L20b Engine Dieseling

[datsunaholic]

The 2-wire temperature switch was for the EGR. It sends power to the EGR relay under the dash.

 

The anti-dieseling solenoid was one of the 3 wires going to the carb originally. Used to have a plug, with:

 

White w) Blue stripe (Anti-dieseling solenoid wire)

Blue w) White stripe (Choke heater wire)

Yellow w) Red Stripe (BCDD solenoid wire).

 

You don't need the BCDD wire with the weber, it's useless.

[motavated]

So if I hook up the white wire with the blue stripe with the anti diesel solenoid I am golden? Nothing else is needed? Sweet!

 

as you can see I have the return line blocked off since I dont know how to connect it. This pic also shows the fuel line going into the carb.

 

and this one is a pic of the wires...

Also how would one install the solenoid to the weber carb? I probably would have to ask the carb's direct guys to help me out with that one..

 

Or how would one hook up the fuel return?

[racerx]

I know someone who is selling a Smog legal 32/36 weber that was going to be installed on a 20r (toyota). Call Joe at (510) 706-9480, still in the box..not sure of the price..regarding your disealing maybe your running too rich/lean, how's the sprak plugs?, choke can also be getting stuck...

[motavated]

Is the choke supposed to stay open when turned off? it stays open...

[yello620]

Adam, installing the solenoid is easy. You know how to remove the idle jet and jet holder right? The solenoid is just a new jet holder. Super easy, just add keyed power to it to activate the solenoid.

 

However, i think that you have other issues besides the solenoid. I would start by getting the return line hooked up and verifying all the choke adjustments.

Since you asked about the choke staying open, this makes me think that you have a choke issue that is being hidden/masked by a primary idle adjustment issue.

[yello620]

 

Sooner you accept this the sooner you will be FREE.

 

 

You have got to be kidding me..............What kind of advise is this??

[motavated]

Adam, installing the solenoid is easy. You know how to remove the idle jet and jet holder right? The solenoid is just a new jet holder. Super easy, just add keyed power to it to activate the solenoid.

 

However, i think that you have other issues besides the solenoid. I would start by getting the return line hooked up and verifying all the choke adjustments.

Since you asked about the choke staying open, this makes me think that you have a choke issue that is being hidden/masked by a primary idle adjustment issue.

 

well I heard the choke that is electric is heated electronically and make it open after a while so it can warm up the car. It closes after a while but not automatically.

 

How do you connect the fuel return... I had to plug it up because i might of had it connected wrong. I had both hoses connected to the intake... How do you connect them????

[motavated]

Well I installed a fuel pressure regulator and that did not work. I am glad I did since my fuel line was rusted! Set the pressure at 2.5 and new line and it idles smoother... Doesn't tremble at all... But it still diesels!

 

Will try the solenoid next.....

[motavated]

Her is a pic of what I did... Good? No good? critique?

[sinner720st]

i dont think you need to have someone tune your engine. 8degrees advanced sounds safe (im running 13 on my z24) there is a crooked screw under the idle speed, this screw is almost perpindicular to the idle speed screw and is called idle air mixture. after your car warms up (drive to the store and back) pop hood with flatblade screwdriver in hand find screw close your eyes and listen as you turn that screw when you get the smoothest and highest idle this is called lean best idle mixture. be sure you dont get idle speed screw confused with the mixture screw. i do this generally twice a week depending on the weather change. when it is adjusted right it idles like a 2010 nissan sentra (smooth) just a wee bit louder. dont know if this will help your run-on situation

 

another problem might be a vacuum leak. a vaccum leak will also make tuning carb impossible... now that i think about it im pretty sure you have a vaccum leak. cant help any further than that. please check before dumping money into a new carb. start your diagnosing with the easy cheap stuff, if nothing chenges then you can start throwing parts at it (kind of like les schwab would do)

 

if that pressure reg is mr gasket im not to sure it will be very accurate. and i dont know how necissary because carburetors get fuel down throat by venturi action and that takes velocity. so higher fuel pressure will probably just make you carb puke fuel out or something, but lets hear how you like that regulator

[racerx]

I think there's an article on the How to section on tuning 32/36 if not they are all over the internet. My 510 has an L18 and installed new 32/36 weber..it diesels once in the blue moon. I think you should try to adjust the carb first and check for vacuum leaks...not sure the history of the carb but you need to have a base line by tuning the carb first, they are very easy to adjust. I've had these carbs in like 5 cars and never installed that cut off solenoid, did not need it. Carbs, it does not matter what type, will diesel once in awhile..not always.

[racerx]

Someone says they adjust these carbs every 2 weeks???Once these carbs are adjusted you don't need to adjust them like all the time.

 

Here try this, it was in another section of this site.

 

http://www.racetep.com/webjettune.html

[banzai510(hainz)]

Sooner you accept this the sooner you will be FREE.

 

 

It means you have to live with it ,as Mine does it also. Some people it drives them nuts with it desieling.

I just hit the pedal as I shut the key Off and youll loose vacuum as the throttle plate opens and most times it will shut off OK.

