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1992 Ford Bronco
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Discussion Starter #1
So I've recently acquired a retired FWC Bronco that sat for many many years before I obtained it. During my process I did the essentials needed to get it running and road worthy. Yesterday I took it on its maiden voyage. Full round trip of about 75 miles, not constant driving, hour one way, hour back. I notice a super slight hesitation, very slight, it almost felt as if the converter was going into lockup it was so slight... Made it home, not a single issue. Today I go pick up my car trailer, not a single issue on the way there which is about 13 miles, on the way back it starts the infamous surging shit... Not at a stop but yet under throttle, anymore than half throttle and it's wanting to shut down, pop it in neutral a few times let it clear its self up, keep it going. Stopped and put 8 gallons in it thinking it's a fuel starvation issue cause the fuel level is trash and I didn't replace it.. starts up at the pump, no issues, pull back out and it's starts it again. Looking at places to check and possible parts that are failing due to sitting for 10 years.

Keep in mind, it's only doing this under acceleration of half throttle or more.

Tank was dropped, soaked in cleaner, scrubbed, new pump motor and element installed. New filter.

I'm pretty mechanically savvy so fixing it myself isn't the issue, it's diagnosing while driving.. 馃槀 and it really feels like a fuel issue but I could be wrong and it could be tps or something..

Thanks in advance.
IMG_20210106_121005744_HDR~2.jpg
 

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If it is not a Bronco, it's just not worth driving.....
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First thing I would rule out is a vacuum leak. These old trucks have brittle vacuum lines in them now and if there is a leak it will exhibit symptoms like you described.

Read this thread starting at post # 9 for a great tutorial on looking for vacuum leaks.

That is where I would start.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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Sounds like a sensor going out, a dirty idle air control sensor, possible TPS or vacuum leaks are always a possibility on the Ford EFI hard plastic vacuum lines, they get quite brittle with age.

Running the error codes will help find which sensors have problems in the EFI computer, I picked one up at autozone for $29.99, saved me way more than that many times now.

172937


The sensors are all simple to replace, & after 10 years sitting, I would check the resistance ohms & output signal of every sensor the EFI uses. The proper values can all be found on this site by using the search function here on what they should be if good.

The hard plastic vacuum lines get brittle, and leak even though they look fine, many times they are not. Best bet is to replace every one of them at this age.

Then wiring could be corroded internally, best to check the signals at the pins at the computer. I had a problem where the O2 sensor resistance was in spec, but still throwing a code. So I checked the voltage at the pin & had no signal? Knowing this, i found the connector pins atnthe top of the engine were corroded a simple cleaning & it was fine.

The battery ground to the frame,, then tonthe block, also get very corroded with age & should be replaced & you should also clean all the grounds under the hood,, as they cause all sorts of odd things to happen too. Its all just age related....

Looks like a good Bronco to save, and one step at a time, the forum can help with whatever you need.
 

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1992 Ford Bronco
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Discussion Starter #5
Yea I have seen this forum seems to be full of pretty knowledgeable individuals regarding these trucks.

I'm gonna change the fuel pressure regulator tomorrow, remove iac and brake clean it and do the same with the tps. I'll check the grounds again as well as the vacuum lines and probably just get some line and replace them all to be done with it.

It's definitely worth saving. FWC took good care of these trucks and it only has 127k on the clock so it runs like top. I may cut the cat off as well just to eliminate all possible culprits
 

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1992 Ford Bronco
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Discussion Starter #6
So I cleaned the IAC and really no difference other than I go half throttle now til It starts to act like it's needing fuel.. just got the FPR today so I'm gonna change that out tonight and see if it's still wanting to act like a fool.

What's weird is it's completely fine in park.. will go full throttle with no issue and acting like a fool needing fuel. Just when your running down the road it does it..
 

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1992 Ford Bronco
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Discussion Starter #7
And it don't surge or act like it's hunting for a idle.. hoping this fpr is just gunked up..
 

