Car almost dies after spirited driving

[Simeon]

Definitely use a gauge. Probably would even if it did have a scale. 

[silasmoon]

Any recommendations? They seem to run the gambit, and many aren't accurate unless they're at room temperature. I suppose I could measure it, disconnect the gauge and leave it. Malpassi makes the filter king, but I hate the idea of proprietary filters. 

[Simeon]

It's not good practice to leave a gauge in circuit for fuel so choose one from a reputable tool manufacturer that you can install and remove. 

[silasmoon]

So I finally got my pressure regulator and gauge installed. The gauge, without the regulator, showed the pump putting out 9 PSI. I then added the regulator and tuned it to about 2.0 PSI. I drove the car this morning and it drove like garbage. Died all the time, horrible throttle response, etc. So I pulled over after 20 minutes and gave it another crank on the pressure regulator, to set it a bit higher.

Drove around a bit more, a lot better, but the car still dies at idle. I can blip the throttle to save it, and it's now doing it a lot when cold, and almost when warm. I pulled over and raised the idle advance to 20 BTDC. It felt very gratuitous, but the car didn't die and idled alright. I am pretty disappointed the fuel pressure didn't fix it. 

A side note, the other day in stop and go traffic my brake pedal went rock solid. I pulled over, checked the linkages, and disconnected & reconnected the vacuum hose. Brakes returned to normal and have been fine for 2 days now. I thought perhaps there was a vacuum leak there, and sprayed carb cleaner around the booster. No effect on idle speed (car was on the choke circuit warming up). When I sprayed the carb clean right into the carb throat, the engine choked a bit and slowed. 

Heading to Bay Area 02 tomorrow, and quite sad the car isn't in tip top tune. Hoping the mass of experts might suggest something though. 

[Dudeland]

How old is the carb? Mine had the crap beaten out of it. Got a new one and now it runs like a champ. 

[silasmoon]

Carb is brand new - 38/38 of Spanish make. I was at Bay Area swap meet today and spoke with a handful of people which resulted in the following suggestions and fixes:

• "It's got a 292 cam in it, let it warm up. You own a race car now. You might have to keep it idling, just blip the throttle. Drive the car."
• "It's the throttle linkage getting caught on the heater hose, pull that away." -> Zip-tied it 1/2 higher than it was
• Timing - I worked with a very nice 2002'er I met and we dropped the idle down to 16 BTDC. I think this was it, and after some initial putzing it didn't do it again. (Fingers crossed)
• The exhaust manifold was just a smidge loose on one of the cylinders, so we tightened it up. I run a 2002Tii exhaust manifold. 
• Opened up the choke throat plates a smidgeroo. They were pretty much shut tight when on, and I backed them away about 1/8 inch

So far it's been a lot of fixes. Maybe it was the sum of all the parts? I did learn a lot and have wrestled more with my car as a result. I will continue to fix and learn and share. 

[Dudeland]

Super cool! 2002 people are awesome! (IMHO)

 

keep us posted.

[silasmoon]

So I dropped my idle speed timing down several degrees and I believe that has helped a lot. I do still get intermittent run-ons when turning the car off however. I fully suppose this is indicative of the car still being too far advanced. I submit to you my 123+ curves. Car runs a 292, 38/38, on CA 91 octane vegan veggie fuel. 

 

 

[silasmoon]

I am starting to go crazy with this issue. The car loves to randomly die, and the idle is extremely inconsistent. Sometimes I will idle at 1100 - sometimes it will sit at 600. I tried to set my carb up *again* and I noticed I cannot, for the life of me, get the car to actually idle with the idle speed screw only 1/2 turn in. Weber notes this points to "larger issues." I had set the idle to a pretty tame 15 BTDC @ 1,000 RPMS. But had to go a full 1 1/4 turns in before I could even get the car to idle roughly to turn the mixture screws. 

[Simeon]

Have you checked your throttle and linkage? Does the throttle consistently snap shut when you release?

 

you really shouldn't be getting this much variation in set up unless the amount of air or fuel is varying dramatically. Ignition advance varies speed too but we have to assume that the one thing that isn't happening is that the 123 is varying. This leaves the carb and the likely culprit being the throttle since you haven't changed the jets and haven't adjusted idle between attempts. Vacuum leak is the other thing but I am sure you have ruled that out. 

[silasmoon]

I always appreciate your comments @Simeon and wish I could buy you a brew for all the help you've offered. I also suspected the throttle linkage, but it has full travel and doesn't bind anywhere as far as I can tell. The two meshing gears on the 38/38 travel their full range and the plates go fully vertical and snap shut to horizontal when I actuate the linkage with my hand. Next time the idle starts to bounce around I will pop-off the air-cleaner and inspect the plates. This isn't always the easiest thing in traffic, and it tends to rear its head more in the first 30 minutes of driving. 

Regarding vacuum leaks I have suspected that from day one, but I have sprayed a prodigious amount of carb cleaner all around gaskets and seals. I tried to really snug down the carb to the manifold today and noticed one bolt was a little loose (praying to Bavarian Motorlords this is the issue). I also checked if the manifold to engine was snug (can't really reach the bottom bolts without taking the whole thing apart). The engine should change idle speed if I find the leak as I understand it, but I've never seen that so far. I will keep spraying and praying. 

