Head scratcher
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Joined: Oct 2007
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From: Blount County
Head scratcher
I have a 1987 F-250 4x2 with 5.0L and 4 speed mannual transmission. I replaced the engine with a new long block. Here is the problem, when the engine gets to operating tempture it will not take fuel. I also back fires thru the throttle body. I have replace all sensors, new fuel pump and filter. I have removed the thermostate and still have the problem, just takes longer to heat up. I have had it to several shops and no one can figure it out. HELP!!!
Junior User
Joined: Oct 2007
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From: Aromas, CA
I know you might have already thought of this. Where are the fuel lines run? Are they close to anything that might cause them to be vapor locked? The only sympotm that is throwing me off is the fact that the timing is to advanced.
Fleet Mechanic
Joined: Aug 2007
Posts: 1,805
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From: Piney Woods of East Texas
On the long block, did you install a new timing gear set. And is the timing set correctly. Back fireing through the tb indicates timing. I would install the stat back in, without one it will never get to operating temp in a timely manner. Also make sure you fuel pressure is correct on the rail. if it's low you will run real lean and rough.
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New User
Joined: Oct 2007
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From: Blount County
I did reinstall the stat. Timing gears and chain are new. Truck starts and runs pretty good when cold, but will not take fuel once it gets to operating tempture. Acts like it is vapor locking but I did not think an EFI system could vapor lock.
Fleet Mechanic
Joined: Aug 2007
Posts: 1,805
Likes: 245
From: Piney Woods of East Texas
Yes a EFI will normal not vapor lock due to it circulate excess fuel back to the tank with the regulator. What is your fuel pressure running on the rail? >35psi. Also what is your vacuum running at idle?
Do you have a scanner you can connect and look at inputs. Interested if the problem only exist when the computer goes into closed loop. Also retrace all of the vacuum lines. If your vacuum is low, uses propane gas and snoop for your leak.
Do you have a scanner you can connect and look at inputs. Interested if the problem only exist when the computer goes into closed loop. Also retrace all of the vacuum lines. If your vacuum is low, uses propane gas and snoop for your leak.
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