next logical step...

rocco79/138

True Classic
OK. I have actually buttoned everything up on the '79 loosely but buttoned all the same. I put the last couple pieces on Thursday afternoon and made a very short run... After a long down time I got the engine back on line with the usual stuff... Plugs, cap, rotor, wires new fuel lines, filter. Knew the front crank seal was leaking so I replaced that and set the mechanical timing correctly. Getting fuel the the carb was a bit of a challenge but a recheck of all the fuel lines revealed a crack in the tank to pump line(that is why they all got replaced) Once the tank was emptied of old fuel and new added I got it to start and run... Actually built a reach rod to turn the key through the passenger window while standing at the engine bay so I could operate carb and adjust distributor to get it to catch. These things go so much better with more than one person but being an advanced party guy means nobody but me and the need to create a work around for these tasks. Got it to run and set timing and it seemed to idle fairly well for not having run for 8-9 years. Would start and run quite easily after that... Would actually rev quite strong as it warmed up, no smoke nothing to cause any alarm. So I was quite surprised when just a 100 yards into the first little run it sort of just tripped. It shuttered a bit then rolled fine and when I shifted from first to second had good torque and then just transitioned from OK to not... loaded up and would not come up on power again. Sort of acted like fuel problem. I checked the timing with my light because I think the dist shifted reset and retorqued the hold down. Rechecked mechanical timing, though the car is not acting like a timing problem(maybe advance but not initial) I will get 5 gals to put in the tank in case I am having a pick up problem. I have some fuel stabilizer I can toss in as well. Question is: Has anyone experienced a similar start up issue? Quite close and it runs/ran too good to be a big deal. Thanks for the input and will keep you posted!
Rocco
 
dragged crap into carb? was there a filter right before it?
hopefully not but head gasket? is there oil in the coolant or vice versa?
 
You have a '79, and the '79 motor has about 83 bazillion vacuum lines that are connected through a thermovalve that opens as the motor warms up. A vacuum leak in these only shows up after the motor starts to warm up.

If you have the stock carb for the '79 it will a 28/30 DHTA with a vacuum-operated secondary, and that can do all sorts of strange things under power when the secondary opens that it won't do revving at idle.

But follow up on jvandyke's suggestion about crud in the carb first.... That's the explanation more often than not. What you're describing sounds like what happens when the primary idle/transition circuit is flowing properly but the primary main is not. It doesn't help any that in these carbs the idle/transition circuits draw fuel from a port a bit higher in the float bowl than the main circuit, so it's easy for the main to be sucking water and crud while the idle/transition circuit is working fine.
 
Actually built a reach rod to turn the key through the passenger window while standing at the engine bay so I could operate carb and adjust distributor to get it to catch.

Your friendly local autoparts store will sell you a remote starter switch for ten bucks or so. It's just a pushbutton with two long leads, you connect one of the leads to unswitched 12 volts (alternator output, starter lug, battery positive terminal) and the other to the starter solenoid (or anywhere along the path from ignition switch to solenoid). Now pushing the button will crank the motor
 
thanks for the info...

Not any contamination in the oil... Would not be a disaster though because I have a cam I am not going to install at this time but if I had to replace the head gasket I would have the head checked and valve job done so setting the head back up would include the cam upgrade... Switching due to the engine heating up is the ticket! My '86 had a leak in the hose that runs from the valve attached to the head which closes when it comes to run temp... Chased that thing forever till I found the problem... Got a couple crab rebuilt kits so I can go there if needed but the shift from PRI to sec when op temp is achieved falls right in line with the behavior. Thanks again...
I did not mention in initial post but my dad had this car for the past few years and he never met a vacuum line he would not yank! Lots of evidence of very shoddy work throughout the cars life and 41,000 on the odometer is a pretty good sign that not much happening good regarding upkeep!
I am familiar with the remote start switch just never needed or acquired one before and my woodshop was 12 miles closer than the parts store... On the upside if the wrong person ever found out how much $ I have pumped into this "little" project my start stick would be a great cane so I could be up and around sooner...:laugh:
Rocco
 
is there a posting somewhere that...

Covers the basics of the vacuum system so I could easily identify which hoses need to remain and which can be deleted? Some can go away and be plugged but others need to have the vacuum input to function properly. There is a manifold on the left (drivers side) of the engine which has two ports broken off... Will trace the remaining hose to see if it could be the problem. I put an upgrade manual carb on my GVL but I really like the water controlled (no human input) choke system. Not really into any sort of super performance but prefer ease of use and drivability. I am sure that I am in the minority but I have never had an issue with the car... Power wise, braking, whatever I have been pretty happy since '81 when I bought my first new one... So I am really just trying to get things close to stock and functioning as close to design as I am able to considering whatever damage others have done to the car.
 
OK...

This is the diagram you seek... can be found in BEST OF X WIKI in the technical info section.



The 3 port valve opens when hot coolant circulates sending vacuum to the Dizzy to advance and the Carb to operate the secondary. Also to the Gulp calve...

Broken bungs could be a real problem with what you describe...

This is Carb drawing is CLOSE enough to show you what you should be doing with the FOUR brass "screws" between the two venturis (looking down the throat) of the carb.



They are labeled 49 -57 and come out in FOUR long pieces... DO NOT CONFUSE THEM, KEEP THEM IN ORDER.

With a WHITE cloth clean them and blow them out and insure you can see LIGHT through all the orifices... DO NOT USE PINS or anything else but a soft bristle brush to clear a clog.

After snugging them back down... start the car. If it runs ANY different than it did before... GOOD or BAD, but DIFFERENT... the problem is in the carb also. Maybe not all, but part of it. The car will need to be completely disassembled and "boiled out".

