Screaming engine Options

[TonyA]

Here are the symptoms. 2.0 engine running duel Webber’s no chokes. Tried to go to C&C this morning a really cold 45 would not start so I sprayed a little starting fluid into carbs it fired a little because I really want my coffee. Sprayed a little more it fired up and screamed to 5-6K Rpm. Had to turn the key off. Let is sit a little while fired it up again and again screaming to 5-6K. Throttles not stuck. Started again and it idled nicely. Without touching the gas pedal it screams again to 6K. My only thoughts are the new fuel pump that I installed back in July which ran great all summer may be the cause. Any other suggestions. Help I need to get my coffee.

[TonyA]

Here are the symptoms. 2.0 engine running duel Webber’s no chokes. Tried to go to C&C this morning a really cold 45 would not start so I sprayed a little starting fluid into carbs it fired a little because I really want my coffee. Sprayed a little more it fired up and screamed to 5-6K Rpm. Had to turn the key off. Let is sit a little while fired it up again and again screaming to 5-6K. Throttles not stuck. Started again and it idled nicely. Without touching the gas pedal it screams again to 6K. My only thoughts are the new fuel pump that I installed back in July which ran great all summer may be the cause but if it’s producing to much pressure suddenly how could it dump fuel without opening the throttle? Any other suggestions. Help I need to get my coffee.

[mate914]

Here are the symptoms. 2.0 engine running duel Webber’s no chokes. Tried to go to C&C this morning a really cold 45 would not start so I sprayed a little starting fluid into carbs it fired a little because I really want my coffee. Sprayed a little more it fired up and screamed to 5-6K Rpm. Had to turn the key off. Let is sit a little while fired it up again and again screaming to 5-6K. Throttles not stuck. Started again and it idled nicely. Without touching the gas pedal it screams again to 6K. My only thoughts are the new fuel pump that I installed back in July which ran great all summer may be the cause. Any other suggestions. Help I need to get my coffee.

unplug the power to fuel pump. If it runs for a few seconds normal, check pump pressure.

I never needed starting fluid. Just pump the gas a few times with key on, then start.
Matt

[Superhawk996]

Look for massive vacuum leak, bad gaskets, misadjusted linkages, or air bypass screws that are too far open.

Engine shouldn't be able to sustain 5000-6000 rpm on closed throttle plates - simply can't pull that sort of air volume past a fully closed throttle plates.

Not ruling out too much fuel pressure but even if it is getting too much gasoline from overflowing float bowl, it still needs air to burn it.

[Shivers]

If it wasn't for the last rise in rpm, I'd say starting fluid takes less oxygen to fire. You spray a bunch in there you can get run away, until the starting fluid burns off. But if it finally went to idle and then screamed back up, maybe intake manifold air leak like stated above.

[Shivers]

Ooooop's

[TonyA]

Thanks guys. Gaskets all look good from the outside I did not disassemble yet. Everything was fine when I parked it two weeks ago. So if there is a vacuum leak somewhere it is still getting way to much fuel and it would still be a faulty pump correct? It did idle at one point and then ran wild so how could that happen if there was a vacuum leak that suddenly closed up. The pump sounds like it does not stop like the fuel injector type. Is this normal on the carb fuel pumps? Not sure where I purchased it.

[Superhawk996]

Thanks guys. Gaskets all look good from the outside I did not disassemble yet. Everything was fine when I parked it two weeks ago. So if there is a vacuum leak somewhere it is still getting way to much fuel and it would still be a faulty pump correct? It did idle at one point and then ran wild so how could that happen if there was a vacuum leak that suddenly closed up. The pump sounds like it does not stop like the fuel injector type. Is this normal on the carb fuel pumps? Not sure where I purchased it.

None of it really makes sense.

Gotta start somewhere. Too many unknowns. Too much fuel without air will simply cause flooding or a super rich mixture.

I don't like guessing at things. I'd just put a fuel pressure gauge on it -- 3 psi is normal for carbs.

After that you're left with the basics like disconnecting the throttle cable and linkages to make sure something isn't binding and that throttle plates are really closed at idle.

I'd then pull mains & idle jets to make sure something isn't plugged and causing a lean condition (though this is higly unlikely that you'd be running at 5K RPM's lean with throttle closed).

After that you're pulling the carbs and checking gaskets.

After that you're cleaning and rebuilding the carbs, resetting air bypass and mixture screws, resynching the carbs, and finally readjusting linkages, and might as well retime it too.


