srgnt pepper Posted August 14, 2009 Share Posted August 14, 2009 i have an 88, 2wd comanche and when i try to start it the engine turns but doesn't start, though sometimes it will. any ideas on what the problem is?! Link to comment Share on other sites More sharing options...
LoTGoD Posted August 14, 2009 Share Posted August 14, 2009 Is it out of gas? :dunno: Seriously...that's a pretty vague question. Have you checked for spark? Can you hear the fuel pump running? Is your fuse panel corroded from a leaky clutch master cyl? Link to comment Share on other sites More sharing options...
Wildman Posted August 14, 2009 Share Posted August 14, 2009 The other question is............ Is the gas Fresh??? Or has this MJ been sitting for a couple months and the gas went south. You really need to check if you have fuel pressure at the rail, and If you have spark (leading to a bad CPS) After you check a few items, get back and report what you find. Link to comment Share on other sites More sharing options...
fiatslug87 Posted August 15, 2009 Share Posted August 15, 2009 Sounds like the CPS see below: Link to comment Share on other sites More sharing options...
Wildman Posted August 15, 2009 Share Posted August 15, 2009 What's this........With a '90 XJ........ "Checked with DRB II Scanner........." :rotfl2: "......Showed no stored trouble codes......" :rotf: Where they plug the code reader in..........the cigarette lighter???? :doh: Seams like a nice quick $80 diagnostic charge :roll: Link to comment Share on other sites More sharing options...
fiatslug87 Posted August 15, 2009 Share Posted August 15, 2009 ........With a '90 XJ........ Actually it was for my '90 MJ, shows you how much the Service Manager knew. Seams like a nice quick $80 diagnostic charge :roll: Yeah, that was in '94, I was naive back then, plus this site didn't exist (for that matter very few sites)!!! :rotfl2: "Checked with DRB II Scanner......Showed no stored trouble codes......" What scan tool is used to connect to the 6 way (D1) and 15 way (D2) diagnostic connectors that are between the relays and the coolant bottle? I know codes are not stored, but I thought there were real-time outputs. And back to the original question, can you hear your fuel pump prime every time regardless if it starts or not? I had a loose harness connection by the e-brake causing intermittent fuel pump issues. Link to comment Share on other sites More sharing options...
Eagle Posted August 15, 2009 Share Posted August 15, 2009 What is used to connect to the 6 way (D1) and 15 way (D2) diagnostic connectors that are between the relays and the coolant bottle? I know codes are not stored, but I thought there were real-time outputs. They are. You probe each one with a multimeter. The Renix system does NOT store trouble codes. You got hosed for an $80 diagnostic that they could not possibly have run. And back to the original question, can you hear your fuel pump prime every time regardless if it starts or not? I had a loose harness connection by the e-brake causing intermittent fuel pump issues. Not necessarily. The pump stops running when the pressure in the fuel rail reaches the required pressure. If you try to start and get a fail to fire, walk away, then come back and try again before the pressure has bled down sufficiently, the fuel pump may not need to run ... so you won't hear it. Link to comment Share on other sites More sharing options...
jeepdoggydogB Posted August 15, 2009 Share Posted August 15, 2009 ........With a '90 XJ........ Actually it was for my '90 MJ, shows you how much the Service Manager knew. Seams like a nice quick $80 diagnostic charge :roll: Yeah, that was in '94, I was naive back then, plus this site didn't exist (for that matter very few sites)!!! :rotfl2: "Checked with DRB II Scanner......Showed no stored trouble codes......" What scan tool is used to connect to the 6 way (D1) and 15 way (D2) diagnostic connectors that are between the relays and the coolant bottle? I know codes are not stored, but I thought there were real-time outputs. And back to the original question, can you hear your fuel pump prime every time regardless if it starts or not? I had a loose harness connection by the e-brake causing intermittent fuel pump issues. Mike-Interesting conversation about this here http://www.naxja.org/forum/showthread.php?t=71302 Looks like a Renix code reader did in fact exist, but like has been said no stored codes. In 1994 Comancheclub probably would have been a chatroom in AOL, or a dialup BBS which I am pretty certain didn't exist, I love and appreciate this site! Link to comment Share on other sites More sharing options...
