1/2 Way Across the Country with a new problem

[kmcrofton]

Hi all,

I am 1200 miles into my 2000 mile trip relocating with the Air Force, and had a new problem surface today. This is on my 72 SerIII 2.25 Petrol.

Basically after the truck gets warm it will begin to sputter and backfire when pushed above cruise speed (hill or accel).

Here is what I have done, and what I will do tomorrow. Any additional help is greatly appreciated.

Done:
Carb cleaner sprayed into butterfly and exterior
Fuel Filter replaced
Sediment bowl emptied on Fuel Pump (Pump is 3 months old)

Do tomorrow morning
Dissassemble parts of carb and spray with cleaner
Change out plugs with gapped ones (.030) and wires
Look for loose bolts and blown gaskets on exhaust manifold and on exhaust line

I am leaning towards it being the exhaust manifold or a loosening of a connection of the exhaust after reading similiar postings in the past.

I also have a new distributor I may change out.

The truck ran fine for the 1st 700 miles in the last 2 days. Today, it just gradually started, no big noises to kick it off.

If anyone knows of anyone who works on Series in the Dallas/Fort Worth area, please let me know as well.

[Terrys]

Check your points.

[Jeff Aronson]

Done:
Carb cleaner sprayed into butterfly and exterior
Fuel Filter replaced
Sediment bowl emptied on Fuel Pump (Pump is 3 months old)

Do tomorrow morning
Dissassemble parts of carb and spray with cleaner
Change out plugs with gapped ones (.030) and wires
Look for loose bolts and blown gaskets on exhaust manifold and on exhaust line

>I assume that the reason this comes up when the Rover is warm is because you have the choke out when it's cold, so there's more gas in the mixture. When you push the choke in, the problem becomes more obvious to you. Is this correct?

The sputtering and backfiring after running for a while lead me to suggest these issues:

1. Your points might have closed up a bit and/or are pitted. As suggested by Terry, check the gap and also check for a blackened or pitted surface. It's worth taking them out of the distributor to do this. If you have another set, it's just as easy to replace and regap them. Also, check the rotor and cap for wear.

My II-A experienced similar problems on high speed travel; it would buck and sputter. I went through all the carb cleaning solutions only to find that the points had pitted out and needed replacement. Once that was done, the car ran perfectly.

Lastly, do check the distributor shaft itself for any wobbling. If there's any movement, your points will open to the wrong gap with increasing rpm. That will cause the sputtering you describe.

Backfiring is either unburned gas in the cylinders [too rich running] or bad timing. It would be worth checking the timing AFTER you've checked and gapped the points. If it's off it will cause the running problems you've described.

2. The high speed jet in the carb [which one do you have?] might have a slight amount of junk in it. It takes very little to affect the mixture. If there's a clog then the carb might not be able to deliver the mixture called for by the vacuum. Carb cleaner sprayed through the jets [mixture, high speed and idle] as well as the orifices you can reach will be helpful.

If you have a Weber or a Solex, remember there's a small filter inside the carb, too, that needs to be cleaned out. On both cars, it's located inside a large bolt on the carb float part of the carb body.

3. Check the intake manifold gasket at the head with a spray of carb cleaner. If it changes the rpm, then you're sucking air and affecting the mixture.

4. It's not very likely, but did your fuel sediment bowl show any evidence of water in the gas?

5. Again, not very likely, but I once had a similar problem when a rubber fuel line from the steel line out of the fuel bowl to the carb started to disintergrate from within. So it was sending tiny particles of rubber into the float bowl, which then would clog the jets under acceleration. When you open up the top of the carb, look for bits of junk in the fuel chamber. That's a sign that you may have these clogs occurring.

6. Again, less likely, but when running for a short time at speed, is your coil hot to the touch [not warm, hot]? If it's breaking down under load, the car will sputter and backfire, too. It's not a common problem but it has happened to me, also.

Good luck with your trip and keep us informed of your progress.

Jeff

[scott]

where are you and where are you head'n?

[kmcrofton]

No progress so far. Leaving fort worth now for schreveport. Plugs,wires did not change much. I'll look at the points again before I leave. Thanks for all the help.

[kmcrofton]

Checked the point gap and it was right at .014-.015. It looked a little bit white, but could not tell if it as pitted. We sanded a bit off each point. That was about all I could finish in the chickfila parking lot. Off to louisiana.

[Mercedesrover]

My guess is crap on the pick-up screen in the tank.

[adkrover]

What about a vacuum leak affecting the advance mechanism?