If it runs GREAT the same scenario needs to be done... as this crud will come back to HAUNT you at the MOST embarrassing time, guaranteed!

I say to you to look in Wiki as well as the 1.0 Version Best Of section not because I am too lazy to post, but that you will find things for yourself much faster than posting here.

Do keep us apprised of your exploits...
 
thanks to all...

Clearly looking the other way and pretending it could not possibly be will not work when reanimating these cars! Even though I did not want to spend my evening poping the carb off for a look-see it was the ticket! As mentioned the secondary was the culprit. Not so much as the shift from cold to warm it was just stuck. Having it out allowed me to clean and free properly without pouring a bunch of junk through as it ran... Tony I will trace the vacuum lines tomorrow and see if the broken one is going the the advance... If so I can swap for another set yes? Did not go through everything but my guess is that the little valve just opens to allow the one to draw a vacuum on the other hose... I do have another fish to fry though while removing the carb I saw no evidence of coolant from either hose supplying the choke control. Really need to flush everything and refill and bleed cooling system. Other than that it is ready to insure and get plate! I will rebleed the brakes and just go back over every part I touched and check to make sure it is where it belongs and torqued if needed. Really nice little car and it runs great! Have not been in a driving X in years! Oh! I do need to finish the exhaust but I have a stocker I can bolt up till I can get to it.
Thanks and Regards
Rocco
 
This my cue to comment

It looks like you have found the main issue, for now. But when you go deeper, keep these thoughts in mind.

Since the topic comes up a lot, I have been thinking about doing a little write-up on emission controls for future reference. But for now I will just say that the vacuum controls on the '79 are relatively simple and operate well, but they, like X 1/9s, require maintenance.
There are only four components of the 79 vacuum system that you might need to check, the gulp valve system, the egr, vacuum power valve, and vacuum accelerator pump.

Stall-outs after warm up can be associated with a stuck open egr, which is a big vacuum leak that the choke cover with extra fuel until the choke deactivates. To check, unbolt the supply tube at the intake and slip a small tab of sheet metal between the connection and the manifold and re-bolt..

The gulp valve can be stuck open. To check , slap a big square of duct tape over the bottom of the valve and see if that helps. The gulp valve control is another thing, but we can leave that until later.

The red, yellow, and green thermovalves on the flywheel end of the cam box/head are simple and easy to test. The red one controls the egr and whether it works or not should not be your problem. It should be open when the engine warms, and closed when cold. But is not a particular leak of concern. The yellow one controls the power valve. It is of concern. It should be closed when cold and definitely needs to be open when the engine is warm. The green one controls the power valve and needs to be open when cold and closed when warm. Then the vacuum capsules in the carb that these control could be busted, too. To test these, take them off and run hot water over them for a few minutes in a sink and check if you can blow through them or not as per the specs above.

Of course the vacuum lines to any of these devices could also be the culprit.
 
Many thanks

Good information all around... Thanks also for the wrap up Larry! I should be able to stay on top of this with all the information I now have.
Thanks again,
R
 
I checked my car as well as several Fiat manuals and the green thermovalve controls the vacuum accelerator pump. It is still driving me a little crazy because with the vacuum accelerator pump connected to the green thermovalve, I noticed that the accelerator pump nozzle dribbles fuel. With the vacuum accelerator pump disconnected there are no fuel dribbles and the car runs great. Can anyone tell me what the vacuum accelerator pump is designed to do? Is there a solution for the dripping pump nozzle? I want to avoid any issues that disconnecting the vacuum accelerator pump may cause.

1979 X1/9 1500, engine is all stock because my car has to pass a smog check every 2 years.

thanks,
Tommy
 
I checked my car as well as several Fiat manuals and the green thermovalve controls the vacuum accelerator pump. It is still driving me a little crazy because with the vacuum accelerator pump connected to the green thermovalve, I noticed that the accelerator pump nozzle dribbles fuel. With the vacuum accelerator pump disconnected there are no fuel dribbles and the car runs great. Can anyone tell me what the vacuum accelerator pump is designed to do? Is there a solution for the dripping pump nozzle? I want to avoid any issues that disconnecting the vacuum accelerator pump may cause.

1979 X1/9 1500, engine is all stock because my car has to pass a smog check every 2 years.

thanks,
Tommy
Tommy, I know what you are describing. My '79 had similar issues. As was stated earlier in this old thread, the '79 has a huge amount of vacuum controls and emissions gadgets. Frankly it is a nightmare. And that '79 carb is another common problem area.

Initially I wanted to get my '79 running in stock form (the car was completely original) so I could compare that to whatever improvements I later made. After verifying the engine was solid, and sorting out all of the vacuum stuff, making sure all of the emissions equipment was working, and sorting all of the electrical issues, it still would not run right. I rebuilt the carb twice and in the process discovered other issues with some of the carb's external devices. Eventually after spending considerable time and money, I decided it wasn't worth the effort and expense to try and revive that carb. Some of those defective attachments are extremely hard to find and prohibitively expensive. So I ended up going to plan "B" and stopped trying to make it work correctly in stock form.

If you do it right, you can replace the carb with a better design, simplify the vacuum mess, and still pass smog in Calif. I realize this does not answer your question and isn't what you want to hear. I know in the beginning when others told me this I was a bit miffed because I really wanted to get it working in stock form (at least initially). However the fact is these '79 carbs are old, worn, and were not well designed in the first place. A better system will net smoother running, less emissions, and more performance...a win/win/win.
 
Back
Top