It will become obvious that I am not the best mechanic in the world so keep that in mind when you hear my questions.
My 1970 914-6 (GT replica w/ twin plug 2.5) is not feeling too well. A job change kept me away from the car for several months and now you guessed it - it will not run.
What have I done so far... I suspect that the gas is bad so I drained the gas from the tank, replaced it with new gas (even put in a couple of gallons of high octane racing fuel (I know the fuel is OK now).
What the car is doing... It will start if I put a little gas in each carb (has 40 MM PMO's) it starts right up and NOW if I keep my foot in it I can keep it running. It will not idle and it does not hold a constant RPM with no change in throttle position?
I think the fuel psi could be the issue or there is something wrong with the carbs(different settings on the regulator between 3 psi and 9 psi do not seem to help or hurt)? Could the PMO's be plugged with crap (when I left the car sitting I ran it out of fuel prior to storing the car). Maybe the factory fuel pump is going bad. The car was set up like the GT with the factory fuel pump moved up front. Car ran fine before storage (actually would flood really easily prior to the storage period). Does someone rebuild the factory pumps as I have an extra that is leaking badly and thought I might re-build it and try that but would rather not just "swap parts".
Any thoughts, Thanks.
Full Version: What's wrong with the fuel system?
Plugged idle jets? Today's fuels do break down quite quickly, and I wouldn't be surprised if the jets didn't get blocked.
The same think could happen to the fuel pump I imagine, but if you have fuel pressure, it should be OK. I run mine at about 3.5 psi, the Webers don't like high fuel pressures!
The same think could happen to the fuel pump I imagine, but if you have fuel pressure, it should be OK. I run mine at about 3.5 psi, the Webers don't like high fuel pressures!
Worst case is the fuel sock filter in the tank is stopped up. Has it ever been replaced?
If your PMO's have screw on fuel filters, they may be clogged with gunk...since you have fuel pressure up to the point where you have your pressure regulator.
If it runs and just won't idle, it's probably the idle jets. Not that uncommon for them to get gummed up.
When you say it won't idle, does it cough and sputter before dying?
Try blowing out the idle jets. See below, these are the idle jets. Unscrew them out, and make sure there is nothing in the end at the hole on the point. There are 3 on each side. Not sure if yours have a small o-ring, but don't lose them!!
Click to view attachment
If that doesn't help, maybe it's just the adjustment screw on the linkage that's off. My experience is that engines with carbs never seem to work the same after a time off....no clue why.
This isn't a good picutre, but on the front of the carbs where the throttle cross bar is there is a stop adjustment screw that stops where the throttle returns to on idle. Try adjusting both sides a little to see if it will up the idle enough to stay running. You may have to readjust back after a while...the engine may correct itself after some time.
Click to view attachment
When you say it won't idle, does it cough and sputter before dying?
Try blowing out the idle jets. See below, these are the idle jets. Unscrew them out, and make sure there is nothing in the end at the hole on the point. There are 3 on each side. Not sure if yours have a small o-ring, but don't lose them!!
Click to view attachment
If that doesn't help, maybe it's just the adjustment screw on the linkage that's off. My experience is that engines with carbs never seem to work the same after a time off....no clue why.
This isn't a good picutre, but on the front of the carbs where the throttle cross bar is there is a stop adjustment screw that stops where the throttle returns to on idle. Try adjusting both sides a little to see if it will up the idle enough to stay running. You may have to readjust back after a while...the engine may correct itself after some time.
Click to view attachment
Thanks for all the quick responses.
I will check the idle jets. and let you know what I find (thanks for the pictures).
The car was REALLY hard to start and with much time it seems to be getting a little better. It will NOT start on its own (without putting a little gas in each carb) and if I keep the throttle on it will run.
