I have a 93 f150 with a 5.8, e4od, short box, 1 rear tank. When the problem started the truck would run crappy sometimes. I haven't driven the truck much in the last few years but when I did the problem seemed to slowly get worse. It is very hard to start and when it does start, pressing the accelerator stalls the engine. The cel test gave me a 126 and a 128 which are MAP codes, however the map tested out just fine with a vacuum pump and multimeter(on hz of course). I dropped the tank removed the fuel pump, cleaned it and it does pump. I don't have a pressure gauge however to see how much it is actually pumping or to check at the rail. I also replaced the fuel filter, cap, roter, plugs, and wires. I have ran lucas cleaner through the fuel system as well. I really cant afford to buy a new fuel pump if it "might" be the problem so any ideas would be appreciated.

 

Go to Autozone and get a pressure gauge - they have them in the "loan a tool" kit.

 

Also I forgot to mention I replaced the pressure regulator as well. I don't have an Autozone near me and the local parts stores don't rent one.

 

have you checked the injectors?
You might want to run seafoam instead of lucus.
Lucus is more of a lubricator, seafoam cleans gunk out.
I do it every 3000 miles on my trucks and cars and keeps them clean, well as clean as they can be.

 

I have not checked the injectors, is there any way to get at the pass side without taking off the plenum?

 

cant get to the bolts that hold the fuel rail but the plentums arnt had to take off just make sure u get a new gasket they are only a few dollars n cheap insurance

 

No, they're diagnostic codes which mention the MAF. Codes aren't for parts - they're for systems. What's the WHOLE definition of each code? If one of them is "MAF open circuit/short circuit", then it's no surprise that your MAF tests fine but the codes appear.Then buy a fuel pressure gauge.