Kris smith

Ok so since I've gotten the jeep in January when it's cold over night the jeep will crank and crank it will try to start it will sputter a bit but nothing I've tried giving it gas feathering the throttle nothing I have to wait till it's warmer out side and it will start. Since I've gotten it I've done plugs cap rotor wires tps CPs idle air checked timing and spark. I just got done wih an ax15 swap and new crank sensor. All was great all weekend this morning it was cold maybe 30 out side it cranked and cranked sputtered but nothing what am I over looking ?

freegdr

Its a shot in the dark try tapping the map sensor next time it wont start mine was having same issue just by luck I did this with a 1/2 wrench it started .I did this then next two times it would not start it started after each time I tapped it. It has not done it since I replaced the sensor two years ago.

cruiser54

Have you checked the output voltage of the CPS?

Did you adjust the new TPS?

Have you ever clicked on the pink link in my signature and done posts 1 through 4?

Kris smith

Cruiser I have done almost all of your mods and checks. The tps has been adjusted into spec I haven't checked the CPs voltage I figured the new sensor would be ok seeing as how it's the one from the oem manufacturer. I'll check when I have time came home today after work and fixing my other car and jeep still won't start. I guess I don't have to worry about the drive shaft being too short of I can't drive it

cruiser54

CPS voltage is super important. Check it and let us know.

Kris smith

Ok will do

Kris smith

I was tumbung through the Haynes Book and I read under the no start when cold section about fuel pressure I will check that as well while I'm there. Because once I do get her fired off she runs like **** and once warm runs fine and will re start easy. So when I have some daylight when I get off work I will check the CPs and fuel pressure.

Kris smith

Well it started this morning but ran like hell like as every miss or a carbed small block without a choke

cruiser54

Have you checked the cPS and fuel pressure yet?

Kris smith

No I'm in the shop all day I bright it to work with me. I will check it when I clock out at 5 pst

DFlintstone

Take a look here while you are at it;

There is a brittle little tube. It comes out of a rubber plug, low on the engine side of the throttle body. It runs back to the firewall, then up to your MAP sensor sort of high up there near center on the firewall. CRUCIAL!! The MAP will tell the ECU to dump fuel with less/no vacuum. Any crack or blockage and it will be pig-rich. (black smoke, fouled black plugs).(maybe flooded) You can pull the line off the MAP and feel for vacuum with your finger. If it runs!

Kris smith

Map sensor is ok I have replaced the line. Crank sensor when cold puts out .45-.5v ac
Fuel pressure key on engine off is 40 psi running it's 30 psi

Kris smith

My co worker had a vantage pro and we will scope the fuel pump to see of ots dropping out. I'm running out of ideas

DFlintstone

Cool...I'd still triple check that MAP tube. I might try a shot of starting fluid while it's not firing. I Might also pull a plug and see if it's wet....

You did the sensor ground test and got less than one ohm? The left hand, drivers side of the three on the MAP is one place to check. Guess I might have 1.5 ohms on my "cheap-0 meter".


Boy, that's odd. Cruiser on the CPS and me on grounds! (backwards)

Kris smith

I've done the sensor ground test I've done most if not all of the things in cruisers link. All grounds fixed c101 cleaned and checked. CPs advanced and modded replaced thottle body cleaned tps replaced and adjusted map sensor line checked and rechecked againa and again I checked it while doing fuel testing and crank testing also sprayed brake clean and found no vacuum leaks. This is starting to bugg me. Usually cruiser says do this and when I get around to doing it how he says it fixes it this time everything has either been done or checked