96 bronco wont start

[broncotough]

I've been having a problem starting when the truck gets warmed up. I would have to pump the gas, and it would stumble a few minutes but eventually get going. A few days ago it overheated. Forgot to turn on electric cooling fan. Stalled at an intersection and would not start even after cooling it off for hours (it always started fine when cold). After towing it home i checked fuel pressure at the rail @10psi. Replaced filter and got the same result. After replacing fuel pump i got 35psi at the rail. Still wont start.

Some things to add

It has spark. Air filter is clean. Cap, rotor, plugs, all seem good,

Has good gas 35psi at rail. I hear all my relays clicking in.

Only codes were lean bank1 &2 erasing them did nothing to help

Out of curiosity i rotated the distributor clock wise engine fires runs horribly for about 10secs then dies. Reset dis to original position still no start. I can hear clicking and relays as i rotate distributor by hand. If i play with the distributor i can get random firing but no start in its correct position. Done this with and without the spout connected.

Kinda at a loss as to were to go from here. My gut tells me whatever was preventing proper startup before has now finally kicked when i overheated it. Thanks for any suggestions

 

[miesk5]

yo B,

I'll ask a few Qs and get back to you a little later; I have an appointment @1300 hrs.

Does Starter Motor Crank Normally or Slowly?

Did you use a Scanner to obtain the Codes?

What are the Codes?

Do you believe you have a vacuum leak?

96 Bronco Normal Engine Vacuum at Idle (15-22 in-Hg)

Vacuum Leak Diagnosis

The air handling system is designed to provide defrost when no vacuum is applied to any of the three air door vacuum motors. This is done to prevent a situation where defrost cannot be obtained due to a system vacuum leak. Instead, a leak in the vacuum control circuit will send all airflow to the defroster outlets. This condition may occur during acceleration (slow leak), may exist at all times (large leak) and may happen only when certain specific functions are selected, indicating a leak in that portion of the circuit.

The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel. Because of the materials used, the vacuum hoses should never be pinched off during diagnosis to locate a leak. Use Rotunda Vacuum Tester 014-R1054 or equivalent to locate vacuum leaks. A wood golf tee can be used as a plug when it is necessary to plug one end of a vacuum hose for leak test purposes.  

Extended cranking because of a "No Start" can load the exhaust system with raw fuel, damaging the catalytic converter after the engine starts. After the "No Start" condition has been repaired, disconnect the secondary air supply, run the engine until surplus fuel is used up, and reconnect the secondary air supply.

 

[broncotough]

Thanks for the fast reply. I have the battery on a charger in between cranks. It cranks normally. The codes from my scanner are po171 and po174. I always throws those codes. And it is very possible im leaking vacuum. When i get home from work ill try to find any leaks and report back thanks again

 

[miesk5]

yo B,

YW!

DTC P0171 & P0174 Lean Troubleshooting;

"...These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel).

Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor (MAF) that is not reading airflow accurately, an EGR valve is not closing (DPFE) and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow). I

f the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator (FPR) or dirty fuel injectors..."

Check FPR by pulling vac line off, any gas aroma or gas in line, replace FPR bec. internal diaphram is ruptured

 

[broncotough]

Checked fpr, seems ok no smell of gas as close as i can sniff for it with vac line off. As far as i can tell vacuum lines are good.

 

[broncotough]

Got 35 to 40 psi at the rail, spark at the plugs this ones got me good lol.

The only time it even attempts to start is when the distributor rotated clockwise way out, but never when on the mark.

Has my timing changed?

 

[Seabronc]

Maybe you should check the condition of the timing chain.  Make sure timing marks line up and there is no slop in the chain or broken and worn teeth.  That's a bit of work, but rotating the distributor to get it to start makes me suspicious. 

Good luck,

>-

 

[broncotough]

Im thinking the same. Even if the chain slipped though, i would of thought it would make some popping\pinging noise. It cranks smooth. Timing chains are not that expensive so if im checking it, ill just replace it.

Any chancess a faulty MAF or IAC could cause a no start. This truck has more sensors then my other broncos. My others were easier to diagnose. fuel+air+spark= run this truck doesn't understand this equation. Lol

You guys are awesome, and have been very helpfull to me. Thank you very much /emoticons/[email protected] 2x" width="20" height="20" />

 

[miesk5]

yo,

Can you borrow a timing light?

