Jump to content

70' 510 Won't Start - L20 w/ twin Weber 40 DCOE carbs.


sBay510

Recommended Posts

Hi Guys,

 

Long story short, I have a 71’ 510 with a L20 w/ twin Weber 40 DCOE carbs. I didn’t have the opportunity to get it in and start it up for about a year. I did have a battery tender on the battery to keep it alive. Now that I have the chance to hop in the car, I can’t get it to start. It will turn over, but not start.

 

I have tried to use starting fluid and it roars to life, but then just dies out. The starter is running/turning so I do not think that’s the problem. The last time I had the engine running, I purposely used most of the fuel in the tank. I put in a fresh half tank load of fuel in it recently before trying to start it.

 

The car has an electric fuel pump in the trunk next to the fuel cell. It turns on when the key is put into ACC. I can hear it buzzing and working. I’m fairly new to working on carburetor engines, so I have been doing a lot of reading on this forum and online in general. I have tried leaving the pump on for about 2-3 min to fill up the fuel bowls in the carbs. Both fuel lines for each carburetor have a in-line fuel pressure gauges (under the hood – pretty close to the carbs) and are reading at approx. 3 – 3.5 psi after the bowls are full. I have taken off the fuel lines, put the open end into a bottle and turn the ignition on to ensure fuel is actually getting pumped to the carb..which it is. So I do not think fuel delivery to the carb is the issue either. I have pumped the gas pedal anywhere from 3-6 time before trying to crank the engine – as I have read to do so – but still will not start.

 

Since I was able to get some results with starting fluid, I then resorted to spraying some gas into each venture body. After I sprayed fuel into them, the engine started up for a few seconds (I was so happy), but then died again. I did this multiple times with varying results. Since I’m at least able to get it running for a second or two, I assume I can rule out any spark issues. After a while, I noticed the starting attempts was taking a toll on the battery, so I attached a jumper batter pack to it to charge/assist. I’ll be getting a brand new battery this week.

 

At this point, I’m thinking it is some type of fuel delivery problem within the carb and going into the throttle body (Accelerator pump circuit?). With the ignition and fuel pump on, I tried opening and closing the throttle plates via the linkages under the hood ( I hope that makes sense) to see if any fuel would squirt out into the venturis, but no fuel was squirting out. I checked in all 4 openings and no fuel was squirting. I should be seeing fuel squirt out at this point correct?  

 

I have read to take the top cover of the carb off and check the needle valve since it might be stuck since the car sat for a while. I have not checked the needle valve yet. What exactly should I be testing/looking for?

 

I really want to fix this issue myself and get the car started. I feel like I can almost get the car started, but I need to fix a minor things. I really do not want to take it into a shop, but I’m going to have to if I can’t resolve it.

 

Please help.. I would greatly appreciate any assistance from you guys.

 

Thank you in advance!

Link to comment
  • Replies 39
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

I took both lines off.

 

So should it be squirting fuel when the accelerator is activated? I even shot a video just to be sure since it was kind of hard to see into the barrels.. Didn't see any fuel squirting unfortunately.

 

Should I take the top cover of the carbs and mess around with the needle valve and ball check valve at the bottom of the bowl?

 

I'm at a loss. Any help appreciated. Thanks

Link to comment

I took both lines off.

 

So should it be squirting fuel when the accelerator is activated? I even shot a video just to be sure since it was kind of hard to see into the barrels.. Didn't see any fuel squirting unfortunately.

 

Should I take the top cover of the carbs and mess around with the needle valve and ball check valve at the bottom of the bowl?

 

I'm at a loss. Any help appreciated. Thanks

YES!!! Also  check the filter under the big brass filter cover on the carb...

Link to comment

leaving it for 1 year should not be bad as I leave my 510 for a year and have no proplems

 

Do you get gas squirting out the fuel pump before the carbs???? Pull the hose and point in safe direction and see if it squirts alot of gas. If yes then its most likely ok.

 

I would open the jet blocks and see if the condittion of the jets Maybe the plugged, carb cleaner

  • Like 1
Link to comment

Pull out the jets, emulsion tubes and mixture needles and clean them out.

 

Ok, will do. Is there a specific method to this? Do i just use a can of carb cleaner to clean them out?

