Dead YJ

[matts88yj]

My YJ has the Mopar MPI conversion kit that was swappin in about 4 years ago. On my way home from work yesterday my Jeep started to sputter at 2400RPM until abour 2600RPM which then after that point, would rev like usual. I tried this out in all of the gears and it only happens in 3rd and 4th gears under a load. I replaced the fuel filter and CPS with no luck. I checked and I have fuel pressure at the rail and I can hear the pump cycling like normal and I have spark. I did bleed the fuel line of air as well after I changed the fuel filter. I tried to start her even after the fuel filter swap and now she just cranks and cranks. Doesn't start at all. TPS was also replaced about a year ago. Anything else I should take a look at or test out? This is driving me nuts to say the least. I can't even go a year without something screwing up with the engine.

Note to self and fellow forum readers: Never do a stroker swap.

Another thing that made my heart sink to the floor was that in the past my Golen Engine Service stroker went through 2 oil pumps and 2 distributors. The first sign of this was that oil started to leak out around the base of the distributor. Well I looked at her today and there is some oil just starting to come out. To make a long story short, Golen screwed me out of an additional 2 grand in time, labor, and parts getting it back together. Being in college and paying your own way as well as this being your only rig to get back and forth to work in sucks big time.

Thank you for any and all ideas!!!:drownz:

[vk0896]

Sounds like it's time to take that puppy into a mechanic and make your problem his problem...check for spark at the plugs then work it back from there, check for fuel pressure at the rail...if you get stumped, rather than get frustrated and angry like I would be, I think I'd have the experts take a look... fortunately, you chose the FI system which is the stock unit, so if you take it to a dealer, it won't be uncharted territory...good decision.

[matts88yj]

If I don't get any other ideas Im going to take it to the shop tomorrow on my buddies trailer.

I have spark at the plugs and fuel. Im leaning towards it being the computer. She wants to go but just wont start for some reason. We will see what turns up and I will keep you posted! Any more info is greatly appreciated!

[vk0896]

Yeah, do let us know how that all works out..obviously, I'm REAL interested!

[matts88yj]

UPDATE: Well after letting her sit for a while I started her up and she ran for about 10 seconds then shut back off!!! Now Im really confused about this one! Tried a few other times and she sputtered to life then shut off right away. Any other attempts it was just cranking over and over. Im going to let it sit and try and enjoy my weekend. Its goin to the shop tomorrow.

[butch6924]

You need to pull the codes before you throw any more parts/money at it. Most auto parts stores will do that for free. I realize that the vehicle is dead in it's parking spot so that's probably not an option. The next step would be to figure out how to pull the codes yourself. Most FI kits have a key sequence that will flash the check engine light to let the operator know what codes to investigate.

All that said, I had similar performance issues twice, once it was the o2 sensor, the other time, it was the TPS.

Any time the computer is getting the wrong information, it'll adjust, timing and air/fuel mixture. A lot of poor running vehicles are due to sensors. In some cases, even the computer can fail. I have NO idea how to check that but hopefully you can get that info from MOPAR since it's an aftermarket product. They should have some such support.

Best of luck and keep us posted.

[vk0896]

He probably wont have a check engine light...it's a kit conversion...

[matts88yj]

I don't have a check engine light but there is a lead for it in the harness but I have no light for it in the dash or anything. I know this is going to be something stupid just out of my range of shadetree mechanic's skill level. Thank you for the good luck wishes!! Hopefully it isn't anything too major!!!

[Mechman71]

IMO what you need to do is check the injector pulses. Pull one of the injector plugs and use a VOM to check across the terminals while it's being cranked. If you get signal, then chances are it's a more involved repair than you should tackle without a scanner.

Just a wild idea, but you should check the engine ground wire while you're at it. Run a jumper cable from the alt bracket to the frame and see if it starts. A failed ground cable will cause this problem too.

[vk0896]

There is, I believe, the hookup for the scanner in the wiring loom...mine hangs out around the brake booster, you can pull the codes from this, I believe...

[matts88yj]

UPDATE: SHE IS ALIVE!!!!! This morning my dad and I went out to the Jeep and he wanted to make sure my cat wasn't clogged. While he was checking for exhaust pressure she fired right up and now runs even better than ever!!! Im guessing that since there was no fuel in the filter, it took a while to get the fuel through the filter and then start pumping it steadly to the fuel rail. Those filters probably hold close to about 12 ounces of fuel since they are the size of a soda can. Thank you for all of your help!!!

[vk0896]

When I first fired up my engine after the Mopar FI installation, it took many cycles of the fuel pump before pressure built at the fuel rail. I checked this by depressing the Schrader valve on the rail...now that I went back and looked at your original post, what you say now makes sense... never thought about it...put this in yer little bag of tricks, and make sure you check that valve next time you change the filter...Good job!

[matts88yj]

Funny part is that I did check it and was getting fuel at the rail! It must have made an air pocket in there and didn't want to run obviously but now she is running well! Thanks again for the help guys!!!