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1994 Ford Bronco 5.0L XL Hesitates when Starting/Hesitates when Accelerating.

CDA 455 II

ANFAQUE2
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Hesitation when starting started earlier this week; thought it was the POS starter acting up.

This morning hesitated starting up, then when leaving the neighborhood, noticed hesitation when I attempted to accelerate.

Also notice once the RPMs were up it appear to work fine; although I never got out of the neighborhood/I never got to 35MPH.


I'M NOT MECHANICALLY-INCLINED; so the only thing I can think of is clogged fuel filter and/or 257,000-mile factory fuel pump dying.

I have .25 tank of gas.


Any and all help/suggestions are appreciated and encouraged.
 
Was it raining? Or cool and damp out?
Only happens during first startup?

If so that usually means cap rotor and plug wires.
 
I'm going the fuel system route first.


What's the plastic clips on the new fuel filter lines:

Fuel Filter.jpg



Are they just a cheap tool to undo the barbs on the fuel line connectors?:confused:
 
I'm going the fuel system route first.


What's the plastic clips on the new fuel filter lines:

Fuel Filter.jpg



Are they just a cheap tool to undo the barbs on the fuel line connectors?:confused:
The hose ends slide over the 'barb' and the white plastic pieces slip into the hose ends to hold them on, so you can destroy the old ones when removing them. Put a bunch of gas in it as ethanol attracts water, you probably have junky gas.
 
The hose ends slide over the 'barb' and the white plastic pieces slip into the hose ends to hold them on, so you can destroy the old ones when removing them. Put a bunch of gas in it as ethanol attracts water, you probably have junky gas.
I think I know what you're talking about. :homer:


nOOB/dumb question:
Are they required? :confused:

Here's my current set up with SS clips holding fuel lines and filter together:

_nc_ohc=H3OUZqfoyjgAX_uX1jJ&_nc_ht=scontent-sea1-1.jpg
 
Just relieved the fuel pressure via the shrader valve on the fuel rail.


Not a lot of pressure (and fuel) came out; is that normal?
Could be, depends on how much pressure the system holds when the engine is off. I wouldn't bet it would hold a lot. That's why the pump runs for a couple seconds when you first turn the key to the "on" position.

Get one of these: Test Gauge

It will screw onto the schrader valve. Should have 50-60 psi if I remember correctly.
 
Could be, depends on how much pressure the system holds when the engine is off. I wouldn't bet it would hold a lot. That's why the pump runs for a couple seconds when you first turn the key to the "on" position.

Get one of these: Test Gauge

It will screw onto the schrader valve. Should have 50-60 psi if I remember correctly.
Awesome gauge, but dumb question:
What's the clear tube for?

71Y2eRQzR0L._AC_SL1500_.jpg
 
I think I know what you're talking about. :homer:


nOOB/dumb question:
Are they required? :confused:

Here's my current set up with SS clips holding fuel lines and filter together:

_nc_ohc=H3OUZqfoyjgAX_uX1jJ&_nc_ht=scontent-sea1-1.jpg
Those are the newer reuseable metal retainers. Also remove the gas cap when doing this work so it doesnt drain the tank on you. I bet the clear tube is to see air purged after hitting the button on the gage.
 
also once your done cycle the ign a few times to fill the filter with fuel
 
Completed changing out the 5y.o. fuel filter.

This was in said 5y.o. fuel filter:
_nc_ohc=jR1fVuXCdocAX8oC4ff&_nc_ht=scontent-sea1-1.jpg



After a couple of start-attempts, fired up Bronco and let it warm up.

Gently rev'ed engine; hesitated/shook engine before RPMs increased.


Took it for a spin around the block.

Tried to accelerate; same thing: hesitated/shook engine before RPMs increased/speed increased.
 
Sounds like it was ready for fuel filter anyhow.

I would go right to a nitrous system next.
:grinpimp:

well, cap, rotor, wires plugs first then nitrous.
 