Set the timing on an EFI Ford

http://web.archive.org/web/20131229164125/http://oldfuelinjection.com/?p=71

by Ryan M

btw, while cranking the engine. If the fuel pump relay kicks on when cranking, the TFI & Stator are good.

This is by Ford for DTC P0171 & P0174 Lean Troubleshooting;

DRIVEABILITY SERVICE TIPS FOR OBDII VEHICLES ONLY TSB 01-9-7

http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=113510

P0171 - System Too Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The code is set when the adaptive fuel tables reach a rich calibrated limit.
Fuel System:
· Contaminated fuel injectors
· Low fuel pressure or running out of fuel (fuel pump, filter, fuel supply line restrictions)
· Vapor recovery system (VMV)
Induction System:
· MAF contamination
· Air leaks between the MAF and throttle body
· Vacuum leaks
· PCV system concern
· Improperly seated engine oil dipstick
EGR System:
· Leaking gasket
· Stuck EGR valve
· Leaking diaphragm or EVR
Base Engine:
· Exhaust leaks before or near the HO2S
· Secondary air concern
Powertrain Control System:
· PCM concern       P0174 - System Too Lean (Bank 2) Same as DTC P0171, but Bank 2. See Possible Causes for DTC P0171

 

[miesk5]

yo,

IAC,

Long Crank Times may be traced to a sticking Idle Air Control (IAC) valve, TSB 97-9-5 for 95-96; "...After a 1-4 hour engine soak time, long crank times and/or long crank to start followed by a stall may occur on some vehicles. No further stalling or rough idle will occur after the engine is running. The long crank and/or stall may be due to the Idle Air Control (IAC) Valve sticking. Replace the AC Valve with a revised AC Valve if no Diagnostic Trouble Codes (DTCs) are present."
Source: by Ford

http://www.stangnet.com/images/stories/docs/sn95_TSBs/97-09-05.pdf

IAC related Code in a 96;

DTC P1506, P1507 & Possible Causes; "...Idle Air Control Overspeed Error/ Idle Air Control Underspeed Error; A vacuum leak, a damaged IAC assembly, a stuck IAC valve or throttle valve typically sets one or both of these codes. The IAC can be checked with a scan tool, sensor tester or multimeter. A vacuum leak is one of the most common causes and can be checked with a vacuum pump..."

DTC P1504, P1506, P1507 Idle Air Control (IAC) & Possible Causes

http://web.archive.org/web/20101011143054/http://www.nloc.net/vbforum/performance-specialties/90899-gen1-tuning-info-lots-more.html

P1504 - Idle Air Control (IAC) Circuit Malfunction This DTC is set when the PCM detects an electrical load failure on the IAC output circuit. IAC circuit open
VPWR to IAC solenoid open
IAC circuit short to PWR
IAC circuit short to GND
Damaged IAC valve
Damaged PCM
The IAC solenoid resistance is from 6 to 13 ohms.
IAC valve stuck open
Vacuum leaks
Failed EVAP system
Damaged PCM
The IAC solenoid resistance is from 6 to 13 ohms.

P1506 - Idle Air Control (IAC) Overspeed Error This DTC is set when the PCM detects engine idle speed that is greater than the desired rpm. IAC circuit short to GND
Damaged IAC valve
Disconnect IAC valve and look for little or no change in engine rpm as an indication of a stuck or damaged valve.
P1507 - Idle Air Control (IAC) Underspeed Error This DTC is set when the PCM detects engine idle speed that is less than the desired rpm. IAC circuit open
IAC circuit short to PWR
VPWR to IAC solenoid open
Air inlet is plugged
Damaged IAC solenoid
Damaged PCM
The IAC solenoid resistance is from 6 to 13 ohms
Disconnect IAC valve and look for no change in engine rpm as an indication of a stuck or damaged valve

 

 

[Seabronc]

I believe your truck has a Crank shaft position sensor which tells the computer when it is at TDC for cylinder #1.

>-

 

[broncotough]

Ok i got a light and set base timing at 10* btdc. Spout was out when i set it. Reinstalled spout after.

Still no start.

While cranking i rotated the dizzy by hand and it ran! But the timing marks where way off.

Is it possible somthing in my distributor is whack.

Timing has somthing to do with this.

