Stalling with quick acceleration

[flyboy599]

Hey guys! So it's been four years of active duty since I have had time to play with my Opel. I got back to the storage where I left it and found everything in good repair. Now you will have to excuse me but I'm not terribly mechanically inclined when it comes to cars. I'm an aircraft mechanic but still need to be kicked in the right direction when it has more than three wheels. :-)

Alright so problem 1 has been going on for a while. Slow acceleration is fine. Anything moderate to hard causes the carb to shudder and engine to almost stall unless you ease off. I have a Weber redline (the one with the cable choke). So I took the cover deal off and the outboard barrel is pretty black while the inboard looks brand new. I didn't do the install or tuning of this guy by the way... She idles at 800 and has this problem at all RPM's and gears though it is the worst from a standstill.

I've got books on the GT but none on the aftermarket carb.... :-(

Thanks guys!

[Redskinsjbs]

Sounds to me like an accelerator pump problem. I dont know which carb you have (Redline is just kind of like a kit manufacturer for Webers), but an accelerator pump is a piston whish holds gas and is only used when the throttle is pressed down significantly.

You are getting stuttering and the like because when you jam on the throttle, you are opening the valve for the jets in the carb, which are directly pressurized by the fuel pump. There is normally a little buffer and pump can keep pressure, but with the valve all the way open, the gas begins to flow out of the jets in unison with the movement of the pump, which produces an uneven flow and therefore sketchy engine response.

The accelerator pump is there to continue the existence of this buffer. It is basically a small container of gas which gets shot into the carb if the throttle that is being asked for would result in a loss of this buffer...

Now I will let the real engine boffins step in and tell me how wrong I am and also give you the correct answer.

[First opel 1981]

In addition to the poster above, check to make sure your distributor internals are well lubed. The condition you described can also be caused by a malfunctioning vacuum advance.

Additionally, 4 year old gas isn't the best stuff to run your car on. You might be surprised when you have run through a few tanks of gas.

Since the car has been sitting for 4 years, you should also run a can of fuel injector cleaner in one of the tanks of gas. Also, replace your fuel filter. Wouldn't hurt to spray a can of carb cleaner through the jets as well.

[BQS4]

One thing that has not been mentioned, is that the accel pump is a 5 minute replacement job. So, go on-line and either Gil might have them, or google up any of the on-line weber carb suppliers and get the accel pump diaphram (less than $5) and along with the other tweaks mentioned, should solve your problem.

[hrcollinsjr]

Remove your accelerator pump diaphragm, walk into a real auto parts store and ask for an accelerator pump diaphragm for a (pick early '70's 4cyl. application, Pinto or Mustang II, Chevette or Vega with Holley 5200 carb) and compare them. Say, "this one will work" and "thank you". Previous posters have probably answered your question. Accelerator pump diaphragm, stale gas, and it never hurts to check out both advance mechanisms, mechanical and vacuum in the distributor. I've run across several stuck mechanical advance mechanisms over the years.

Harold

[flyboy599]

Thanks guys! Alright so accelerator pump diaphragm, carb cleaner, injector cleaner and new gas. Sounds like a plan to me. Are there any diagrams on taking this guy apart? Should get a chance to do all of this hopefully this weekend and let you know the results.

[BQS4]

Originally Posted by flyboy599 Thanks guys! Alright so accelerator pump diaphragm, carb cleaner, injector cleaner and new gas. Sounds like a plan to me. Are there any diagrams on taking this guy apart? Should get a chance to do all of this hopefully this weekend and let you know the results.

Go to this link:
http://www.webercarbsdirect.com/v/vs...3236DGAVEV.pdf

You remove cover #29 (in the diagram) 4 screws hold it on, and there's your accel pump diaphragm. Peel it off and pop the new one back in, replace the 4 screws and you're back in business.

[tekenaar]

Originally Posted by First opel 1981 In addition to the poster above, check to make sure your distributor internals are well lubed. The condition you described can also be caused by a malfunctioning vacuum advance. Additionally, 4 year old gas isn't the best stuff to run your car on. You might be surprised when you have run through a few tanks of gas. Since the car has been sitting for 4 years, you should also run a can of fuel injector cleaner in one of the tanks of gas. Also, replace your fuel filter. Wouldn't hurt to spray a can of carb cleaner through the jets as well.

. . . between the fixed plate and movable points plate controlled by the vacuum advance/retard, however, other than a dab of grease on the visible tension steel ball at the outer edge. The movable points plate has three teflon buttons that provide "lubrication" for it and separation from the fixed plate. Oiling it will just gunk it up over time . . .

[tekenaar]

Originally Posted by BQS4 Go to this link: http://www.webercarbsdirect.com/v/vs...3236DGAVEV.pdf You remove cover #29 (in the diagram) 4 screws hold it on, and there's your accel pump diaphragm. Peel it off and pop the new one back in, replace the 4 screws and you're back in business.

. . . hmmm, didn't warn him about the diaphragm return spring . . .

[tekenaar]

Originally Posted by flyboy599 Thanks guys! Alright so accelerator pump diaphragm, carb cleaner, injector cleaner and new gas. Sounds like a plan to me. Are there any diagrams on taking this guy apart? Should get a chance to do all of this hopefully this weekend and let you know the results.

. . . how about this . . .

[wrench459]

Originally Posted by flyboy599 Alright so problem 1 has been going on for a while. Slow acceleration is fine. Anything moderate to hard causes the carb to shudder and engine to almost stall unless you ease off.

Sounds like a fuel delivery problem to me.
It cant handle the fuel flow...possible fuel filter,tank filter,fuel pump and so on.

[GoinManta]

Last but not least.. on top of all the above.

Check for a vacuum leak at the carb or intake manifold..

Vacuum leaks in the Opels can cause all sorts of intermittent problems.

[baronbors]

The sock has been removed from your gas tank- hasn't it?

[flyboy599]

So yesterday I got some fresh gas, dumped some injector cleaner in there and used some spay on carb cleaner. Also fixed a few other things as well as some routine maintenance. Spent a considerable amount of time with the engine running, the top plate off the carb reving it up and watching the acceleration jet squirt fuel. Pretty neat! During hard acceleration it would backfire so I think we have it narrowed down to a problem with that guy.

I replaced the fuel pump already and it has an inline fuel regulator which I have turned all the way up right now. The fuel line has been replaced with an aftermarket steel braided one. The fuel line itself routes around the nose section of the car and the filter unit is mounted forward of the radiator in the middle. The previous owner, way back when, use to race Opels but retired before the car's completion. So, from what I understand, this is not a stock setup. I suppose the fuel filter could be a possible issue. I'm also wondering if the electric fuel pump I installed is strong enough to maintain positive pressure through all of this... What do you think?

I didn't remove the diaphragm yet. I was going to then had this vision of fuel spilling on the hot exhaust manifold and a very bad day after that! So I will when the car is cold.

Thanks for the diagrams! I printed it off and it is on my garage wall. :-)

[First opel 1981]

I forgot to mention something. I'm assuming you are running a Weber carb...
When I rebuilt the carb on my sons GT I somehow missed a small piece of gunk. It was about the size of a pin head but when it landed in the perfect spot, it shut the car down.
What I am saying is you might have some gunk in your float bowl that is interfering with the normal fuel distribution within your carb.

[hrcollinsjr]

IIRC 3.5 PSI is max. fuel pressure for a Weber!

Do you still have points and condensor in the distributor? If the dwell is off it can cause the popping you're referring to.

Harold