RV stalls at stop signs and red light

StellaLunaGardens · September 18, 2018, 02:47 PM

My 1969 Dodge (M300) Winnebago D24, has issues... highway driving is fine, but she stalls at red lights and stop signs.

I noticed a hose missing on my carburetor, see attached pictures. One end where the hose attached is a short metal tube, someone plugged this with silicone, where I believe the other end attached is a metal tub held on with a nut. Am I correct that these are to run together like I see in the picture?

I went to auto Zone, and found some tubing that fit, (lawn mower fuel line). This did not fix the problem.

Would adjusting the idle mixture screw help fix this problem?

Thank you!

StellaLunaGardens · September 18, 2018, 02:53 PM

It took me awhile to figure out how to shrink pictures

Rickf1985 · September 18, 2018, 07:15 PM

Been a real long time since I worked on an emission type Holley but I can tell you that the pipe on top will not affect you idle, The bottom one may. If you feel suction on the line and it is not hooked up to something then it will affect the idle just due to the vacuum leak alone. But I can yell you from looking at the inside of that carb that it is rusty and crusty and your idle problems could be caused by any number of clogged passageways. Did this vehicle have an air cleaner on it? To answer your question about the mixture screws you can try but count your turns from where you are now so you can come back to this spot if it does not work. Holley carb idle mixture screws can be pretty touchy. Do not turn more than 1/8 to 1/4 turn at a time and then give it a full minute to stabilize.

legomybago · September 18, 2018, 07:52 PM

I would get rid of your lawn mower tubing and that piece of metal tubing you attached it too and just put a piece of rubber hose like your (Holley) pic shows between the two vacuum/vent ports. Not sure what is going on with the metal tubing...But like Rick said, you probably have issues with the idle circuit, which usually means rebuild the carburetor. Try adjusting your idle.

RCND · September 21, 2018, 08:58 PM

Howdy StellaLunaGardens:

This looks like a universal Holly 600 CFM replacement carburetor. They are set up to use either electric or hot air choke systems.

That upper tube is for fresh air from the air horn of the carburetor. It does connect to the tube held on by the threaded nut. This setup is for choke systems that used hot air to release the choke plates to the open position.

In this application there would be pipes in the exhaust manifold. The fresh air would connect to one pipe, and the choke would connect to the other using short pieces of vacuum hose. It didn't matter which went on what tube. If no hot air from exhaust, just loop as shown in the bottom picture.

I have used many of these carburetors and found that their jetting is good for a wide range of displacements. The only issue I ever had with them is the secondary spring was usually too light causing a bog a WOT ( a lot of people think this is a lean condition, NOT SO). Holly sold a tuning kit with a variety springs that fixes the issue.

If you think you maybe pulling the float bowls for what ever reason, get yourself a half dozen or so of the transfer tube o-rings. They never seen to reseal after first use. Also an extra set of fuel bowl gaskets. The blue ones are supposed to be reusable, talcum powder on the black ones will keep them from tearing.

Take care
Robert

RCND · September 21, 2018, 09:35 PM

StellaLunaGardens:

I just reread your post and realized I didn't address your stalling problem. Two possibilities come to mind, water in the fuel bowls or blown power valve.

Today's gas has a lot of water in it and it doesn't take much to affect carburetor's metering. Modern fuel injection is not affected so much by this but it plays hell on the injectors.

The second thing maybe a blown power valve. A backfire can rupture the power valve. Newer Holly's have a check ball installed on the bottom of the throttle plate housing to prevent this from happening.

You will have to crack the fuel bowls to drain them of water. To check the power valve remove the primary fuel bowl, the valve is the big round thing with flat sides.

Use a crescent wrench or what ever to remove it. Kinda hard to check if ruptured, you can suck on the large side to see if leaking, if you like the taste of gasoline.

If you just want to replace it, make sure the number stamped on it matches. This is the vacuum that it opens at.

Good luck. Later.
Robert

HandyDan · September 22, 2018, 09:53 PM

My Holiday Rambler is not a Dodge, but it was doing the same thing. Gets really scary when you lose brakes and steering when the motor dies. My problem was the seal at the bottom of the carb. There is a heated choke valve that sits in the manifold and on mine the valve had worn a hole in the top and was shooting hot air at the bottom of the carb. It burned a hole in the bottom seal of the carb and caused it to suck air. It wasn't a problem above 1000 rpm but drop below that and it died. Just something to consider. My two cents worth and worth every penny.

HandyDan · September 22, 2018, 10:17 PM

Here is the post from back in 2015. http://www.classicwinnebagos.com/forum/index.php/topic,11654.msg66727.html#msg66727

Rickf1985 · September 23, 2018, 02:52 PM

Here is another thing to consider, I still stick to my theory that the carb is in serious need of a rebuild but if it has not been tuned in many years you are now running gas with ethanol in it. This gas requires a different A/F mixture settings at idle and Holley carbs are very sensitive to idle mixture settings. Try resetting the idle mixture . Replace that tube as was mentioned from top tube to bottom tube first. But as dirty as the inside of that carb is and if it was sitting for any length of time it needs to be rebuilt.

tmsnyder · September 24, 2018, 08:46 AM

^^^ What Rick said.^^^^

Or just put a new one on there, that thing looks really crusty. A brand new Edelbrock Performer is what? $200?

Rickf1985 · September 24, 2018, 09:56 AM

New Holley 320.00 https://www.summitracing.com/parts/hly-0-80457s/overview/

New Edelbrock 349.00 https://www.summitracing.com/parts/edl-1406/overview/

These are 600 CFM carbs to match the Holley pictured on yours. I am assuming you have a 318.

Rebuild kit for the Holley, Would have to get the number off of the carb to verify this is the right kit though. 30.24 https://www.summitracing.com/parts/hly-37-119/overview/

RCND · September 28, 2018, 09:34 PM

Howdy StellaLunaGardens:
[/size]
[/size]What did you find out about your issue. Please share with us so others who may have the same or similar problems have the information.

[/size]BTW your list number is stamped on the choke air horn. Then top number is the list number, the lower number is the date code.

[/size]Take care.
[/size]Robert

RCND · September 28, 2018, 09:43 PM

Howdy StellaLunaGardens:

WOW. Don't know what happened there.

I was asking what you found out with your issue. And would you please post the info so others who may have the same or similar issues could learn from your experience.

BTW. Your list number is stamped on your choke air horn. The top number is the list number. The lower number is the date code.

Take care.
Robert