Calgary Jeep Association
4x4 Related Groups => Tech Talk => Topic started by: Marco on February 05, 2011, 03:03:51 PM
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After a ridiculous amount of time effort and a ton of money we still cant find a way to get our YJ to run. We recently got a 2.5l motor from a member on here ( of which was running great when i seen it) but cant seem to get the thing to run worth a poop.
New to us motor(which ran good in his jeep) plugs wires cap rotor fuel lines fuel filters sensers numerous gaskets even the computer we changed
Starts pretty easy runs ok for a few mins then quits. could repeat that process over and over. Takin it for a test drive reveiled Very diffucult to keep running coughing and sputtering. The only thing that was different from the swap is that little two prong peice above the buterfly on throttle body. does anyone know what kind of fuel pressure the line should have at the throttle body? we may have used a fuel pump from a different year.vacumn hoses appear to be looking ok. If i cant find the solution soon i will be looking to take it in to a shop where there familiar with these motors.preferably not chrysler stealership where apprentices only know computers (with all due respect).
its a 1990 yj 2.5l lifted on 33's everyting else factory (ish) thanks for any thoughts.
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After it dies is there still pressure in the fuel rail?
What (if any) codes are you throwing?
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didnt even look into the fuel pressure yet. gonna go to can tire and get a fuel press
tester ( i want one anyway)
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Well you should have 14.5psi @ 2000rpm however if you're having trouble getting it to stay running that may be fun to try to test :P
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hmm ok.i shall try that. just trying to rule out fuel and spark and go peice by peice again lol.thanks
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fuel pressure should be 14-15 psi at idle .
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sweet thanks jay. ill try this if it doesnt work maybe i can bring it to you perhaps? :)
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if you can't figure it out I would be glad to help I will send you a pm with somethings to try ;)
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Was the old eng doing the same? If so what is common between the two? Did the new to you eng come out of the same year?
Are all the sensor wires conected?
Do you have the plug wires in the right location? ( have to ask)
Is the timing correct?
No damage on the cap or rotor? ( have to ask)
What about the coil, is it still good? Nothing left in the air box? ( rags, leaves etc)
When you do get it to run, if you give it gas will it stay running? and not idle?
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well no.the old engine had a trillion miles on it so we dicide to get rid of it.it did run. plugs cap rotor wires coil all brand new to this install. plug wires for sure in right position. runs good and will idle for about a minute or so. if i twist the throttle linkage i can kind of keep it going then its just dies. tried this in hot and cold temps also.
im pretty sure i remember it coming out or the same year jeep or close.they looked identical side by side on the floor too. we did change the header from the old one and put it on the new one instead of lame manifold but i cant see that making a difference.
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Does the choke work? If it does try and disconnect it, if not make it work or heat up the intake with a hair dryer till its warmer and see if it runs better.
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Did you keep the original flywheel with the motor or use the new one? was there a difference in years on the two motors? Pick ups sometimes vary from one ecm to another,..
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Not sure if this helps or not - but when it came to switching the fuel pump on my 2.5l I was warned to be sure to get the same year - there are two types (one you can draw fuel through, the other you can't) and apparently the two styles do not intergchange. sorry I know very little anout what the exact difference is and wether that factor is irrelevant or not, but if your running out of options maybe that's an aspect you haven't considered yet ???
g'luck