HEAP of JEEP

Having problems with my 90 4.0 auto. Its my wife's DD this winter.

This morning, she started it up, then realized she forgot something in the house, so turned it off to take her keys and go get whatever she forgot. When she tried to restart it a couple of minutes later, it would crank, but no start. She ended up taking the other car, and didn't try starting the Jeep the rest of the day.

When I got home from work, I tried starting it, and it started right up. At that point, it had been sitting for about 9 hours. I let it run for a couple of minutes. Idle was fine, so shut it off and tried to restart it. Crank but no start.

So, popped the hood to check what I could with my limited tool collection. I don't have a fuel pressure tester, but I released the pressure at the rail and fuel came out quite forcefully. I hooked up a spark tester at the coil, and was getting spark, so checked for spark at a couple of the plugs and had spark there too. Just for giggles, I pulled the dizzy to check that and the rotor, and the contacts did look a little worn, so I will be replacing those. Then I started pulling plugs, and they all looked the same. A soft tan color, and checked the gaps, and they were all spot on.

So buttoned everything back up, and went to try and start it again, and it acted like it wanted to catch for a second, then back to just crank/no start, until I floored the gas pedal. As soon as I pushed the pedal to the floor and tried to start it, it started right up.

I took for a quick drive down the block, and let it warm up a bit. When I got back to the house, I shut it off, and tried to restart it three times. All three times it started right up.

So, at this point, my mind is leaning towards the coolant temperature sensor not giving correct readings. They're fairly inexpensive, so even though I hate throwing parts at a problem, I'm not sure what else to consider at this point. So, I could really use some advice on what else I might check from those with experience.

cruiser54

Flooring it cuts fuel to the injectors.

Could be running too rich. CTSs rarely fail BTW.

How's the hose from the MAP to throttle body?

I've got a Tip for that at www.cruiser54.com. No photos yet. You could be the guinea pig, eh?

SteveMongr

I had the same or very similar issue with my 1996 that was intermittent in the beginning, and got worse.
No start, just crank, until throttle was pushed to floor, then it fired up. Along with the smell of raw fuel.
Had a CEL code for the coolant temp sensor and/or its harness. Upon removing and inspecting sensor I noticed a patina or corrosion on the contact points of plug, the connection of sensor to wire harness. Cleaned the contact points with emery cloth and have not had the issue return, it's been over one year.
Coolant temp sensor is located in thermostat housing.

Like Cruiser54 says, "Refresh connection before replacing component"

HEAP of JEEP

Thanks guys. Gotta trust the Cruise. That gives me some other directions to look in.

cruiser54

Have you completed Tips 1,3,4, and 5 yet?

HEAP of JEEP

1 & 5, Yes

3 & 4, Not yet, but I will obviously get on that. Thanks Cruiser!

HEAP of JEEP

Just an update:

Completed the tips Cruiser54 mentioned, and have not had any repeats of the original problem.

I still can't definitively say what caused it, but cleaning and refreshing all of the connectors and grounds seems to have solved it.

cruiser54

Well, imagine that!!

Roler

It's good to see some things haven't changed....

cruiser54

Hey!! You're still hanging upside down on the earth?

Roler

Yeah mate, still here on the big island....It's been a year since last exchanged thoughts here, I noticed! Thought see how you were going just before you hit the 30.000 posts mark..

cruiser54

First off, welcome back! !!
Check this out:
www.cruiser54.com.

Roler

Thanks mate.
And of course I clicked that link already haha. Look at you and that fancy website! Great idea. Consider starting a forum on it, too?

cruiser54

I don't know about a forum. Salad was kind enough to help me get the site so I could keep everything under one roof. It was getting tough to maintain more than 4 sets of my Tips across numerous forums.

DFlintstone

Howdy Rooler! Sweet Pete, your page looks great! Hey, a friend without a computer just got an 88. Is there somewhere where I can print the whole shebang in one shot?