93 4.0 fuel problem.
 

Hey guys, I’m new to this forum. I’m trying to get some help with my 93 ranger with 4.0. I had the fuel pump go out on me. So I jacked it up drop the tank changed it out put everything back together like it was supposed to change out the in-line fuel filter put everything back together. I started it up while I still have the rear on jackstands. And it ran fine as soon as I jacked it up and took it off the jackstands and let it down about 10 seconds went by and the motor cut off. I tried to start it back up with no luck. So I jacked it back up out of curiosity and it started right up and ran just fine.As soon as I let the jack back down the tires hit the ground taken seconds went by it cut back off again. I checked all my connections doesn’t seem like it’s leaking fuel anywhere so I’m kind of stumped. Any help from you guys would be much grateful and appreciate it thank you.

Silly question, but how much fuel is in the tank?

I have 3/4 of a tank. I thought about it being low myself but it’s good. I just find it odd it runs fine if I have the back of the truck jacked up but not level. My first thought would be weak fuel pump and the gravity is helping it flow but it is the second new pump I put in.

Fuel pump runs for 2 seconds when key is turned on, but only 2 seconds, you can HEAR it run in the cab, a HUMMMM from behind cab
Cycle key on and off as much as need so you KNOW what it sounds like
Then lower truck back down and see if you hear it running then

I did do that. I can hear the pump kick on. I wonder if I’m sucking air from a fitting. I know the vacuum line going to the vent at the top back of the tank shouldn’t cause an issue should it? That’s just for the canister isn’t it?

Yes, thats for the EVAP system so no it wouldn't cause a no start issue

If the pump is running then engine should start

Do you "know" there is 3/4 of a tank of gas or does the gauge just show 3/4 tank?

No on the sucking in air, that would effect starting at any angle

Its a puzzler, for sure

Yes sir I know for a fact. After I dropped the tank for the first time I cleaned the little bit of crud in the tank. And added three 5 gallon cans of gas after I re installed the new pump and tank. What get me is the fact I can jack it up and it runs fine but not on level ground. I thought about installing a helper pump but I don’t see where I’d need it. But I do have a question about the fuel regulator. When I cycled the pump at the top regulator fitting it came out of the top of the regulator and not the braided line. I thought the braided line was the supply line to the fuel rail?

The IN from filter goes to the fuel rail, drivers side between upper and lower intakes
The OUT back to tank comes from the FPR(fuel pressure regulator), passenger side below alternator

Both are braided in engine bay

Gas tank Pump---->>-----filter-------->>--------------fuel rail

FPR------->>------------------------->>-------------------Gas tank

So I just had time to mess with the truck. Jacked it up and got it running slowly let it down and you got it to where it would actually idle. Roughly but idle. I shut it off and I put a fuel pressure gauge on it initial key on engine off it’s about 40 psi. I left it on and started the truck I dropped down about 30 psi and would bounce between 30 and 35 when I got close to 3540 and acted like it wanted to cut off so I gave it some fuel and it leveled out at about 40 psi. Back t idle it would maintain just above 30 and start bogging at closer to 35. Any opinions?

Reads normal for a 1997 and older Ranger EFI

So I finally figured out what the problem was. The first time I dropped the tank and changed the pump, when I went to get gas I got bad gas with water in it and didn’t realize it. Hence being able to run while jacked up. The water went to the front of the tank.

Good find :biggthump

Never would have suspected that