Nofeartoys Posted April 14, 2016 Share Posted April 14, 2016 I have 88 mj with a 89 4.0L swapped Vehicle has poor acceleration power and sputters at times. I get fuel pressure to find 35 psi while running but when hard accel fuel psi drops low ,with regulator vac off psi is 45ish and still under hard throttle even in neutral the psi drops low. The crank sensor has been replaced,fuel pump and filter has been replaced with Delphi pump assembly still same condition present. I adjusted tps to make sure set properly. These injectors open at 29psi correct? (Black colored injectors) Also with fuel gauge connected and bleed off on gauge is opened to test flow. Engine dies. (( as if fuel system doesn't have enough flow to keep up) this happened with old and new fuel pumps...Also. is their any factory fuel pump assemlies out there? Mine was pretty much garbage when I removed it. Please let me know of any idea on this issue. My thought is fuel regulator not holding flow back. Since issue is still same after aftermarket fuel pump installed and with original . Thank you in advance Link to comment Share on other sites More sharing options...
Nofeartoys Posted April 15, 2016 Author Share Posted April 15, 2016 Update I bypassed ballast resistor, installed fuse in place of resistor.now vehicle running better. Not sure if ballast cause or is this masking another issue with regulator not holding pressure properly? My ballast reading 1.5 ohms. Stamp on resistor says 1.1 ohm. What is normal running output voltage of ballast.?? Mine was like 5.4 volts with 13.8 voltage into ballast.. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 15, 2016 Share Posted April 15, 2016 Update I bypassed ballast resistor, installed fuse in place of resistor.now vehicle running better. Not sure if ballast cause or is this masking another issue with regulator not holding pressure properly? My ballast reading 1.5 ohms. Stamp on resistor says 1.1 ohm. What is normal running output voltage of ballast.?? Mine was like 5.4 volts with 13.8 voltage into ballast.. Keep in mind that your fuel pump grounds in a real crappy spot. Behind the left taillamp....... Since you have ah 88, I would strongly suggest going to www.cruiser54.com and performing Tips 1 through 5. Link to comment Share on other sites More sharing options...
Nofeartoys Posted April 15, 2016 Author Share Posted April 15, 2016 Thx cruiser for info.,most of them already done. Except coil pack and headlamp I even eliminated c101 firewall connector I double check also. Thx again. Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 15, 2016 Share Posted April 15, 2016 Update I bypassed ballast resistor, installed fuse in place of resistor.now vehicle running better. Not sure if ballast cause or is this masking another issue with regulator not holding pressure properly? My ballast reading 1.5 ohms. Stamp on resistor says 1.1 ohm. What is normal running output voltage of ballast.?? Mine was like 5.4 volts with 13.8 voltage into ballast.. Mine is 14V in, ~10V out. Check the factory ground behind the left tail lamp. It's a poor ground location at best, so it doesn't hurt to run another fuel pump parallel ground to a spot on the frame physically closer to the pump. Try a fuel flow test as detailed here: http://www.lunghd.com/Tech_Articles/Fuel_System/Fuel_Diagnostics.htm Link to comment Share on other sites More sharing options...
Nofeartoys Posted April 15, 2016 Author Share Posted April 15, 2016 Thank you hornbrod for voltage readings of the ballast good info. And I will take yours and cruiser advise and clean tailamp area ground and also will add ground near fuel pump connector. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 15, 2016 Share Posted April 15, 2016 Update I bypassed ballast resistor, installed fuse in place of resistor.now vehicle running better. Not sure if ballast cause or is this masking another issue with regulator not holding pressure properly? My ballast reading 1.5 ohms. Stamp on resistor says 1.1 ohm. What is normal running output voltage of ballast.?? Mine was like 5.4 volts with 13.8 voltage into ballast.. Mine is 14V in, ~10V out. Check the factory ground behind the left tail lamp. It's a poor ground location at best, so it doesn't hurt to run another fuel pump parallel ground to a spot on the frame physically closer to the pump. Try a fuel flow test as detailed here: http://www.lunghd.com/Tech_Articles/Fuel_System/Fuel_Diagnostics.htm Do this: http://cruiser54.com/?p=249 Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 15, 2016 Share Posted April 15, 2016 http://cruiser54.com/?p=249 Hmmm. I didn't know you had a writeup for that already. Link to comment Share on other sites More sharing options...
