Rarely Starts, when it does doesn’t last.

[zak]

1992. Inline6. 152,000ish miles.

 

Drove to work the other day everything seemed fine. Went to lunch, went to drive back to work and it wouldn’t start. Had a buddy come to help me out as soon as he got there I tried again just for laughs and it fired up no problem, ran for about a minute, idle speed fluctuated a little but nothing extreme, and then died. Afterwards it won’t start unless it’s sat for a while and will only stay running for a minute or so if I don’t touch anything, if I touch the gas at all it immediately dies. One time I gave it gas, white smoke started coming from the throttle body.

 

I’ve changed the fuel filter, fuel pressure regulator, fuel pump relay, ballast resistor, fixed a questionable vacuum line 90 elbow, and poured a bottle of seafoam in the gas tank. Rented a fuel pressure tester from autozone and it read around 35 while not running, I couldn’t get it running while the pressure tester was hooked up. Could it be the fuel pump? Was hoping not to drop the gas tank but if it has to be done it has to be done. Check engine light has never came on until today when I got it to run for about 30 seconds and forgot to put the gas cap back on after relieving the fuel pressure to switch out the pressure regulator.

 

I’ve had some friends tell me that it would also be the MAP sensor but I tested that today and it was reading 5.2 volts, crank shaft sensor, which I’ve been told it wouldn’t start at all if that was the problem. Or possibly a throttle body sensor.

 

Changed the sparkplugs, wires, coil, and dist. cap a few months ago with slightly better OEM parts. I don’t think any of those would be the problem.

 

Any ideas? Suggestions? Going to try the fuel pump tomorrow. Thanks for the help.

[ComancheKid45]

Could definently be a failing CPS, but it sure points more towards a fuel problem. You don't have to drop the tank to replace the pump although it may make it a bit easyer depnding on your height. Otherwise it really sounds like a ballast resistor issue, double check that area and the wiring before digging into the fuel pump and just make sure everything is for certian alright there :thumbsup:

 

Good Luck! ;)

[HOrnbrod]

Since it's a 92 and threw a code, it's still in ECU memory if you haven't disconnected the battery. Check the fault code and it may give you a clue where the problem is. That's what it's there for. :D

 

http://www.comancheclub.com/forums/viewtopic.php?f=9&t=29857

[zak]

Finally got the fuel pump in today, which was a fun 2 day experience. I’ve seen the other posts and read around that the replacement fuel pump from autozone, advance, napa, ect, is a pain to get it to fit right, with some mods, I got it snuggly back into the tank (I couldn’t find the discontinued Bosch pump anywhere locally and since this is my daily driver waiting for shipping from summit or rockauto didn’t sound too appealing). NO LUCK, same problem. Checked the fault codes and got 12 and 24, battery, cause it had been disconnected, and TPS, replaced the TPS, NO LUCK. Double and triple checked the wiring with and around the ballast resistor, everything seems fine.

 

Finally we checked the distributor cap and rotor... may have been the problem all along, in addition to the spark plugs. The last thing I would have thought it would have been since I changed the plugs, wires, cap and rotor, and coil in October. Switching them out tomorrow morning, hopefully this is the problem. At least I have all new fuel system parts?

 

Here’s the parts I ordered from summit in Oct, anyone else ever have any issues with them?

 

ACCEL 140021 - ACCEL Mopar Remote Super Coils http://www.summitracing.com/parts/ACC-140021

Bosch Automotive 4508 - Bosch Platinum IR Fusion Spark Plugs http://www.summitracing.com/parts/BCH-4508

Davis Unified Ignition 35100RD - Davis Unified Ignition Cap and Rotor Kits http://www.summitracing.com/parts/DUI-35100RD

Taylor Cable 84049 - Taylor ThunderVolt 8.2mm Spark Plug Wire Sets http://www.summitracing.com/parts/TAY-84049

[HOrnbrod]

Checked the fault codes and got 12 and 24, battery, cause it had been disconnected, and TPS, replaced the TPS, NO LUCK.

You have a 24 TPS fault code. If the input and/or output is faulty on the three pin connector, just replacing the TPS won't fix it. The TPS must be tested as follows:

 

The throttle position sensor is connected to the throttle shaft on the throttle body. It sends throttle valve angle information to the PCM. The PCM uses this information to determine how much fuel the engine needs. The TPS is really just a simple potentiometer with one end connected to 5 volts from the PCM and the other to ground. A third wire is connected to the PCM. As you move the accelerator pedal with your foot, the output of the TPS changes. At a closed throttle position, the output of the TPS is low, about a half a volt. As the throttle valve opens, the output increases so that, at wide open throttle, the output voltage should be above 3.9 volts. Testing can be performed with an electrical meter. Analog meter is best. You are looking for a smooth sweep of voltage throughout the entire throttle band. While slowly opening and closing the throttle, take note to the movement of the voltmeter needle. There should be a direct relationship between the needle motion to the motion of the throttle. If at anytime the needle moves abruptly or inconsistently with the movement of the throttle, the TPS is bad

 

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.

 

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.

 

The TPS is sensitive to heat, moisture and vibration leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced. A TPS may fail gradually leading to a number of symptoms which can include one or more of the following: -

 

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics! It should be verified early in the troubleshooting process, when a transmission issue is suspected!

 

• Poor idle control: The TPS is used by the ECU to determine if the throttle is closed and the car should be using the Idle Air Control Valve exclusively for idle control. A fault TPS sensor can confuse the ECU causing the idle to be erratic or "hunting".

• High Idle Speed: The TPS may report faulty values causing the engine idle speed to be increased above normal. This is normally found in conjunction with a slow engine return to idle speed symptom.

• Slow engine return to idle: A failing TPS can report the minimum throttle position values incorrectly which can stop the engine entering idle mode when the throttle is closed. Normally when the throttle is closed the engine fuel injectors will be deactivated until a defined engine RPM speed is reached and the engine brought smoothly to idle speed. When failing a TPS will not report the throttle closed and fueling will continue causing the engine to return to idle very slowly.

• Engine Hesitation on Throttle Application: The TPS is also used by the ECU to determine if the driver has applied the throttle quicker than the Manifold Air Pressure sensor can read. The fueling is adjusted accordingly to cope with the sudden increase in air volume, however a faulty sensor can cause the ECU to ignore this data and the engine will "hesitate" when applying the throttle. In extreme cases with the engine at idle, a sudden application of full throttle can stall the engine.

• Engine Misfire: A fault TPS can report values outside the denied acceptable range causing the ECU to incorrectly fuel the engine. This is noticeable as a slight misfire and can trigger the misfire detection software and/or Malfunction Indicator Lamp (MIL) light on the dashboard. Extreme cases can cause excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.

[zak]

Thanks for all the help. After replacing more parts and retesting stuff, it was finally showing no spark, ended up being the Excel Performance coil I put in last Oct went bad... replaced it with a standard one from the autopart store and its running like a champ again, at least I got a bunch of new parts and sensors out of it???