One note that keeps coming into the back of my head. During all of this - one day seemingly randomly - the brake booster failed and my brake pedal was rock hard. I disconnected the hoses, checked everything, re-assembled and it was fine thereafter. I ordered entirely new hoses, seals, gaskets, check valve, etc. from Blunt but it is taking weeks for it to arrive.

[silasmoon]

More thinking today after I spoke with some gear heads outside of the 2002 community. Perhaps my idle jet (.50) is too large and there isn't sufficient pressure at low RPMs to properly atomize the fuel and it causes the intermediate hunting issue as the fuel pools. The other suggestion from a muscle car owner was that since I am running a 292, trying to keep the idle at 900 RPMS is just plain too low, and I should bump it to say 1,100 or 1,200 since it's more of a hot-rod now anyways. 

[silasmoon]

This continues to be a complete and total nuisance for me. Warm or cold. The car will almost die when making a rapid transition from the main circuit to the idle circuit. Things I have tried thus far:

• Check religiously for vacuum leaks. The car will idle at 1,000 with only a *slight* hesitation in the needle.
• Installed a fuel pressure regulator and set it to 2.8 PSI. 
• Set my floats to 40mm / 50mm (18mm from gasket to float horizontal with a 2mm needle travel)
• Moved my idle advance between 15 degrees and 18 degrees to test. 
• Done a valve adjustment to .007 across the board on an ice cold engine. 
• Unhooked the vacuum advance
• Changed my vacuum curve on the 123 to kick on at 600 RPMs with no luck and at 1500 RPMs with no luck
• Tried .50 idle jets / .55 idle jets and a .50 and a .55 mixture
  • The .50 idle jets force me to screw in the idle speed screw more than 1/2 turn to keep the car running to set best idle. Weber notes this denotes the need for a larger jet. 
  • The .55 idle jets let the car idle with the idle speed screw 1/2 turn in, but the mixture screws can be tightened all the way in and the car won't die. This shows the jets being too large. The plugs looked a bit rich with the .55 surprise surprise. 
  • I have .52, .47 and .45 jets on the way. 

The only thing left is to ditch the 123 and try a normal mechanical distributor, but I really don't want to drop $300 on a new dizzy just to have it maybe not work. The other longshot is possibly the power-valve gasket is torn on the 38/38 and doesn't disengage during idle, but the carb is brand new. I figure if the jets and dizzy don't solve it the carb is coming apart. 

With a 292 cam the idle vacuum is about 5 Hg/in, due to the overlap. I believe this in part is causing the need to crank up the idle speed-screw to let in more air. Some other hot-rod forums noted that folks will drill holes in the throttle blades, but that seems excessive. :/

Edited May 31, 2017 by silasmoon

['76mintgrün'02]

I would definitely take that carb apart, just to look everything over.

I left the power valve spring assembly too loose during my rebuild.

Tough to trouble shoot those screws from the outside.

It is not that hard to open it up and make sure everything is as it should be.

 

I assume you have brass floats, with the 40mm setting?  Plastic are 35mm, I believe.

 

The one-two-three is probably not your problem.

 

Do you still have the 32-36?

maybe try that.

(I sure like mine ... old as it is : )

 

Speaking of the power valve, I believe it opens with a vacuum signal.

Some guys on an Opel site were nipping length off that spring, to make it cooperate with their vacuum signal.

I thought that was kind of cool... but is probably not your problem.

 

Take it apart and blow everything out again.  One little tiny chunk of crud could be giving you fits.

 

Sorry I do not have more to offer.  I sure would like to help.

Tom

 

[zinz]

Couple things in no particular order:

 

Fuel line at the tank sender... did you ever replace the plastic sleeve? (easy... just snip off a 1" piece of the plastic fuel line in the trunk). You say you are using 5/16" hose at that location... you really need the sleeve on the sender with that size fuel line; otherwise, it won't seal properly and the fuel pump will pull air before pulling fuel.

 

I'm doubtful the 123 is causing your troubles.  What coil are you using? Does it require the ballast resistor? Are all the electrical connections crimped and tight?  recheck all of these... 

 

What plugs and wires are you running? Resistor plugs? Resistor wires? Resistor rotor? 

 

+1 with Mint's suggestion of putting the old 32/36 back on to isolate the problem to the 38/38.

 

Now... your brake booster...  This is weird one.  You had one event where the brakes went hard and it felt the booster failed. That doesn't just happen for no reason. There could be a small tear in the diaphragm of the booster; on decel, vacuum rises and if there is any leak in that booster it could pull vacuum past it. Here's an experiment you can try to isolate if the booster is the culprit to your engine stumble. Remove the booster's vacuum line from the manifold and plug the manifold port.  Does this make any difference?  You can test drive like this, but be careful... you will have brakes, but they will be much harder.

 

You could also simply install the vacuum gauge on a Tee into the brake booster vacuum line and while the engine is running, have someone step on the brakes and look for any fluctuation in the vacuum signal.

 

...pretty frustrating, for sure.  I think you will have an "AHAAA!" moment soon enough.

 

Good luck,

 

Ed