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Hello to All.... I wish to thank all the members and especially you Mr. Ludell for all the time spent on our endless problems.... I have reviewed all the posts that might pertain to my problem and do not wish to ask a question that can be easily answered by simple review... My YJ has had an.. "on again / off again" problem that may not be related to this exact problem but it just seems to have never been 100 % or maybe even 80%... The current problem started on an outing in the woods ..drove fine climbing, downhill and 4wd.. coming back the engine began to act like it was starving for fuel..the harder you press on the gas the more it chocked out...would idle fine..no power.. So... I took it to mean a faulty pump and ordered same...pulled tank ..found sock off the pump..Problem solved ??..decided since I have a new one might as well drop it in.. "nice to have a trail spare anyway".. replaced tank with new filter... went to fire it up ...no start..no apparent fuel at the TBI....Now it wont run at all... So... check electrical to pump ..fine..check lines..fine.. Ordered a Pressure gauge...slap it on the TBI access port ..No pressure.....Check pressure before the TBI... jumps to 50 psi...way to much..?? checked inline with " T " Key on 25 psi.. Start..jumps to 50 psi..no apparent fuel returning to tank.. SO.... rebuild the TBI... bad regulator..Maybe...clean, replace TPS , new injector, and filters while its apart... " Nice to have trail spares anyway" reassemble...try to start ...no fuel.... So....Back to ZERO.... No fuel getting past the Regulator... Remove TBI..reinspect , reassemble..try to start...no fuel Also the CPS..MAT sensors replaced during the last session...Of unknown problems..."Nice to have trail spares anyway" When fuel is manually poured in the carb. she fires right up and I can keep it running if i drizzle it in.. So... it runs if i can figure out how to get my wife under the hood with a squeeze bottle while I drive....Could work...Maybe.. Make a great hood ornament...Should switch that around encase she reads this..She Drives....ya sounds better... The questions are.....will the pressure spike to 50 psi if there is no return to tank..? Is 50 psi just way to much ..? Will to much pressure cause the regulator to shut down so to speak..? Is it possible the spring in the regulator is bad ,The kit did not have a new spring...Seems a weak spring would allow to much fuel...did try to adjust with set screw...no Fuel...? The TBI is clean no blockage in ports...so what could be stopping the flow... Other than the regulator... ? "Did I just answer my own question..Maybe" Why are my troubles worse now after the repairs..At least it ran at idle before? Your Attention , Patience and experience with this matter will earn you my admiration and a box of Girl Scout cookies...of your choice Jamie
Here is 1987-90 Jeep YJ Wrangler and Jeep XJ Cherokee/MJ Comanche 2.5L TBI diagnostics information in PDF form. The first document includes all sensor and switch tests plus adjustments that affect engine tune, idle and reliability. Wiring schematics and ECU pin locations, test plugs and diagnostics included. Jeep 2.5L TBI Complete Diagnostics-Sensors-Switches.pdf Jeep 2.5L TBI ECU Inputs and Outputs.pdf Jeep 2.5L TBI MAP Sensor Test.pdf Jeep 2.5L Timing Chain and Tensioner.pdf Jeep 2.5L Valve Timing Check.pdf Jeep YJ 2.5L TBI Sensors and Pinout.pdf YJ Wrangler 2.5L TBI Wiring of WOT to ECU.pdf Jeep YJ 2.5L ISA Wiring Diagram.pdf 1987-90 2.5L TBI Intake Manifold and Sensors.pdf 1987-90 YJ Wrangler 2.5L TBI Emissions System Parts.pdf YJ Wrangler Fuel Filter and Guard.pdf 2.5L TBI ISA Motor Adjustment.pdf Used in conjunction with the many forum exchanges (search under "All Content" and "2.5L TBI" in the search box), plus the Jeep 2.5L TBI troubleshooting article at the magazine website, this information will help solve your Jeep YJ Wrangler or XJ Cherokee 2.5L TBI troubles. In references, the Model 81 is the Jeep YJ Wrangler. The Model 60/70 is the XJ Cherokee and MJ Comanche Pickup. Moses