 

This won't affect any of the tuning (screw adjustments) made to the carb will it?

Link to comment

leaving it for 1 year should not be bad as I leave my 510 for a year and have no proplems

 

Do you get gas squirting out the fuel pump before the carbs???? Pull the hose and point in safe direction and see if it squirts alot of gas. If yes then its most likely ok.

 

I would open the jet blocks and see if the condittion of the jets Maybe the plugged, carb cleaner

 

Ok, that make me feel somewhat better to hear that you leave your car for a year too. 

 

Yes, i get a lot of gas pumping out, so the fuel pump is most likely ok. I’m getting around 3 – 3.5 psi up to the carbs.

 

Ok, I will try to pull out the jet and emulsion tubes and clean them with carb cleaner.

 

Thanks

Link to comment

Battery is getting weak but does not mean it's gone.  I think your gas is bad sitting for a year.

 

As I mentioned in my original post, I used most of the gas up the last time I had it running, to avoid the fuel just sitting in the tank, so I don’t think that is the issue. I just put in some fresh gas into the tank. 

Link to comment

Probably old gas in there. Depending on the temperature and environment of your area, what happens to one car, may not happen to another in a different location. The emulsion tubes and pilot needles are pretty small. They clog up the fastest when stuff sits. Do you have a manual choke on those carbies? If so, this should give a little more juice to bypass the pilots. Might give you an idea about where to start. If you do take the carbs off to clean em, get a guitar string, "full set" of generic electric strings. They work great to get through all the small orifices. <--Yep, I said it!!

Link to comment

I assumed you have a choke on these and use it.

 

My Mikuni 44 mm set you have to choke it and choke it only to get it to start. But Im the owner and i know this

Since your the owner of this car you know already the quirks of the car.

However my other 510 with 40s I just pump the carbs a couple times then try to start it and will run on NO choke.

 

 

Maybe by by chance can you hear inside the carb if the accell pump is squirting gas in there?  I seen a guy  they had the carbs rebuilt and the guy put the acell diaphrame in there upsidedown.  But this was running before so I assume 99% this is not it.

 

 

put Stabil gas treatment next time.

 

on the carbs is a top plate. take the cover off and unscrew the jet bolcks. Maybe reshearch YOUTUBE or soem carb DCOE places for soem basic main incase something happens.

 

you can replace the fuel filter and cut open the old one to give a indication of it being dirty. Most 510 tanks are clean and not alot of rust.

 

1 year isnt too long for gas to go bad. I think I seen on Baa Baa Black sheep squadron Pappy Boyington was stuck on a island and they found a old plane got it running and flew back to base. Or was this McGiver?

Link to comment

Probably old gas in there. Depending on the temperature and environment of your area, what happens to one car, may not happen to another in a different location. The emulsion tubes and pilot needles are pretty small. They clog up the fastest when stuff sits. Do you have a manual choke on those carbies? If so, this should give a little more juice to bypass the pilots. Might give you an idea about where to start. If you do take the carbs off to clean em, get a guitar string, "full set" of generic electric strings. They work great to get through all the small orifices. <--Yep, I said it!!

 

It was stored in a garage in Los Angeles for what its worth. 

 

To be honest, I'm not sure if they have a choke and have been looking for signs of one.. The choke cable is not attached to anything that's for sure. I've read that most Weber DCOE don't have chokes, but a starter circuit?  I believe i found it on the top part of the carb but I'm not sure. It looks like the following and I'm assuming if the lever is activated one way, it turns the choke on. IDK3255601800_1_hr.jpg

 

Guitar string huh? Ok, i look into that and cleaning methods.

Link to comment

I assumed you have a choke on these and use it.

 

My Mikuni 44 mm set you have to choke it and choke it only to get it to start. But Im the owner and i know this

Since your the owner of this car you know already the quirks of the car.

However my other 510 with 40s I just pump the carbs a couple times then try to start it and will run on NO choke.

 

 

Maybe by by chance can you hear inside the carb if the accell pump is squirting gas in there?  I seen a guy  they had the carbs rebuilt and the guy put the acell diaphrame in there upsidedown.  But this was running before so I assume 99% this is not it.

