'92 4.0 won't stay running....

[STRUCK]

Did the swap on my ranger, changed the entire harness under the hood(firewall out). Got it running but it will start go to a high idle then when it comes down to the normal idle it gets real ruff and dies. I try to give it gas to keep it goin but it hesitates and dies. I replaced the maf, tps, and pcv valve, and it does the samething. It also holds a cel the whole time.

I'm at a loss and could use some help, anybody?

 

[Mr99Ranger]

Replace iac with advance auto Part No. 21764 then disconnect battery, leave sit for half hour,reconnect bettery, start it up. Worked great on my 99 when it was idling at 250 rpm and stalling like crazy.

 

[Mr99Ranger]

Heres the iac valve. to replace all you gotta do is remove 2 bolts (blue) and pull off the connector (green.) Save the bolts cause the new one doesnt have them but it does have a gasket.

 

[STRUCK]

Thanks guys I'm gonna try that after work tomorrow. I'll let you know if it works.

 

[red93terror]

also man make sure you dnt have any air leaks downstream of the maf. thatll really piss off the ecu and make it die. i had this happen on my mr2 and it was a major pain in the nerts to diagnose.

 

[STRUCK]

Replaced the iac and disconnected the battery for about an hour. Its better, it idled rough for a few minutes then got real rough and died. I started it back up it idled and was about to die so I tried reving it to keep it running and it would be real hesitive to rev up and wouldn't hold an idle. 1500rpms and up is smooth but under that its rough. Still has a cel.

Red93terror, I made sure everything was tight(tb, intake, etc..) and all my vaccum lines are good.

 

[Mr99Ranger]

Do you know anyone with an obdI code reader? If so, pull the codes from the cel and see what its telling you. also, have you inspected all your vacuum lines and your intake tube? what about MAF? Glad to hear the iac helped. Good luck and keep us posted!!!

 

[Mr99Ranger]

Also, when you did your swap did you keep your 2.9 fuel pump or upgrade to either a 4.0 pump or higher flow aftermarket unit?

 

[STRUCK]

I'm trying to find someone that would be able to come by and read the codes. All my vaccum lines are good, replaced the MAF, and the intake tube is good. I still have the 2.9 fuel pump, but I heard that you don't have to change it unless thats not true?

 

[Mr99Ranger]

I'm not sure of the flow rates on either pump but i was always told the old 2.8 and 2.9's didnt have as high of flow fuel pump in them, and that it didnt provide the pressure the 4.0 pump did. I dont know if thats true or not maybe ill try to find some specs. a little later.

 

[STRUCK]

I found a guy that has a scan tool, he's stopping over tomorrow so hopefully we'll get this figured out. Thanks again and I'll keep you posted on what happens.

 

[RumpRangerSTX]

I'm trying to find someone that would be able to come by and read the codes. All my vaccum lines are good, replaced the MAF, and the intake tube is good. I still have the 2.9 fuel pump, but I heard that you don't have to change it unless thats not true?

i'm still using my 2.9 fuel pump let me know if u need help

 

[STRUCK]

Haven't had time to work on the truck been real busy at work. Figured I would give an update since I had some time to mess with it today. Just did a fuel pressure test and my fuel pump is definatly on its way out, showed 35psi not running and 42psi running. Going to order a new pump and fuel filter tomorrow, and since Im off work for 2 weeks starting Monday Ill have some time to get her running again.

 

[multiranger]

i'm still using my 2.9 fuel pump let me know if u need help

I used a 2.3 fuel pump on my 4.0 when I swapped motors