Great site, glad I found it! I have a 1990 E250, which was being used as a storage shed when i found it. I have done much work on this 4.9, replaced head, crank, lifters, pushrods, oil pump, injectors, etc..It's been running reasonably well since, I have put about 13k miles on it, it has a minor hesitation but is livable. I had also replaced the tps, air idle solenoid, o2 sensor, motor had come with a new egr valve, and after reading some posts here, I made a stainless restricter plate with a 5/16" hole. Problem is economy. I get about 10 mpg. In reading through previous posts I got a lot of insight as to the "idiosyncrasies" of the EFI 300. I understand that the correct mark on the damper is the thin scribed line, and that the true timing marks are on the bracket bolted to the timing cover, on the passenger side of the block, not the cast marks on the drivers side. Heres where the problem comes in...I don't have the timing bracket bolted on the passenger side. It wasn't there when I pulled the crank. (This motor had been molested in the past, the journals weren't even in order.) I have seen this bracket on other sixes, is it possible to bolt one on without pulling the damper? Are there other means to time? Should I pull the spout and just advance until it rattles, then back off a little? Would I do this at part throttle? or at idle? Would I use a vacuum guage and hunt for "20"? Would really appreciate some advice here, as I believe this motor could run a little better. Thanks all.

 

If it sat for a long time I would run 2 bottles of heet and 2 bottles of iso heet to remove water from the equation. It can cause a lot of problems that seem to be other things(sensors,electrical gremlins,etc.) You could have some sitting on your injectors and the computer is getting a lean signal and putting more fuel to it but the clear injectors cylinders are just getting more fuel and not burning completely, causing your bad mileage and the hesitation. Run the water dryer on whatever is in the tank 3/4,1/2,1/4 tank run it until 1/8 tank then refill with fuel and 2 more bottles of isoheet
No i don't work for them I have seen alot of vehicles with water in the gas and mechanics replace sensors and everything they can think of, but it was just simple water. With gas prices as high as they are and people running around with less than a full tank, condensation builds up on that empty space causing alot of problems.

 

I would bump the timing up (advance it) a degree or so at a time and drive the vehicle. When I started to get pinging at low rpm under load, back the timing off to the previous setting. I have timed many of my vehicles this way regardless of what the timing marks indicate. A slight ping under heavy load is acceptable, and is going to be your best performance and mileage timing.

 

You can not set the timing of the 4.9 EFI by ear as described above and get good results. It won't start knocking until you've got about 25 degrees of initial in it and power starts hurting at abouty 16 degrees.

If I were in your shoes this is what I would do:

Either buy a piston stop or make one from an old spark plug and install it in number one. Rotate the engine one direction by hand until it hits the stop. Make a mark on the balancer at zero degrees using the timing marks on the driver's side of the timing cover. Then rotate the engine by hand the other direction until it hits the stop and make another mark. Use a taper measure to find the point exactly between the two marks and mark it as your new TDC mark. Now you can set the timing using the cast in marks.