Go Back   iRV2 Forums > iRV2.com COMMUNITY FORUMS > Vintage RV's
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
 
Thread Tools Search this Thread Display Modes
 
Old 12-14-2015, 08:36 PM   #1
Senior Member
 
Inthe70s's Avatar
 
Join Date: Sep 2011
Location: Castle Rock, CO
Posts: 305
Frustrated with '79 Ford Class C

Hi all and happy holidays! One of my toys is a '79 25' class c motor home built on a Ford E350 chassis with the 460 4 bbl carb and C-6 tranny. It has 46K original miles and is in excellent original condition. It started this problem where after it is driven about 3 or so miles it goes from running smooth and like a top to suddenly dropping in RPMs and wanting to die while at idle, unless I give it some gas. It used to have a hesitation at stops but after the carb was rebuilt, that was resolved. I changed all of the fuel lines and filters and cleaned out both tanks. It has a stock mechanical fuel pump as well as a Carter elec fuel pump. It does it regardless if it's 90 degrees outside or 9 degrees. It's not running hot. It runs exceptionally smooth, starts on the first turn and idles very smoothly.....but then suddenly drops after a few miles. I'm going to change the spark plugs, spark wires, coil, distributor cap and ignition module since they can probably stand to be changed. Any other thoughts? Thank you in advance for your help!
__________________

__________________
'74 F350 44K,'79 11' Mitchell Camper, MINT All Original
'79 Mitchell 25' Class C, 460 46K, MINT All Original
'97 Rexhall Aerbus, 60K, 460, F53, MINT All Original
Inthe70s is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 12-14-2015, 09:00 PM   #2
Senior Member
 
Chinewalker's Avatar


 
Winnebago Owners Club
Join Date: Jan 2014
Location: Alberta
Posts: 129
Vapor lock?

Maybe the fuel line running too close to the exhaust manifold causing fuel to vaporize at low flow?

I used to have a '80 C class with a 460 and remember wedging a folded piece of galvanized tin between the header and the fuel line.
__________________

__________________
2004 Winnebago Journey 36G 330Cat
2004 Grand Cherokee BlueOx
Chinewalker is offline   Reply With Quote
Old 12-14-2015, 09:17 PM   #3
Senior Member
 
Inthe70s's Avatar
 
Join Date: Sep 2011
Location: Castle Rock, CO
Posts: 305
Quote:
Originally Posted by Chinewalker View Post
Vapor lock?

Maybe the fuel line running too close to the exhaust manifold causing fuel to vaporize at low flow?

I used to have a '80 C class with a 460 and remember wedging a folded piece of galvanized tin between the header and the fuel line.
I thought that too but this doesn't quite have the same feel as vapor lock and trust me, I know vapor lock after having several older cars. I had also insulated all of the fuel lines and re routed them as far away from heat sources as possible. Plus it seems strange that it would do this when its 10 degrees outside and it's barely warmed up at 3 miles?
__________________
'74 F350 44K,'79 11' Mitchell Camper, MINT All Original
'79 Mitchell 25' Class C, 460 46K, MINT All Original
'97 Rexhall Aerbus, 60K, 460, F53, MINT All Original
Inthe70s is offline   Reply With Quote
Old 12-14-2015, 09:28 PM   #4
Junior Member
 
National RV Owners Club
Workhorse Chassis Owner
Join Date: Nov 2015
Location: Brownstown MI
Posts: 11
It sounds like it's going lean when the choke comes off. Have you blocked off the egr valve? This was a common problem back in the day when i was working at a ford dealer. Loosen up the bolts and slide a small piece of cardboard between the valve and where it mounts and run it, if it runs fine there might be a piece of carbon holding it open. There is a gasket with a screen in it that will keep it from happening again. If it still does it remove the cardboard and look for a vacuum leak. You can spray carb cleaner around it will pick up rpm's if you hit the leak area.
__________________
dennisthe is offline   Reply With Quote
Old 12-14-2015, 09:37 PM   #5
Senior Member
 
Chinewalker's Avatar


 
Winnebago Owners Club
Join Date: Jan 2014
Location: Alberta
Posts: 129
Heat riser valve? (if one is installed)

Automatic choke operating correctly?

Just a couple of thoughts. Here's hoping you get things sorted out.
__________________
2004 Winnebago Journey 36G 330Cat
2004 Grand Cherokee BlueOx
Chinewalker is offline   Reply With Quote
Old 12-14-2015, 10:11 PM   #6
Senior Member
 
Inthe70s's Avatar
 
Join Date: Sep 2011
Location: Castle Rock, CO
Posts: 305
Those are all good suggestions and I'll have to research them. I did just replace the choke pull off as that was not operating properly but didn't seem to make any difference. I don't remember if I also mentioned that I did check the fuel psi and it seems appropriate per factory specs. There's a fine line between enjoying a good challenge and being driven nuts!
__________________
'74 F350 44K,'79 11' Mitchell Camper, MINT All Original
'79 Mitchell 25' Class C, 460 46K, MINT All Original
'97 Rexhall Aerbus, 60K, 460, F53, MINT All Original
Inthe70s is offline   Reply With Quote
Old 12-15-2015, 08:45 AM   #7
Senior Member
 
Join Date: Feb 2010
Posts: 4,492
Get a vacuum gage and place it on the center hump and see what it tells you.