PS -- when you say no chokes -- are they disabled? Are the choke plates removed AND the enrichment pistons disabled?

[brant]

Are the air cleaner/s off?
Verify the butterfly’s are closed.

Fuel won’t burn without air
Not your fuel pump

[emerygt350]

If the butterflys are closed it has to be a vacuum leak, perhaps taking advantage of your previous rich condition.

[914Toy]

Thanks guys. Gaskets all look good from the outside I did not disassemble yet. Everything was fine when I parked it two weeks ago. So if there is a vacuum leak somewhere it is still getting way to much fuel and it would still be a faulty pump correct? It did idle at one point and then ran wild so how could that happen if there was a vacuum leak that suddenly closed up. The pump sounds like it does not stop like the fuel injector type. Is this normal on the carb fuel pumps? Not sure where I purchased it.

None of it really makes sense.

Gotta start somewhere. Too many unknowns. Too much fuel without air will simply cause flooding or a super rich mixture.

I don't like guessing at things. I'd just put a fuel pressure gauge on it -- 3 psi is normal for carbs.

After that you're left with the basics like disconnecting the throttle cable and linkages to make sure something isn't binding and that throttle plates are really closed at idle.

I'd then pull mains & idle jets to make sure something isn't plugged and causing a lean condition (though this is higly unlikely that you'd be running at 5K RPM's lean with throttle closed).

After that you're pulling the carbs and checking gaskets.

After that you're cleaning and rebuilding the carbs, resetting air bypass and mixture screws, resynching the carbs, and finally readjusting linkages, and might as well retime it too.


PS -- when you say no chokes -- are they disabled? Are the choke plates removed AND the enrichment pistons disabled?

Follow Superhawk's guide which is the logical trouble shooting/fix.

[TonyA]

Can’t work on it for a few days but I will start with either the fuel pressure test first or disconnect the linkage etc to see if throttle is closed FB completely. Then remove everything and install new gaskets. I don’t know enough about these carbs ? On choke plates etc. It was a southern car. PO installed the carbs. Thanks everyone.

[PlaysWithCars]

You didn’t happen to replace a clutch or throttle cable recently did you? Any correlation to the high idle speed and when you have the clutch pushed in? They can get wrapped around each other when you replace them and you’ll get this result when the clutch is pushed in (disengaged)

[Spoke]

Something doesn't sound right with this issue. First off, if there is a vacuum leak with carbs, the engine will run lean and not run well. Plus since it has dual carbs, it is unlikely that both sides would develop a vacuum leak at the same time.

As previously mentioned, if there is an high fuel pressure issue the engine would run very rich and not well at all. I think I'm on board with the thought that the butterflies are hanging up.

[infraredcalvin]

If it wasn't for the last rise in rpm, I'd say starting fluid takes less oxygen to fire. You spray a bunch in there you can get run away, until the starting fluid burns off. But if it finally went to idle and then screamed back up, maybe intake manifold air leak like stated above.

My 6 did this when bringing it back from the dead… it took longer than expected for starting fluid to burn off… I never did understand how the engine would runaway like that with closed throttle….

[emerygt350]

Check the butterflies first. Just look to see if they are seating. No need to disassemble anything but the air cleaner if you need visuals rather than lever position. While watching the butterfly have someone start the car.

If that all looks fine, I would get a buddy to turn the car over while you physically block off most air entering the carbs with your palms. See if you can modulate the rpms. If not you have the mother of all vacuum leaks. If you can, and the butterflies are closed, have your buddy spray carb cleaner everywhere till you find the vacuum leak. I would suspect a large hose leak (like pcv size on a FI motor) but I am not sure what you have on yours.

I suspect one side will be enough to make it race under no load.


Do you have a pcv?

[rgolia]

@TonyA - if you need a second set of hands I am in. Odd condition, only time I had something like that happen was when the accelerator cable was hanging up.

[930cabman]

I always use starting fluid when the temps drop below 45- 50F, never had a problem. Our '85 Alfa spider with Weber 40DCOE has the "starter circuit" which have never been able to work properly. Not sure why you would be seeing very high rpm's? especially if the throttle plates are closed?

[Front yard mechanic]

I wish I could get my engine to scream it just likes whimpering (IMG:style_emoticons/default/dry.gif)

[slivel]

+1 on checking the throttle plates. It's the easiest place to start troubleshooting the problem. Shine a light down the carb and see if the plates are closed. Then run the linkage open fully and let it close. Check that the linkage is allowing the plates to fully close and that there is not some binding or other interference keeping the plates partially open.