Ford Bronco Hard start after sitting ? Also exhaust question - Ford Bronco Forum
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post #1 of 101 (permalink) Old 01-04-2017, 01:16 PM Thread Starter
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Ford Bronco Hard start after sitting ? Also exhaust question

Hey guys,

I have been chasing this issue for a while now. The truck takes like 5 seconds after it has been sitting after 30min - 2 hours and three seconds to start when COLD. How ever when I start the truck before the 30 min mark it takes only 1 - seconds and it fires right up. Now today i waited 30 mins after a long drive but this time I primed the pump twice and it took 2 seconds. So what dose this mean. I have done a full tune up all new exhaust with 02 sensor. tested and replaced the fuel pump filter and fuel pump relay. Still no change. hooked up my code reader and got 111 one everything so that means it passes the test. Could this be the charcoal canister ? every time since i owned this truck it would shut the pump off while refueling.

Bronco Info:

Engine: 5.8 v8 (351W)

Year: 1994

Also the air pipe to the cat is cut when I re did the exhaust should i connect it ? The new cat DID NOT have an air tube connected like the old one. Dose this mean that the cat dose not require one?
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post #2 of 101 (permalink) Old 01-04-2017, 02:15 PM Thread Starter
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Also one more thing to add it seems to start worse the warmer it gets.
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post #3 of 101 (permalink) Old 01-04-2017, 03:16 PM
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Yo G,
Today is a bad headache day, so Imwill suggest one easy test, ok?

Long crank times may be traced to a sticking Idle Air Control (IAC) valve (TSB 97-9-5, April '97); "...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 IAC Valve with a revised IAC Valve if no Diagnostic Trouble Codes (DTCs) are present."
Ford Motorcraft units are best.

IAC Overview and easy test by Ryan M @ Fuel Injection Technical Library Idle Air Bypass (IAB)
Excerpt;
"...bring the engine up to operating temperature. Allow the engine to idle without any driver input to the throttle or pedal. Go under the hood, and disconnect the electrical connector to the IAB. If the engine begins to stubble or stalls the IAB is functional and does not need to be repaired. If the engine idle does not change you should remove the IAB for inspection..." read more Ryan describes the IAC as IAB.

With IAC out inspect the passageway into the throttle body, clean it if needed.


Or it could be the pump's Supply Check Valve, which is normally closed; opens when the outlet pressure from the energized pump exceeds the opposing check valve spring force. When the pump is de-energized (i.e., engine is shut off), the supply check valve closes to maintain pump prime and fuel supply line pressure.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
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post #4 of 101 (permalink) Old 01-04-2017, 03:42 PM Thread Starter
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I Just found something out the truck starts fine if I loosen a gas cap and big HISSSSSSS comes out. it even idles better what could that mean. The IAC valve is new and the wiring was tested with a meter
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post #5 of 101 (permalink) Old 01-04-2017, 05:35 PM
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on my '94, I had a fuel pump that exhibited some of the same symptoms you are experiencing. After trying to find the cause of a hard or no start when warm, and throwing a ton of parts at it including IAC, FPR, Fuel Filter, etc. I went and checked the fuel pressure. The pressure was just a little low, but what I noticed most was the pressure release line (the line attached to the pressure gauge with the little hose attached that relieves the pressure when you push the button) was full of bubbles! Eventually, I cut the floor and put in a new fuel pump assembly, when I pulled the old pump out, I found that the top of the pump had partially separated from the bottom.

(If SuperMotors was working, I have a picture, and maybe if SuperMotors ever comes back up, I'll post it.)

I think the because the pump top was partially separated from the lower housing, the pump may have been sucking in air in addition to the fuel, causing a cavitation in the pump, and mixing the air with the fuel, and that was the reason for the "bubbles". I have two Broncos and when I checked the fuel pressure on the '96, the pressure relief line DID NOT have the bubbles in the fuel.

"The simplest solution is usually the best solution" - Occam's Razor

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post #6 of 101 (permalink) Old 01-04-2017, 05:43 PM Thread Starter
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Thanks for the reply. The fuel pressure is good a shop and I both checked it out and it was with in spec. I just replaced my gas cap with one from napa with a vented one and just driving it home was a noticeable improvement.
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post #7 of 101 (permalink) Old 01-04-2017, 06:06 PM
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There is a vent line that runs from the fuel tank to the charcoal canister (the black box on the frame below the battery), I'm not sure that the original gas cap is vented. You may find that something else has failed, causing your problem. But if your state doesn't emission test, you can't mess with success.

