Ben-88Comanche Posted July 24, 2007 Posted July 24, 2007 I was driving and it sputtered a little and died. Ive done everything i know how to do, fuel pumps working, fuel rail is pressurized, ignition coils fine, distributor caps good, batterys fine, got spark, but when i took the spark plugs out no smell of gas. For some reason the injectors arent injecting. I doubt theyd all die at the same time, or all get clogged at the same moment. i think something is wrong with the electronics controlling them. Ive been told they are powered by fuseablelinks, not fuse boxes, but i don't know anything about fuseable links or how to tell if their broken. If anyone could help me it would be greatly appreciated. :cheers:
rockhardzj Posted July 24, 2007 Posted July 24, 2007 Does someone local to you have an ECU of the same or similar year that you can borrow to test? Thats the only thing I can think of, but I've been wrong before...
87manche Posted July 24, 2007 Posted July 24, 2007 the injectors and ecu get power from the same fusible link that power the fuel pump, so if the pump has good voltage the link is good. Does it have spark? if it doesn't have spark that's a dead giveaway for a CPS failure.
ROADLESS Posted July 24, 2007 Posted July 24, 2007 Sounds like a bad crankshaft position sensor (CPS) to me. Normally I don't condone replacing suspect parts because it can turn out to be a 'hit and miss' game and thusly expensive. However, because this is a common problem, and difficult to test, it's a good idea to have a spare one on hand anyway. The CPS is located on the upper portion of the flywheel cover on the drivers side and yes it is a PITA to R&R :eek: .
rockhardzj Posted July 24, 2007 Posted July 24, 2007 Sounds like a bad crankshaft position sensor (CPS) to me. Normally I don't condone replacing suspect parts because it can turn out to be a 'hit and miss' game and thusly expensive. However, because this is a common problem, and difficult to test, it's a good idea to have a spare one on hand anyway. The CPS is located on the upper portion of the flywheel cover on the drivers side and yes it is a PITA to R&R :eek: . I should have thought of this... My 98 ZJ had some issues earlier this year, but it would at least run really rough, I wasnt able to figure it out, my mom's mechanic was surprised it even ran. Turned up my CPS was half eaten by the flywheel... :eek:
87manche Posted July 24, 2007 Posted July 24, 2007 Sounds like a bad crankshaft position sensor (CPS) to me. Normally I don't condone replacing suspect parts because it can turn out to be a 'hit and miss' game and thusly expensive. However, because this is a common problem, and difficult to test, it's a good idea to have a spare one on hand anyway. The CPS is located on the upper portion of the flywheel cover on the drivers side and yes it is a PITA to R&R :eek: . I should have thought of this... My 98 ZJ had some issues earlier this year, but it would at least run really rough, I wasnt able to figure it out, my mom's mechanic was surprised it even ran. Turned up my CPS was half eaten by the flywheel... :eek: ouch. as much as I hate throwing parts at things, with a renix rig there's no code to tell it's bad. And to test it a multimeter just isn't good enough. I know that the FSM specs out an ohm reading for it, but that's an educated guess at best. To properly test it you'd really need an o-scope. anyway, it's the #1 cause for no starts/spark/injectors, and it's a pretty common failure due to the harsh enviroment it lives in. Have fun replacing it. You'll need about 14" of extensions, a wobbly socket, and you might want to drop the trans x-member so you can get at it easier. DO NOT DROP THE BOLTS IN THE BELLHOUSING! use grease or something in the socket to keep the bolts from falling into the hole in the bellhousing. If you drop them in there you're gonna be pulling the trans.
JeepcoMJ Posted July 24, 2007 Posted July 24, 2007 ...if you drop them in you will be removing the inspection cover, that's about it...
87manche Posted July 24, 2007 Posted July 24, 2007 not if they get hung up against the flywheel and in your clutch. ask me how I know. turned a relatively simple job into an all afternoon ordeal.
500 MJ Posted July 24, 2007 Posted July 24, 2007 ?unbolt the tranny crossmember, let it down and get about 3' of extension on your ratchet. crawl underneath and loosen it up from under the truck. Make the job easy. It is more work to do it this way but it should save some time and scraped knuckles. Just my $.02
JeepcoMJ Posted July 25, 2007 Posted July 25, 2007 not if they get hung up against the flywheel and in your clutch. ask me how I know. alright, how do you know? :P fyi a nice air ratchet gets in there snug and saves you smashed fingers and lots of dinkin around. I find that there is enough room for me to get it done even with a ratchet and no extensions...and I have big hands. I figure the reason I can do it that way is cause I'm norwegian.
Ben-88Comanche Posted July 25, 2007 Author Posted July 25, 2007 yea ithas spark after not starting for 3 days, i went last nite and it started then died, Like a fuel filter failure or having water in the gas line. Thinking about draining some fuel from the fuel rail with the engine cranking, and adding dry gas to the tank, seeing what happens. If that doesnt work, ill change the fuel filter. I just changed the fuel filter like a month ago tho, so if that fixes it, time for a new tank <=/
Guest junkyard Jim Posted July 25, 2007 Posted July 25, 2007 Sounds like a weak CPS or the harness is melted to the exhaust manifold.
87manche Posted July 25, 2007 Posted July 25, 2007 well if it's got spark it's not the CPS. got fuel pressure check?
carnuck Posted July 25, 2007 Posted July 25, 2007 oops! replied wrong! melted harness and weak CPS will spark sometimes.
87manche Posted July 25, 2007 Posted July 25, 2007 I just thought of another thing to check. The fuel pump ballast resistor on the drivers side fender. Jumper those two spade connectors with a appropriate sized wire and see if it fires.
ROADLESS Posted July 25, 2007 Posted July 25, 2007 well if it's got spark it's not the CPS. got fuel pressure check? 87manche, Good call on checking the fuel ballast resistor. However, I have to disagree with you on the CPS/spark issue. I believe that he can have spark with a bad CPS. That is why his engine starts (and shortly dies). The CPS is no longer receiving/transmitting the proper amperage to keep it running. Ben-88Comanche, I still believe you have a bad CPS. here's a good link to sensor diagnostics. Page down near the end for CPS diagnostics: http://www.lunghd.com/Tech_Articles/Eng ... ostics.htm
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