 

 

put Stabil gas treatment next time.

 

on the carbs is a top plate. take the cover off and unscrew the jet bolcks. Maybe reshearch YOUTUBE or soem carb DCOE places for soem basic main incase something happens.

 

you can replace the fuel filter and cut open the old one to give a indication of it being dirty. Most 510 tanks are clean and not alot of rust.

 

1 year isnt too long for gas to go bad. I think I seen on Baa Baa Black sheep squadron Pappy Boyington was stuck on a island and they found a old plane got it running and flew back to base. Or was this McGiver?

 

The previous owner did a lot of the work on the car, so I only know some of the quirks from driving and fixing things on my own. I've had plenty of experience with fuel injected engines, but this is my first time with carburetors, so i feel someone lost.

 

I have read that with sidedraft Webers, that pumping a few times before starting w/ No choke is the normal procedure to start. I tried with no luck. It could be because no fuel is squirting though.

 

I will try to take carb cover off and remove the jets to clean/inspect.

 

 

if you have a hole in one of the carb floats,once full of fuel the float will sink, and car will die. This happened to me with twin s/u carbs.

 

Ok, i will take the carb cover off and look at the floats to see if they have any holes. But if this is the case and they are sinking, wouldn't that be adding more fuel to the mixture, thus flooding the engine? Im somewhat confused. 

Link to comment

dont cheack on the float bowl stuff yet. Do only basic before your ripp apart a carb. If anything tap on the fuel inlet that goes to the carb. On my Mikunis it would run out of gas. I think the needle valve that lets gas in would get stuck closed. I would tap it while cranking or just tap it then it would fill up with gas then  run. This was a hard one to find

 

if flooding ck the spark plugs. if wet

How about get soem new plugs then try to start it. But you did say it starts with the starter fluid so highly dought that its flooded as the plugs would not fire( i think)

 

 

Im not familiar with webers and the starter circut. You know the car and how to start it.

Link to comment

dont cheack on the float bowl stuff yet. Do only basic before your ripp apart a carb. If anything tap on the fuel inlet that goes to the carb. On my Mikunis it would run out of gas. I think the needle valve that lets gas in would get stuck closed. I would tap it while cranking or just tap it then it would fill up with gas then  run. This was a hard one to find

 

if flooding ck the spark plugs. if wet

How about get soem new plugs then try to start it. But you did say it starts with the starter fluid so highly dought that its flooded as the plugs would not fire( i think)

 

 

Im not familiar with webers and the starter circut. You know the car and how to start it.

 

Did you end up replacing the stuck needle valve on your Mikuni, or just did some cleaning on them?

 

With starting fluid , or even gas, it will fire up only for a second or two. The engine doesn't fully start. But yea, i don't think the engine is flooding. If anything..maybe the opposite..its thirsty?

Link to comment

no I never did clean it I just ran it. Maybe stuck soem gas cleaner in there but never happen again after about 3 times. then it forever stopped. I never drive this car but run it say maybe one every 3 weeks and replace the gas out every 1.5 years

 

i see. ok, well im going to take the cover off probably this weekend and clean some pieces. 

 

 

there should be a drain for the carbs,drain them of fuel,then see if it fires,as soon as the float bowl fills with fuel,it will die if you have a hole in float. (flooded)

 

Understood. I will check to see if i have a hole in the float, thanks. 

Link to comment

Do you have a manual choke on those carbies? If so, this should give a little more juice to bypass the pilots.

 

 

I assumed you have a choke on these and use it.

 

My Mikuni 44 mm set you have to choke it and choke it only to get it to start.

All carbs benefit from a richer mixture to get started when engine is cold. SU's don't even have an accelerator pump you could use to force a rich condition by repeatedly pumping the gas. The choke on the SUs lifts the jet allowing more gas in. I know these are not SUs but maybe the same thing.

 

This is why I say unlikely both carbs would have a sunken float or common problem.

Link to comment

I would definitely take the top cover off and check all the circuits under there before removing them all together. Although, removing them is not very difficult at all. Here is the 1st part of 2 videos that will show you the carbs being rebuilt. May offer good guides: https://www.youtube.com/watch?v=4dxO1TPWhlE

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.