Hesitation ('pause') under load; going up hills; 3rd & 4thh gear

[henry]

1971 510 SW 1600

Hello,

    I think that it could be either fuel or electrical related. Is there a quick way to find out  which it is?

      And then work from that?

     Thank you,

      Henry

  

[datzenmike]

Replace the fuel filter. They are cheap and easy to do and if you don't know when it was changed last then it's over due. Should be replaced every 3 years. This may not help but cheap to fine out.

 

What may be happening is a partly clogged filter reduces the gas that available to the carburetor. When driving normally everything is fine but under heavy load climbing a long up hill the engine uses up all the gas in the float chamber and the pump can't replace it fast enough because of the restriction. It will stumble like it's running out of gas but otherwise idles and drives normally.

[henry]

Thanks Mike; I will do that first.

    Henry

[banzai510(hainz)]

manual or auto trans???

I would check the timming and adjust it if needed. check the point gap if still running points

If a dual point distributor I would make it a single point distrisbutor or find a single point distributor and put a Pertronix or get a later matchbox distributor.

 

dusal point distributos one really needs a dwell meter and I never figure them out. I went Pertronix backin the day and never looked back

 

 

as mike said the fuel filter also. But I think it would cut out

[carterb]

I had a cracked fuel line between the filter and pump.

It made the pump very inefficient as it would suck air as well as fuel.

Going up hills on the freeway it would loose power and cut out as the float bowl drained with the fuel pump unable to keep up.

Replaced cracked hose with new, problem solved.

--carter

[datzenmike]

A loose clamp also but on the suction side of the pump only.

 

 

A bad filter will feel like it's running out of gas. (because it actually is) Definitely loss of power and may feel like the ignition is being turned on and off. It may surge ahead then fall on it's face over and over till you let off the gas.

 

A filter that is in the act of plugging up with sediment will only do this under heavy load like climbing a hill or entering a freeway and accelerating hard up to speed. Over time it only gets worse. 

[Jesse C.]

I could also be junk at the bottom of the tank getting stirred around and causing the surge

[datzenmike]

The filter should still collect anything that is drawn up the fuel line. I emptied a tank of rusty brick colored gas through a funnel a hose and an in line filter. What came out was a champagne color clear gas that I put in my 620 and drove. I sure didn't expect it to take the color out but it did.

[edekalil]

On 1/7/2021 at 8:15 PM, datzenmike said:

Replace the fuel filter. They are cheap and easy to do and if you don't know when it was changed last then it's over due. Should be replaced every 3 years. This may not help but cheap to fine out.

 

What may be happening is a partly clogged filter reduces the gas that available to the carburetor. When driving normally everything is fine but under heavy load climbing a long up hill the engine uses up all the gas in the float chamber and the pump can't replace it fast enough because of the restriction. It will stumble like it's running out of gas but otherwise idles and drives normally.

Once someone put chicken bones after they ate the chicken off em in my gas tank of my Goon while it was parked on Rampart St. In New Orleans  while I was at work. I keep several fuel filters in my car cause it would just shutdown going down the interstate. I'd pull over lift the hood and change the filter and then off I'd  go. All ways keep some extras in the car.

[datzenmike]

I wonder if henry had a plugged fuel filter and is driving around and not replying.....

[henry]

Folks, my apologies for not replying sooner -  Well I did replace the fuel filter & it did not change that hesitation under load. I went ahead & looked at all the plugs. As they're pretty new they all looked good.  But I did omit some information on my original post:

    As I've  been working on the car for almost a year without really driving it, I've had the same gas in the tank. ( ...about 3/4 full ). I wonder if the old gas has any bearing on the problem.  Went &  fill it up with high  premium gas but it still doing it.  Maybe I'll even add a bottle of something in the tank. I'm thinking of checking the following:  Sufficient fuel pressure; Vacuum advance unit & possibly the condition of the coil itself.

     Another issue that I'm having ( ..i don't know if it's all related ) is that the engine will not turn its' self off when I turn the key off. I've got the idle screw all the way back, where it's not even making contact. I did balance the air- fuel mixture with a vacuum gauge. But the motor will not run below 1100 RPM. So when I turn it off it's running that fast. I have to have it in first & pop the clutch. Timing seems to be right. 10-BTDC, & no vacuum leaks.   Well that's the state off affairs  so far.  Thank you to everyone that responded. Henry

  PS: that's a funny story Edekalil.