Those years were when many odd things were attempted for smog that were not real good ideas but before efi.

Sounds like a temperature monitor is indicating engine is warmed up and to come out of open loop (not really but close) then go into closed loop where the smog controls start acting.

Get the Haynes or Chilton manual that covers your chassis and it should be able to guide you.

E350 van may be close enough but try to get as close as possible.

You should complete your "full tune up" as it is warranted but may not cure what ails your engine.

Paint thinner in a squirt can or water in a spray bottle do same for vacuum leaks.

Good luck
__________________
Tony & Lori
1989 Country Coach Savannah SE
TQ60 is offline   Reply With Quote
Old 12-15-2015, 08:59 AM   #8
Senior Member
 
77Travco's Avatar
 
Join Date: Oct 2015
Location: Kerrville, Texas
Posts: 160
EGR valve.
__________________
77Travco is offline   Reply With Quote
Old 12-15-2015, 09:09 AM   #9
Senior Member
 
Join Date: Dec 2014
Posts: 151
Sounds to me like it,s running out of fuel,the pickup tube in the gas tank could be blocked,just my 2 cents
__________________
Mr Plymouth is offline   Reply With Quote
Old 12-15-2015, 03:53 PM   #10
Senior Member
 
Join Date: Dec 2014
Posts: 151
Or it can be a very weak fuel pump.
__________________
Mr Plymouth is offline   Reply With Quote
Old 12-16-2015, 07:34 AM   #11
Senior Member
 
Inthe70s's Avatar
 
Join Date: Sep 2011
Location: Castle Rock, CO
Posts: 305
Thank you to everyone that responded as they are all good suggestions. I think I will do my maintenance, see how it runs but now I'm leaning towards the EGR issue. That seems to make the most sense although it could be anything. Whatever the culprit is, it seems to act up after it is well warmed up and relatively soon after it has warmed up so something is reacting to the temperature and timing. If you like tinkering and restoring older vehicles like I do, then it's what I always say..."its always something"
__________________
'74 F350 44K,'79 11' Mitchell Camper, MINT All Original
'79 Mitchell 25' Class C, 460 46K, MINT All Original
'97 Rexhall Aerbus, 60K, 460, F53, MINT All Original
Inthe70s is offline   Reply With Quote
Old 12-16-2015, 10:24 AM   #12
Senior Member
 
Fleetwood Owners Club
Ford Super Duty Owner
Join Date: Dec 2014
Location: Northeast Ohio
Posts: 143
The 460 engine was known for intake manifold leaks at the heads. When it's warm and running bad, pour some water (I use to use an empty anti-freeze jug)along the sides of the intake manifold where it's bolted to the heads. It will really run bad or stall and you may see steam come out the tail pipe if it's leaking. I had one where you could see a bathtub drain swirl at the point of the leak.

You can also use the water trick by pouring it slowly over different items, when the water is sucked in at the source of the vacuum leak you'll know it and can better pinpoint it. Works better than carb cleaner and won't ignite..........

Remove the vacuum hose from the EGR valve to eliminate the control source (could be mixed up vacuum hoses or bad thermal vacuum control switch).

Also remove the gas cap to see if it's a tank venting issue.
__________________
2000 Fleetwood Southwind 32V - Ford F53 V10 6.8L
Randalpho is offline   Reply With Quote
Old 12-16-2015, 11:52 AM   #13
Member
 
Vintage RV Owners Club
Join Date: Jul 2012
Posts: 95
I know you say you changed the filters. On the 84 Ford 460 we had there was a filter in the carb under the fuel line attach fitting ( I am currently having a senior moment and trying to remember what it is called" It was a 100 micron filter. we had the same problem you describe.
You need a 1 inch wrench to get the fitting off the carb. After I changed it, problem gone... After that I carried a spare one because some you ng parts guys gave me a blank stare when I asked for a filter that goes in the carb.
__________________
Mr.Geritol is offline   Reply With Quote
Old 12-16-2015, 05:23 PM   #14
Junior Member
 
Join Date: Nov 2015
Posts: 9
..........I'd bypass the factory fuel pump and hook the electric pump directly to the carb and drive it . I'd also put some gas in a clean 1 gallon container , insert the suction hose for the electric pump into the container and see how well it runs , again with the factory pump bypassed . You may need to drop the fuel tank and examine the intank screen filter pickup for blockages . I hope you solve your problem . , santex
__________________

__________________
santex is offline   Reply With Quote
Reply

Tags
class c, ford, rust



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Ford defect bucsfan116 Ford Motorhome Chassis Forum 6 10-15-2015 10:00 PM
maverick..2008 ford, one slide class c..want to buy lformby Class C Motorhome Discussions 3 09-20-2015 06:10 PM
Serious ? for those who prefer Class C's SissyBoyBob Class C Motorhome Discussions 168 05-27-2015 08:28 AM
Buying used Class B LeeOts Class B Motorhome Discussions 6 12-26-2014 09:31 AM
2013 Ford Class A Chassis OBD BobWW Ford Motorhome Chassis Forum 8 09-13-2014 06:55 AM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 10:47 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.