Hey everybody, I'm new here but to the point now. I have an 88 4.0 I6 and about a month ago one of my fuel injectors/ fuel pressure regulator started leaking, so I figured time to upgrade and got some all new 4 hole injectors and regulator installed that and started it up, it ran ok untell I put it into drive and it puttered and the idle was rough. Figured I forgot to reset the pcm so I did that and later started it up and it ran smoothly untell a few days ago. I was coming back from an off-roading trip and had to do some four wheeling and I stopped to re-strap some gear and as soon as I got back in and put it in drive it started puttering again and had the rough idle so got it home and checked everything and it looked alright. Also I checked my distributor and rotor and spark plugs and nothing looks wrong and all electrical components work in that system. So does anybody else have this problem or and idea of what it could be. Thanks.

 

I'd start by checking your fuel pressure, might be the warning sign of an aging fuel pump.

 

Good chance you bumped the line from the throttle body to MAP during the injector install.

MAP sensor tube
There is a brittle little tube. It comes out of a rubber plug, low on the engine side of the throttle body. It runs back to the firewall, then up to your MAP sensor, behind the valve cover, higher up on the firewall. It has one vacuum line as already mentioned, with a 3-wire plug in the bottom.
CRUCIAL!! The MAP sensor will tell the ECU to dump fuel with little to no vacuum to the MAP. Any crack or blockage and it will be pig-rich. ( black smoke, fouled black plugs, must hold your foot to the floor to keep the engine running). You can pull the line off the MAP sensor and feel for vacuum with your finger. If it runs!
A visual inspection usually reveals any issues with the line from the throttle body to the MAP sensor.

 

AND, since you've got an 88 and seem interested in eliminating issues and maintaining your Jeep, click on the pink link in my signature and perform the "fixes" in posts 1 through 4 for starters.

 

I visually inspected the tube and also did a running check and there is no blockage or cracks and it has vacuum

 

I'll try to get that done today or tomorrow, do you k ow what paid it's suppose to be at?

 

Huh?

 

Stupid phone, do you know what psi the fuel line is suppose to be at?

 

31 @ idle with the vacuum hose connected to the fuel pressure regulator and 39 with the hose unplugged.

 

Checked the pressure and it's running about 28 normally and 34 with out vacuum tube.

 

Weak fuel pump or MAYBE clogged up fuel filter.

Could also be that the rubber hose inside the fuel tank that connects to the pump is split.

If you do decide to replace the pump, do not use Airtex brand.

 

Is it fuel injected

 

Uh, yeah. NbT?

 

Check the throttle position sensor I had the same problems and I changed the tps and it fixed everything

 

His fuel pressure is too low. That needs to be addressed before running down any new rabbit trails.