I am struggling with how to descibe what the car is doing. If I try to hold a constant RPM it is not possible. It will stay for a second then start to die and of course I then blip the gas. Even with no change in throttle position the RPM "drifts". If I let the RPM's get below 2000 the car runs pretty rough (lots of "motor shake" and will die if it gets below 1500. When I watch the fuel psi it does seem to fluctuate a bit so I may change the fuel filter just for grins. If I keep the RPM's above 2500 - 3000 it runs OK and is not missing.
I will check the idle jets. and let you know what I find (thanks for the pictures).
The car was REALLY hard to start and with much time it seems to be getting a little better. It will NOT start on its own (without putting a little gas in each carb) and if I keep the throttle on it will run.
I am struggling with how to descibe what the car is doing. If I try to hold a constant RPM it is not possible. It will stay for a second then start to die and of course I then blip the gas. Even with no change in throttle position the RPM "drifts". If I let the RPM's get below 2000 the car runs pretty rough (lots of "motor shake" and will die if it gets below 1500. When I watch the fuel psi it does seem to fluctuate a bit so I may change the fuel filter just for grins. If I keep the RPM's above 2500 - 3000 it runs OK and is not missing.
If you pump the gas a few times before trying to start it, can you get it to start without putting gas in the carb?
Try this too: you need someone to help you here. Look down into each stack, and have someone pump the gas once or twice you should see the jet inside squirting fuel into the throttle body. If one is not, then it's clogged.
It could also be the float is stuck. does the fuel look approximately at the same level in all of the site windows? Doesn't have to be exact, but you should at least see fuel in all of them.
Try this too: you need someone to help you here. Look down into each stack, and have someone pump the gas once or twice you should see the jet inside squirting fuel into the throttle body. If one is not, then it's clogged.
It could also be the float is stuck. does the fuel look approximately at the same level in all of the site windows? Doesn't have to be exact, but you should at least see fuel in all of them.
Interesting question. A couple of times it did start yesterday after it died but 99% of the time I had to put gas in the carbs to get it to start (runs really good until that gas is gone then it is a real chore to keep it going). This is why I wonder about the fuel deliverability? I will try to get the wife to help tomorrow (she loves the gas/exhaust smell and the nice quiet blipping of the throttle). I should probably yell at my PCA friends for assistance instead. Will try your suggestions.
Back to basics. Check that your fuel pump is working properly... both pressure and delivery.
Cold weather and no chokes makes this harder in the winter, but it sounds to me like a delivery problem. I have seen several cases over the years when a pump would happily get up to pressure quickly, but would not deliver the proper volume under load.
If the car ran ok before, and the linkage/synchronization was ok, then then linkage is adjusted properly and your filters are likely fine, but I'd check them anyway.
Webers have all of the jets accessible from the outside. Write down what your settings are, then remove and clean them all up and see what happens.
Good luck!
Cold weather and no chokes makes this harder in the winter, but it sounds to me like a delivery problem. I have seen several cases over the years when a pump would happily get up to pressure quickly, but would not deliver the proper volume under load.
If the car ran ok before, and the linkage/synchronization was ok, then then linkage is adjusted properly and your filters are likely fine, but I'd check them anyway.
Webers have all of the jets accessible from the outside. Write down what your settings are, then remove and clean them all up and see what happens.
Good luck!
Starting a carbed car, after it has sat for a month or 2, can be a bit of bother.
It does sound if if there is a delivery problem.
Pop off an air cleaner. Run the fuel pump for 30 seconds or so....if you don't have a separate switch for that just turn on the ignition switch. The carb bowls should be full in 30 seconds or so. Hand operating the linkage while looking down the throats should provide a healthy stream of gas from each accelerator pump nozzle.
No gas, look up stream for the problem. If gas is good, downstream. That will give you a place to start.
A cold motor is a stinker to keep running. Mine required constant goosing the throttle for the first minute or so....then ran just decent till warmed up a bit.
A side note. If the car has sat for a week or more crank the motor over (making no attempt to start it) for 30-45 seconds to get the oil out of the sump and into the oil tank. 9eleben motors have a nasty habit of draining back ALL of the oil into the sump. Yours may not....but do you know?
