| Author | Message | ||
| LOU MURDICA (Loucon)
Registered Member Username: Loucon Post Number: 20 Registered: 3-2006 Posted From: 64.27.5.211 Rating: N/A |
I have a 1992 8V-92 mechanical throttle. The problem is it starts great and runs for about 3 minutes 750 rpms and then goes to 1000 rpms and stays there. The other problem is The piston that pushes on the throttle arm that stops you from giving it any fuel. When you step on the pedal does not work. And will not such back in. if you take the two Screws out holding the piston to the throttle it drives fine but the rpm stay too high. does this make sense | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 575 Registered: 7-2006 Posted From: 66.217.106.149 Rating: |
Re: "does this make sense" It does, if your fast idle is on. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1161 Registered: 12-2000 Posted From: 76.66.19.91 Rating: |
Yup, fast idle. Electrically controlled, pneumatically activated. Air pressure builds shortly after engine start and pushes the cylinder out. happy coaching! buswarrior | ||
| Cameron Jones (Crazy71)
Registered Member Username: Crazy71 Post Number: 78 Registered: 12-2006 Posted From: 72.49.253.33 Rating: N/A |
My MC8 is same way. The fast idle kicks in when the air pressure comes up. If your fast idle switch is off, take it out and check it to make sure it isn't a bad switch. If somehow it is staying on, you can bypass the fast idle air actuator. Mine has a rubber hose going to it. I have bypassed similar air hoses by crimping them off with a pair of needle nosed vise grips. You could also take both lines off of it and hook them together I believe. On my 8v-71 the fast idle is the smaller brass looking one.. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 716 Registered: 12-2000 Posted From: 76.3.169.171 Rating: |
First, Is your fast idle switch in the OFF position? I think you have one of 2 problems. First, the fast idle solenoid is probably leaking air past the seal allowing air to enter the fast idle piston and appling the fast idle OR you have an electrical problem that is causing your fast idle solenoid to be energised. If you disconnect the electic connection to the fast idle, then start the engine and still have the problen, it is the solenoid. If it works properly with the electric disconnected, you have an elctrical problem. | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 264 Registered: 8-2006 Posted From: 74.33.63.106 Rating: N/A |
You should have no electical power to the fast idle solennoid when the parking brake is off this will disengage the fast idle so like Jack said it probably the solenoid. yours could be wired different from mine but most are not (Message edited by luvrbus on January 16, 2008) (Message edited by luvrbus on January 16, 2008) | ||
| LOU MURDICA (Loucon)
Registered Member Username: Loucon Post Number: 21 Registered: 3-2006 Posted From: 64.27.5.211 Rating: N/A |
I've owned this bus for 9 years and never had a fast idle and there is no fast idle switch. even when I take the plunger on the plate so it hits nothing it still idle high. I will take the brake off and see if it releases the plunger and see if i get throttle control. I will also try to take a picture. thanks | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 87 Registered: 10-2006 Posted From: 71.239.202.82 Rating: |
You might be sucking air someplace on a fuel line. | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 265 Registered: 8-2006 Posted From: 74.33.55.186 Rating: N/A |
Lou,does your bus have a Jake Brake | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 17 Registered: 11-2007 Posted From: 58.165.223.77 Rating: |
There are two air cylinders associated with fast idle - one that locks out the throttle linkage and one that operates directly on the rack. On an 8V71 anyway | ||
| LOU MURDICA (Loucon)
Registered Member Username: Loucon Post Number: 22 Registered: 3-2006 Posted From: 64.27.5.211 Rating: N/A |
one that locks out the throttle linkage. this is what it is i think. yes it has a jake brake. |
