I borrowed a snap on digital timing light to check timing on a 93 f 250 5.8w.
It read 3 degrees before top dead center.
The tachometer on the dash reads 900 rpms yet the timing gun is all over the place from 360 to 780 rpms.
The timing light is also sporadic, missing flashed intermittently.
Yes I disconnected the spout.

I just need help on what to do next. Thanks

 

Recheck how and where you were placing the trigger pick-up for that fancy light.

For reference: Fuel Injection Technical Library » Setting the timing

 

I did put it on number5 also got the same rpm readings. Slid it down close to the sparkplug away from other wires.

 

I suggest you return that light to whom ever you borrowed it from. Or enlist their assistance with using it. Not that you are doing anything wrong....

 

It's supposed to go on number 1 plug wire.

For reference... in case you're more familiar with Chevys..

 

I had it on number one first. So you guys are sure it is the timing gun and not my truck. I read in the instruction book that came with the timing light that if the rpms did not match I needed to do the necessary adjustments??

 

The timing light RPM is varying by ~400 RPM. Does the truck actually exhibit this type of rolling idle? You did not mention it. If the truck appears to have a steady idle I suspect your diagnostic tool is actually a door stop in disguise.

 

I got a new light and it works just fine it is only a inductive light. I am reading that my timing is at 2 degrees BTDC.
Would this indicate that my chain may have jumped? I bought this truck 4 months ago. It has always been a gas guzzler.
Anyways, where should I start to get this truck in better running shape. I have no codes took care of them already.

 

No.. timing chain jump is not at all common on these motors so I'd suspect somebody before you just set it incorrectly. Factory timing spec is 10deg BTDC with the spout plug disconnected, set it there for starters and do a test drive to see how it runs.

Heavy fuel consumption could be a lot of things or several problems together. Have you pulled the codes to see if anything is flagged? Are the tires stock sized? What gearing does the truck have? See the calibration decal on the drivers door pillar for this info, axle codes can be decoded here..Ford Axle Code Chart .: Articles
Also check fuel pressure and for the presence of fuel in the vacuum line attached to the regulator, that would indicate a ruptured diaphram which means it should be replaced. Spec on fuel pressure is 38-45psi with vacuum removed and 32-35 with vacuum. Also does the truck get the same fuel milage on both tanks.. assuming a dual tank truck? There is a common fuel transfer problem that was addressed by a TSB that put an external check valve on the supply line at the tanks, but it can still occur if the check valves inside the fuel delivery modules inside the tanks completely give up.

 

First off my buddy was reading it wrong...sorry but it is only 7 degrees BTDC. My axle I guess is this....H5 4.10. 3800 FORD LIMITED SLIP 1991
going off the 8th and ninth digit in my vin number. I have w= 5 speed HD overdrive manual tranny.
My tires are factory to spec LT285 75 r16.
In case I did that wrong here is a picture.


I have no codes I took care of them last month.
Where can I get a inexpensive vacuum tester for the fuel pressure? Btw ford just changed out my fuel pressure regulator 2 weeks ago it was a recall.
I did think I was getting better gas mileage from the back tank.

Thanks for helping me with this I really wanted learn these things.

 

The "H" in your VIN denotes you have a 5.8 liter engine. The 5 is a "check digit".

The Axle Code listed on your door jamb sticker is 35, which equates to a 6250 lb. axle w/4.10 gears.

You are much better off to rent a fuel pressure gauge from AutoZone, Advance Auto or other store. I have a cheap one from Harbor Freight, I rarely use it.

 

Ok I rented a fuel tester and the pressure koeo front tank 4psi rear tank 8 psi. Both tanks 32psi koer.
Is there any other tests I can run while I have this tool?

 

4 & 8 KOEO? I assume you cycled the key from Off to Run once? If so that pressure is awfully low.

32PSI with the engine running at idle is within specification. Remove the vacuum hose from it, it should go to ~45 PSI.

Put the hose back on, verify the pressure returns to ~32 PSI then shut off the engine. See what the pressure bleeds down to at 30 seconds, 3 minutes then 10 minutes. If the pressure drops dramatically, like back to 4/8 then you may have a bad injector leaking down, a faulty fuel pressure regulator (yes I understand it is new) or bad check valve in a fuel tank. You might try this test on both tanks.

 

Yes I read that you were supposed to take off the vacuum line and I tried the line above the fuel injectors and there was no change and I tried another by the throttle body and no change. I wonder if I have the right vacuum line?

 

The vacuum line you are looking for will be on something that looks like this :