New owner intro; engine bucking issues (possibly ignition or vacuum?)

[Shin Hayata]

Hi.
New member, recent Festiva owner. Glad to be here.
1988 L, carbureted, 4 speed, factory air, purchased in Dec 2016 from estate of original owner
Car is stock, rust free and complete.
Good quality pictures to follow at some point; my digicam recently failed. Any photos posted in the interim are via my tablet.

To date, I've attended to the following:
-Fresh Castrol 5W-30, and new filter
-Drained radiator and refilled with Prestone 50/50 (more drains/refills to follow in upcoming months to fully flush the system. I am familiar with the "Cascade flush" mentioned on this forum.)
-Resurrected non-functioning windshield washer system
-Replaced grotty PCV valve grommet (the PCV valve still tests ok; I have a new Purolator spare if necessary)
-New tires
-Other things related to aesthetics (new floor mats, etc.)
-------------------------------
I really miss having a passenger side mirror. Please message me if you have a clean, complete assembly to sell via PayPal.
-------------------------------

Issue:
I've been driving the car during these cold Pennsylvania mornings. Until today, the car has started, idled, accelerated and cruised in a reasonably satisfactory manner. This morning (28 F), I started and briefly warmed up the car as usual (the car is parked outside at night).

Ten minutes later, whilst on a divided two lane highway and maintaining a speed between 55 - 60 mph, the car began to periodically shudder (buck) at steady speed. It was consistent enough that I decided to turn around and come home. The bucking was a bit more pronounced as I would pull away from a stop and shift gears.

The engine idles quietly and correctly, and the bucking isn't evident if I'm in 4th gear and press the accelerator aggressively. I checked the plug wires on the dist. cap when I got home; all were securely seated.

I'm at a loss as to what caused the driving experience to deteriorate literally overnight.

I'm going to install new Autolite #64 plugs and a new Purolator F23170 fuel filter this morning. The plugs wires appear to be new(ish) and look great.

Any additional suggestions will be greatly appreciated.

If I remove the dist. cap, what should I look for and attend to? It's been many years since I've had to fiddle around like this, so thanks for your patience.

I've used the Search function, and have reviewed threads such as these:

http://www.fordfestiva.com/forums/showthread.php?7771-Vacuum-diagnosing-your-car

-and-

http://www.fordfestiva.com/forums/showthread.php?14073-HELP!!-Emission-Vacuum-hose-diagram-or-blowup&highlight=vacuum%20diagram

I don't have a vacuum tester at time. After eyeballing the many hoses (hardly conclusive, I know), everything seems intact and connected.

Thanks so much.


P.S. - Per the following photo, is there a preference for which side of the fuel filter is used for the In connection (i.e., coming from the fuel tank)? There's no indicator arrows on the filter body. Air flows through both sides without any difference. Thanks again.

Purolator F23170 fuel filter.jpg

[TominMO]

Looked at pics online for this brand and part #, and found one that has an arrow. The tube that comes from the center of the filter goes to the carb.

[bravekozak]

welcomsign
Remove the sender from the fuel tank and check the fuel intake sock, look for water/gas separation, sludge.
Then replace the in line fuel filter.

If all that doesn't help, then change to an Escort carb and throw away your computer control module.

[Shin Hayata]

Spark plugs and fuel filter replaced.
The plugs were just snug, so to speak, and two of them had gaps that were fractionally out of spec.
The fuel filter was grotty, as illustrated below.

A 10 minute test drive confirmed that the bucking was gone, and the car is running as it should. I'll test it again on a cold early morning just to be sure. I may also start using ethanol-free gas as I'm able. The car presently has a tankfull of 89 E10. With that in mind, I'd have been surprised if phase separation after one day was the cause of the stumbling.

I'd like to drain and refill the gearbox next. What's the secret for removing the knurled nut that secures the speedometer cable? Space is very limited down there, and I don't want to damage the surface of the nut. Thanks again.

Fuel and spark.jpg


Edit: Hillbilly -- I replied to your private message (I'll take the mirror), but my Sent Items folder is empty. Thanks.

[Shin Hayata]

OK, I was able to loosen and remove the knurled nut without drama.
The driven gear assembly rotates in place, but won't come loose (up). I don't want to pry on the tab for fear of breakage. Using a pliers to pull up on the assembly would seem to require force sufficient to damage the threads.
Suggestions?

[Shin Hayata]

Ok, enough fussing from me.
Driven gear assembly removed with needle nose pliers and hope.
Old(?) transmission fluid drained. It was a light amber color that looked like fresh engine oil.
2.5 quarts of Castrol Dex/Merc added.
Reassembly occurred without drama. This rite of passage is done.
Another 15 minute test drive; car is running very well. So glad to have gone to the trouble to change all of the fluids (save the brake fluid, which is next) in order to establish a base.Speedometer driven gear.jpg

[dalebwilson]

Be careful tightening down the speedo gear assembly. Over tightening the 10mm bolt will crack the pot metal housing.


Sent from my iPhone using Tapatalk

[Shin Hayata]

Thanks. I made the bolt just snug enough.
No love for the Mazda 121 engineer who thought up that design, that's for sure.

Sent from my SM-T330NU using Tapatalk

[FestYboy]

How local to me are you?

[Shin Hayata]

I'm just one county over, Festy.
I used to have an apartment in Ephrata, actually.
I have to get to the Green Dragon soon. A good reason to drive my little blue Ford...


Sent from my SM-T330NU using Tapatalk

[TominMO]

Whenever I owned a carby car, I always kept a spare fuel filter and the tools needed to change it somewhere in the car. Saved my butt a couple of times on long trips! They seem to need changing about every 10K miles, in my experience. Look for 'em on sale at Rock Auto and stock up.

[Shin Hayata]

Tom, that's good advice. Thanks for suggesting it.

[FestYboy]

I'm just one county over, Festy.
I used to have an apartment in Ephrata, actually.
I have to get to the Green Dragon soon. A good reason to drive my little blue Ford...


Sent from my SM-T330NU using Tapatalk

Sweet! One more member to add to the locals list. And since you're close-ish, I can make myself available for diagnosis/repair in needed.

[WmWatt]

Pretty sure bucking (formerly backfiring?) is an ignition/spark/timing issue. Hope your cleaning fixed it.

[Shin Hayata]

The bucking returned this morning. Odd, because I went for a prolonged drive last evening, and the engine ran as well as I'd want it to.
The next thing I'll do is examine the filter sock in the fuel tank, as suggested, and take a closer look at the many vacuum lines.