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post #8 of 101 (permalink) Old 01-04-2017, 10:20 PM
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I've had this same issue with my BKO since I got it. Exact same. New IAC, new fuel pressure regulator, new pumps (rail and tank), new gas cap, new injectors, TB inspected, new fuel reservoir (thought the check valves might be sticking), new fuel lines, wiring inspected. That's just on the fuel side.

I thought the ignition might be to blame instead, so, I tested and replaced many old parts that were "questionable." Motorcraft coil, plugs, wires, and a brand new (non-rebuilt) dizzy.

All replaced items are Motorcraft, except, for the in-tank pump which is a Delphi and the dizzy which is Richporter. Absolutely, nothing has changed about the "hard-start", which is just as the OP describes. In the morning, I have to prime twice to get it to fire in a short period. Otherwise it'll crank and crank.

Everything tests fine electrically, and in mechanical operation. I just don't know what I'm missing, so, I gave up because it has never failed to start, it just takes excessive cranking after it sits for more than 5 hours/over-night. If I'm bleeding fuel pressure, which is what I suspect, I have no idea from where. In the summer, it's, also, worse. My theory is that the fuel pressure in the lines/fittings/tank become greater with the ambient temperature (thermal expansion) and force the leak-down to become more rapid.

I mean, why would I have to prime twice in the morning? Are my lines, just, bleeding down, somehow? That's got to be it, right?

Eric
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post #9 of 101 (permalink) Old 01-05-2017, 12:30 AM
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Had similar issue with my 89' when I first got it. It was a gamble when it was cold, but refused to start after reaching operating temperature and shut off. Had to let it cool about 10-15 degrees, then it'd fire right up. Replaced air charge temperature sensor which was in pretty bad shape when I pulled it. Fires up immediately now, hot or cold.

Was also experiencing massive hiss/vacuum with fuel cap removal. Replaced with vented cap = No more hiss.

Not sure if this will help or not, but good luck to ya.
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post #10 of 101 (permalink) Old 01-05-2017, 04:58 PM Thread Starter
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Well last night I took it for a long drive with the new fuel cap and WOW the truck is running 100% better and starts faster I will keep you guys updated. Make sure if you have replaced your gas cap MAKE SURE IT IS VENTED advanced auto only sells non vented ones. I went to NAPA and no more problems but like i said ill keep you posted if it stays fixed and or if this problem comes back.
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post #11 of 101 (permalink) Old 01-05-2017, 05:02 PM Thread Starter
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Quote:
Originally Posted by silver70 View Post
I've had this same issue with my BKO since I got it. Exact same. New IAC, new fuel pressure regulator, new pumps (rail and tank), new gas cap, new injectors, TB inspected, new fuel reservoir (thought the check valves might be sticking), new fuel lines, wiring inspected. That's just on the fuel side.

I thought the ignition might be to blame instead, so, I tested and replaced many old parts that were "questionable." Motorcraft coil, plugs, wires, and a brand new (non-rebuilt) dizzy.

All replaced items are Motorcraft, except, for the in-tank pump which is a Delphi and the dizzy which is Richporter. Absolutely, nothing has changed about the "hard-start", which is just as the OP describes. In the morning, I have to prime twice to get it to fire in a short period. Otherwise it'll crank and crank.

Everything tests fine electrically, and in mechanical operation. I just don't know what I'm missing, so, I gave up because it has never failed to start, it just takes excessive cranking after it sits for more than 5 hours/over-night. If I'm bleeding fuel pressure, which is what I suspect, I have no idea from where. In the summer, it's, also, worse. My theory is that the fuel pressure in the lines/fittings/tank become greater with the ambient temperature (thermal expansion) and force the leak-down to become more rapid.

I mean, why would I have to prime twice in the morning? Are my lines, just, bleeding down, somehow? That's got to be it, right?

