[pszczepan]

Hi !

I have Jeep Chrokee 1989 wiyh 4.0 l. I have also service manual and till now I checked couple things:
- fuel is delivered to fuel rail
- I have spark on Spark plugs
- I looked into the spark plug whole during the cranking and I noticed that so much fuel is going to the chamber. I think that fuel has enough power to put out the spark from plug and thats why engine cannot start.

Could you write me which sensor is the most important for injector pulse width - maybe the sensor does not work and ECU gives to long pulse width and thats why the sparks are wet.

Thanks for any advie
Pawel

[jlmclean]

About the only thing that would control the fuel mixture at startup would be the throttle position sensor. If it's out of adjustment and the computer thinks the throttle is open more than what it really is, this could cause a rich mixture. The system is designed with a "clear flood" stage. Before you try to start the engine, press the throttle wide open (just as you would do with a flooded engine with a carburator) and then turn the ignition to crank the engine. Hold the pedal wide open through the process. This allows the engine to turn over and the injectors will not spray any fuel.

[marioct]

I had the same problem in my 89 and it was the crank position sensor. I would have all of the above but no start. I replaced the sensor(on top of the tranny bell housing), and no problem since. Cannot hurt to try.

[XJING]

Here is the 'Go to link" for renix sesor diagnostics... Good luck
http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

[pszczepan]

Marioct wrote - his problem was in Crank position sensor. Is there possibility that I have spark (CPS must work) and this sensor is demaged anyway and this is the reason that engine cannot start?

[Rock Kustoms]

if you have spark, ckp is good

try starting w/ the tps unplugged (after cleaning he plugs ofcourse)

[jlmclean]

Here's a test to run on the crank position sensor. Locate the CPS on the drivers side of the bellhousing )in about 10-11 oclock position) and trace the wire up to the plug (should be somewhere around the rear of the valve cover). Unplug and connect an ohm meter to the two prongs in the plug. It should read 200 +/-75 ohm's. Then switch the meter to AC Voltage. Spin the engine with the starter and the meter should read .5-.8 VAC. I do know that they will run with voltage as low as .25 VAC but .5-.8 are the specs.

[jlmclean]

Here's the test for the throttle position sensor. Locate the TPS and follow the wires to the plug. Straight drive will have a flat three wire plug and automatics will have the three prong plug plus a square four prong plug. Use the three prong plug. It's terminals are marked A,B,&C. Leave the plug connected and backprobe the connections. Connect the ground lead of your meter to B. Connect the positive to A. Turn the ignition switch to "on" and you should have a reading of 5 VDC or something just under that. Connect the positive lead to C. That reading should read (multiply your first reading A to B by .17) or a little below. Example: 5 VDC x .17 = .85 VDC. Also work the throttle through its range (idle through full throttle) with the meter still connected to B & C and notice that there is a smooth increase, no dead spots and no sudden increases.

[marioct]

Good info. I hope it works out for you.

I do know that I had spark and still no start. After replacing the sensor, my truck runs perfect. Maybe the sensor is not giving the correct voltage??