Cannot rev up
Thread Starter
|
New User
Joined: Nov 2006
Posts: 3
Likes: 0
Cannot rev up
Hi There
We bought this used 86 F350 6.9 diesel. It ran fine, until ran low on fuel then it cannot rev up to 1100RPM. We changed the big diesel fuel filter and it ran well.
Pass week we ran low on fuel and repeating the same problem of cannot rev beyond 1100RPM and idling is rough.
Today we changed the big fuel filter but the condition didnt improve.
So what have we missed? Is there another filter which we didnt knew about?
Is there two fuel pump? One sitting on Passenger side front right corner of the engine or if standing infront of truck is your left side. And the fuel distributor pump.
TIA
We bought this used 86 F350 6.9 diesel. It ran fine, until ran low on fuel then it cannot rev up to 1100RPM. We changed the big diesel fuel filter and it ran well.
Pass week we ran low on fuel and repeating the same problem of cannot rev beyond 1100RPM and idling is rough.
Today we changed the big fuel filter but the condition didnt improve.
So what have we missed? Is there another filter which we didnt knew about?
Is there two fuel pump? One sitting on Passenger side front right corner of the engine or if standing infront of truck is your left side. And the fuel distributor pump.
TIA
Posting Guru
Joined: Aug 2006
Posts: 2,175
Likes: 0
From: Kent WA
When you "ran low on fuel" the second time, did you fill up the tank? If not give that a try. There have been numerous posts on the board here about cracked fuel pickup tubes in the tank. If they crack the fuel pump starts sucking air somewhere at around 1/4 to 1/2 a tank. If filling up the tank fixes the problem, then you know the pickup tubes are cracked and you have to drop the tanks to pull them out and repair/replace them.
Thread Starter
|
New User
Joined: Nov 2006
Posts: 3
Likes: 0
Thanks folks, we'll try to look at these areas see if it can be fixed.
I notice there is a valve just like the tire valve that if I push in it will bleed diesel out, there seem to be clean Diesel, no air nor water coming out.
Last time before the filter change, if the truck had been rested for several hrs it seem to run normal. Consistent with something clogging, if let her sit the material kind of not clogged up against the filter or whatever.
SO there is no other filter besides the main great big one.
I notice there is a valve just like the tire valve that if I push in it will bleed diesel out, there seem to be clean Diesel, no air nor water coming out.
Last time before the filter change, if the truck had been rested for several hrs it seem to run normal. Consistent with something clogging, if let her sit the material kind of not clogged up against the filter or whatever.
SO there is no other filter besides the main great big one.
Posting Guru
Joined: Oct 2003
Posts: 2,438
Likes: 0
From: Monroe, WA
Does it still have the fuel separator on the firewall? That's the one to the outside of the brake cyl/booster. Most have been disconneted by now, maybe your's was missed.
Pull the hoses off it and hook them together and try it.
Pull the hoses off it and hook them together and try it.
Thread Starter
|
New User
Joined: Nov 2006
Posts: 3
Likes: 0
Thanks
Looks like the sep was not here. Is it good idea to buy another one?
I am letting the truck to sit for a day. Last time it ran better after it had been sitting for a day without doing anything else.
Looks like the sep was not here. Is it good idea to buy another one?
I am letting the truck to sit for a day. Last time it ran better after it had been sitting for a day without doing anything else.
Post Fiend
Joined: Nov 2004
Posts: 5,638
Likes: 1
From: Manitoba
I notice there is a valve just like the tire valve that if I push in it will bleed diesel out
Take the Schrader valve core out and hook a hose and pressure guage to the outlet.........crank engine see what you get for pressure, should have 4-6 psi from a good lift pump.
Volume test same place hook a hose to it crank over the engine 10 seconds you should get 1/3 pint of fuel minimum or 1 pint at 675 rpm in 30 seconds... engine running
Important the fuel shutoff solenoid (FSS) wire on the IP should be disconnected if you do not want a start just cranking. Re connect FSS after test complete.
Once the firewall water separator is disconnected there is no stopping the water from getting to the IP. Ip insides will rust, when they do things do not work right.
You can still use the water separator as designed, but you must block the drain hose with a bolt and clamp afterwards to eliminate air intrusion.
Ensure there is power to the FSS on the IP continually when ignition power applied and a warm engine. Someone may have switched the wires and the FSS shuts off fuel but the IP will pull enough to run sometimes.....but poorly.
FSS is the front drivers side spade connector.
Last edited by PLC7.3; Nov 6, 2006 at 11:09 PM.