[datzenmike]

Find the idle cut solenoid. It's hex shaped, on the right rear of the carburetor and has a red wire running to it. It's job is to cut off fuel when the ignition is turned off to prevent that run on you describe. A simple test is to not start the engine but turn the ignition on off on off several times. What you should hear near the back of the carburetor is a soft click each time. Try that.

 

I'll assume that you have nothing so the easiest fast but reliable fix is to follow the red wire around to the front of the carburetor where it plugs into the harness. Run a new jumper wire from this plug to the 12v side of the ballast resistor near the coil. This will be the new power supply for the idle cut that switches on and off with the ignition.

 

With the idle cut working gas can now get down to the idle circuit so you will need to adjust both the mixture and the idle speed.

[banzai510(hainz)]

a 71 had a cut off selinoid?????????????????????  I don't think it did.

 

car still running with the key off is a bad volt regulator. Try unplug the volt regulator then shut key off.

 

However the above might not be the proplem cause you adjust the mixture and noting happen?

Maybe you have the speed screw in so far IN your not even using the idle mixture circut

 

check these things first

 

 

30 min job and its fixed or at least trouble shot.

 

whats the choke doing when warmed up? This manul or elelctric choke?

[datzenmike]

I assumed the carb was changed and was waiting for reply on the idle cut. Maybe has L20B.

[banzai510(hainz)]

most people don't get that option when buying a Weber carb with the Idle cut off selinoid

[henry]

Hi everyone,

   So this thing is a1971 510 SW

   1.6L -  Hitachi carburetor -  2 Barrel - Model 328 (rebuilt 2 years ago ) -  Dual points ( except that I converted to electronic ignition a long time ago )

   The carburetor has this cylinder like looking thing on it's side with 2 wires coming out of it (except that the wires were cut off??? ) It's called a decelerator solenoid according to the manual.

 Is that what stops gas from entering engine when key is turned off?  I guess I can assume that it's not working.  Are they still available on the market??

   I though of retarding the timing a bit & adjusting it to run a bit leaner so it would run slower at idle. ( ..stupid idea?? )

                                                                                                                                                                                                                                                                                                                                                          " Maybe you have the speed screw in so far IN your not even using the idle mixture circuit "

           No, the speed screw is not making contact at all!  The choke is working fine. It's a push-pull.   I would like to keep the engine stock.

       Thanks folks,

             Henry

           

             

    

[bananahamuck]

 Have you adjusted valves?  
tight valves will make L motors run weird as hell. 

[Crashtd420]

If the idle screw isnt touching then you might have too much tension on the throttle cable....

Maybe disconnect the cable and see if the idle drops.....

 

Also I saw a couple different responses on it still running after shutdown..... 

 

Are you saying the power doesn't shut off or is the engine dieseling after shutdown....

 

[banzai510(hainz)]

1 hour ago, henry said:

Hi everyone,

   So this thing is a1971 510 SW

   1.6L -  Hitachi carburetor -  2 Barrel - Model 328 (rebuilt 2 years ago ) -  Dual points ( except that I converted to electronic ignition a long time ago )

   The carburetor has this cylinder like looking thing on it's side with 2 wires coming out of it (except that the wires were cut off??? ) It's called a decelerator solenoid according to the manual.

 Is that what stops gas from entering engine when key is turned off?  I guess I can assume that it's not working.  Are they still available on the market??

   I though of retarding the timing a bit & adjusting it to run a bit leaner so it would run slower at idle. ( ..stupid idea?? )

                                                                                                                                                                                                                                                                                                                                                          " Maybe you have the speed screw in so far IN your not even using the idle mixture circuit "

           No, the speed screw is not making contact at all!  The choke is working fine. It's a push-pull.   I would like to keep the engine stock.

       Thanks folks,

             Henry

           

             

    

push pull choke means a manual carb and assume it DONT have a idle selinoid.

I cant explain the 1100rpm with no speed screw turned in.  was this fine before ??? Or after you did something this happened?  Do a timming chain or oil pump install (distributor timming)???????

 

 

 

so if you shut the key to OFF and the motor is still running fine then its the external volt regulator that seems to do this (various post on this before) I have never had this happen myself.  I will assume you have the stock alternator and stock volt reg on fender strut area.  Like I said turn key off then pull the volt reg connector then it should stop.

 

If it still running by dieseling that's different   Most L 16 with the stoch head and stock carb don't do this unless its just plain worn out and sucking gas in from somewhere.

 

 

[datzenmike]

2 hours ago, Crashtd420 said:

If the idle screw isnt touching then you might have too much tension on the throttle cable....

