Slimjim

I have a 1990 Cherokee with a 4.0L. just recently it started taking forever to start up. I have replaced the crank sensor and TPS with no change in crank time. Also on acceleration it spits and sputters like the timing may be off. If I floor it, it runs and accelerates fine, until i let up on the pedal, then it goes back to running like garbage. any ideas???


UPDATE!! the spitting and sputtering only happens once the vehicle has reached operating temp.

tjwalker

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.

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!

Slimjim

5-7 seconds of crank time is not normal. I have replaced the cap, rotor, plugs, wires, fuel filter, coil, ignition control module, crank sensor, throttle position sensor recently. Not only does it crank a long time before starting, it also spits and sputters on acceleration except for w.o.t

kstopp

I would test the MAP sensor. What brand of parts did you use when you replaced all these things:

DFlintstone

TJ is a real pro. Anyone here getting info there should feel lucky. Now that we know some basics have been done, (sans filling your info), try cycling the key on/off a couple, few times 5 secs or so apart, then turning to start. See if that helps. Renix both needs to hit 300 RPM and complete a rev and a 1/2 or two before it will fire.

Right up top in the link in my sig is Cruisers Tips. Cleaning/upgrading your grounds is highly recommended. If the "poor mans prime" makes it start faster, the check valve in your fuel pump is the first suspect on the list. Likewise, you would be smart to go borrow a free fuel pressure tester and see that your pressure is around 39Lbs, with the vacuum line off, and about 10 lower with it on. That could be your, "on acceleration it spits and sputters like the timing may be off". There is no timing adjustment.

While you have the gauge, see how the pressure drops off after you turn it off. I forget the speck, but it should have something after 20 minutes IIRC.

Slimjim

i used all BWD except for plugs, i used champion copper #344