Engine bogging down

[Turbodime]

My wife Maquel took the RV into get emissions and it passed.
On her way home she called to tell me she ran out of gas. I grab 5gallons and head out, fill it up and I head out to the gas station and before we make it a mile it starts to bog. I came off the throttle and coasted for a little and got back on it and it was fine for a short time then it started bogging/starving.
It has two new pumps, filters, cleaned tank and a new fuel lines. When I first ran it there was no issues so I'm thinking that I should have cleaned the carb.
It's a low mile RV so I think the carb is worth a rebuild.

The state emissions only ran the engine at idle and load and there was no inspection. It came from the factory without cats so I'm thinking of omitting the AIR system to free up some better mileage.

[cook elandan]

 5 gal may not be enough in the tank to keep it running.

[Stripe]

Turbodime is right.  Five isn't enough to go a mile in some of these rigs, I had same thing happen and had to put minimum of US$20 in the tank.

[tiinytina]

5 gallons spread over the 48" x 24" approx tank measurements (80 gal tank) ... is like 1/2" of gas if running on the flat.... 

Tina

[circleD]

I've had the same thing happen when I checked my tank when it was dry.  I put in 5 gallons and looked in there to see only the bottom covered in gas. Try to keep at least 10-20 gallons if you use it normally or just pull it and start the genny. Evaporation and that monster 454 take it ALL  . But its worth it!

[Turbodime]

After talking with Maquel this morning, she had the same symptoms I experienced before she thought she was running out of gas. She left the emission place and it started to bog on her. She drove it on the shoulder for a half a mile trying to get it to the gas station, but she got worried she would get stuck in the middle of the street so she pulled over, then called me.
The tank was just cleaned out and a new sending unit installed. You guys are right about it needing some make up fuel. When I first filled it on the bone dry tank it took 8gal before the fuel gauge came off the “E” just a smidge. At the first 5gals of that 8gals I started it and let it idle for 30min just to check everything was working.  I figured it being a big tank it would need at least 10gals to be a minimum to run flat down the road and get in quick to a gas station.
When I pulled up to fill it, the needle wasn’t on “E” but I figured the sending unit could be wacky and I’ll have to figure out in the future where empty really is on the gauge.  I put 20 more gallons in and I was still having the issue, so I’m thinking it’s not the fuel being too low.
Then I thought it could have been vapor lock with her waiting in line for emissions.  I ruled that out last night, I took it for a drive at midnight and the issue started right back up.
I’m going with the carb and after reading a good post that Kev started, and reading other Quadra-jet issue and remedies on the net I’m going to dive into the carb. Never worked on a quadra-jet’s just took them off my buddies Chevy’s and tossed them in the scrap bin. I have plenty of experience with carbs growing up in the dime a dozen muscle cars 80’s era.

Thanks for your comments.

[DaveVA78Chieftain]

I take it you found the GM Quadrajet manual:
http://oldcarmanualproject.com/manuals/Carbs/Rochester/QJet/1973/pdf/1973%20manual%20complete.pdf

and: http://www.corvetteclub.org.uk/files/downloads/how_to_tune_a_qjet.pdf


Did you replace the filter in the carb itself?

Dave

[Froggy1936]

Turbodime, The filter in side the carb at the fuel inlet could be your only problem . The Quadrajet is a very good carburator but extremly complicated . Though you can rebuild them fairly easily if they dont have bowl leaks or worn shaft bushings . Take your time Take a lot of photo,s read the instrutions twice . Lay out the parts as you dissesemble it then take a photo Read the instrutions again (this time they will make a little more sense)  You can use kerosene to bench test accelerator pump operation and test check valve,s/balls. There are a lot of books on rebuilding them if you want to try to locate one . They will have all the special tricks that may be necc . But if it was working fine before it should be just a cleaning that is necc .There are also replacement carbs available . But there are none better than a Quadrajet that is working properly  Frank

[legomybago]

I like that corvetteclub write up on the basic tuning and trouble shooting, I will keep that one handy. I did have a good one for the Thermoquad, but I need to locate it, took me a while to find a good write up on basic set-up and tuning for the laymen on the TQ.. It was written by a guy they call "the demon" I think? Thanks Dave

[DaveVA78Chieftain]

YW - I am a collector of this stuff however, I end up posting most of it here.  I belief Demon (as in Dodge Demon) no longer provides all the  stuff he use to (parts, rebuilt carbs, etc.).

