93 Grand Cherokee-Won't Start in Cold

D did pass the time by typing:

With as many miles as you have on that I6 you would be better off rebuilding and stroking it out to 4.7. It would be cheaper and you wouldn't have to run higher octane fuel.

That's odd because pumping on a fuel injected vehicle doesn't do anything in particular besides confuse the ECU. Pumping is an old carb trick.

That sounds like air lock or leakdown. (see below)

Water in the fuel can freeze in the hoses and block the injector rail. But if you have that much water in the system it's going to run like hell.

I'm not tending toward that anymore after what you said, but the ASD relay is what kills your engine and fuel pump in the event of an accident or runnaway motor (ECU dies), Sometimes it can fail and cause no-start or other problems.

Do the leak-down test.

It's not described there yet, but basically after checking to see that the pressure is correct you turn off the engine and check to see that the gauge doen't fall more than about 20psi or within 30min. If it drops like a rock you have a problem. Either the backflow valve in the pump is shot or the fuel pressure regulator is. Further tests would then be needed to figure out which one.

NP, and thanks. :)

I don't mind html that much, but it's hard on some newsreaders and most newgroups frown on it.

Doug, there is a rationale to flooring the pedal in cold weather AFTER you screw up the first start. The gas that floods the cylinders never evaporates and it stays flooded unless you open the hole up enough to get some air thru the system. I was messing with mine MJ last winter and managed to stall it just after it started. Well, that really smart computer in old Rennix system seems to figure that if the engine died while it was trying to keep it running that it needs a bunch of throttle/bypass air/fuel when it restarts - PITA! Anyway, it will flood it but good and at -5 or so it takes a good battery and patience to finally flush the @#$% thing out so that it runs. Starts one cylinder at a time: chug... chug chug... chug chug chug... etc. until it finally gets going. The first winter I was at the AF Academy I was instructing in the T-41 (Cessna 182) and if we flooded those suckers we either pulled the plugs and dried them of figured that bird was parked til the next thaw. The smart thing is to follow the book and don't touch the gas when starting but if it floods down you sure better consider it on the re-start.

Will Honea did pass the time by typing:

Don't know if the ZJ reacts the same way as a Mercury does. If you floor the pedal in the Mercury it tells the computer to shut off all fuel. The OP described "pumping" the pedal as well, I was commenting on that.

You can stop it from flooding by removing the fuel pump relay. ;)

If it starts when you hold the pedal to the floor, it was likely flooded badly.

Holding the pedal to the floor usually sends a signal indicating a flood when the starter is turning so the injectors don't fire allowing the gas already in there to catch. It then will chug a little with lots of black smoke and quickly mellow out.

That indicates to me a spark issue.

Mike

D wrote:

At 12/5/03 04:23, DougW bespake thusly:

Never had this happen *yet* on a ZJ, but if you get ice in the fuel line and it jams a !@!@$# injector open, you get a pretty good flood condition in a hurry. Even a partial open jam will make the engine run like crap until the rail gets warm enough to melt the ice.

Doug, Aw, I was just dreamin' on the supercharger anyway. Many years past that. Thanks for the help, again, and here's an update, I threw an old moving blanket over the engine compartment last night. I really don't know if it had anything to do with it, but the old lady started on the 4th revolution, smoothly idling and behaving well. The leak-down test intrigues me and I'm going out to do that now. Through this and some other problems I've had with her, fuel supply has always been my suspicion, over spark. I know many things can affect the supply. Used to have an Audi 5000 Turbo. It had a closed fuel management system and several problems I had with it kind of echo what I'm experiencing. Anyway, not out of the woods yet, but getting there. Thanks to yours and others help. Denny

Lon Stowell did pass the time by typing:

Tell me about it. Got an ice block up in Colorado last winter. Only source could have been the gas station in Dalhart TX. The pump was a bit sluggish (my first clue) and was most likely sucking water.

A bottle of fuel drier fixed it right up.

D did pass the time by typing:

You might want to throw a bottle of O2 sensor safe fuel system cleaner with water dispersion ability in there. (gunk makes one and there are several others) That will suck up the water and help keep ice away.

I'll get some of that tomorrow, first thing Doug. Doing the leak-down test, everything seemed normal. Ignition on and pressure jumped up to just below 30psi. Started up and held just above 30. Revved up a little and it jumped to maybe 35 and then back to 32 or so. Shut down and it stayed at about 28 for a long time. Reason I'm having so many 'abouts' is the reading is on the low end of the meter and can't tell the exact reading. So, I'll Gunk her tomorrow and we'll see where it goes. You all have been awfully patient with me and I appreciate it. When I get back in with results later, I'll post new since this thread is getting awfully long. That's the proper thing to do right? Thanks Denny

D did pass the time by typing:

That's fine. Usually if the pump is shot you won't even get 20psi and if it's going to leakdown the fall is noticeable. Sounds like your fuel system is good. Just another thought, how old is your fuel filter?

It's best to put additives in just before filling the tank. Take a long screwdriver with you. Use it to hold open the filler door so the additive doesn't splash all over the place.

Doesn't matter to me. Not sure what the max thread depth is for OE but going by other groups we're not even close.

My Audi 5000T was very tempermential about starting. In cold weather, if it didn't start right away it would flood. I got pretty good at jumping out and pulling the Fuel Pump relay, jump back in, crank it to clear the cylinders, jump back out, put the fuel pump relay back in and start it up. A real PITA Finally got the Fuel Injection system adjusted correctly and then it started fine.

Then an idiot made a left turn right in front of my daughter and that was that for the Audi.

I changed the fuel filter last year when I was having some other problems. Saw it seemed pretty easy to do, so while I was under there I did it thinking she was getting pretty long in the legs.

Well, the old lady has been dead all day in the cold. Any more thought's on this cold start problem guys? Really nothing new to report other than good fuel pressure. Guess the spark is not there. What in the ignition is affected by the cold? Thanks. Denny

"D" wrote in message news:WTLzb.106072$ snipped-for-privacy@twister.rdc-kc.rr.com... Update to this problem. I got a can of starter fluid and tried it. The car seemed much more willing to start, but still no joy. It did huff a lot more, but didn't actually start. In my view, this points to more of a fuel problem than electrical? If there's concurrence on that, what in the fuel control system would be so subject to the cold temperature? Would appreciate additional thoughts. Thanks. "D" wrote in message news:OxKzb.105969$ snipped-for-privacy@twister.rdc-kc.rr.com... Hi all. Hope to find some suggestions here. 93 Grand Cherokee Laredo, 6 cyl, auto, 4wd, air etc. Has 220,000+ miles, been excellent and still is. Problem is when the temp gets into the 30's, it will crank and crank, give a huff or two like it's trying to start, but no go. New plugs, wires, Oxy sensor, other things over the last couple years. Read a forum message somewhere on a similar problem and the fellow said he finally took off the ECM and heated it in the oven. Seemed it had a crack in the insulating material that let moisture get in and freeze. Or something like that. Possible related symptom; the engine, when running well, gives a 'miss' on acceleration at right around 2800 rpm and has for years. I've gone through most everything but am really suspect of the MAP sensor or the ECM now. I've had a lamp on under the hood for overnight, but no help to start today. I would appreciate any ideas or suggestions for this old beauty. Thank you.