86' Bronco II vapor lock/gas issues

BrokeAsAJoke · Sep 8, 2013

I have an 86' bronco 2 I had vapor lock issues. I replaced the fuel pump and fuel filter. Now I am still have lock issues. It runs good for about 20 mins idling, then starts sputtering like it is out of gas. When I press the pressure release valve it has pockets of air. Am I still having vapor lock or is their a crack in one of the seals along the fuel line and I am sucking in air there? Any help and suggestions would be appreciated. I am new to this forum and trying to get pics up of my bronco. Thank you for your time.

Bully Bob · Sep 8, 2013

Hi Broke.., welcome..!

An over heating eng. usually causes vapor lock. (and fuel lines to close to the eng. block.)

"...or is their a crack in one of the seals along the fuel line and I am sucking in air there?"

This is most likely. The lines/tube can also crack. they won't always have a noticable leak but will allow

air in via the suction.

BrokeAsAJoke · Sep 8, 2013

Ok so as a nice fix to see if it is overheating, could I wrap the lines in thermo tape? The engine was overheating at one point. I changed the hoses, thermostat, got a new radiator, last things I am gonna change is the clutch fan assembly and get a better fan. The bronco still overheats while idling.

Since the lines/tubes are cracked since I am gonna have to inspect it and take apart everything would it be better to replace the lines? If so would nylon or aluminum tubes be better?

Thank you just need more insight into how to fix ruby, what my bronco is called.

Bully Bob · Sep 8, 2013

It is usually pretty important to "flush" the entire cooling system when replacing the radiator.

The fan clutch is important. I once bought an aftermarket one & it didn't work fr. the get-go. (went with factory)

Maybe they've improved (aftermarket) over the years..?

Usually the fuel lines are visible for the most part. I doubt they need replacing however, I've never owned a B-II

so not sure where they run. A leak can be fixed.

The system can probably be pressurized to test.

Just noticed you mentioned "pressure release" valve.., sooo.., this must be fuel-injection..???

I can't advise on that.., maybe someone will chime-in with FI experience. That should be 100% fuel under pressure.

BrokeAsAJoke · Sep 8, 2013

Yes ruby is fuel injected, the lines are along the frame and visible. When I replaced the radiator I flushed the system to ensure it was clean. That's the issue I checked the lines and there are no leaks, that is why I was wondering if it is a bad seal. Since I am going to have to drop the tank again I figured I may as well replace the line and connector which is why I asked if aluminum or nylon would be a good replacement. So I should go ahead and replace the fan and fan clutch assembly before doing the lines in case that is the issue I am having then?

Bully Bob · Sep 8, 2013

IMHO, yes.., if a fan clutch is faulty.., overheating is possible.

Overheating isn't really good for any engine. No idea what could req. a fan replacement...?

The BII wasn't designed to run hot..., soooo.., solving that issue would be 1st. priorty for me.

Have you tested the fan clutch..??

I'm not sure what "seal" is involved..?

The fuel lines are designed pretty tough for the "FI" engines. As well as any rubber hoses anywhere on the conection points.

These hoses have to be "FI" rated.

I doubt the actual fuel lines need replacment.., Factory or equivalent should be used (as good or better) if there is a rotted/bad line.

BrokeAsAJoke · Sep 9, 2013

The blades are cracked but not broken on the fan, the clutch is the only thing that is left to be replaced along the cooling system besides the water pump. The seals I am talking are the seals on the connector along the fuel line. The pump, the filter and the injectors. I believe the air that is leaking into my gasoline may be a cracked seal. How would I test the fan clutch? I will first make sure the bronco does not run hot before I start messing with the fuel lines. Thank you for your help bully bob.

Bully Bob · Sep 9, 2013

I'm sorry nobody's jumping in here.., All our experts must be on vacation... ^_^ /emoticons/[email protected] 2x" width="20" height="20" />

I'm hardly a FI "guru" but I can guide folks in the proper direction (hopefully)

I don't think "FI" lines/connections/seals can "****" air.., being under "hi" pressure, they would squirt fuel. :glare:

"The blades are cracked but not broken on the fan"

This isn't a priority.

The fan-clutch should move, by hand, freely (eng. off eng. cold) .

A fully warmed eng. (eng. off) there should be some resistance to moving the fan by hand.

And, if there's no noise or leaks fr. the clutch..., it's OK.

Water-pumps don't fail exactly. They leak to warn you the seal has failed.

Bearings & shafts can fail but that's rare. They will make a lot of racket in these cases.

