manche Posted October 17, 2007 Share Posted October 17, 2007 i have a 89 Comanche with a 2.5l and recently my engine has been eating alot more gas then usual i used to get about 19 mpg but now it down to 8mpg when i accelerate if i floor it it dies out and like bogs but if i raise my accelerator just a little it accelerates more then when i had it floored i was told it was the reg. but i need a second opinion Link to comment Share on other sites More sharing options...
Pete M Posted October 17, 2007 Share Posted October 17, 2007 Could be a leaky injector dumping too much fuel into the engine. Link to comment Share on other sites More sharing options...
manche Posted October 17, 2007 Author Share Posted October 17, 2007 so how would i fix that ? and do you think its the reg. then? Link to comment Share on other sites More sharing options...
mjeff87 Posted October 17, 2007 Share Posted October 17, 2007 Can't remember, is the 89 TBI or MPI? If it's TBI the regulator is on top of the throttle body, but the test port is sealed. You have to drill it out and attach a specific fitting to be able to test fuel pressure. Jerry's (tjbliley) MJ has this already done. But your problem sounds like it's TPS related. I'd start by checking it, and adjust if necessary. Jeff Link to comment Share on other sites More sharing options...
tjbliley Posted October 17, 2007 Share Posted October 17, 2007 Sounds to me like a bad tps, or injector/seal. There should be a port to add a shrader valve to that will enable you to check fuel pressure. you need to run it and watch the injector in the throttle body. see how much fuel is being dumped. use a mirror cause if it is dumping it could backfire in your face. It also could be the fuel pump. check that as well. Link to comment Share on other sites More sharing options...
carnuck Posted October 18, 2007 Share Posted October 18, 2007 Check the hose on the MAP sensor. When the rubber was cracked in mine it did that. Also, if the Orings in the TBI unit are leaking, gas goes down waaay too fast! Link to comment Share on other sites More sharing options...
manche Posted October 21, 2007 Author Share Posted October 21, 2007 i went through my paper work and it seem the mj had a 4.0 before it was swapped would a 4.0 fuel pump matter ? Link to comment Share on other sites More sharing options...
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