My truck just suddenly started idling like crap! I had the idle set at 650rpm's and everything was good until day before yesterday now the idle is jumping from 700-1300 rpm's and sometimes it will die. Once i rev it up or start driving it drives fine!
The truck has a new distributor and rotor,plug's and a weber 34/34 with exactly 3.5psi of fuel pressure.
All vaccum lines have been disconnected except for the distributor advance.
I know the timing is off thats one thing i need to set but it ran fine.
1986 Kingcab z24 2bbl auto
Modified by damn at 6:01 PM 1/10/2010
Need Help/Opinion's
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PEZi
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FN-QR
so it does run fine once driving... as in 100% fine?
i was gonna say it might be the headgasket... but i'm thinking no on that
check the baseplate of the carb and all other areas of it for vac leaks...
i was gonna say it might be the headgasket... but i'm thinking no on that
check the baseplate of the carb and all other areas of it for vac leaks...
Re: FN-QR (PEZi720)
Yeah once i start moving it run's like normal has good power and everything. I guess im going to have to pull the carburetor again and triple check for leak's.PEZi720 wrote:so it does run fine once driving... as in 100% fine?
i was gonna say it might be the headgasket... but i'm thinking no on that
check the baseplate of the carb and all other areas of it for vac leaks...
I also pulled all the plug's yesterday and they didnt look quite right but that could be from the timing being off. I put some carb cleaner in the gas and filled up with 91 octain from a cheveron hopefully i could be a bad tank of gas.
Re: FN-QR (PEZi720)
Dude im stumped???PEZi720 wrote:did you put the cleaner in the gas before or after this problem?
Yes i put the cleaner in after the problem...Truck still runs like crap at idle.
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PEZi
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FN-QR
is the 700-1300 idle cyclical? as in does it continue in the same pattern at all times?
if so... how much time are we talking in between each 'cycle'?
i had a similar issue a while back and it did end up being vacuum issue
if so... how much time are we talking in between each 'cycle'?
i had a similar issue a while back and it did end up being vacuum issue
Re: FN-QR (PEZi720)
Do you have a manual or automatic transmission? Manuals are supposed to have the idle set at 700 rpms.
Have you cleaned out the egr, or is it deleted?
Spray starting fluid on all your vaccum plugs (one at a time) to see if they are making a good seal.
Have you cleaned out the egr, or is it deleted?
Spray starting fluid on all your vaccum plugs (one at a time) to see if they are making a good seal.
Re: FN-QR (dogred)
It's an Automatic no leak's fromt he carb base and yes my egr is deleted. I found the problem...Rocker's needed to be adjusted! Pretty weird that it could suddenly start idling like s*** butdogred wrote:Do you have a manual or automatic transmission? Manuals are supposed to have the idle set at 700 rpms.
Have you cleaned out the egr, or is it deleted?
Spray starting fluid on all your vaccum plugs (one at a time) to see if they are making a good seal.
Went ahead and replaced the intake manifold gasket only to find out that i didnt seal it on right and it's burning coolant Lol im burned out on it today i will install a new gasket tomarrow and hopefully get it to seal this time!
Re: FN-QR (PEZi720)
Yeah but ive never seen any vehicle that had coolant passages running through the intake manifold before. It's smoking pretty bad right now white smoke but no water in the oil so tomarrow im going to see if i can get the gasket to seal better.PEZi720 wrote:well its good to hear you got it running at least
Re: Need Help/Opinion's (damn)
Well just an update...The truck still has a slight idle problem...Not as bad but yep it's not idling right. Im starting to look into the sensor's and emission's system to see what control's what.
Funny thing is you can disconnect the computer and 02 sensor on this truck and it will still run.
Funny thing is you can disconnect the computer and 02 sensor on this truck and it will still run.
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flinterman2000
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Re: Need Help/Opinion's (damn)
Thats basically because it has a distributor and the fuel is controlled by vacuum.
Re: Need Help/Opinion's (flinterman2000)
Can you explain alittle more....The computer throttles back the fuel pump? How does it control fuel.flinterman2000 wrote:Thats basically because it has a distributor and the fuel is controlled by vacuum.
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jtbenfie
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Re: Need Help/Opinion's (damn)
it barely can. the couple of electric selinoids in the carb allow it to shut off fuel completely or slow the flow down a little, but it is still a carb. it will run without the computer, maybe not well, but it will run.damn wrote:
Can you explain alittle more....The computer throttles back the fuel pump? How does it control fuel.
Interesting that adjusting the valves fixed alot of the idle, my idle sucks....maybe its time for me to run the overhead.
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flinterman2000
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Re: Need Help/Opinion's (damn)
Its still a carbed system. The computer only limits the supply of fuel to ensure not too much fuel is supplied for the throttle position. With out the computer the pump supplies the maximum amount of fuel it can and the carb does the rest. The venturi in the carb controls the amount of fuel atomized for combustion. Whether the computer is there or not the venturi controls the amount of fuel used through vacuum. The wider open the throttle the more vacuum, the more vacuum the more fuel used.
