SUMMIT CRUISERS
SILVER Star
Vehicle 92 3FE with 350K.
About a year ago we noticed it would sometimes take 3 swings of the key to get the motor started. Lately it has even taken as many as 7 attempts. In the last 30 days it has failed to start completely 3 times (about once/week). After an hour or so, it would always start.
What has been done to truck in the last year: new cat and muffler, new fusible links, used AFM that was tested per FSM, new denso oxygen sensors, new fuel sock and filter, new battery cables, new battery, new starter contacts, new spark plugs, wires, cap and rotor, new starter.
Whenever it wouldn't start we always had spark, the starter would always crank, and we would install a jumper in the diagnostic box to run the fuel pump. Fuel pump was always humming like it should. Spark-check, Fuel pump running-check. CEL light on when starting-check. No CEL codes retrieved-check.
Yesterday, we rented (free tool loan program) a fuel pressure tester from Autozone. I removed the cold start injector line from the fuel rail and tapped into there for the test. The fuel rail is the best place you can accurately test the fuel pressure required for the injectors. With the fuel pump bypassed through the diagnostic box, we turned the key on and got 42#'s of pressure. FSM states 37 to 46 psi. All is good, right? After about 30 minutes we noticed that the fuel pressure had dropped to 0. So we turned on the pump again and had 0 pressure. What? How could that be? The pump is running.
Next I go under the truck and squeeze the return line/hose and feel fuel going through it back to the tank. So how could it be bypassing?
At this point I go up top and notice the fuel damper at the end of the fuel rail. This is the one that usually has a plastic cover over it and when removed you will notice a small screw (known as the "magic screw") in the middle of it. I tap on the damper and immediately notice the fuel pressure increase to 10, 20, 30, 42 psi.
Several years back I found the screw out of the damper laying inside the cap. I found several threads that mentioned the "magic screw" and to screw it in to get better fuel mileage. So I did so with no notable difference in performance or fuel economy.
As I unscrewed the small screw I noticed the pump off/fuel relief pressure increase. As I tightened it down I noticed the pump off/relief pressure drop to 0. I ended up setting it out as far as possible to where relief pressure would not create a drop when screwed in. I added locktite on it and put the plastic cap/cover back on.
In conclusion, I know the fuel damper acts as a pressure relief valve when the truck is not running. Ours was intermittently stuck in an open relief position which could have been caused by tightening down the "magic screw". Since the fuel pump is only activated in the start position, this is a reason why some vehicles are taking longer for the engine to start.
Today I have noticed smoother idle, better performance and will be checking fuel mileage and report back. Last tank was 10.3 mpg for city driving.
A new one with the metal gaskets will be ordered shortly. Part #2327031080 is the number I have found but will confirm with CDan when ordering.
About a year ago we noticed it would sometimes take 3 swings of the key to get the motor started. Lately it has even taken as many as 7 attempts. In the last 30 days it has failed to start completely 3 times (about once/week). After an hour or so, it would always start.
What has been done to truck in the last year: new cat and muffler, new fusible links, used AFM that was tested per FSM, new denso oxygen sensors, new fuel sock and filter, new battery cables, new battery, new starter contacts, new spark plugs, wires, cap and rotor, new starter.
Whenever it wouldn't start we always had spark, the starter would always crank, and we would install a jumper in the diagnostic box to run the fuel pump. Fuel pump was always humming like it should. Spark-check, Fuel pump running-check. CEL light on when starting-check. No CEL codes retrieved-check.
Yesterday, we rented (free tool loan program) a fuel pressure tester from Autozone. I removed the cold start injector line from the fuel rail and tapped into there for the test. The fuel rail is the best place you can accurately test the fuel pressure required for the injectors. With the fuel pump bypassed through the diagnostic box, we turned the key on and got 42#'s of pressure. FSM states 37 to 46 psi. All is good, right? After about 30 minutes we noticed that the fuel pressure had dropped to 0. So we turned on the pump again and had 0 pressure. What? How could that be? The pump is running.
Next I go under the truck and squeeze the return line/hose and feel fuel going through it back to the tank. So how could it be bypassing?
At this point I go up top and notice the fuel damper at the end of the fuel rail. This is the one that usually has a plastic cover over it and when removed you will notice a small screw (known as the "magic screw") in the middle of it. I tap on the damper and immediately notice the fuel pressure increase to 10, 20, 30, 42 psi.
Several years back I found the screw out of the damper laying inside the cap. I found several threads that mentioned the "magic screw" and to screw it in to get better fuel mileage. So I did so with no notable difference in performance or fuel economy.
As I unscrewed the small screw I noticed the pump off/fuel relief pressure increase. As I tightened it down I noticed the pump off/relief pressure drop to 0. I ended up setting it out as far as possible to where relief pressure would not create a drop when screwed in. I added locktite on it and put the plastic cap/cover back on.
In conclusion, I know the fuel damper acts as a pressure relief valve when the truck is not running. Ours was intermittently stuck in an open relief position which could have been caused by tightening down the "magic screw". Since the fuel pump is only activated in the start position, this is a reason why some vehicles are taking longer for the engine to start.
Today I have noticed smoother idle, better performance and will be checking fuel mileage and report back. Last tank was 10.3 mpg for city driving.
A new one with the metal gaskets will be ordered shortly. Part #2327031080 is the number I have found but will confirm with CDan when ordering.
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