I also have the How to Carter carburetor (AVS, TQ, etc.) book as well as the How to Rochester Quadrajet book as well as the how to set up Holley book.  The Holley one is great in that it talks to setting up each carb function which can also be translated to other carbs like the TQ and/or Quadrajet.

Almost forgot   D:oH! ,  How to Fuel Injection!

Dave

[Stripe]

If all else fails, these guys have been the best for me. Damn fast shipping and easy to return the old core.


http://www.guaranteedcarburetors.com/cgi-bin/shopper.cgi?preadd=action&key=CTMHT4650


Mark even knows where it is.  He's not too far from them..

[legomybago]

Yes! It was Demon. He was on a forum explaining his simple 3 or 4 step process for setting up a TQ...I always wanted a Dodge Demon when I was younger...but now I think they are ugly!! 70 Charger all the way W%

[Turbodime]

Yes, I have the Quadra-jet manual. I’ve been lucky in that I grew up in a time when carbs were all the rage and EFI was just coming in, so I’ve worked on just about everything out there just never a Quadra-jet.
The carb filter is new and don’t know if it’s really needed due to the inline filter and the tank screen but it’s there doing its job. It feells like either the float is stuck or there is something clogging the needle valves seat. 

[DaveVA78Chieftain]

My collection of Quadrajet stuff:

GM Quadrajet Service Manual

Quadrajet Rebuild and Adjustment

How to Tune a Quadrajet

Quadrajet Troubleshooting

I also have How to Rebuild & Modify Rochester Quadrajet Carburetors by Cliff Ruggles however I cannot distribute that.

Dave

[cncsparky]

I've rebuilt carbs in the past, but after doing the math, I sent my carb in to SMI.  After buying a gasket set, and tools to replace the throttle shaft bushings, and things like surfacing the baseplate that I don't have equipment for, it became apparent the $200 or so they charged was worth it!  You might check it out.

http://www.smicarburetor.com/products/sfID1/85/sfID2/86/sfID3/9/productID/428

[Turbodime]

Diving into it tonight. Local parts house has a rebuild kit and with all the resources and the A/C running and my tunes on, I have a peaceful night of work.

Thanks for the resources. I’ve been downloading everything to my Maquels kindle so when we're on the road I will have manuals at my fingertips. Its not fun troubleshooting from my iphone but will be a back-up
.

[Stripe]

Did he just say A/C RUNNING???

[DaveVA78Chieftain]

LOL - Yep,  one of them things you can do in Arizona

[M & J]

Yeah, I saw that.... I didnt want to know.

[Turbodime]

It's been a warm winter and I've ran the a/c for the last month off and on in my car. Just had to rub it in a little:)

[Turbodime]

Har har:) didn't get around to the carb last night but I'm sitting here in shorts looking at this view.

The previous owner said his mechanic changed the carb filter, but come to find out it looked to be original and it was plugged up good. The carb is in really good shape and with less then 30k it shows.

[Froggy1936]

Is that before or after cleaning ?

[Stripe]

My, what an AWESOME looking RV...  What model is it??  W%

[Turbodime]

Yes it's before cleaning. It's the carbs first rebuild and I just finished it up. Nothing out of the ordinary. I got side tracked installing 2 new 6v trojan's. Going to try and get the gen running tomorrow.

Model is a HR 34cs with twin beds in the rear. I wish it had the bed above the cockpit. 

[Turbodime]

It's all back together and running great. I also cleaned up the gen's carb and ran some Gibbs in the spark-plug holes and intake then let it soak for an hour. Cranked it over and it broke free.  Ran in the plugs and started it.  Loaded it with lights, fridge and a/c for an hour and ran smooth.  It only had 29hrs on it.

My wife and I ran it down the highway with the gen running the a/c's and it ran great with no bogging and better yet, the cruise controller worked flawlessly