bbhall89

I have a 94 grand cherokee with a318 5.2l v8. When i got it the first thing i did was give it a tune up, it was having problems before that but it seemed the tune up made things worse. It was drivable kinda but if you used the brakes it would stall and choke when trying to start back up. Now it won't start at all. I've dropped the tank and replaced the pump, the filter, i don't know if there's more than one tho. Replaced the disc under the rotor on the distributor, and as i said gave it a tune up. I've got spark so I'm thinking its a fuel problem, no check engine light whatsoever. When i turn the key to the on position tho the abs light comes on for about 3 seconds then goes off the engine turns but will not start. I checked the oil and its low but all i had was synthetic and didn't want to AD that to non, will get oil to add but in the mean time please help.

czettlera

Hi I'm not really into 5.2 engines as I have a 4.0, but for any engine if you put anything flammable in the air inlet, for example at the air filter, and it starts up, even for a little, than You have most likely fuel problem. In that case you should check fuel pressure. Anyhow I would try to check the fault codes if the pcm, see what it shows.

dave1123

I'm thinking kind of out-of-the-box but maybe you've got a vacuum leak in the power brake unit. My key to this is it stalls when you hit the brake. A bad vacuum diaphragm will cause a BIG vacuum leak and it was probably getting worse over time. Disconnect the hose at the manifold and plug it. See if it will start after that.

bbhall89

Ok so i dropped the tank..again..and there's a fitting that's supposed to go on top of the fuel pump that makes it so the hose doesn't get kinked and i didn't put it back on.but that's beside the point. I got it started with a fitting on there and now when i start it it starts right up but the RPMs sky rocket..like 3 or 4 thousand. Then slowly go backdown and when it goes down the engine sputters and back fires into the intake and will eventually stall. now it's got a check engine light on. But i don't want to drive it and i can't pull a code cuz it's not that new. Is there a bad sensor maybe or what does this sound like to anyone?

dave1123

A '94 should be OBDI which you can get the codes from the flashing CEL light. Turn the key on, off, on, off, on and wait. The CEL should start flashing. If there are no codes set, you'll get a code 55 (5 flashes, a pause, then 5 more flashes) which mean "end of test". Other codes show up before this.

My '89 Chevy truck was OBDI.

bbhall89

I kinda feel dumb for asking this but what is the cel? Obviously a light on the cluster but which one?

dg61683

check engine light ( CEL)

dave1123

I likewise have only had the 4.0 in my jeeps, but I seem to recall there is sometimes a problem with the gasket on the bottom of the intake manifold leaking on the 5.2.

bbhall89

Ok thank you for answering my stupid questions lol. Anyway just checked the cel and it blinked once, paused then twice, then paused, blinked once again, paused, then three times, then the 5 and 5, so I'm guessing obd1 codes 12 and 13?

Bustedback

My guess is that you have the firing order off.

bbhall89

12 -*Direct battery input to PCM was disconnected within the last 50 Key-on cycles.

*13 -*No difference recognized between the engine MAP reading and the barometric (atmosphere) pressure reading from start-up.*

Those are the codes I'm getting. And i made sure i put the ignition wires on the right plugs and checked them with a source as well. It's not that. Anyway where can i find the map sensor? Is it the little one that's on the throttle body?

dave1123

It's the rectangular black box on the front of the throttle body.

bbhall89

Alright, I've got a parts car that i can pull a lot of parts off of. So I'll try that and go from there. Thank you Dave, you've been a huge help.

bbhall89

Alright, I've got a parts car that i can pull a lot of parts off of. So I'll try that and go from there. Thank you Dave, you've been a huge help.

bbhall89

Ok so far so good, changed the map sensor and nothing happened, but changed the tps and it started right up and ran sweet. Turns out the high idle was from the cruise cable holding the throttle open lol. But I'm gonna be putting it back together tomorrow and testing it out.