I regapped the driver side spark plugs and took the Bronco out of the neighborhood for a spin.


From a dead stop the bronco hesitates/sputters but slowly accelerates.

Once up to 30+MPH everything runs normal. :confused: :confused:


It seems like as long as the RPMs are up, it works fine.

From a dead top or coasting/idling is where the problem is.


I don't think I have a fuel pump problem. 🤷‍♂️

CAP and ROTOR problem? 🤔🤔
 
I regapped the driver side spark plugs and took the Bronco out of the neighborhood for a spin.


From a dead stop the bronco hesitates/sputters but slowly accelerates.

Once up to 30+MPH everything runs normal. :confused: :confused:


It seems like as long as the RPMs are up, it works fine.

From a dead top or coasting/idling is where the problem is.


I don't think I have a fuel pump problem. 🤷‍♂️

CAP and ROTOR problem? 🤔🤔
My 460 was doing the exact issue a few months back. ended up being a bad TFI module
 
My 460 was doing the exact issue a few months back. ended up being a bad TFI module
I disconnected the neg cable and let it sit for 90min.

Reconnected neg. cable/started Bronco/let engine warm up/took her for a spin.


I would say an improvement of 30-40% was had, but it still sputtered/hesitated.

As long as the RPMs were kept up; I shifted into 1st and drove/it responded well.


Does this sound like it might be a TFI/ignition control module problem?
 
No. You need a fancy wrench for the bolts for the tfi, but it just unbolts from the distributor/heat sink. There is a pick up in the distributor that does go bad on occasion, resulting in a no start condition, and that requires removing the distributor and either disassembling it or replacing it.

Check the cap, rotor, and plug wires first before dropping money on a tfi module. >90% of the time the tfi will leave you sitting dead once it heats up, it usually doesn’t present drivability problems.
Ok; rotor/cap/wires.


I'll admit; rotor and cap are in need of replacing.

Said rotor/cap/wires are 5 years/30,000~miles old.
 
How about rodents chewing on shit in the passenger side top of engine? they love to build mouse house and hang out under the intake
 
Rotor and cap get installed this morning and we'll see what happens...


I'll admit; so this has been just an overdue routine maintenance project.

Good learning curve for me because I've never owned a DD this long (17 years) and this old (27y.o.).
 
What is this/what does this do?

_nc_ohc=OlPO0mcWq98AX906nE5&_nc_ht=scontent-sea1-1.jpg


Can air blow out of it?

Also; can it sound like small engine exhaust (put-put-put-put.....)?


There's air being blown perpendicular to the radiator fan's air; right there in that specific area. :confused:
 
After further research; I found out it's an EGR valve.

And symptoms of an EGR valve going bad is precisely what I'm dealing with.


So; I ordered one from Rock Auto for $64 with delivery of this Friday. 🙄

Auto Zone and O'reilly's wants $107! :eek:

Auto Zone/O'reilly's/Amazon has a 2 week delivery date. 😬
 
After further research; I found out it's an EGR valve.

And symptoms of an EGR valve going bad is precisely what I'm dealing with.


So; I ordered one from Rock Auto for $64 with delivery of this Friday. 🙄

Auto Zone and O'reilly's wants $107! :eek:

Auto Zone/O'reilly's/Amazon has a 2 week delivery date. 😬
O’Riellys has 20% off orders over a $100 right now for Labor Day.

Edit: Gets you closer to the Rock Auto price if you’re in a rush.
 
When replacing the EGR valve;
When swapping the EGR valve valve position sensor over to said new EGR valve, can I reuse the old EGR valve position sensor gasket or do I need a new one?

For reference; the sensor that sits on top of the EGR valve:
ohc-olpo0mcwq98ax906ne5-_nc_ht-scontent-sea1-1-jpg.jpg
 
I had this same issue years ago on a 92 5.0 and it ended up being the TPS (Throttle Position Sensor)
 
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