Nofeartoys Posted April 15, 2016 Author Share Posted April 15, 2016 Thank you both for replies..The tailamp was already cleaned Recleaned eyelet and reinstalled ground. Went under vehicle and made new ground to fuel pump harness and secured to clean new frame mount.. Cutout out old splices for sensor grounds for injectors and map,tps,intake temp etc and soldered their groups together. Added extra Grounds to those circuits also. (Lol over kill ) verified tps at adjustment (ok .84 v ) cleaned all connectors and contacts for coil pack.My truck did have some erratic sensor voltages when harness wiggle test preformed.. Thank you mj tech forum for all help and info. Appears main issue was crappy fuel pump and high resistance is ballast. Causing low volume fuel,system. Drove vehicle today to find good power and able to spin tires. (Ballast still bypassed. Until I get new one then will recheck.. Vehicle will be getting ballast and fuel regulator and tps to give me piece of mind and known new parts ,since vehicle history is unknown to me..Also I will been doing injector upgrade sometime in near future..The only thing i knew about this truck was it sat for few year due to disassembled engine. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 16, 2016 Share Posted April 16, 2016 http://cruiser54.com/?p=249 Hmmm. I didn't know you had a writeup for that already. You REALLY need to peruse my website. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 16, 2016 Share Posted April 16, 2016 Thank you both for replies..The tailamp was already cleaned Recleaned eyelet and reinstalled ground. Went under vehicle and made new ground to fuel pump harness and secured to clean new frame mount.. Cutout out old splices for sensor grounds for injectors and map,tps,intake temp etc and soldered their groups together. Added extra Grounds to those circuits also. (Lol over kill ) verified tps at adjustment (ok .84 v ) cleaned all connectors and contacts for coil pack.My truck did have some erratic sensor voltages when harness wiggle test preformed.. Thank you mj tech forum for all help and info. Appears main issue was crappy fuel pump and high resistance is ballast. Causing low volume fuel,system. Drove vehicle today to find good power and able to spin tires. (Ballast still bypassed. Until I get new one then will recheck.. Vehicle will be getting ballast and fuel regulator and tps to give me piece of mind and known new parts ,since vehicle history is unknown to me..Also I will been doing injector upgrade sometime in near future..The only thing i knew about this truck was it sat for few year due to disassembled engine. You are doing a great job. Hang in there and we will prevail!!! Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 16, 2016 Share Posted April 16, 2016 http://cruiser54.com/?p=249 Hmmm. I didn't know you had a writeup for that already. You REALLY need to peruse my website. :shake: Drama queen......... Link to comment Share on other sites More sharing options...
cruiser54 Posted April 16, 2016 Share Posted April 16, 2016 http://cruiser54.com/?p=249 Hmmm. I didn't know you had a writeup for that already. You REALLY need to peruse my website. :shake: Drama queen......... LOL. You go girl!!!! Link to comment Share on other sites More sharing options...
Nofeartoys Posted May 10, 2016 Author Share Posted May 10, 2016 Just an update on the mj. Tested several time find good fuel pressure at idle but under load pressure would drop after two fuel filters and Delphi new Cherokee pump ( noisey and fuel gauge reversed. Still same issue. Installed bosch fuel pump onto mj fuel pump brackets assembly and cleaned debris from tank. ( much quieter and guage correct). Still had issue finally I removed inlet hose to fuel rail to test fuel volume going into rail. Found low volume ( partial 16 ounce water bottle with key cycle). I happened to look into fuel hose quick connect to find debris in hose. Used coat handle and loosed up debris. Put water bottle back onto hose and cycled key again. And found debris now in bottle including some bug which looked like a popcorn kernel ..reassembled and roadtested truck. Now vehicle has power under load. Yikes. The drama is gone finally. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 10, 2016 Share Posted May 10, 2016 Just an update on the mj. Tested several time find good fuel pressure at idle but under load pressure would drop after two fuel filters and Delphi new Cherokee pump ( noisey and fuel gauge reversed. Still same issue. Installed bosch fuel pump onto mj fuel pump brackets assembly and cleaned debris from tank. ( much quieter and guage correct). Still had issue finally I removed inlet hose to fuel rail to test fuel volume going into rail. Found low volume ( partial 16 ounce water bottle with key cycle). I happened to look into fuel hose quick connect to find debris in hose. Used coat handle and loosed up debris. Put water bottle back onto hose and cycled key again. And found debris now in bottle including some bug which looked like a popcorn kernel ..reassembled and roadtested truck. Now vehicle has power under load. Yikes. The drama is gone finally. Way to stick with it and thanks for the update. Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 10, 2016 Share Posted May 10, 2016 Just an update on the mj. Tested several time find good fuel pressure at idle but under load pressure would drop after two fuel filters and Delphi new Cherokee pump ( noisey and fuel gauge reversed. Still same issue. Installed bosch fuel pump onto mj fuel pump brackets assembly and cleaned debris from tank. ( much quieter and guage correct). Still had issue finally I removed inlet hose to fuel rail to test fuel volume going into rail. Found low volume ( partial 16 ounce water bottle with key cycle). I happened to look into fuel hose quick connect to find debris in hose. Used coat handle and loosed up debris. Put water bottle back onto hose and cycled key again. And found debris now in bottle including some bug which looked like a popcorn kernel ..reassembled and roadtested truck. Now vehicle has power under load. Yikes. The drama is gone finally. Was there a strainer on the pump suction line or was it MIA? Link to comment Share on other sites More sharing options...
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