'95 XJ 4.0 - Hard Start & Fuel Pump Frustration

[jerstw]

Looking for some input that seems to be a bit different from what I have found after searching the forum.

1995 XJ 4.0 with 91,300 miles. Has been getting progressively worse on hard start but it seems to start up just fine when the engine is cold or has sat more than a few hours. Did fuel pressure test a month ago and was showing little to zero bleed down so started with cleaning the IAC valve, noticed it was sticking a bit so replaced it. Still hard start.

Next, moved on to replace the fuel pump. Bought a Bosch 69544 which is the listed part number for a 1995 XJ, but to my surprise when we pulled the fuel sending unit / pump assembly it has a fuel sending unit / pump assembly that matches which I 'think' is from a 1993 XJ as the fuel pump looked more like the Bosch 69302 (which of course seems to be out of stock any place we could find in the next 3 days so went with the Napa / Carter pump for a 1993 XJ and got to work; my best guess is when the previous owner installed a new fuel tank the shop he had do it installed the fuel sending unit and pump assembly which was for a 1993.

So...new IAC valve, new Napa / Carter fuel pump (circa 1993 version) and STILL hard starting. Thus here are the questions I am hoping this group can provide some insight to...

1. Did the factory ever in 1995 use a fuel sending unit and pump assembly which would not allow a direct replacement pump Bosch 69544 to fit?

2. Is there any reason I should now replace the entire fuel sending unit and pump with which I assume is the correct version for a 1995 XJ (one which would allow the use of the Bosch 69544)?

3. Given I am still having hard starting issue, in particular when the engine is a bit warmer is the next step to try installing Bosch 4-hole injectors or is there anything else I should try first?

Thanks for any insight.

 

[Unclewolverine]

I have a 95 as well but have never dropped the tank so I can't help you with the pump, but your exact hard starting issues have been cured by several members by putting in new GOOD quality injectors.

 

[Woodswanderer]

Test and replace cam sensor...


codename 99 problems: Daily driver/tow rig build thread

 

[Lost_Wrench]

I just went through those same symptoms on my 96 xj. It started fine when motor was cold and then took several crank/prime cycles to start once warmed up, and progressively got worse over time. I had no check engine codes throughout this issue. I replaced injectors twice, spark plugs, sensors, even the head gasket. It ended up being the fuel pump. I replaced the cheapo Chinese auto zone pump mine had with a better crown automotive assembly and it has never run better or started up faster.

I think what happens is when those pumps go bad they work ok when starting cold but then overheat in the tank, thus becoming harder to start once it's warmed up and has been running awhile. Let it cool down awhile and it will start up fine again. Rinse, repeat.

What psi was your fuel pressure at when you tested it?

Any check engine trouble codes?

Does your jeep have the fuel pressure regulator up on the fuel rail or is it attached to the pump assembly inside the tank like mine?

Is your fuel pump accessed from the side of the tank or from the top of the tank?


Where I got confused with mine was when I tested the fuel pressure. It was 30 psi when it should have been 49 psi. 3rd gen and some 2nd gen XJ's should have 49 psi at the rail, while many older ones apparently only require 31 psi. Double check what yours should be. Our Jeeps probably have differing fuel delivery components based on their years but I would still STRONGLY recommend taking a second look at your fuel pressure and fuel pump before moving on to injectors and sensors, etc.

 

[jerstw]

Thanks for the responses. The new fuel pump (Carter) works great but simply did not fix the problem. Will try the cam sensor / ignition pick-up next and then go to injectors.

Mine has the pressure regulator on the fuel rail so it is to be in the 31 psi (+/- 1-2 psi) range per the service manual from 1995. Have learned the 95 to 96 was the transition year for the fuel pump, regulator (rail or in-tank) and sending units so at least leaving the process a bit more educated.

 

[jerstw]

Well, the saga continues. The last couple days it has become much more difficult to start and today my son and I finally had a chance to work on it a bit.

Got it running, long hard start today, pulled it in the garage, replaced the crankshaft position sensor...go to start it back up and just turns over, never runs (@#$%). So we then installed the new cam sensor (a.k.a. ignition or distributor pick up), same result. Confirmed it is getting plenty of fuel at the fuel rail, cranks just fine, just cannot get it running.

So to date it was a new TPS, everything in the ignition has been replaced (Performance Distributors FirePower Kit with coil, wires, cap, rotor, along with pick up and plugs), new fuel pump and filter, IAC valve, and then the new crankshaft position sensor. No check engine codes (OBD I) and once it is running it runs very well just cannot get it started now.

Given it has fuel and pressure at the fuel rail, I do not believe there are any other sensors to replace (correct me if I am wrong) and everything in the ignition system is new thus my only avenue left seems to be the injectors...but before I order them we are going to call up a local shop tomorrow and see if they want a crack at diagnosing to rule anything out before I order up some Bosch 4-hole (seems to be the replacement injectors of choice unless someone has a different point of view let me know).

 

[mangot2]

So, I assume you have checked for and verified spark? Also, the fuel pressure regulator on the fuel rail is a blessing and might want to swap that out if it's original, since all your other fuel system components are new . . .

 

[CJR]

Jerstw,

I don't own a 95XJ, only a 88XJ & a 00XJ. But my WAG( Wild A___ Guess) would be to look at the Computer/Power Distribution Center. It may be an intermittent ground loss of some sensor that the computer is "looking for" before it authorizes completing the start sequence or it could be a relay not resetting . What I'd carefully look for are electrical/mechanical relays that may not be resetting because of internal corroded contacts. Swapping some relays around helps to see which ones are not resetting. Hope this helps.

Bet regards,

CJR

 

[old_man]

A bad ASD relay can lead to hard starts.