fiatslug87 Posted August 15, 2009 Share Posted August 15, 2009 They are. You probe each one with a multimeter. The Renix system does NOT store trouble codes. You got hosed for an $80 diagnostic that they could not possibly have run. I know codes are NOT stored and they would still charge me for the diagnosis no matter what they used scanner or multimeter or ... And back to the original question, can you hear your fuel pump prime every time regardless if it starts or not? I had a loose harness connection by the e-brake causing intermittent fuel pump issues. Not necessarily. The pump stops running when the pressure in the fuel rail reaches the required pressure. If you try to start and get a fail to fire, walk away, then come back and try again before the pressure has bled down sufficiently, the fuel pump may not need to run ... so you won't hear it. Sorry, I thought it was implied to listen upon initial attempts after sitting when the key is turned to the Acc position (first click), hard to hear the pump prime while cranking. Thanks Joe, interesting read. Funny, Eagle posted on that thread also. Link to comment Share on other sites More sharing options...
Eagle Posted August 15, 2009 Share Posted August 15, 2009 Sorry, I thought it was implied to listen upon initial attempts after sitting when the key is turned to the Acc position (first click), hard to hear the pump prime while cranking. The "Accesory" position is not the first click. Accessory is the opposite direction from the Run and Start positions, and does not energize either the fuel pump or the ignition. The first click toward "Start" is "Run," not "Acc." The fuel pump does run with the key in the "Run" position -- IF the pressure in the fuel rail has bled down enough to need it. If you park overnight and turn the key on (to "Run") you'll typically hear the fuel pump run for 2 to 4 seconds, until it builds pressure. If I drive one of my trucks home, shut it down, and a few minutes later turn the key to "Run," the pressure is still up and the fuel pump does not run. Link to comment Share on other sites More sharing options...
Wildman Posted August 16, 2009 Share Posted August 16, 2009 Yeah, that was in '94, I was naive back then, plus this site didn't exist (for that matter very few sites)!!! :rotfl2: I meant no harm by my statement, I too was naive in '94, and didn't know anything about the MJ's back then, only over the past 7 years have I've gotten into these beasts. In fact........I don't think I was even on the www until '96-'97 (after Al Gore Invented it) :teehee: I know how it is, the vehicle is broken down, and your at the mercy of a repair shop, and well.......your fresh meat to them. bottom line is.........a voltage meter is the best diagnostic tool for the Renix system. Link to comment Share on other sites More sharing options...
Oizarod115 Posted August 17, 2009 Share Posted August 17, 2009 hey guys... don't be so quick to call BS on the scanning... i scanned my 89 friday with our snap-on MODIS scanner... and it gives alll sorts of nice info you can't get easily elsewhere. you plug into the two yellow-capped ports near the relay center. Link to comment Share on other sites More sharing options...
dunl Posted August 17, 2009 Share Posted August 17, 2009 First, where can you find one of these scanners? :brows: Secondly, take a wire and jump terminals 5 and 6 to see if the pump runs. Link to comment Share on other sites More sharing options...
aemsee Posted August 17, 2009 Share Posted August 17, 2009 Sorry, I thought it was implied to listen upon initial attempts after sitting when the key is turned to the Acc position (first click), hard to hear the pump prime while cranking. The "Accesory" position is not the first click. Accessory is the opposite direction from the Run and Start positions, and does not energize either the fuel pump or the ignition. The first click toward "Start" is "Run," not "Acc." The fuel pump does run with the key in the "Run" position -- IF the pressure in the fuel rail has bled down enough to need it. If you park overnight and turn the key on (to "Run") you'll typically hear the fuel pump run for 2 to 4 seconds, until it builds pressure. If I drive one of my trucks home, shut it down, and a few minutes later turn the key to "Run," the pressure is still up and the fuel pump does not run. How does the pump "know" that there is pressure in the rail? There are no pressure sensors in the fuel system. There is no feedback from the pump to the ECU. Also, there is a Jeep/ Eagle adapter kit that allows the DRB II to connect with the Renix system through the two connectors. It came with adapter boxes, cables and DRB II cartridges for the 87 to 90 Jeeps and the Mitsu products. If you would like I could post a pic sometime of the set up. The dealer I was at was throwing out all the "old, obsolete" tools a while back, and I managed to grab a couple of DRB II's and adapter sets. :D If you check e-bay the stuff shows up occaisionally. Link to comment Share on other sites More sharing options...
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