 

Most webers dont have the anti desieling selinoid option so You have to live with it.

 

This will most like happen with a open chamber head(U67 ect.....

[datzenmike]

8degrees advanced sounds safe (im running 13 on my z24)

 

13 degrees? Stock is 3-5 degrees. I didn't think a Z series would run without pinging on that much advance.

 

Are both sets of plugs firing? Pull the #1 intake and exhaust side plug wires off, put an old plug in the end, lay on the valve cover and crank over. Is there spark in both???? I would imagine the intake side is working and the exhause is not. This would allow a higher advance.

[hang_510]

Someone says they adjust these carbs every 2 weeks???Once these carbs are adjusted you don't need to adjust them like all the time.

once i had it dialed, i dont think i adjusted it again, maybe the idle after a plug change.

the DGV was on 3 different motors too.

 

no cut off soleniod and no diesleing either.

[racerx]

No, no I am not saying I adjust mine every 2 weeks, if you follow this thread there's a memeber that said he adjust his evey 2 weeks and I am saying you don't that's why I had ????? marks at the end of mys sentence. Yes, I am very aware of these carbs...

[hang_510]

there's a memeber that said he adjust his evey 2 weeks

wasnt directed at you... just that thats overkill. :blink:

 

 

set and forget on a DD! :)

[motavated]

I ordered the solenoid and waiting for it to arrive. Also I have 1979 vented fuel cap.... Does that hurt the truck as a leak? I checked the booster already and its ok... I will wait and post the results. I just need the part...

[Logical1]

Cheaper Fix: Go with an electric fuel pump! Once the power is cut, fuel pressure is gone. = No fuel for the engine to 'diesel' on... Good electric fuel pumps are a HELL of alot cheaper then a new carb! I also hear that older engines with carbon build up can cause dieseling because the carbon has irregular surface area and can ignite gas like a ember from a fire. I ran some seafoam through my intake a while back and it cleared up my run-on quite a bit :)

[motavated]

Cheaper Fix: Go with an electric fuel pump! Once the power is cut, fuel pressure is gone. = No fuel for the engine to 'diesel' on... Good electric fuel pumps are a HELL of alot cheaper then a new carb! I also hear that older engines with carbon build up can cause dieseling because the carbon has irregular surface area and can ignite gas like a ember from a fire. I ran some seafoam through my intake a while back and it cleared up my run-on quite a bit :)

 

I am going to try the seafoam. That is a good idea. Also the electric pump is a great idea as well. The reason I dont think its a carbon buildup problem is because the engine was supposedly rebuilt.... Supposedly but probably not very well...

[datsunaholic]

Cheaper Fix: Go with an electric fuel pump! Once the power is cut, fuel pressure is gone. = No fuel for the engine to 'diesel' on... Good electric fuel pumps are a HELL of alot cheaper then a new carb! I also hear that older engines with carbon build up can cause dieseling because the carbon has irregular surface area and can ignite gas like a ember from a fire. I ran some seafoam through my intake a while back and it cleared up my run-on quite a bit :)

 

 

Electric pumps: That's not true in a carbbed engine. The carb bowl has enough fuel in it to run the engine at idle for several minutes, even with the fuel pump off. It is true for EFI, but EFI won't diesel once the injectors are cut off.

 

That's where the idle cut solenoid comes in- it shuts off the idle circuit in the carb. But if the idle is set too high, the mains are going to keep providing fuel until the engine stalls and all vacuum is gone. Or, like my folks old Fairmont, it'd just diesel until the carb ran out of fuel (10 minutes later).

 

Carbon buildup does cause dieseling- it turns an engine into a very inefficient glowplug engine (like a old model airplane engine).

[datzenmike]

Automatic: leave in drive and shut off, put in park

Standard: Leave in 4th, brake on, lift clutch and turn off.

[hang_510]

Or, like my folks old Fairmont, it'd just diesel until the carb ran out of fuel (10 minutes later).

:rofl: :blink: :rofl:

[sinner720st]

I think im the one everybody is talking about "adjusting carb every two weeks. well its true. i never have played with jets and i only adjust the idle mixture never much but my jet is prob too small or something. as for datzen mike i am not sure i am running on all 8 plugs but i never have ever had ping problems. the sticker says 5 degrees. i just thought that was to pass DEQ but im not in DEQ zone. it pulls good usually runs smooth and the only two things running off vacuum is distributor and brakes. not trying to steal thread, but im learning too

[motavated]

I think im the one everybody is talking about "adjusting carb every two weeks. well its true. i never have played with jets and i only adjust the idle mixture never much but my jet is prob too small or something. as for datzen mike i am not sure i am running on all 8 plugs but i never have ever had ping problems. the sticker says 5 degrees. i just thought that was to pass DEQ but im not in DEQ zone. it pulls good usually runs smooth and the only two things running off vacuum is distributor and brakes. not trying to steal thread, but im learning too

 

I'm cool. Mods can always add to the title if shit gets too crazy. Like Insomniacs #3...

 

But I dont care...

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I got the solenoid today.... But something major happened to my bro's car that needs more attention that this.