Fuel problem and a burning smell?

[Ranger4x4newb]

As of lately my fuel economy has dropped, no changes in my driving habits. The only thing ive done on the truck is new diff fluid (75w 140 synthetic) new tcase and transmission fluid and the addition of a tranny cooler and external filter. The burning smell has been prevelant nearly since i ourchased the truck only getting worse and worse. Could there be a problem with fuel leaking and burning off? Theres no smoke under the hook just a neasuating smell.

 

[RonD]

Could be cat converters over worked by rich mix

Poor MPG would also be part of that.

how many miles on the O2 sensors?

2 new upstream sensors(V6) are usually needed after 100k

Also Clean the MAF sensor, that is computers main sensor for fuel mix
O2 sensors are the last say though

 

[Ranger4x4newb]

I just out in new denso upstreams and a reman maf less than 4000 ago

 

[RonD]

Did the O2 sensors look blackened, like a rich fuel mix had been running

'98 Ranger will have a Fuel Pressure regulator(FPR) and run 35-40psi of fuel pressure.
FPR will toward the front passenger side of the engine.
Return Fuel Line will be connected to it
It will also have a Vacuum line, remove this vacuum line and check it for fuel
If FPR diaphragm starts to leak you can get a fuel smell and some fuel will get sucked into the intake causing rich running and smell.

I would rent/get a Fuel Pressure gauge, put it on the fuel rail's schrader valve(looks like tire air valve).
With engine running you should have steady pressure above 32psi.
Unhook FPR vacuum line, pressure should jump up to close to 40psi.
Turn off engine and pressure should hold above 28psi, basically for a month or two.
If pressure is slowly falling then you could have leaky FPR or fuel injector.

Pull each spark plug and look for one that is blacker than the others, that could mean that injector is leaking.

 

[Ranger4x4newb]

The old sensors didn't look black but they were glazed from heat and were more of a brown color. I have a pressure gauge so ill check pressure and let you know the findings when i can. Thank you for all the help.

 

[Ranger4x4newb]

Well i just checked it and at idle im at 65 psi.. Could that be because the engine was cool? Should i warm it up to perform this or is my fpr bad?

 

[cp2295]

No I'm fairly certain a 98+ is a returnless fuel system which runs at 65psi. So you should be good. 97 was the last year of the return system from what I've read and remember...don't quote me though [emoji23]


Sent from my iPhone using Tapatalk

 

[RonD]

Yes, Ford switch to returnless fuel system in '98 so it can be either 35psi or 65psi depends on when it was made in '97/'98, all '99 and up were returnless.

Did the 65psi hold after engine was shut off, key off?

Returnless systems have an Fuel pulse damper at the end of the fuel rail near the firewall, it also has a vacuum line attached, check it for fuel

 

[kimcrwbr1]

The burning smell could be oil dripping on the manifoldor exhaust pipe? possible valve cover gasket or intake manifold leaking out the valleys where the head and block meet together.