It does sound if if there is a delivery problem.
Pop off an air cleaner. Run the fuel pump for 30 seconds or so....if you don't have a separate switch for that just turn on the ignition switch. The carb bowls should be full in 30 seconds or so. Hand operating the linkage while looking down the throats should provide a healthy stream of gas from each accelerator pump nozzle.
No gas, look up stream for the problem. If gas is good, downstream. That will give you a place to start.
A cold motor is a stinker to keep running. Mine required constant goosing the throttle for the first minute or so....then ran just decent till warmed up a bit.
A side note. If the car has sat for a week or more crank the motor over (making no attempt to start it) for 30-45 seconds to get the oil out of the sump and into the oil tank. 9eleben motors have a nasty habit of draining back ALL of the oil into the sump. Yours may not....but do you know?
QUOTE(J P Stein @ Dec 16 2011, 12:20 PM) 
Hand operating the linkage while looking down the throats should provide a healthy stream of gas from each accelerator pump nozzle.
duh....not sure why I was thinking you needed someone on the pedal - yep, just hand operate the linkage...
I hadn't had my coffee for the day yet when I posted what's above...so take it all with a healthy dose of skepticism...
Happy happy joy joy... worked the linkage and had only one working (five not working). Pulled them all and found most plugged with crap? Replaced fuel filter (did not appear to be bad but not expensive).
After cleaning all the idle jets jumped in the car and cranked it up. It ran fantastic, idled fine. WOW. Very cool. Let the car warm up, aired up the tires and drove it for the first time in almost a year.
What a drag having to leave the car sitting. My job will pull me away in a few weeks. I have 2 gallons of 112 octane racing fuel mixed with 2 gallons of 91 octane (w/ some 5 or 10% freakin ethanol) for a total of 4 gallons in the tank.
Ideas on what to do with this fuel.? The guy at the fuel place said the VP C12 does not break down like the new gas does but still wondering if I should drain all the fuel out before I leave again? Is pulling the fuse on the pump and running the carbs out of fuel OK as well?
Thanks for all the great advice and input.
After cleaning all the idle jets jumped in the car and cranked it up. It ran fantastic, idled fine. WOW. Very cool. Let the car warm up, aired up the tires and drove it for the first time in almost a year.
What a drag having to leave the car sitting. My job will pull me away in a few weeks. I have 2 gallons of 112 octane racing fuel mixed with 2 gallons of 91 octane (w/ some 5 or 10% freakin ethanol) for a total of 4 gallons in the tank.
Ideas on what to do with this fuel.? The guy at the fuel place said the VP C12 does not break down like the new gas does but still wondering if I should drain all the fuel out before I leave again? Is pulling the fuse on the pump and running the carbs out of fuel OK as well?
Thanks for all the great advice and input.
QUOTE(david63 @ Dec 16 2011, 11:27 AM)
Happy happy joy joy... worked the linkage and had only one working (five not working). Pulled them all and found most plugged with crap? Replaced fuel filter (did not appear to be bad but not expensive).
After cleaning all the idle jets jumped in the car and cranked it up. It ran fantastic, idled fine. WOW. Very cool. Let the car warm up, aired up the tires and drove it for the first time in almost a year.
What a drag having to leave the car sitting. My job will pull me away in a few weeks. I have 2 gallons of 112 octane racing fuel mixed with 2 gallons of 91 octane (w/ some 5 or 10% freakin ethanol) for a total of 4 gallons in the tank.
Ideas on what to do with this fuel.? The guy at the fuel place said the VP C12 does not break down like the new gas does but still wondering if I should drain all the fuel out before I leave again? Is pulling the fuse on the pump and running the carbs out of fuel OK as well?
Thanks for all the great advice and input.
That must be part of Murphy's law. I've never had that problem.....had most of the rest, tho. It doesn't bode well for the cleanlines of the carb's internals.
A tear down/cleaning /rebuild would be advisable.
