BLDTruth

Hey Steve can you comment on the fuel pressure - I know that the 300 had two different fuel specs in this era of trucks - some were 45-60 psi and some were 35-45psi like the V8's. The OP is seeing 40-42 psi which would be great for a 302 but if its the 300 that requires the 45-60 psi, it could explain why he is having so many issues.

Also the lack of any fuel pressure with KOEO make me think there is an injector stuck open, or something along those lines.

To the OP - if you haven't changed your fuel filter or don't know when it was last done - do it - even if it doesn't fix the problem, its a $10 maintenance item.

jbeebe

I have a fuel filter sitting in my garage, it'll go in tomorrow morning. thanks!

Steve83

Every spec I've seen for the 4.9L says it should be up in the 50-60psi range. Mine has always run perfectly at 35-40 (because I use JY pumps from V8s), and it will run at 12~15 (when the tank is nearly dry). These injectors can't stick open unless they're mechanically crushed (like in a wreck; but even then, it's not likely).

mike100

I would buy the entire assembly for the crossflow issue (front tank). It takes a little practice to be able to get one apart without breaking the 25 year old plastic. Hopefully you get somewhere with the fuel filter too.

raski

Fuel pressure specs for the 4.9 are as follows:
1987-1994......45-60 psi
1995-1996......30-45 psi
The OP's pressure is below spec for 1993. Check the pump.Connect a fuel pressure gauge, start engine, pressure should be 45-60 psi, pull vacuum line off the regulator, pressure should go up and no raw fuel present at nipple, if so replace regulator. While observing pressure, goose the throttle, if the pressure jumps down momentarily then goes back up, the pump is weak. Pressure should drop very little if any if it is in good shape.

BLDTruth

Thanks raski - I knew there was a changeover at some point in the 90's but wasn't sure when.

Starting to wonder if the OP's fuel filter has never been changed. Could explain everything. Still a little stumped on the KOEO results.

jbeebe

I just replaced the fuel filter. The one that was in it wasa motorcraft in good condition and looked no more than a few years old. It still has the same symptoms as before, on either tank I hear the pump priming, but then it cranks and cranks and doesn't start.

Steve83

IDK where you're getting that - my '95 PCED says:

jbeebe

So the Motorcraft fuel pump is about $320. I'm hesitant to pull the trigger and it not be what's wrong. How could the front fuel pump failing also cause the same poor running conditions and low fuel pressure when the rear tank is selected?

Is there something else I could check or do to have a better idea, or is replacing the front fuel pump my best bet?

Thanks everyone!

BLDTruth

Did you ever try pulling the vac line off the FPR while it is running and see what happens with pressure?