NC-MJ

Hellcreek- I had the same problem you had. The hose from the fuel pump was gummy and split. All the rubber seals on the fuel pump had deteriorated and were sitting in the bottom of the tank or crumbled when touched. I had to drop the tank and drain the gas to get all the rubber seal fragments out. Now I have a clean fuel tank, and a new fuel pump with hoses. The Truck turned over on the first try and ran with no problems. Took a test spin and all seems to be in order. :cheers: Thanks to all who posted tips and suggestions. Now that I have the truck running, it is time to start thinking about with plans for my build!

Thanks for the info. I have replaced everything I can think of that might have been causing the problem. This truck sat for the last 10 years with very little use. It wouldn't surprise me if I had the same problem. If it would stop raining I could get back to work! :cheers:

Thanks for the info. I will skip this unit and go with the pump only replacement. Maybe this is what is preventing the truck from turning over and running. I guess I need to check all the vacuum lines too. Are there any vacuum lines that if damaged/rotted could prevent the truck from starting if I get the pump replaced??

Has anyone had any experience with 1AAuto.com? http://www.1aauto.com/1A/fuel_pump/Jeep/Comanche/1AFPU01329 If I were to get a new pump, what do you guys think about this unit and the price? Thanks.

When tested the fuel pump in the past, I removed the fuel line right before the fuel rail. When I would try to start the truck, gas will flow through the line and start filling my bottle if I turn the ignition over. Fuel does appear to be entering the fuel rail.

My question for the group is, and forgive me if my thought process is off here, but do you think the fuel pump is only strong enough to pump fuel without pressurization? I was thinking that if the pump wasn’t strong enough and could not pump fuel to a pressurized system then it wouldn’t be able to force fuel to spray out of the end of the fuel injectors. It also might account for the zero fuel pressure reading. :dunno:

Interesting. If I pour gas in the throttle body, it will start, and run for a few seconds and then die. But it won't start on it's own. I have to wait for the part to come in to find out for sure.

Just an update guys. Thanks for all the feed back. 1. Fuel pressure regulator is brand new. 2. Fuel pump ground is clean. Still no dice. 3. Bypassed the fuel pump relay and the pump comes on and you can really hear it pumping. Still no dice. 4. Fuel Pump is the original unit so wires should be correct. If I do change the pump I will keep the wiring in mind as to not hook it up wrong. One thing new today, I did notice that my ballast resistor was cracked in half and was free hanging from the fender. I have a new one on order. Do you guys think this is what is preventing the truck from turning over?

I tested the fuel pump again to see if I was getting any fuel pumped from the back of the truck to the motor. I hooked up a hose and bottle to the fuel rail and I got a quarter liter worth of fuel from turning the truck over for 15 seconds or so. I hooked everything back up and did the “gas in the throttle body” trick and truck turns over for 15 or 20 seconds and then stalls out. I went out and picked up a gauge to test the fuel pressure when I started to motor using the “gas in the throttle body” trick. I hooked up the gauge and turned over the motor for 15 to 20 seconds and when I went to check the gauge, I see zero pressure being registered. I retested about three more times and still no pressure is being read on the gauge. My new question for the group is, and forgive me if my thought process is off here, but do you think the fuel pump is only strong enough to pump fuel without pressurization? I was thinking that if the pump wasn’t strong enough and could not pump fuel to a pressurized system then it wouldn’t be able to force fuel to spray out of the end of the fuel injectors. It also might account for the zero fuel pressure reading. :dunno: Thanks! NC-MJ

Eagle - Fuel Filter was replaced along with the Crank Position Sensor and the Fuel Pressure Regulator. Hornbrod - I will give that a shot tomorrow and see what I come up with. I appreciate all of the advice guys. I would love to get this truck back on the road.

I checked the fuel smell tonight and it didn’t smell like gas but more like varnish. I siphoned as much as possible from the gas tank and added about 8 gallons of fresh fuel and two bottles of fuel injector cleaner. When I went to start the truck, it would turn over and run a little longer but if I took my foot off the gas, it still stalls out. When I go to check the fuel rail to see if there is good pressurization, I get a small pressure leaking sound when I press the schrader valve but no gas shoots out as me. I guess I will definitely have to get a fuel pressure test gauge to see what the rail pressure is topping out at when the motor does turn over with the gas in the throttle body trick. Is there a chance I have a clogged fuel line? Or is this possibility a failing fuel pump?

Thanks Eagle and Carnuck for responding. I was able to get the truck to turn over using the spoonful of gas in the throttle body suggestion. As long as I kept my foot on the gas it would run. If I took my foot off of the gas pedal, the car would start chugging and then it would stall. I could only keep the engine running for 10 to 15 seconds at a time. Eagle/Carnuk – From what I described above do you think my injectors are not working properly or do you think I have another problem which is preventing the MJ from running normally? What would you guys recommend for my next trouble shooting step. Thanks NC-MJ

Hello everyone! This is my second week as a Jeep Owner and I am hoping you guys can help me with my first problem. I have been reading this forum and I have found posts that are similar to my issue but the symptoms of my problem do not exactly match up with what others are experiencing. Let me give you a break down on what I have and what my problem is. I am the second owner of a 1989 Jeep Comanche Eliminator 2WD 5SPD Short Bed with 126,000 original miles. The previous owner, a family member, stated that the truck started in the driveway but while in reverse backing down the driveway, the MJ just turned off and could not be restarted. There were no prior problems up until this point. When I go to start the truck it will only crank but not start. Having read other owner posts, I checked/replaced the following items. 1. Fuel Pump- I am getting power to the pump and the pump is pumping gas. I put a 20 oz soda bottle over the fuel line and cranked one crank and almost filled the bottle up. 2. Fuel Filter- Replaced original filter and it looked normal for 126,000 Miles. 3. Pulled spark plugs and inspected them. All were in good order and we have ignition at the end of the spark plugs. 4. Checked distributor cap – Button looks good and points were in good shape. 5. Crank Position Sensor –Replaced original with new CPS. I can crank it but the motor will not start. 6. Fuel pressure regulator- I disconnected the fuel line before the FPR when. I cranked the truck thinking fuel would run out into my test bottle, but nothing happened. My next thought was that I might have trash in the line. I attempted to blow out the line with compressed air but I only seemed to get blow back from the fuel that was in the line mixed with the air. I cranked the motor again and still no fuel in the test bottle. I installed new FPR and still no luck. I thought I would post to the Tech Forum before I spent any more money in the hopes someone here can point out the error in my diagnosis and maybe help me get my MJ back on the road. Thanks for reading. NC-MJ