My 89 W150 has a mechanical fuel pump cover plate. I removed the plate to see if I happened to have a fuel pump eccentric on the cam gear. All I see is a bolt. My question is how can I tell if I have the short cam shaft or the long one so I know if I can just buy the eccentric and switch to mechanical pump?

 

Why do you want to replace the fuel injection?

 

Several reasons. 1. Fuel pump is no longer available 2. More tuning options with a carb and 3. Like to clean up the engine bay from all the dang vacuum lines and such.

 

Ok, that's reasonable.

Might consider an external in-line electric pump. The wiring is already there, and would take much adaptation. Then you don't need to worry about if the mechanical is even going to work.

 

there is no point using in line and wiring is not really that simple since the computer controls when fuel pump relay turning on so if you get rid of all the sensors that tell the computer what is going on the fuel pump will no longer turn on. you would need to install addition sensors and wiring to control the fuel pump plus in tank pumps are better anyways.

also fuel pumps are available unless you have damaged the sending unit. yes sending units are no longer available but the fuel pump itself is replaceable

 

You can adapt the later model year pumps to work.

 

The PCM just controls a relay. It would be simple matter to just have the relay engage with ignition in start or run.... and use a return style regulator to prevent flooding the carb.

 

seems risky hooking the pump up to run as long as they key is in the on position especially if he ever got in an accident. would be better off to spend a bit more and do it properly by installing a oil pressure switch to turn on the fuel pump.
https://www.motortrend.com/how-to/sa...l-pump-wiring/

 

I have a three 89-90 trucks with LA engines. The fuel pump and strainer are still available.... and quite cheap at rockauto.

Edit: the one i had apart to reseal the timing cover, i looked up the fuel pump eccentric, and it looked like it would simply bolt on.

 

I had a feeling the 89 had the long camshaft so I need the eccentric. I have located a engine wiring harness from a 87 along with the fuel tank so I believe this will be an easy project.