91 Laredo

This a a new to me cherokee (1994 Sport Auto).

I've noticed on the last few mornings its hard to start when cold. I will crank once and it will start but die immediately. I try it again and it starts but will barely run until I give it a little gas then it catches and idles correctly.

After that its fine until it sits and cools down for a long time. It seems that it has to be really cold too. Today when I left for work it started okay (not great) and was around 50 degrees. When I left work this morning it wouldnt start and was around 38 degrees.

I've recently replaced the fuel filter and did a complete tune up. I also ran some seafoam in the tank and crankcase.

I spoke to the dealer regarding the fuel pump and he advised that those usually go bad when the vehicle is difficult to start when Warm.

I dont want to start throwing parts at this thing, but I would like to get this issue resolved. Any ideas?

REWSTER

check your battery?

Jeepebago

Just a guess, but it almost sounds like bad vaccuum lines.
Maybe you would benefit from a block heater to help with cold morning starts. I have one for my '96, and it really helps out.

93XJLI

battery

BuckB91XJ

Thoroughly clean your entire Throttle Body, to include removing the IAC motor and cleaning the bore. Also read the IAC out and read the (TPS) Throttle Position Sensor out. There are procedures for this all over online, Just google it. Clean the throttle body with a toothbrush and carb. cleaner. If none of this works there is a really easy way to test your fuel pump and fuel pressure regulator. Plug a pressure gauge into the tstprton the fuel rail. Start the Jeep. You should have (31 PSI +- 2 PSI). If this reading is good then your fuel pump is good. Now, unplug the vacuum line going to your fuel pressure regulator. You should, now, have around 38-39 PSI. If this reading is good then your fuel pressure regulator is good. These few simple tests will save you a lot of money in what I call shotgun troubleshooting...I.E. throwing parts at it. I hope this helps.

91 Laredo

Any specific vacum lines I should check or are notorious for having issues?

The battery was replaced about a year ago (the 2nd one under warranty)

I will try and clean the T-body, etc.. next week when I have some extra time. While a block heater would be nice, I dont feel that its really necessary in Oregon as it rarley gets below 30 degrees here. My last Cherokee never had any issues.

Any other thoughts? Would you agree w/ the dealer that it doesnt sound like a bad fuel pump as its only difficult when cold?

Thanks

91 Laredo

Update (somewhat) -

It was 30 degrees when I left work this morning.

I read somewhere that someone was having a similar issue and would "double prime" the fuel pump. Basically turn the key on, then off, then on again.

Gave it a shot and while the Jeep had the slightest hesitation to start, it fired almost immediately, didnt die, and idled correctly.

I emailed the PO, and she stated she honestly has never had this problem on the past (I believe her).

Is it possible that when I degreased the motor something happended? Wet sensor or something?

stumper

engine cranks over fine? right? not a battery problem. Clean that IAC [idle air control] that should say it all. Just like BUCKB says, clean the TPS and throttle body. get a can of spray cleaner of either throttle body of Carb. cleaner, use that toothbrush your younger brother or sister does not like too use and scrub away, this should take you less than 0.5hrs, if you have some mechanical knowledge. it's easy work, if your not sure, get your buds to show you. Stumper.

91 Laredo

Update -

Okay, I cleaned the throttle body and the IACV valve (very gunked up, I pulled it out and thought there was another gasket on there, but it was just carbon deposits packed and shaped like one )

Anyhow, the T-body wasnt too bad, but was alittle dirty. The passage to the IACV was pretty nasty Took a tooth brush to it and scrubbed her down.

This morning wasnt as cold, I think 33, but it started on the first few cranks and seemed to run okay, better than it has been.

Questions -

Anything else to try? I keep comparing it to my old 91 that never had any issues when starting regardless of temperature (and I never cleaned the T-body. Maybe because that got wheeled Sooo hard and really saw some R's.)

When I did clean the IACV, I was pretty careful and really didnt get up inside the main body of it, pretty much cleaned the plunger. I heared these are pretty sensitive.

Also, I didnt clean the TPS, I heard not to mess with these as they will need to be recalibrated by the stealer?

notorios B-O-B

How hard to install block heater? Where?

hubbazoot

Block heaters mount directly to the bottom of the engine block itself, so installing them can be a pretty involved process.

As for the starting issue, I would recommend checking your battery and eliminating that possibility. My XJ starts totally fine even in temps as cold as -20F and that's without the block heater . I would just check everything involved with starting the vehicle (battery, starter motor, fuel pump, vacuum lines, etc) and make sure that they are all in good running condition.

godzuki87

my wife has a 93 cherokee and we had similar probs. replaced fuel pump, filter, distibutor,fuel pump resistor. each fix worked for a very short time. what actually fixed the prob was bypassing the resistor. it seems that the fuel pump would start then shut down due to to the resistor heating up and shutting off the pump.

EvilBlackXJ

I vote for a vacuum leak.

chefeagles

Will a thicker gauge wire from the battery to the starter help any with faster starts in the cold?
I have advanced auto top of the line battery and a new starter. And mine starts "slow" when its really cold in the teens.

93xjri

Clean your IAC like everyone else has suggested.