Eric
Make sure you have a vented gas cap. 3 years ago i bought an non vented one by mistake and put the old motocraft back on after thinking it was effecting the starting. Here is what I have on the truck currently. https://www.napaonline.com/napa/en/p...703_0323305597 this made a world of differance.
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post #12 of 101 (permalink) Old 01-11-2017, 02:07 AM Thread Starter
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So it turns out its not fixed :( and it takes a really long time to start. Also when it sits for about 30 mins to a half a hour the tach jumps to 2000 rpms is this normal.
I found out that the hard starting is worse when the gas level is below a quarter of a tank.

any Ideas ?

EDIT: mine acts just like silver70
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post #13 of 101 (permalink) Old 01-11-2017, 01:53 PM
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Yo,
Following is for a 94; CHECK FUEL PRESSURE LEAKDOWN

My 96 had symptoms of @ faulty Supply Check Valve, that is normally closed, but opens when the outlet pressure from the energized pump exceeds the opposing check valve spring force. When the pump is de-energized (i.e., engine is shut off), the supply check valve closes to maintain pump prime and fuel supply line pressure.
The valve is not repairable or available.

My issue was on first start of the day; starter cranks normally with ignition key, engine turns over with slight, hesitant stumble @ low RPMs for no more than a second then engine gets up to fast idle and runs well, runs and starts as new the rest of day with shut-down periods running from 5 mins to 4 hours. Lately, it is starting like new.
My remote start was same.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!

Last edited by miesk5; 01-11-2017 at 03:14 PM. Reason: Changed image url
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post #14 of 101 (permalink) Old 01-11-2017, 03:04 PM Thread Starter
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WOW thanks for the reply but I cannot view the image. So dose this mean the truck will always have this issue ? There has to be a way to get a new one. No? What you said your Bronco did its EXACTLY what my Bronco is doing. Did you do any thing to remedy this situation.

EDIT: The picture is showing now sorry.
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post #15 of 101 (permalink) Old 01-11-2017, 03:42 PM
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Yo G,
YW!
We tried a generic brand of fuel system cleaner. Not much change at first, then over-time it got better, regardless of ambient temperature.

Have not seen or heard of anyone replace the check valve, even if it was available.

Have chatted with someone here in recent past about the possibility of adding an aftermarket fuel rated check valve to the fuel line to FPR, rail, & FIs.
Never heard from that person again.
I was thinking of inserting a Russell in-line check valve.
"Russell check valves are designed to allow flow in one direction and prevent flow back. They feature a 304 stainless steel check piston that delivers optimum flow with minimal restriction and pressure loss."

Ask local mechanics if this is feasible.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
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post #16 of 101 (permalink) Old 01-11-2017, 04:08 PM Thread Starter
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Thank you for all of this info. Now could I just replace the whole assembly. I found the whole assembly on JBG here 1990-1996 Ford Bronco Sending Unit Kit, 33 Gallon-Broncograveyard.com. But first I would like to try the fuel system route. If you don't mind me asking what brand did you use and yes When I used injector cleaner in the past is starts like a new truck and uses less gas.
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post #17 of 101 (permalink) Old 01-11-2017, 04:29 PM
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You could just replace the pump. When mine went bad, I cut the access hole and replaced just the pump. The fuel level sender unbolts from the pump assembly. JBG has just the pump for considerably less.



1990-1996 Ford Bronco In Tank Fuel Pump KIt Aftermarket-Broncograveyard.com
1990-1997 Ford Bronco and F-Series Truck In Tank Fuel Pump KIt-Broncograveyard.com

Get a new sealing ring and gasket too.

The instructions for the access hole are at:

1983 Ford Bronco Bronco Fuel Pump Access Hole pictures, videos, and sounds | SuperMotors.net


This is what mine looked like when I pulled it, I don't know how the top separated from the bottom of the assembly, but it was what was causing the cavitation and air being mixed with the fuel.


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post #18 of 101 (permalink) Old 01-11-2017, 05:04 PM Thread Starter
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The fuel pump was replaced about 5 years ago with a new unit. But idk if the replaced the whole assembly or just the pump. Also I try to look in to the after market check valve. Also what fuel system cleaner should I run in there.
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post #19 of 101 (permalink) Old 01-11-2017, 07:29 PM
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Yo G,
Looked through my Word file and it was Chevron Techron Complete Fuel System Cleaner
Bought at Advance Auto.
Check walmart for lowest price.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!
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post #20 of 101 (permalink) Old 01-11-2017, 07:47 PM
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Great info guys, marked for future reference...........
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