Re: Need Help/Opinion's (flinterman2000)
So then with an aftermarket Weber 34/34 you dont need the computer.
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flinterman2000
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Re: Need Help/Opinion's (damn)
No. But you should add a FPR if you don't have one.
Re: Need Help/Opinion's (flinterman2000)
I have one but it lowers my fuel pressure to below 2psi.flinterman2000 wrote:No. But you should add a FPR if you don't have one.
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turbojunker
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Re: FN-QR (PEZi720)
The carb shouldn't have anything to do with it. Your pump is probably stronger than his.
Re: FN-QR (turbojunker)
If you replace your carb does that delete the fuel air mixture silenoid? Did you check to see if your cat is clogged?
Re: FN-QR (PEZi720)
Stock pump.....With out a FPR the psi is between 3.5-4psi with the FPR set at 3.5psi the pressure will drop to around 2psi if i set the FPR to 5.5psi only then does it go to right below 3.5psi.PEZi720 wrote:that might be true... damn, what pump are you running?
Im not running cat's
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PEZi
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Re: FN-QR (damn)
i'm wondering if this might be the reasondamn wrote:
Stock pump....
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turbojunker
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Re: FN-QR (damn)
What kind of FPR do you have? I ran one of the dial type ones on an RX7 I had and the markings on it were completely inaccurate.damn wrote:
Stock pump.....With out a FPR the psi is between 3.5-4psi with the FPR set at 3.5psi the pressure will drop to around 2psi if i set the FPR to 5.5psi only then does it go to right below 3.5psi.
Im not running cat's
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flinterman2000
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Re: FN-QR (PEZi720)
It's not the carb. It's the FPR or the fuel pump.PEZi720 wrote:see... mine lowers the fuel pressure... but not as low as yours... my guess is that it must be the difference in carbs
Yes it would. Webbers do not have idle or fuel air solenoids.dogred wrote:If you replace your carb does that delete the fuel air mixture silenoid? Did you check to see if your cat is clogged?
Re: FN-QR (flinterman2000)
It was a cheap silver dial one probably isnt accurate at all.turbojunker wrote:
What kind of FPR do you have? I ran one of the dial type ones on an RX7 I had and the markings on it were completely inaccurate.
Ok so today i went and took a good look at all the factory set settings on the carburetor. My carb is a progressive meaning both barrel's are supposed to open at the same time. Found that they were not doing that. The secondary wouldnt start to open until the primary shaft had already turned about 90" so i turned the screw clockwise which open's the blade on the secondary barrel and my idle started to clear up.flinterman2000 wrote:It's not the carb. It's the FPR or the fuel pump.
Yes it would. Webbers do not have idle or fuel air solenoids.
Before when i would rev the engine there would be a hesitation i think it was becuase the primary was opening and the seconadry was lagging behind and from what i understand the carburetor shoot's enough fuel for both barrel's opening at the same time.
The idle is now much more stable! I hope it last's and maybe this was my problem the carburetor was supplying enough fuel at idle for both barrel's to be slightly cracked but the secondary was closed..Im going to drive it for a few day's and see if anything changes.
I also disconnected the computer.
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PEZi
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FN-QR
you have the 34 right?
i get what you're saying but its synchronous... not progressive... progressives are the ones with different sized barrels... and technically on yours there is no primary or secondary... they work at the same time all the time (thus the name synchronous)
and yes... if both sides are synchronized properly it will run MUCH better... took me a while to dial in
i get what you're saying but its synchronous... not progressive... progressives are the ones with different sized barrels... and technically on yours there is no primary or secondary... they work at the same time all the time (thus the name synchronous)
and yes... if both sides are synchronized properly it will run MUCH better... took me a while to dial in
Re: FN-QR (flinterman2000)
Thanks for the info.flinterman2000 wrote:It's not the carb. It's the FPR or the fuel pump.
Yes it would. Webbers do not have idle or fuel air solenoids.
Re: FN-QR (damn)
Yeah lots of people try to return that type of FPR because they are never correct.damn wrote:
It was a cheap silver dial one probably isnt accurate at all.
Ok so today i went and took a good look at all the factory set settings on the carburetor. My carb is a progressive meaning both barrel's are supposed to open at the same time. Found that they were not doing that. The secondary wouldnt start to open until the primary shaft had already turned about 90" so i turned the screw clockwise which open's the blade on the secondary barrel and my idle started to clear up.
Before when i would rev the engine there would be a hesitation i think it was becuase the primary was opening and the seconadry was lagging behind and from what i understand the carburetor shoot's enough fuel for both barrel's opening at the same time.
The idle is now much more stable! I hope it last's and maybe this was my problem the carburetor was supplying enough fuel at idle for both barrel's to be slightly cracked but the secondary was closed..Im going to drive it for a few day's and see if anything changes.
I also disconnected the computer.
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