Blue88Comanche Posted March 27, 2014 Share Posted March 27, 2014 Today on my way to work the engine in my XJ started acting up. A few times while I was at speed it felt like it lost half its power for a moment then picked up again. Once while sitting at a red light it almost stalled while idling. I am currently at work so I can't check on anything at the moment. But I have ordered the parts to do Hornbrod's Permanent Fuel Rail Pressure Gauge Mod. I have been wanting to do it for a while and decided now would be a good time. How would one go about testing fuel injectors? As far as I know, they are the ones that came with the truck from factory. This weekend I will check the spark plugs, if I have the money I may replace them anyway. The Plug wires where replaced within the past 5 years, I just don't recall exactly when. The Jeep has about 185,000 Miles. I am 85% sure most of the sensors, ignition, and fuel components are original, less the spark plugs and wires. Link to comment Share on other sites More sharing options...
Eagle Posted March 27, 2014 Share Posted March 27, 2014 A clogged catalytic converter usually results in loss of power. Link to comment Share on other sites More sharing options...
1987Comanche Posted March 27, 2014 Share Posted March 27, 2014 Sudden loss of power and stalling sounds like it could be a vacuum leak. What kind of shape are the vacuum lines in? Link to comment Share on other sites More sharing options...
Blue88Comanche Posted March 28, 2014 Author Share Posted March 28, 2014 I know I have a small vacuum leak for a year or so. It just started acting up in the past week and more so today. But on the way home it did fine. Link to comment Share on other sites More sharing options...
benjy_26 Posted March 28, 2014 Share Posted March 28, 2014 SEE PEE ESS. That's what my XJ started doing when the CPS went lsouth. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 28, 2014 Share Posted March 28, 2014 SEE PEE ESS. That's what my XJ started doing when the CPS went lsouth. And it's testable. Renix CPS Testing and Adjusting Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark. Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad. The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark. Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected. You should get a reading of .5 AC volts. If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer. Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off. A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8” from the stock 5/16”, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts. Revised 01-26-2013 Link to comment Share on other sites More sharing options...
1987Comanche Posted March 29, 2014 Share Posted March 29, 2014 How old is the fuel pump? It may be on the way out Link to comment Share on other sites More sharing options...
Blue88Comanche Posted March 29, 2014 Author Share Posted March 29, 2014 The fuel pump is likely to be the original. Link to comment Share on other sites More sharing options...
Blue88Comanche Posted April 1, 2014 Author Share Posted April 1, 2014 I installed the fuel pressure *gauge mod and idling at a cold start is at about 30 - 31 psi Another question, is there a difference between the Renix and HO fuel rail? That port the gauge goes on seems to be located differently on Hornbrod XJ. * Edit Link to comment Share on other sites More sharing options...
cruiser54 Posted April 1, 2014 Share Posted April 1, 2014 What's the fuel pressure mod? Link to comment Share on other sites More sharing options...
Blue88Comanche Posted April 2, 2014 Author Share Posted April 2, 2014 There is a link in my first post to Hornbrod's fuel pressure gauge mod It just adds a gauge to the fuel rail Link to comment Share on other sites More sharing options...
88whitemanche Posted April 29, 2014 Share Posted April 29, 2014 Any luck to this? I'm having similar issues Link to comment Share on other sites More sharing options...
Blue88Comanche Posted April 30, 2014 Author Share Posted April 30, 2014 I haven't worked on it any. and won't be able to this weekend as well. I know none of the sensors where replaced in the past 10 years. I bought a replacement coil to have as a back up. I eventually just want to replace all the sensors and the coil... just need time and money. Link to comment Share on other sites More sharing options...
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