High idle, stutter at 2500rpm

[SoFlo 02]

Recently bought a 75 euro spec 2002, first drive went very smoothly but when I got it home it started having problems.
 
Signs are:
-steady 1500rpm-2000rpm when warmed up
-heavy stutter at 2500-3000rpm in all gears, warm or cold engine.
-if I fully engage the gas pedal it runs smooth (only tested once)
-stutters when revving in idle as well
 
All I've done to the car is replace the battery.
The shop I bought it from said they replaced the distributor cap and rotor because it was the wrong one, according to them. Besides that it is up to date on maintenance.
 
This is my first 2002/carb'd car so I'm not sure which carb it has. But it is entirely stock.
 


 
Engine bay before removing air cleaner
 

 
Carb without choke engaged.
 

 
Carb with choke fully engaged
 

 
The hose under the air cleaner looked to have a slight crack starting. Hard to see in the picture, more noticeable in person
 



 
Different angles of the carb.
 
If any more information is needed let me know and I'll try my best!
 
I love my new 2002, despite only driving it 20 miles problem free [emoji23]
 
-Shamus

[SoFlo 02]

Here's a couple pictures of the car in question!


Sent from my iPad using Tapatalk

[zinz]

EXCELLENT PICTURES, Shamus !! Please take a gold star out of petty cash.

 

Now the fun begins and we can all chime in with a myriad of "could be this?"

 

I see the accelerator pump is wet looking... I'm guessing that it's diaphragm is wasted.  This would give stuttering acceleration which would eventually smooth out once the engine built rpms.

 

 

I would also check the vacuum line leading from the carb towards the distributor... make sure it is connected to something and is not open.  Any vacuum leak will give poor idle and acceleration.  your engine should idle smoothly at no more than 950 rpm (when everything is set correctly).

 

I would also pull your plugs and check the timing.  All these things work in concert and can cause poor running when not set correctly.  

 

Overall, it appears to be a nicely-sorted out engine bay, I'd bet you can get it running nicely in no time.

 

Ed 

 

 

[SoFlo 02]

EXCELLENT PICTURES, Shamus !! Please take a gold star out of petty cash.
 
Now the fun begins and we can all chime in with a myriad of "could be this?" [emoji4]
 
I see the accelerator pump is wet looking... I'm guessing that it's diaphragm is wasted.  This would give stuttering acceleration which would eventually smooth out once the engine built rpms.
 

 
I would also check the vacuum line leading from the carb towards the distributor... make sure it is connected to something and is not open.  Any vacuum leak will give poor idle and acceleration.  your engine should idle smoothly at no more than 950 rpm (when everything is set correctly).
 
I would also pull your plugs and check the timing.  All these things work in concert and can cause poor running when not set correctly.  
 
Overall, it appears to be a nicely-sorted out engine bay, I'd bet you can get it running nicely in no time.
 
Ed 
 
 

Thank you!

A quick forum search shows that the accl pump is easily found at most auto part stores and takes about 10 minutes or so to replace. Is there a way to test the pump before buying a new one or should Indio it for good measure?

I have to go to the store to get a timing light (finally), so I'll check a couple of the hoses before I go to get fresh ones.

Thanks for a point in the right direction!

-Shamus

[esty]

you've got the original single barrel solex....you'll get a lot better performance out of the car and many more smiles with a weber 32/36 but you'll need to buy a 2 bbl manifold

[SoFlo 02]

you've got the original single barrel solex....you'll get a lot better performance out of the car and many more smiles with a weber 32/36 but you'll need to buy a 2 bbl manifold

Eventually when I start learning about the engine aspects of the car more and when I have a break from school my much more mechanically inclined friends are going to help me switch to EFI. Despite their best effort to convince me to swap in a m20 [emoji23]

Also, once I have the engine sorted out and have the car reliable I'll be ordering one of your carpet kits! I've read great reviews.

[zinz]

Just noticed something...

 

Is your throttle return spring closing the throttle completely? (this would give a high, inconsistent idle) It just looks like it's hanging slightly loose.   Esty suggested this in your other thread, actually.

 

Have you tried backing off the idle speed screw to reduce the engine's idle speed ?  Also, you can easily remove the idle jet and spray it out with carb cleaner as they are notorious for getting crud in them and causing poor running.

 

Hope this helps.

 

Ed

 

Edited March 3, 2017 by zinz

[zinz]

Just rebuild the whole carburetor if you are going to replace the accelerator pump.  Kits available online.  Rebuilding a single Solex is child's play and shouldn't take more than hour or so... your's looks pretty clean, but I see leaking gaskets and such.  Rebuild kit will include an accel pump.  ....but you could just replace the pump in about 5 minutes and likely solve your problem.  

 

Stick with the single Solex for now, they are bullet-proof.

 

Ed

 

 

[SoFlo 02]

Just noticed something...

 

Is your throttle return spring closing the throttle completely? (this would give a high, inconsistent idle) It just looks like it's hanging slightly loose.   Esty suggested this in your other thread, actually.

 

 

 

Is the throttle control spring the one in the smaller circle or longer one? I did a quick search and it mentioned a spring on the firewall

 

EDIT: I think I see the spring you're talking about. Im not currently by the car but I'll definitely check it out when I get home.

[zinz]

It's the spring on the top edge of the firewall.  You will see several spots where you can easily move the attachment points to give good spring action.  It should provide some tension at fully-closed to insure the throttle butterflies are closed completely.

 

In your picture, the top circle is an adjustment to the choke mechanism, the lower circle is merely the cable shroud for the choke cable.  It's not necessary to mess with either of those at this time.

 

Ed

[Mark92131]

Change your fuel filter and the cloth covered fuel lines from the firewall to the carb.  The cloth covered lines will hide cracks that can cause fuel delivery issues to the carb (low fuel pressure) and a clogged fuel filter can cause fuel starvation issues that will produce a stumble.

 

Those single barrel Solex carbs are bulletproof, you should have this sorted quickly.  To set up the carb with the engine off, you need to back off the Idle Speed Adjustment screw until it just touches the throttle linkage, then turn it clockwise 1.5 turns.  Then turn the idle mixture screw, just left and under the acelerator pump clockwise until it seats, (not to tight to avoid damaging the needle valve) and then turn it out (counter clockwise) 1.5 turns.  Start the engine, it should barely idle.   Using the idle mixture screw, turn it in until the idle becomes rough and then back out until the engine runs smoother, you are searching for the spot where the engine idle is highest and smooth.  Once the engine is high and smooth, use the idle speed adjustment screw to back the idle off to 850-900 RPM and you are done.

 

Good luck,

 

Mark92131

['76mintgrün'02]

While you are changing fuel lines, take a look at the ones in the trunk.  (You will find them under the plywood floor on the right side).  If they do not look new, replace those too.  They are often overlooked.

[Son of Marty]

I'm with Mark thats about the nastiest fuel filter I've seen on a gas engine, if a rebuild on the carb doesn't help start looking for vacuum leaks around all the hoses and gaskets around the intake manifold just spay carb cleaner or WD40 at the gaskets and see if it helps smooth things out if so there's your leak.

[SoFlo 02]

Thanks everyone! I'm about to head home and spend my weekend off on this car!

[SoFlo 02]

The spring seems fine, it's not very strong but it's holding everything up well.



I was removing the air cleaner again and noticed this gaping hole in the inlet from the air filer to cleaner. That looks like a problem [emoji23]