Engine backfire and Idles rough

[rnimares]

Was driving my IV at about 70mph when it started to lose power and backfiring. I was able to get back to the house and checked fuel pump and filter,plugs and points but still unable to fine problem. I know gas is getting to carb.
the car is now hard to start, and idles rough and then stops. any Idea's of what I should be looking for.

Thanks

Rick

 

[Chuck Ingram]

Was driving my IV at about 70mph when it started to lose power and backfiring. I was able to get back to the house and checked fuel pump and filter,plugs and points but still unable to fine problem. I know gas is getting to carb.
the car is now hard to start, and idles rough and then stops. any Idea's of what I should be looking for.

Thanks

Rick

You don't say you checked the timing.
It sounds like the coil has gone and died.Replace the coil is what I would suggest.Back firing is the clue.

 

[Series3Scott]

Same thing happened to me and it was a loose rotor. Check both your rotor and the condensor on the distributor before going too far with more complicated things.

 

[Nickodell]

I'm betting on weak mixture. Most likely: an air leak due to a bad intake gasket, loose intake manifold, or even loose hold-down nuts on the carb or a loose or perforated brake booster vacuum hose. Could also be fuel starvation caused by dirt in the jet(s).

 

[lemansvk]

Scott,

I have noticed your avatar and sign-off - are you running an hotel/guest house now? Have you thrashed your car lately Can't wait for the sign-off involving 'towels'

Cheers, Vic

Same thing happened to me and it was a loose rotor. Check both your rotor and the condensor on the distributor before going too far with more complicated things.

 

[Series3Scott]

Scott,

I have noticed your avatar and sign-off - are you running an hotel/guest house now? Have you thrashed your car lately Can't wait for the sign-off involving 'towels'

Cheers, Vic

Let's just say I'm a huge John Cleese fan, especially during the Fawlty Towers years. I'll be working my way through all the different versions eventually.

I won't be thrashing any Alpines, but if someone wants to show up with a derelict Austin or the Morris equivalent I'll be glad to give it a "damn good thrashing".

 

[pdq67]

If you had just pumped gas prior to the problem, you might just have some bad gas. Been there, done that. Easy fix but hard to get rid of the bad gas once it is out of the tank.

 

[agmason54]

Back fire and rough idle...

Hey Rick,
It can only be carburation (fuel) or ignition.My motto is 90% of carb trouble is ignition. Since you say you are getting fuel and not sucking air at the pump and the carb and intake are not fallling off then it has to be igniton... My guess would be bum condenser, bad coil,cracked cap, junk rotor, or worn down points.(what's left?)
I would buy a can of starting fluid and fire up it up and spray the intake and carb base to see if it perks up.If so you are sucking air....[One time I had apples in the tanks of an SIV(little kids love that gas cap).It would run fine on the flat but when pulling a long hill it would die in the exact same spot each time.I had to pull the tanks and pipes and I found 20 crabapples....]
One time the float seat backed out on a two barrel carb and cut the fuel off.....That will ruin your day.
Ruling out vacum leaks and plugged fuel line and starving carbs then it has to be ignition.Once I lost the little spring that holds the vacum advance in place on the distibutor and it really ran bad.The spring is about the size of a fingernail clipping.
I never leave home without a complete working distributor,coil ,fuel pump,1" seal for the clutch slave,tent,sleeping bag,flashlight,canteen and a quart of Castrol brake fluid.No matter where I've been I've always returned....
Now if all of this fails.I bet you may have valve seat recession. This occurs due to lack of lead in the fuel.I've mentioned it before but got very little response.Driving at 70 without overdrive is asking for it.The exhaust valve seats receed into the head in no time. It happened to me once.My car would not fire up after a long hard run.I finally checked the valves and each exhaust valve had lost all it's lash.They were tight against the rocker. I gave them 14 thou and engine fired right up.I would really like to know that I'm not the only Alpine flogger to experience this.If you want to keep the pedal to the metal install modern exhaust valve seats-I did and never have had to set valves for years and I drive cross country annually. I hope this is not the case but I've seen it happen in two different engines.
Food for thought..
Agm

 

[Bill Blue]

Hey Rick,
It can only be carburation (fuel) or ignition.My motto is 90% of carb trouble is ignition.
Agm

Gears, I'm in 100% agreement with your 90%. A bad condenser can make most anyone think they have a fuel pump problem or dirty carb.

Rick, this sounds a lot like a coil problem. Quite often a car with a bad coil will idle and possibly rev, but miss when any load is put on it. A lot of Alpines have had the ignition resistor removed. This puts an additional load on the coil, leading to a shortened life. If your car has no resistor, or it has been bypassed, the coil would be my #1 suspect.

In any event, I'd be sure points, condenser, coil, etc. are good before chasing fuel/carburetor gremlins.

Bill

 

[rnimares]

Hi Al_ Thanks for the information, but not sure what you mean by 14 thou. Hope your not talking $.

Rick

 

[jumpinjan]

Check that distributor. Could be bad rotor, maybe the cap, bad condenser, bad ground through distributor. There is a very small braid that can give a headache.

 

[Ken Ellis]

I believe he's discussing exhaust valve rocker arm clearances, with inches as the unit of measure.

Ken

 

[Nickodell]

Hey Rick,
Now if all of this fails.I bet you may have valve seat recession. This occurs due to lack of lead in the fuel.I've mentioned it before but got very little response.Driving at 70 without overdrive is asking for it.The exhaust valve seats receed into the head in no time. It happened to me once.My car would not fire up after a long hard run.I finally checked the valves and each exhaust valve had lost all it's lash.They were tight against the rocker. I gave them 14 thou and engine fired right up.I would really like to know that I'm not the only Alpine flogger to experience this.If you want to keep the pedal to the metal install modern exhaust valve seats-I did and never have had to set valves for years and I drive cross country annually. I hope this is not the case but I've seen it happen in two different engines.
Food for thought..
Agm

For long-time forum memebrs, this is beating an old drum (what else is a drum for?), but check if your state, like mine, allows you to use leaded gas under the "limited use, antiques and classics" proviso. Matilda, my Series V, runs on 105LL AVGAS (aviation gasoline, 105 octane, low lead) that I obtain from my local municipal airport. This not only prevents valve recession, it allows the full ignition advance the designer intended.

 

[agmason54]

rough idle backfire etc....

Nick,
I'm glad for you and Matilda but me and War Pony like to hit the highway and can't be bothered with limits.The airport works for you -modern valve seats work for me.
Meanwhile... Hey Rick! Did you fingure it out yet?
Agm

 

[Chuck Ingram]

Nick,
I'm glad for you and Matilda but me and War Pony like to hit the highway and can't be bothered with limits.The airport works for you -modern valve seats work for me.
Meanwhile... Hey Rick! Did you fingure it out yet?
Agm

Hey Al
I sent PM but your box is full