Backfiring Issue
Thread Starter
|
Mountain Pass
Joined: Aug 2000
Posts: 139
Likes: 1
From: Marshall TX
Backfiring Issue
It's an all original '50 F-1 with Flathead V-8, 6v positive ground, original style fuel pump, carb and distributor, etc.
I have recently put on a new battery, plugs, wires, points, condenser, coil and set the timing. Since then I have taken it on a few short drives in the past couple weeks and it ran great. Saturday I started on a drive to a car show. It drove fine for about 3 miles then started surging really bad, jerking, shuttering and popping and backfiring thru the exhaust. But, it also had a couple times of running great for 15 seconds or so before returning to jerking and backfiring. I almost made it back home... finally quit running within 1/4 mile of my driveway. I have not attempted to restart since.
What should I look at as the cause of such behavior?
I have recently put on a new battery, plugs, wires, points, condenser, coil and set the timing. Since then I have taken it on a few short drives in the past couple weeks and it ran great. Saturday I started on a drive to a car show. It drove fine for about 3 miles then started surging really bad, jerking, shuttering and popping and backfiring thru the exhaust. But, it also had a couple times of running great for 15 seconds or so before returning to jerking and backfiring. I almost made it back home... finally quit running within 1/4 mile of my driveway. I have not attempted to restart since.
What should I look at as the cause of such behavior?
Thread Starter
|
Mountain Pass
Joined: Aug 2000
Posts: 139
Likes: 1
From: Marshall TX
Would intermittent fuel starvation make it backfire?
...awhile back I had a couple pieces of trash(rust maybe??) settle in the fuel sediment bowl. Perhaps the tank needs to come off and be cleaned...?
...awhile back I had a couple pieces of trash(rust maybe??) settle in the fuel sediment bowl. Perhaps the tank needs to come off and be cleaned...?
Logistics Pro
Joined: Jun 2011
Posts: 4,992
Likes: 420
From: u-rah-rah Wisconsin
I second the notion to start with the fuel line. The crud in the bowl got there from another source - likely the tank. The backfiring doesn't follow completely, but start with fuel, then troubleshoot your spark and air.
DW
DW
Elder User
Joined: Jun 2010
Posts: 934
Likes: 2
From: Sterling, Virginia
Check the engine timing. Could be the distributer is loose or something in it is loose which can cause the timing to retard... casusing the backfire. Then it goes back to the right place (advances timing ) on it's own and it runs ok. Then something slips and retards the timing...back fire. My 2ct
old and in the way
Joined: Jul 1997
Posts: 5,910
Likes: 1,042
From: Lovely Hueytown Alabama
I agree with Zoot.... backfiring is normally a timing problem... check the hold down clamp on the dist, then check around inside for things loose, crossfire on cylinders, etc. new wires/cap should eliminate crossfire... but usually I screw something up when doing anything... never hurts to check..
john
john
Senior User
Joined: Jul 2010
Posts: 106
Likes: 0
From: Palmer, AK
Could be a lean condition or timing. Check for loose carburetor mount or a leak in your intake manifold gasket.
Trending Topics
Senior User
Joined: Nov 2008
Posts: 116
Likes: 0
From: SE IA
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Lead Driver
Joined: Dec 2004
Posts: 7,669
Likes: 13
From: San Jose, CA
I'll throw in a check on the timing chain. Maybe it's loose?
I had a similar issue suddenly develop in my 52, but I'm running the stock OHV 215 6 cyl motor. It was working fine, but started backfiring after driving in a parade. I went through all of the suggestions as made here and still couldn't find the issue. Ended up rebuilding the motor.
I had a similar issue suddenly develop in my 52, but I'm running the stock OHV 215 6 cyl motor. It was working fine, but started backfiring after driving in a parade. I went through all of the suggestions as made here and still couldn't find the issue. Ended up rebuilding the motor.
Thread Starter
|
Mountain Pass
Joined: Aug 2000
Posts: 139
Likes: 1
From: Marshall TX
I will check fuel and timing first chance I get.
It's weird that it ran great as is typical following a tune up then started doing that crazy stuff.
My Flathead 8 has timing gears not a chain... I wouldn't think I had any gears break.
Someone more mechanically experienced can correct me if I'm wrong, but isn't the general rule of thumb if backfiring thru carb it's timing, backfiring thru exhaust fuel/air...?
It's weird that it ran great as is typical following a tune up then started doing that crazy stuff.
My Flathead 8 has timing gears not a chain... I wouldn't think I had any gears break.
Someone more mechanically experienced can correct me if I'm wrong, but isn't the general rule of thumb if backfiring thru carb it's timing, backfiring thru exhaust fuel/air...?
Fleet Owner
Joined: Jul 2004
Posts: 27,283
Likes: 1,046
From: NM
Condensers on 6V systems are the weakest point of the system, and can cause all kinds of problems. The replacements available these days are poorly made (usually in Brazil) and failure within a hundred miles is not at all unheard of.
Thread Starter
|
Mountain Pass
Joined: Aug 2000
Posts: 139
Likes: 1
From: Marshall TX
Update
... finally got around to doing some things to the truck to troubleshoot.
1. Removed fuel tank and cleaned it and blew out line.
2. Everything hooked up correctly firing order wise.
3. Distributor rotating properly and rotor set to #1 and pointer lined up on dot on pulley.
4. Coil tests @ 1 ohm and 8,320 ohms(is this a bit high?)
5. No fire at spark plugs
6. Will a faulty coil cause the backfiring thru exhaust and sputtering?
1. Removed fuel tank and cleaned it and blew out line.
2. Everything hooked up correctly firing order wise.
3. Distributor rotating properly and rotor set to #1 and pointer lined up on dot on pulley.
4. Coil tests @ 1 ohm and 8,320 ohms(is this a bit high?)
5. No fire at spark plugs
6. Will a faulty coil cause the backfiring thru exhaust and sputtering?
Fleet Mechanic
Joined: Aug 2010
Posts: 1,994
Likes: 3
From: Morgan Hill, CA
I'll throw in a check on the timing chain. Maybe it's loose?
I had a similar issue suddenly develop in my 52, but I'm running the stock OHV 215 6 cyl motor. It was working fine, but started backfiring after driving in a parade. I went through all of the suggestions as made here and still couldn't find the issue. Ended up rebuilding the motor.
I had a similar issue suddenly develop in my 52, but I'm running the stock OHV 215 6 cyl motor. It was working fine, but started backfiring after driving in a parade. I went through all of the suggestions as made here and still couldn't find the issue. Ended up rebuilding the motor.
You left out the part about your neighbors calling the police with a report of shots being fired!!
Fleet Mechanic
Joined: Aug 2010
Posts: 1,994
Likes: 3
From: Morgan Hill, CA
On a serious note....yes a defective coil can cause a "no spark" situation.
The values that you measured don't sound too bad, but old coils can have the insulation on the windings break down. Sometimes the result is that the coil shorts out when it's warm.
One other thought...do you have a ballast resistor in line with the ignition wire from the ignition switch? Those can fail as well.
Also...follow up on Albuq's note...check the capacitance of the condensor. Do you have a shop manual to check the specs for the coil and the condensor?? If not, I can look it up for you in my Motor's manual.
Dan
The values that you measured don't sound too bad, but old coils can have the insulation on the windings break down. Sometimes the result is that the coil shorts out when it's warm.
One other thought...do you have a ballast resistor in line with the ignition wire from the ignition switch? Those can fail as well.
Also...follow up on Albuq's note...check the capacitance of the condensor. Do you have a shop manual to check the specs for the coil and the condensor?? If not, I can look it up for you in my Motor's manual.
Dan