84 ford Bronco 2 quits at 45mph

[Kylemynee48]

My Bronco 2 quits whenever I try to drive faster than 45mph. I replaced the spark plugs and ignition wires. I rebuilt the carburetor. I also replaced the fuel filter. I don’t know what else I have to replace to fix it. It was working a year ago then sat for a few months and then the problem started. Please help!!!

 

[RonD]

Welcome to TRS

The Engine is a self powered air pump
Needs good flow of air IN
And good air flow OUT(exhaust)

Restrict either one and limited RPM/speed is the result
Vacuum gauge can be used to test for clogged exhaust, cheap tool and very good for diagnosing engines in general


Spark timing, you mentioned plugs and wires which need to be changed now and then, and spark timing also needs to be reset now and then

 

[Josh B]

Do they still use a timing light? I still have one but wouldn't guess anything still use after 1964

 

[RonD]

Timing lights are very very handy to have

You can of course set timing on engines with distributors
You can check if you are getting spark advance when REVing an engine, on any engine
You can check each spark plug wire for steady strobe flash, on any engine, very handy for "coil pack" spark systems, its obvious if spark is "missing a beat" every now and then, and if it is, you will hear engine misfire at missing beat so its a spark misfire and you now know the cylinder number

Timing lights with the clamp on(inductance) probe are best, as you can change to other spark plug wires easier
I have 3 now, pick them up at garage sales, $5 or less, lol

 

[Cees Klumper]

Make sure to remove the 'spout connector' when setting ignition timing (and replacing it when done). Although that seems unlikely to be your issue. I would also check fuel pressure and flow, the pump(s) may be too weak, fuel filter is clogged or there is debris in your fuel tank. As Ron said, it needs air and of course also fuel and good spark at the correct time. And check comoression, too. Good luck!

 

[4x4prepper]

When I have had to fix that type of problem (flat out dying) once up to speed it has been the TFI module. Only once did I have to replace the distributor itself. On the 2.9L, I had to replace the high pressure fuel pump once because the connector was so bad, it would overheat the pump and shut down.

Same with the FSB and F series, though instead it was the Duraspark box, never had a TFI problem on the full sized trucks with them shutting down while driving at speed.

IF you had an automatic transmission and bad torque converter clutch, that can stall an engine around 40-45 MPH. But, you have a 1985 and manual transmission, so, that would be out. My experiences with bad clutches is they will not kill the engine at speed, they just will not go anywhere while reving to the red line once you got to the higher gears.