Are we sure it's overheating...??? What are you using to determine this..? RU going by the dash gauge..?

The gauge can read incorrectly.., soooo.., verify the over heating first.

BrokeAsAJoke · Sep 9, 2013

I know the fan is not a priority but I am the type of guy who does preventive maintenance. Ok thank you for the fan clutch test will do that here in a bit to see if it is in fact broken. Yes before the vapor lock issue it was overheating and turning off while idling. The temp gauge also read it as overheating when it turned off.

Rons beast · Sep 9, 2013

Thinking through this problem, I first had to agree with Bully, as the fuel is under a pretty high preasure and a seal would leak if it were bad. However, it is possible that the seal/s can retain preasure from leaking fuel, but allow air to enter the system. I have seen this with AC systems, and my home pool pump.

I believe you had checked the FP regulator and it was OK, so I have to believe that if you have air in the closed fuel system it must be drawn in past the seals.

It looks as if the first order is to repair the overheating problem, then I would try to isolate the fuel problem by rigging an auxiliary fuel supply with a separate pump and fuel can.

Finally take a good look at the top of the fuel tank and the connections there. It is a known area where the fuel flex hoses get cracked, and sometimes the fuel that leaks is little and evaporates before dropping on the ground so no leaks are apparent.

good Luck

Bully Bob · Sep 10, 2013

Keep us updated BAAJ..!

After re-reading.., I'm suspicious of the in-the-tank pump (if there is one) -OR- whatever actually picks up the fuel. (pick-up tube)

You could definitely pick up air there.

If there's just one hi-pressure external pump..., air can enter the line between the in-tank pick-up tube and the

inlet to the pump.

Meaning the in-tank pump could have an issue..., OR- the pick-up tube may be faulty.., OR- the line fr. the tank to the

exterior pump is faulty.

Don't see how it's poss. for air to enter a +- 40psi fuel line.

Is vapor lock even poss. on a FI vehicle....????

Rons beast · Sep 11, 2013

I too am hoping to find the cause to this one. I agree with Bully, it is unthinkable that air would be drawn in a system under that pressure. But I have seen it before on the lower pressure side of the fuel pump. It would be great if someone with a Bronco II, could chime in and educate us on the placement and number of fuel pumps.

Bully Bob · Sep 11, 2013

Yep...,

We've gone full circle here & reminds me of what should have been said at the get-go.

(shame on me..!)

THAT IS; BJ should have & should still purchase THE $15 BOOK on this rig.

Or.., check one out at the library.

We always recommend this so as to eliminate all this going in circles & all this guess work...

Point being.., the owner will then know what's there (factory) and, what's been changed/modified

over time by previous owner(s)

THEN..., it's possible for members here to help with problems/issues & be "on the same page".

BrokeAsAJoke · Sep 13, 2013

Ok I am saving up to buy the parts to fix the overheating, I have one more question. There is a module that sits right under the distrubuter. We have a old mustang can't remember the year but the module was going out. The issue was every time it ran and when it warmed it, it would sputter and die. We replaced the module from the junk yard, after words it ran like a dream. Could it be this module, would any of you happen to know the actual name of this part? Thank you everyone for your help, having references have helped a lot of guess work.

BrokeAsAJoke · Sep 13, 2013

Yes I have the book for my rig, just purchased it today.

Bully Bob · Sep 13, 2013

98% yes..., Ford went to electronic ignitions fr. the mid 70's on.

First, it was the Duraspark then the Duraspark II

I'm guessing the B-II did as well. And yes those modules fail at times.

The stator (I think it's called) inside the dizzy can fail also but much more rare.

Your book will call these components out for you, with some pics as well.

BrokeAsAJoke · Sep 14, 2013

Yeah gonna crack open the book. Going to get fan clutch and buy that module, see what happens after that but it is the waiting game now. Pay day is in 2 weeks.

Bully Bob · Sep 14, 2013

You'll notice, in many posts here on this site, our mission is to steer folks away from throwing parts

at problems W/O doing some testing. Or at least several other opinions. (neighbors, shops, auto parts stores)

However in some cases one may not have this option.

I don't think either of those parts are cheap. A little involved but the module can be tested as well.

The repair books usually have a page or two with PROBLEM / POSSIBLE CAUSE(S)

We here are advising mostly fr. memory & it's not unusual to overlook somthing.

The books also show some initial tests.

Hang in there..! You'll get it solved.........

B

86' Bronco II vapor lock/gas issues

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