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I highly doubt its the regulator. To check for a ruptured diaphragm, pull the vacuum line off and see if there's fuel in it. However that would cause a rich condition, not starvation. Best bet is to pull codes. Easy to do without a reader, just ground out the STI port and count the check engine light flashes. The port is underhood on the driver side fender. Single wire gray plug with nothing connected to it, usually in a black cover, unless it's missing. Since it only seems to be affected under load, check the timing with the SPOUT unplugged to verify 10掳BTDC. Plugs, wires, cap and rotor would be a good start as well. Seafoam through brake booster vac line couldn't hurt either, although I'm leaning towards timing/ignition issue.
 

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1992 Ford Bronco
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Discussion Starter #9
Fellow crayon eater 馃嚭馃嚫馃嚭馃嚫馃嚭馃嚫

I changed the fpr, nothing changed, unplugged iac, nothing changed, unplugged tps, shifted funny high idle in park and CEL popped on.

Tomorrow I'll swap the cap and rotor and see where this takes me. Thinking I'll pick up an obd1 scanner and see what it tells me.

I keep feeling like a fuel delivery issue. But I'm prone to over think shit.. I seafoamed it and it got me no where unfortunately. Just gonna keep chugging away at it I guess.

These gremlins are a pain in the ass for sure.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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Spend the $30 on the code reader...

I had a problem before i bought that code reader & just kept guessing & throwing parts at it like you are doing.

I replaced my fuel pressure regulator, coil, engine coolant temp sensor, idle air control sensor, all on guesses from reading other posts here. I was about to start getting into fuel pump replacement. Then I figured I may as well buy a code reader, & a fuel pressure guage to hook to the rail. The fuel pressure was spot on. I hooked up the core reader & it said AIT sensor.

So I had wasted about $80 on parts that were fine, then $30 on a code reader (cuz counting flashes sucks) to find out it was a $14 intake air temp sensor, which was a new part so I would have never guessed it was that. Turned out when I measured resistance on it it was shorted out. The new one reads 0.37ohms @200k

My point is to stop guessing, pulling the codes saves you from buying part after part that doesn't fix the issue.
 

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1982 FSB 302, c6, NP208 manual, manual hubs, manual windows, 3.00 gears LSD rear, 235/75/15 HK ATM
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458 Posts
I had an issue like this on a 300 i6. It was fine with no load on it or cold but once it warmed up it would barely run under load. Mine ended up being the coil to cap wire.
 

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82 XLT Lariat 351w, Edelbrock 1406 4bbl ,C6 auto, auto locking hubs ,33x10.5x15
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First thing I would rule out is a vacuum leak. These old trucks have brittle vacuum lines in them now and if there is a leak it will exhibit symptoms like you described.

Read this thread starting at post # 9 for a great tutorial on looking for vacuum leaks.

That is where I would start.
I second vacuum... And not just the lines, all the stupid little plastic elbows and connectors too...
 

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1992 Ford Bronco
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Discussion Starter #15
I second vacuum... And not just the lines, all the stupid little plastic elbows and connectors too...
Im gonna smoke test the vacuum system tomorrow and see where it takes me. Gonna grab one of those obd1 ford scanners as well
 

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82 XLT Lariat 351w, Edelbrock 1406 4bbl ,C6 auto, auto locking hubs ,33x10.5x15
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Im gonna smoke test the vacuum system tomorrow and see where it takes me. Gonna grab one of those obd1 ford scanners as well
To be honest wouldn't just replacing the old ass lines (that probably need it anyway) be a lot easier? That way u can see the shape of all the connections and eliminate one more potential problem... Plus it's cheap... And you're gonna have to do it sooner or later 馃し
 

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82 XLT Lariat 351w, Edelbrock 1406 4bbl ,C6 auto, auto locking hubs ,33x10.5x15
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Ick... Aren't rusty crusty dry spark plugs usually a sign of a lean engine fire?
 
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