 to 1.6 volts on the Signal (middle wire). If any of the voltages are out of range, there is a wiring problem that needs to be tracked down and repaired. These three wires all go back to the computer. The signal wire (middle) is the only one not shared by other sensors, it goes straight to the computer. The Signal Return and VREF are also provided to other sensors..."Read More
Source: by miesk5 at http://fullsizebronco.com/forum/showthread.php?t=199051


Testing w/DVOM that has a frequency measuring ability & a Vacuum Pump
by easyautodiagnostics.com @ http://troubleshootmyvehicle.com/main_index/ford/4.9L_5.0L_5.8L_map_sensor/ford_map_sensor_1.php

Wiring Diagram in an 86

Source: by Xris at SuperMotors.net
 

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Discussion Starter #13
replaced MAP sensor this morning and voila! running like a top again, thanks to all the input...but now i've got a mysterious oil puddle...oh well, just another thing to figure out!
 
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