1arunem

1988 XJ, factory 4.0. 84k miles.. Will crank/start every time but lately seems to be taking a little longer to 'fire'...


Starter spins engine over well but it needs to rotate the engine a few seconds before she 'fires'.. I was thinking maybe fuel pressure?

I always turn the key 'on', let the pump cycle, then spin it over.


Like I said it always starts (knock on wood) but takes a little longer than I think it should to fire up.


Thanks for any insight...

tjwalker

You may have a failing check valve on your fuel pump assembly. Manual "priming" as you have been doing can limp this along for a while. Here are some other possibilities though. Hope this helps!
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You have a Renix XJ (87-90) By design, the engine is not going to fire until the computer (ECU) gets a signal from the crankshaft position sensor and measures that signal to indicate that 300 rpms while cranking has been met/exceeded.

Somewhat extended crank times should be considered a “characteristic” of your engine, rather than a problem.

You can upgrade the battery and battery cables--at least 4 ga., 2 ga. better--and buy a high-torque starter.

Be sure that all grounds are good. Remove them and freshen them. You cannot tell if the grounds are electrically good by looking at them! Renix vehicles are very sensitive to ground issues.

Your CPS can be a bit weak, too. Unplug it and probe the two wires with your meter set on AC volts. You should get .5 as a reading. Anything down around .35 will cause long crank times and possible intermittent no-starts.

Other than that, performing basic tune-ups on a regular basis is important, (plugs, wires, cap, rotor, fuel filter) The importance of fresh secondary ignition (tune up parts) cannot be overstated.

Good luck!

cruiser54

Pretty normal for the renix.

If it were mine, I would do Tips 1 through 5 in my Pink Link below.

kdot

Mine is also a tad slow to start..figured it was a Renix thing as I have re-grounded everything when I put in the remanned 4.0L.

Shouldn't be an issue.

cruiser54

It is. But you did the right thing. Minimizes it anyway. ADDING grounds and larger cables is noticeable.

DFlintstone

Like the guys said, a Renix will never fire right off, needs to do a Rev or so and reach 300 RPM before it will fire. It supprised me a little when mine went from firing OK, to fiiring better after I cleaned my IAC the other day.

kdot

IAC causes so much havoc when its all gunked up...

cruiser54

It goes Nah, nah, nah nah, Whoom.

cruiser54

Normal maintenance could go a long way toward reducing crank time.

Plugs, wires, cap and rotor. Clean the throttle body and IAC.

DFlintstone

Didn't John Lennon write that?

Btw folx, REALLY enjoying the new white 90. The anti-lock brakes are a fun new thing for me. New tires and most of it gone through, and she feels like a new ride! When all you have left is cleaning the IAT, you made it!.......

To clean my ground gang on the dipstick stud, I loosened the nut. Then I sprayed it well with CRC- QD Electronic Cleaner and shook them up and down a bit, sprayed again, repeated that a few times. Cinched it up and came up with ZERO resistance.
13mm on a shorty extension seems to be the ticket.

1arunem

Thanks guys. I have just gotten a fuel pressure guage (going to check it for giggles) and also need to check the CPS and clean the IAC..

Hopefully that will help. My concern is that it is taking longer to start than it used to.

cruiser54

Keep working on the Tips.

BTW, is your starter covered in oil from leaking oil filter adapter seals?

1arunem

Fuel pressure running is 30psi line on and 38 static.. When I turn the key off, the psi drops to near zero almost immediately.




When I just turn the key to the on position, pressure rises to around38-40 and then immediately drops near zero.???


Starter actually is in pretty good shape as the jeep doesn't have a bunch of leaks thankfully.


I haven't checked the crank sensor yet as it is sleeting outside and I didn't feel like crawling on the ground.

Thoughts on the fuel psi??

cruiser54

There's a test to determine if the fuel pump check valve is letting the system de-pressurize or if the injectors are causing it.

Original injectors?

1arunem

Only one has been replaced to my knowledge. It was leaking externally..