Hit and miss

[Bart Smith]

Hello all, and i hope you can help me. I have recently purchaced my ride which ran real well, I have had it about a month now. It has recently and suddenly started acting up. here are the details. at idle it randomly will throw a pop or crack out the exhaust, not much but enough to let me know something is wrong. Upon acceleration sometimes its fine but most of the time it stammers and sputters a bit then catches its stride. It runs real strong if your foot is in it hard but at steady paces is starts the small stammering and popping like it is struggling to get fuel or something. according to the tail pipe black color it looks to be running a bit rich. Oh these are dual solex carbs.
Abouit 100miles before this started I have replaced the piston rings. it ran fine. one evening when i put her to bed and then the next morning it started this.
The things I have done in hope it was not the carbs are Plugs, cap, rotor wires, fuel filters. checked timing, Coil and have re-checked valve clearances. What bothers me the most is how suddenly this went bad. any help will be appreciated. could it be vacum leak or something hanging up the carbs? I dunno???

[GTJIM]

Do you have a 1.1L 'SR' motor?

Sounds like you had the intake manifold off and have an air leak there somewhere. The rich exhaust my be due to pumping fuel in with the accelerator pump when trying to cover up the lean backfire.

Or maybe some crud has blocked passages in the carb - stirred up when they were removed.

You are closer than us - so will just have to go through a process of elimination.

[73Manta72gt]

Where are you in NC?

[Bart Smith]

Trinity

[Bart Smith]

As it turns out the problem is in one of the carbs. I found this out by trying to find out if all my cylinders were firing. (after doing a compression check on all cylinders), by one at a time pulling my spk plug wires off the dist and listening for performance changes. I found out that I could pull #'s 1 and 2completley off and it had no performance change but 3 and 4 would about kill the engine. then i checked spark to both of these cylinders and it was fine. So then i knew i had compression and spark to the cylinders.
Then i shut off the fuel to cylinders 3 and 4 and it began to run but very rough like it was just holding on. this leads me to believe they are barely getting enough fuel. While it was still running and the fuel was shut off to 3 and 4 i pulled theyre wires off and then THEY had no affect on the performance.
So my conclusion is that either the number 1 and 2 cylinder carb is not getting enough fuel or 3 and 4 are robbing all the fuel. Does this sound logical? Thanks

[tekenaar]

Originally Posted by Bart Smith As it turns out the problem is in one of the carbs. I found this out by trying to find out if all my cylinders were firing. (after doing a compression check on all cylinders), by one at a time pulling my spk plug wires off the dist and listening for performance changes. I found out that I could pull #'s 1 and 2completley off and it had no performance change but 3 and 4 would about kill the engine. then i checked spark to both of these cylinders and it was fine. So then i knew i had compression and spark to the cylinders. Then i shut off the fuel to cylinders 3 and 4 and it began to run but very rough like it was just holding on. this leads me to believe they are barely getting enough fuel. While it was still running and the fuel was shut off to 3 and 4 i pulled theyre wires off and then THEY had no affect on the performance. So my conclusion is that either the number 1 and 2 cylinder carb is not getting enough fuel or 3 and 4 are robbing all the fuel. Does this sound logical? Thanks

. . . front carb is likely not your problem on this twin carb R/SR 1.1 engine, let me explain. The twin carb R/SR engines all used OECS (Opel Emission Control System) with an electronically controlled solenoid that fine tunes mixture of the engine.

Since your rpoblem just started happening recently, it is more likely caused by something changing in the electronics, i.e. bad contact, solenoid gone south, control box malfunction, than something suddenly changing in a purely mechanical device like a carb!

Here are some pics of the OECS that may help your further diagnosis . . .