Maybe disconnect the cable and see if the idle drops.....

 

 

 

 

LOL the 510 is a linkage system. Sorry crashtd

 

The thing with 2 wires is a rudimentary form of BCDD (boost control deceleration device) Not all 510s had this so maybe this carb was swapped on and doesn't have the wiring to support it or owners do stupid things. This might be the cause of your fast idle. The BCDD is a fast idle mechanism for when decelerating to reduce emissions but once slowed down it has to reset for the next time. The wired thing is a solenoid so remove the three screws and lift away carefully. There is likely a pin that may drop out so be ready. There will be  hole for this in the carburetor so seal this with a small patch of duct tape and see if the carburetor can now be idled down. You'll have to adjust the mixture as well.  

 

I'm not sure if power to the solenoid turns the BCDD on of off. So if this fails we may have to ground one wire and jumper 12v on the other.

 

 

[Crashtd420]

1 hour ago, datzenmike said:

 

LOL the 510 is a linkage system. Sorry crashtd

 

Oops.... I guess a tight cable is not going to be the issue then....

[henry]

I did adjust the valves a while back; perhaps I should recheck. And  the throttle is a linkage system.

 

   " Are you saying the power doesn't shut off or is the engine dieseling after shutdown.."

       The engine diesels after shutdown. Sorry, I should have been more clear.

  I did rebuild the carburetor 2 years ago. I think I was careful with it. Timing chain & oil pump have been replaced.

   OK, I will try to remove solenoid & plug cavity. An issue is that the wires have been cut flush with the exterior walls of the solenoid. So there is in effect no wiring left.

         Like I asked before are these units still available?

         Thank you,

           Henry

[datzenmike]

3 hours ago, henry said:

Hi everyone,

   So this thing is a1971 510 SW

   1.6L -  Hitachi carburetor -  2 Barrel - Model 328 (rebuilt 2 years ago ) -  Dual points ( except that I converted to electronic ignition a long time ago )

   The carburetor has this cylinder like looking thing on it's side with 2 wires coming out of it (except that the wires were cut off??? ) It's called a decelerator solenoid according to the manual.

 Is that what stops gas from entering engine when key is turned off?  I guess I can assume that it's not working.  Are they still available on the market??

   I though of retarding the timing a bit & adjusting it to run a bit leaner so it would run slower at idle. ( ..stupid idea?? )

                                                                                                                                                                                                                                                                                                                                                          " Maybe you have the speed screw in so far IN your not even using the idle mixture circuit "

           No, the speed screw is not making contact at all!  The choke is working fine. It's a push-pull.   I would like to keep the engine stock.

       Thanks folks,

             Henry

           

             

    

 

As mentioned this is NOT an idle cut solenoid so no there are none for it.

 

Retarding ignition and adjusting leaner...... this is not the way to set idle speed. At idle there is very little air and gas so the most must be made of it to turn the engine. Timing for the L16 is 10? degrees BTDC. Idle mixture should be adjusted to fastest and smoothest running then the idle speed turned down. Repeat till you can't improve the idle quality and the idle is around 700. If you can't turn the idle speed down enough then this is something else, probably mechanical. Look down the other barrel with a flash light.... is it closed tightly? Something jammed in it? stuck just a hair open??? 

[henry]

Hi Mike,

   So I looked at that solenoid ( BCDD );  removed it & plugged up the hole. Started up vehicle & RPM's shot up to 1500. Installed the BCDD back & RPM's came down  enough

     where I could actually do some adjusting. I've got it down to about 1000 & sometimes the engine shuts down without dieseling.

    I next decided to spray some carburetor cleaner around the base of the carb. When I sprayed at the rear  the engine bogs down. Would that signify a vacuum leak where the base

gaskets are?  ( that would be weird because the gaskets are pretty new - after the rebuild.)  Or maybe a leak in throttle shaft. Perhaps I installed the wrong base gasket??  It did seem a bit confusing at the time having to deal with the spacer also. It was hard to see if everything actually sealed.

      Thanks everyone,

       Henry

      

   

   

      

[datzenmike]

If spraying around the gasket caused a change then the gasket must be leaking. I know it's a pain but remove the carburetor and look at the imprint of the carburetor on the gasket. If it looks OK peel it off and look at the intake side. There may be a tiny piece of old gasket that wasn't removed for the carburetor base or the intake. Check the carburetor base is not cracked. I would try to correct this first before trying to make any adjustments.

 .