Initial Start up sputtering then runs fine?

Hey guys. My 97 xj has been acting weird. This doesn't happen all the time either. I am not to familiar with the whole fuel/sensor set up on these motors so here goes my problem. When it turns over it takes about 6-8 seconds and then starts to run but is just barely hits for about 2 or 3 seconds then it idles up to like 1500 rpm and idles great, then runs fine. Only does this when I let it sit over night or i come out for lunch at work or school. When it revs up there is also a loud sucking sound, but I am thinking this is only the k&n pulling air that i normally don't hear when at rpms that high. I have checked for a vacuum hose loose also and found nothing. I have to drive this thing 5 hours in two days to get my bumpers and i don't want to get stranded. I am thinking a sensor on the throttlebody is bad or my injector/fuel pump could be going south slowly? ANy help is awesome!!!

i posted almost the exact same question on here last week & no one responded...

anyway, i looked at my throttle body & it was very dirty (black). i cleaned it out & it seems to idle fine now when i start it. i also tried turning the key all the way & waiting for a few seconds before i start it. i still feel it's a fuel problem. i started it normally today & it had a rough idle again, so that's why i think it the fuel (filter, pump?). but in the last 7 days after cleaning the throttle body, i've only had the problem once. before i cleaned it, it was happening every cold start like you described.

i don't know about the sucking sound but i have a K&N drop in filter as well & never noticed it...

if it's a sensor, let me know which one...thanx...


eric
99 Cherokee Classic - Flame Red Clear Coat, 4.0L I6, AW4, Selec- Trac, Up Country Suspension Group, Skid Plate Group, Trailer Tow Group, ABS, & every other available Classic options except block heater. Optima Yellow-Top, K&N Filter, Sylvania Silverstars, CATZ XLD Driving/Fog Lights, "Trail Rated" Badge

03 New Beetle Turbo S - Uni Red, 1.8T, 6spd.

well good to hear someone else has this problem. Lets hope someone out there has had a similiar situation and can give us somewhere to start before I have to take it to the stealership.

New bumpers? Do you have the old ones off yet.

I think your 97 has the same fuel system as my 2000 and I have the exact same symptoms. I have used the seach function to check old postings here on and it seems like the check valve on the fuel pump has failed. You can drive it like this for some time with no problems or worries. The fuel line check valve holds the fuel pressure in the line when the motor is shut off. When the valve fails it lets the pressure drop off, slowly like yours or within 10 minutes like mine. The check valve is part of the fuel pump in the gas tank. Try cleaning the throttle body and see what happens. See if you can rent or borrow a fuel pressure gauge and check the fuel pressure after sitting overnight. There are at least 3 ways to fix this. 1 - get an expensive new fuel pump/check valve. 2- ignore it and turn the ignition on and off a few times to build pressure before starting. 3 -install a check valve from some other brand of automobile. I searched and found that a BMW valve ( Part Number 16 14 9 068 988) has been used by others, is inexpensive and works well. I am going to be getting one soon and giving it a try.

Thats awesome to hear! Thank you very much for the part number and info. I think after this weekend I will try to trace down the part and install a new one. Where is that located exactly, on top of the tank on the fuel pump itself? Good to hear the pressure is just bleeding off and hopefully not going to strand me. The bumpers are the stock ones and will be off in a couple of weeks. They are black without end caps. I will be glad to sell them for cheap.

Mine does the exact same thing and my girl freinds does it too. Something else though, some times my Xj, (93 4.0 auto) will stumble at an idle, you can watch the tach needle drop and a split secend latter it revs up and then runs fine. It does does this more at trafic lights. Not trying to steal the tread just seems like we all have almost the same prob. Is the startup in the moring and this acting up at lights conected? Again mine doesn't do it all of the time.
Thanks let me know it the BMW thing works.

Clean the throttle body first, best method is removal and workbench, keep the cleaner away from the plastic parts, they melt
After reinstallation dump a can of Chevron Techron FUELD SYSTEMS cleaner in the tank or SeaFoam or that BG stuff, maybe a couple of cans, it *might* also clean the drainback valve and start it working again.
My 98 is headed for 300,000mi and I put Chevron, Seafoam or Valvoline fuel system cleaner in about every 10,000mi or so. I can kind of feel it when it starts running a bit rough so it varies.
If you can, take pic of the TB before you remove it so you know how it goes back on and what goes where. Just a thought.

black93xj said:

Mine does the exact same thing and my girl freinds does it too. Something else though, some times my Xj, (93 4.0 auto) will stumble at an idle, you can watch the tach needle drop and a split secend latter it revs up and then runs fine. It does does this more at trafic lights. Not trying to steal the tread just seems like we all have almost the same prob. Is the startup in the moring and this acting up at lights conected? Again mine doesn't do it all of the time.
Thanks let me know it the BMW thing works.

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When ever I see a post where two xj's are both acting up the first thing to look at is, what fuel your both using. Your problems sounds like bad fuel.

Well I haven't got around to getting my new back bumper on so I dropped a can of sea foam in the gas tank and the poor start up problem has stopped. I am hoping the check vavle for the fuel pressure was just gummed up or something. Try this before u get the gas tank dropped. LAter

I'm surpised nobody mentioned changing your fuel filter!

I change my annually, its cheap insurance (~$10) and easy to do (on my 96 anyway)

give it a shot, cant hurt...probably due for it anyway!

CaptTrev

CaptTrev said:

I'm surpised nobody mentioned changing your fuel filter!

I change my annually, its cheap insurance (~$10) and easy to do (on my 96 anyway)

give it a shot, cant hurt...probably due for it anyway!

CaptTrev

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Thats alot of work on a 97+, it's on the end of the fuel pump...