316 M10B18 Carbed fuel issues?

Sat May 12, 2018 7:59 pm

If no fuel comes out of the fuel pipe to the carb., when it is disconnected and the engine is cranked, then this is a definite reason why your engine won't run. It may or may not be then only reason, but is the problem to sort first.

Tue May 22, 2018 2:27 pm

Update:
I tried experimenting with disconnecting fuel lines and I have confirmed that the pump is working correctly. This makes me think that the problem is most likely an air leak, probably in the carburetor. So, I'm going to re-gasket the carb. Failing that, I will send it off to be rebuilt. I'm also going to replace the distributor cap (I took it off and cleaned the contacts which had accumulated a fairly large amount of carbon), HT leads and the coil.

Tue May 22, 2018 5:47 pm

It could be the fuel filter

Tue May 22, 2018 7:28 pm

Brianmoooore wrote:If no fuel comes out of the fuel pipe to the carb., when it is disconnected and the engine is cranked, then this is a definite reason why your engine won't run. It may or may not be then only reason, but is the problem to sort first.

Are you saying now that fuel does get pumped when you crank the engine? If not, the above still applies.

Wed May 23, 2018 10:49 pm

Rav335uk wrote:It could be the fuel filter

Fuel filter is fine, just replaced.

Wed May 23, 2018 10:50 pm

Brianmoooore wrote:
Brianmoooore wrote:If no fuel comes out of the fuel pipe to the carb., when it is disconnected and the engine is cranked, then this is a definite reason why your engine won't run. It may or may not be then only reason, but is the problem to sort first.
Are you saying now that fuel does get pumped when you crank the engine? If not, the above still applies.

Sorry if I was unclear, I may have disconnected the wrong line as when I tried a second time with the correct line the pump was working perfectly.

Wed May 23, 2018 11:24 pm

So, we're right back at square one again. The only thing that's been established in this thread is that your car is not standard, and has been fitted with a Weber carb.
What makes you think your problems are fuel related and not electrical?

Wed May 30, 2018 4:27 pm

Brianmoooore wrote:So, we're right back at square one again. The only thing that's been established in this thread is that your car is not standard, and has been fitted with a Weber carb.
What makes you think your problems are fuel related and not electrical?

Well, everything spark related has been replaced/is working correctly, yet the fuel filter is empty all the time. I'm convinced it's an air leak at the carb because of how precarious the gaskets look - surely it's worth rebuilding/re-gasketing the carb for the low price of a rebuild kit?

Wed May 30, 2018 7:48 pm

An internal combustion engine isn't that complicated. As long as it has compression, produces sparks at its plugs at approximately the right time, and is drawing in a suspension of fuel in air at very approximately the right ratio, it will run when cranked.
As far as we know there hasn't been any catastrophic event that will have affected the compression, so the next on the list is sparks. You say you have them, but are they at approximately the right time? Any chance that the distributor has been turned, or is set so that the timing is 180 degrees out?
Last on the list is fuel mixture. If fuel is pulsing from the fuel feed hose to the carb. when the engine is cranked, then that is OK, whether or not the filter is full or not. Is it fresh and uncontaminated (with water) fuel that is coming from the pipe?
If all the above is OK, then carb. problems are next on the list. It would need to be a substantial air leak to stop the engine from running. Blocked jets are a more likely cause.
When faced with an engine which seems to be not running because of undetermined fuel problems, I often feed propane from a bottle directly into the throttle body, and see if it'll start and run on that. This confirms that sparks, timing, compression, etc. are all OK, and the problem is definitely with the fuel system.

Sat Jun 02, 2018 11:35 am

Brianmoooore wrote:An internal combustion engine isn't that complicated. As long as it has compression, produces sparks at its plugs at approximately the right time, and is drawing in a suspension of fuel in air at very approximately the right ratio, it will run when cranked.
As far as we know there hasn't been any catastrophic event that will have affected the compression, so the next on the list is sparks. You say you have them, but are they at approximately the right time? Any chance that the distributor has been turned, or is set so that the timing is 180 degrees out?
Last on the list is fuel mixture. If fuel is pulsing from the fuel feed hose to the carb. when the engine is cranked, then that is OK, whether or not the filter is full or not. Is it fresh and uncontaminated (with water) fuel that is coming from the pipe?
If all the above is OK, then carb. problems are next on the list. It would need to be a substantial air leak to stop the engine from running. Blocked jets are a more likely cause.
When faced with an engine which seems to be not running because of undetermined fuel problems, I often feed propane from a bottle directly into the throttle body, and see if it'll start and run on that. This confirms that sparks, timing, compression, etc. are all OK, and the problem is definitely with the fuel system.

Huge thanks for the wisdom, really appreciate it.

Apart from completely re-timing the engine is there any giveaway sign that the timing might be incorrect? I will admit that timing scares me. I struggle to see how the fuel might be contaminated with water. There is also currently Redex in the system.

I'm still convinced it's a carb issue as it isn't sitting flush with the inlet, almost as if it wasn't torqued correctly. But, as you said, it could just as easily be a jetting problem. I will look into running the engine on propane or some alternative.

I think my next course of action will be to confirm the timing is correct and then, failing that, rebuild the carb. I'll also check any vacuum hoses for leaks.

Can't thank you enough for sharing your knowledge!

Sat Jun 02, 2018 1:56 pm

For a rough check of the timing, turn the crankshaft until pistons 1 and 4 are at TDC and the valves of 4 are open. Remove the distributor cap and determine which pole in the cap the rotor is pointing at. Confirm that the plug lead connected to this pole goes to plug 1.
IIRC, there's also a small notch in the aluminium of the distributor body where the cap fits down onto, that should also line up with the rotor arm at TDC.

Mon Jun 04, 2018 4:22 pm

Brianmoooore wrote:For a rough check of the timing, turn the crankshaft until pistons 1 and 4 are at TDC and the valves of 4 are open. Remove the distributor cap and determine which pole in the cap the rotor is pointing at. Confirm that the plug lead connected to this pole goes to plug 1.
IIRC, there's also a small notch in the aluminium of the distributor body where the cap fits down onto, that should also line up with the rotor arm at TDC.

Right, I'll do this asap.