By all means, run the gas out of them. I'd pump the stuff out of the tank for fear that that combo you have in there is mucking up the works.....blow out the lines also.
Good to hear you got it running.
you may want to try this: run a bunch fuel system cleaner through it on a fairly empty tank. let it run for a while, shut it down and let it sit a day if you can. then start it up, run it again for as long as you can, then do what you said.
Back about 15 years ago, a good friend of mine owned a small Ford dealership and told me this: When you take your car for a 'Fuel System/Injector cleaning', all they do is hook up to a gas tank bypass and run pure system cleaner through it - for at the time $175!! He told me that instead of wasting the $$, to run your car almost to empty, put 3-4 qts of STP or some other fuel system cleaner in, start it up, and let it just idle there for a while (15-30 min). It will run very concentrated cleaner through it and really dissolve any build up. Mostly helps with the carbon build up in the engine and fuel injectors, but it really helps everything.
I do this on each car once per year....when we sold our 993 with 198,000 miles on it, it had never had a rebuild, and still had perfect compression, passed emissions, and burned no oil. Same with our 3.2 in Huey, and the 190,000 mile engine on our Tahoe that runs perfectly.
Just a good inexpensive maintenance trick/idea...and it may help clean out some of what's in your carbs. But JP is right, it may be time for a carb cleaning/rebuild.
Congrats on getting it running!
Back about 15 years ago, a good friend of mine owned a small Ford dealership and told me this: When you take your car for a 'Fuel System/Injector cleaning', all they do is hook up to a gas tank bypass and run pure system cleaner through it - for at the time $175!! He told me that instead of wasting the $$, to run your car almost to empty, put 3-4 qts of STP or some other fuel system cleaner in, start it up, and let it just idle there for a while (15-30 min). It will run very concentrated cleaner through it and really dissolve any build up. Mostly helps with the carbon build up in the engine and fuel injectors, but it really helps everything.
I do this on each car once per year....when we sold our 993 with 198,000 miles on it, it had never had a rebuild, and still had perfect compression, passed emissions, and burned no oil. Same with our 3.2 in Huey, and the 190,000 mile engine on our Tahoe that runs perfectly.
Just a good inexpensive maintenance trick/idea...and it may help clean out some of what's in your carbs. But JP is right, it may be time for a carb cleaning/rebuild.
Congrats on getting it running!
When you leave to go back to your job get a product called "Stabel??" and put into the fuel tank and fill up the tank. Run the car until you know that it has Stabel through out the fuel system.
Product keeps the fuel from deteriorating and minimize water vapor.
Use it on all my vehicles setting at 7200 feet (Flagstaff, AZ) and so far I have not had any trouble starting after they set through the winter.
If you do not have any time, I would look at the fuel tank, sockets and pump up to the carbs. Take a pressure reading and see where you are. I would really like to know what caused the fuel jets getting clogged. Deterioration of fuel????? Maybe, but I would like to know what type of contamination plugged up things. What does it look like? Is the tank dirty and rusty? fuel socks??
Good luck and Merry Xmas. It looks like you got to drive the car a little and that is a great Xmas present.
Steve Hurt
Product keeps the fuel from deteriorating and minimize water vapor.
Use it on all my vehicles setting at 7200 feet (Flagstaff, AZ) and so far I have not had any trouble starting after they set through the winter.
If you do not have any time, I would look at the fuel tank, sockets and pump up to the carbs. Take a pressure reading and see where you are. I would really like to know what caused the fuel jets getting clogged. Deterioration of fuel????? Maybe, but I would like to know what type of contamination plugged up things. What does it look like? Is the tank dirty and rusty? fuel socks??
Good luck and Merry Xmas. It looks like you got to drive the car a little and that is a great Xmas present.
Steve Hurt
FWIW my car regularly sits for 2-6 weeks between use. I try to start it up every 1-2 weeks but am not consistent with that. I've never had problems but nonetheless started using Stabil per recommendations I got. (Esp. since the car has been sitting in shops for extended periods this past couple years.)
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