Doesn't even try to pop over at 10*

Perplexed is an understatement. If its any help i can take photos and have a decent tool selection including meters and gauges, and both Haynes and chiton books. I rebuilt a 86 bronco 302 efi awhile back with no trouble. I thought i was good at this lol

 

[broncotough]

Update: found some chipped plastic in the pickup of the distributor. Replaced it. 100 bucks a autozone. Still same issue. When i rotated the distributor clockwise it fired, i was able to work the throttle and it reved up but i wasnt able to keep it running. It died after about 2 throttle inputs. It wasnt the smoothest when it ran but did seem to have power when i could rev it. Grr 100 bucks... Gone

 

[miesk5]

yo,

I tried to open my Ford Bronco Electrical and Vacuum Troubleshooting Manual (EVTM) - Powertrain Controls and Emission Diagnosis Manual (PCED) EVTM/PCED CD, but this ***** new DELL all-in-one POS will not open  now, despite opening it  few times since I bought & wasted $$ on this POS Dell!!

When checking timing, did strobe jump around?

I'll see if family members can open the Ford cd later or Sat.

 

[broncotough]

The strobe did appear inconsistent. I was blaming the cheapo harbor freight light. I'm wondering if spark maybe too weak. Good luck with the dell mine is working a lot like my bronco atm. Lol ty again for your time

 

[broncotough]

I think I initially misunderstood the question on the timing jumping around. Although the lights a pos, I was able to set and hold timing marks with the Light. The mark holds true.

Since distributor spins off cam, and I can set time on balancer. I'm to think timing chain is good?

 

[broncotough]

Another day another way, im starting to lean towards excessive fuel as the problem. Smells like its flooding. I'm going to pull and clean the plugs. Not sure what to look for, when i sprayed starting fluid down the intake it dont even pop. I think its flooding.

Ill check in later with my findings.

I've found similar problems on forums but nobody ever post the solution... I promise to post a solution to this, and be a hero to the masses.

Recap

Fuel side

So far ive replaced the fuel pump (only one in the tank) and filter, fuel pressure rises to 40psi when key is turned, the needle ticks when cranking. Pulled the fpr vac line, i does not smell of fuel. A hand pump pulled is vac down to -20psi and held it.

Ignition side

Replaced the distributor, checked for spark with plug on fire wall using the key was good. Also checked with plug on block using a jumper on the starting relay also good. i have 2 tfi modules that test good (Grey motorcraft). ignition timing was set to 10* btdc it wasn't far off. but i dialed it in (spout out). The MSD coil had chalky corrosion under one ***** mount. Coil tested good. I cleaned the mounts. Checked wires cap and rotor are all good. Wiggle tested everywhere. Checked grounds.

Rotate the distributor while cranking it will start when rotated clockwise. It will run for a up to ten seconds, accept a few throttle inputs, and even idled once. But it dies quickly and will not start again at any position for some time.

 

[miesk5]

yo B,

BING!

  i have 2 tfi modules that test good (Grey motorcraft).

http://www.myo-p.com/Ford-EEC/EEC%20Help%20files/Files/TFI_grey_or_black.html

Significant Excerpt; (btw, the 96 uses the CCD system that requires the black module)

"...Since these two TFI systems are so significantly different, yet so similar in appearance, parts application problems will inevitably occur. A gray Push Start TFI module will plug right into a CCD system, and vice versa. To make matters worse, parts books are often incorrect on TFI module applications! With the incorrect TFI module installed, the vehicle will run, but driveability and MIL (malfunction indicator lamp) problems will result. For instance, if a gray Push Start TFI module is installed in a CCD system, the computer will not be able to control ignition dwell, and the MIL will illuminate with memory codes for the IDM circuit set, as the gray TFL module is incapable of generating an IDM signal to the computer..."

From discussions w/many people here and in other forums, The MIL (Check Engine Light) sometimes does not indicate a trouble code not light up while driving.

Remote Mount Black CCD "Computer Controlled Dwell" ICM
Ford Bronco -

Wiring Schematic

Motorcraft - DY1077 (supercedes DY679, DY667, DY645)
Ford - 5U2Z-12A297-D (supercedes F1PZ-12A297-A)
Wells - F139
Niehoff - FF413
BWD - CBE40
Standard - LX-241
NapaEchlin - TP29
Delphi - DS10056
Transpo - FM544
 

 

[broncotough]

My truck always ran on grey. I thought the black was push start. Why would it run for years on grey to not accept it now. I'm going to look into this some more