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spj22
06-25-2013, 12:35 AM
Hey all,

I'm having issues with my '98 4.0 Ranger. The vehicles new to me so I'm still working on locating certain parts so location info is much appreciated.

It's had a hard start for a couple months now. 1-3 second delay. I usually give it some gas to get it going. Seems to help. Recently it'll kill every other start, shortly after firing. It fires up immediately after. When I get around the 45-60mph mark the acceleration leaves something to be desired and she'll bog a little. It'll also bog while in idle. Not enough to kill it but enough to delay acceleration if it's more than 30 seconds. I've been putting it in N during long red lights to avoid the delay in acceleration.

Gotta break in the work week coming up and this is the last to-do on this truck. Any help is much appreciated. I'm guessing it's a fuel pressure regulator issue but I'd like a second or 12th opinion on the matter. If someone could point me to the locale of the FPR and the testing port for a pressure guage I'd be much appreciative

Mikeroewave
06-25-2013, 01:22 AM
Hey im new to the site. but that kinda sounds like maybe an o2 sensor on the front. is your check engine light on? on my 2003 i had an issue where it would not idle. i cleaned i think its call ACS on the top of the motor it had a ton of carbon deposits in it. and also mabey clean you air filter. the delay in start could be your fuel filter. That i located on the frame under the driverside door. Usually.
Hope i could help.

RonD
06-25-2013, 01:01 PM
'98 Ranger 4.0l has a returnless fuel system so no FPR on the rail, it is in the tank with the pump.
Pressure should be about 60psi at the rail, there is a schrader valve(like a tire air valve) on the rail to test pressure.
Fuel filter is usually under $10 and not to hard to replace, make sure to relieve pressure in the system first, this doesn't sound like your problem except for the higher speed bogging issue, but could be part of the problem, and it never hurts to replace a filter.


When started cold the engine should idle at about 1,100-1,500rpm, then slowly go down to 700rpm once warmed up.
This is controlled by the IAC(idle air control) valve on the side of the upper intake, it is, in essence, a controlled vacuum leak.
If the IAC valve gets dirty or sticky it can cause poor idle and stalling.
Good news is it can be cleaned :)

The MAF(mass air flow) sensor needs to be cleaned now and then as well, and could cause all your issues.
Have a read here:
http://www.therangerstation.com/tech_library/CleanMAF.html